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Bio 171 2nd exam
Genetic variation and sexual reproduction
209
Biology
Undergraduate 1
02/23/2010

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Cards

Term
Ecosystem Ecology: Why we Care?
Definition
  • Ecosystem ecology seeks to explain the transfer of energy and cycling of matter within ecosystems
  • without energy transfer, there would be no heterotrophic organisms
  • wothout the cycling of matter the soil would lose fertility, plant growth would cease and onece again we could not exist
  • Ecosystem ecologists can address environmental issues that are caused or exacerbated by changes in nutrient cycles and energy flow
Term
Ecosystem Ecology
Definition
the scientific study of interactions between organisms and the non-living world (abiotic environment)
Term
Ecosystem ecologists
Definition

study the flow of energy and the cycling of matter in ecosystems

 

 

 

energy flows but matter cycles

Term
First Law of Thermodynamics:
Definition
  • Energy is neither created or destroyed
  • the amount of energy in the universe today is the same amount that was in the univers when it was formed
  • Energy can be transferred from one body to another
  • Energy can be transformed from one form to another
  • Ecosystems are energy transformers
Term
All organisms including producers undergo
Definition
cellular respiration
Term
Cellular respiration
Definition
takes sugars and oxygen- the end product of photosynthesis- and changes that energy into ATP which is the energy carrying molecule that allows the cells to function
Term
How plants and other Primary Producers Transform energy
Definition
plants and other primary producers capture energy from the sun along with carbon and water and go through a series of chemical reactions that change the light energy into chemical energy- plants release as oxygen gas
Term
Sunlight helps plants to grow. Where does light energy go when it is used by plants?
Definition
The light energy becomes chemical bond energy
Term
Why would a plant that has no light but is watered lose weight?
Definition
photosynthesis can still occur but cellular respiration could not occue so it is losing CO2 and water >decreased weight
Term
Second Law of thermodynamics
Definition
  • energy transfer leads toward entropy
  • At every transfer of energy, some energy is lost to heat to the abiotic environment
  • the amount of useable energy declines with every energy transfer- energy lost as heat
  • this sets a fundamental limit on energy flow through ecosystems
Term
Energy flows through ecosystems:
Definition
Energy flow links the components of ecosystems: primary producers, consumers, decomposers and the abiotic environment
Term
Matter Cycles through ecosystems:
Definition

in contrast to energy matter can cycle from one body or compartment to another

 

for example: the element nitrogen can cycle from the atmosphere (N2 gas) into other inorganic forms (ammonia, nitrate) and into organic forms (proteins, nucleic acids) and then back into the atmosphere

Term
Primary producers provide:
Definition
energy to most ecosystems on earth
Term
Gross Primary Production (GPP)
Definition
total amount of chemical energy produced by photoautotrophs through the chemical reactions of photosyntehsis (in an area during a given time interval)
Term
Producers convert:
Definition
CO2 into sugars
Term
Net Primary Productivity (NNP)
Definition

Gross Primary Production - Respiration

 

GPP minus energy used by producers from cellular respiration- NPP is the amount available to consumers

Term
Globally NPP is about..
Definition
170 billion tons of organic carbon per year- this supports all heterotrophic organisms, including us
Term
All heterotrophs depend on
Definition
Primary Production
Term
Secondary Production
Definition
The amount of new tissue produced by consumers from the foods they ingest during a given period of time
Term
What percentage of energy at one trophic level is transferred to the trophic level above?
Definition

between 5 and 20%

 

on average 10% is transferred to next higher trophic level

Term
Pyramid of Productivity
Definition
All ecosystems exhibit this pattern in which the energy is greatest at the lowest trophic level (=producers) and decreases with each higher trophic level
Term
Why does the pattern of the pyrimid of productivity occur?
Definition
  • A large fraction of energy is released as heat to the abiotic environment with each trophic transfer
  • A large fraction of the energy present at each level is used to keep the organisms alive and functioning (cellular respiration, energy used to searc hfor food, catch prey or escape from preditors)
  • not all organisms at lower trophic levels are consumed
Term
Global Pattern of Productivity
Definition

Except for the world's deserts, terrestrial productivity declines from the equator toward the poles.

 

warm temperatures and high water availability generally increase rates of photosynthesis

Term
Global Marine Productivity
Definition
highest in coastal waters and lowest in the open ocean without respect to latitude
Term
What limits 1^0 Productivity in terrestrial environments?
Definition
  • in terrestrial environments, productivity is limited by temp. and moisture on a global scale (remember biomes?)
  • at smaller scales (within a single biome) terrestrial productivity is often limited by nutrients (especially useable forms of nitrogen)
Term
What limits Productivity in aquatic environments?
Definition
  • In most aquatic ecosystems, primary production is milted by nutrients and light
  • light availability declines rapidly with depth in water, so most primary production occurs near the surface
  • nutrients (particularly phosphorus) appear to limit primar production in the photic zone of most freshwater ecosystems; whereas iron is often limiting in open water marine ecosystems
Term
Energy Flow to deep Sea
Definition

food from above- whale carcasses

other deep sea communities supported by hydrothermal vents

 

significant pulses of organic material (phytodetritus) sink rapidly from surface waters to deepest bethic communities in aggregations called marine snow

Term
Marine Snow
Definition

phytodetritus- dead phytoplankton from the surface of the ocean

 

sinks rapidly to the deepest communities in the ocean to support their life

Term
Functional Ecosystems provide Essential Services such as:
Definition

clean water

oxygen

food

decomposition, nutrient cycling, and fertile soils

protection of shores from erosion

pollination services

- we do not yet know enough to recreate functioning ecosystems

Term
Biogeochemical Cycle
Definition

the path that an element takes as it moves from one compartment or pool to another

 

 

unlike energy, chemical elements remian in the biosphere where they cycle continually between organisms and the abiotic environment when one organism eats another- elements are also transferred - C,N,P, and others

Term
Essential Nutrient
Definition
element required for growth or reproduction or metabolic function
Term
Macronutrients
Definition
building blocks of proteins, nucleic acids, carbohydrates, and phospholipids; required in large quantities
Term
Limiting Nutrients
Definition
nutrients that limit plant growth including N, P, and K
Term
Decomposers
Definition

play a critical role in ecosystems

  • Bacteria, archaea, fungi and a few other eukaryotes
  • make nutrients cycle from detrital pool back abiotic environment
  • break down complex organic molecules (proteins, lipids, carbohydrates) from detritus (dead tissue) into inorganic molecules (CO2, NH4+, NO3-) that can be re-used by other organisms
Term
Detritivores
Definition
often feed on detritus and associated decomposers and break detritus into smaller fragments which increase decomposition rates
Term
Decomposition of detritus limits:
Definition
the rate at which nutrients move through an ecosystem. Decomposition rate is influenced by abiotic conditions and the quality of the detritus as a nutrient source
Term
Decomposition rate is influenced by:
Definition
abiotic conditions. In tropic rainforests highliy diverse decomposer communities quickly break down litter; abundant rain leaches remaining nutrients out- warm temp and moist soils provide favorable conditions for 1^0 decomposers ( bacteria, archaea, fungi)
Term
Global Biogeochemical cycles
Definition
when nutrients leave one ecosystem, they eneter another. the movement of ions and molecules among ecosystems links local biogeochemical cycles into one massive global system
Term
Pool
Definition
amount of material in a given compartment
Term
Flux
Definition
amount of material moving among compartments
Term
The water (hydrologic) Cycle
Definition
Estimates of the amount of water that moves between major components of the cycle over 1 year Solar energy absorbed by liquid water to create water vapor is the energy source dribing the water cycle. Over oceans, evaporation exceeds precipitation. On land, precipitation exeeds evaporation and transpiration (from plants) Water returns to oceans from land via runoff and ground water
Term
On global scale- Total Evaporation =
Definition
total precipitation; water cycle is in global balance
Term
How humans affect the water cycle
Definition
  • ground water replenishment- concrete/asphalt surface reduce the amount of precipitation that reaches deep soil layers
  • conversion of forests/grasslands to agricultural fields increases runoff to streams and decreases groundwater replenishment
  • irrigating agricultural fields removes water from groundwater storage
  • in many parts of the world, people now have to mine water - populations in those parts of the world have already grown past carrying capacity for water
Term
Depleted aquifers
Definition
great lake to the north of michigan and in the middle of the country near texas, colorado, oklahoma and Nevada
Term
Global Carbon Cycle
Definition

largest C reservior is in sedimentary rock; ocean has large active C resivoir, followed by terrestrial communities, followed by atmosphere; geological reservior is not active pool until humans access it such as by burning fossil fuels

photosynthesis takes CO2 out of atmosphere

Respiration releases CO2 into atmosphere

Term
Humans are Changing C cycling through:
Definition
deforestation which decreases primary production and through burning of fossil fuels; both activities also impact other nutrient cycles- increases Co2 concentrations in the atmosphere
Term
The vast majority of molecular nitrogen N2 in the atmosphere is
Definition

unavailable to producers because they can use nitrogen only in the form of ammonium NH4+ or nitrate NO3- ions

 

nitrogen is added to ecosystems in a usable form only when it is reduced or fixes- converted from N2 to NH4

Term
Nitrogen Fixation results from:
Definition
lightning- driven reactions in the atmosphere and from enzyme-catalyzed reactions in bacteria that live in the soil and oceans
Term
Global Nitrogen Cycle
Definition
producers can only use nitrogen when in the form of ammonium or nitrate ions. Producers require N to make proteins and nucleic acids. N moves up the food chain when herbivores eat producers and when carnivores eat the herbivores. N in organic molecules in detritus is converted into inorganic forms that producers require by 1^0 decomposers
Term
How humans are affecting the nitrogen cycle
Definition
human fixed nitrogen in the form of fertilizers, nitric oxide from burning fossil fuels, and cultivation of certain crops are having a major impact- increasing nitrogen fixation
Term
Negative effect of increased nutrient input
Definition
causes algal blooms, when algae die, decomposers populations get large and use up available oxygen in water column, resulting in dead zone
Term
new types of environmental problems that have emerged in the past 50 years
Definition

Climate change

acid rain

hole in ozone layer

"dead zones" in the oceans

Term
Types of Cell Division
Definition

Mitosis

Meiosis

Binary Fission

Term
Mitosis
Definition

produces 2 genetically identical daughter cells

only eukaryotes and only in somatic cells

Term
Binary Fission
Definition

produces 2 genetically identical cells

only in prokaryotes

Term
Meiosis
Definition

produces 4 daughter cells

daughter cells are genetically different

only un eukaryotes; only in germ cells

Term
key roles of mitosis
Definition

development and growth

repair and tissue renewal

asexual reproduction

Term
Mitosis results in:
Definition

2 daughter cells that are genetically identical

same set of chromosomes barring any mistakes in DNA replication

occurs in all somatic cells (Eukaryotes

Term
Each replicated chromosomes are consisted of
Definition

2 sister chromatids bound by a centromere

 

***look at pic in book***

Term

Steps in Bacterial Cell Division

(Binary Fission)

Definition

1. Chromosomes attatch to plasma membrane

2. Chromosome replicates

3. Cell grows ringing of FtsZ protein forms

4. FtsZ ring contricts membrane and cell wall infold

5. fission complete

Term
Asexual reproduction
Definition
one parent produces genetically identical offspring
Term
Sexual Reproduction
Definition
two individuals combine genetic info and produce offspring that are genetically different
Term
Advantages of asexual reproduction
Definition
  • dont need a mate
  • dont need to expend time, energy, or resources to attract a mate
  • fewer risks from predators
  • fewer risks of sexually transmitted diseases (STDs)
  • leads to faster population increases
Term
Disadvantages of Asexual Reproduction:
Definition
  • little genetic variaton for evolution to act upon
  • no way to get rid of deterious mutations
Term
Why does sex exist?
Definition
  • sex produces genetic variation and genetically diverse offspring may be more likely to survive diseases and parasites; therefore more likely to persist in changing environments (red queen hypothesis)
  • sex allows purging of (bad) mutations (Deleterious mutation hypothesis)
Term
Process of Meiosis
Definition

tow consecutive cell divisions which reduce parental chromosone number by half and produce four haploid daughter cells

 

each daughter cell is genetically different from parental cells

 

only occurs in eukaryotes and is restricted to germ cells- located in the testes and ovaries

Term
Diploid number
Definition
having two of each type of chromosome (respresented as 2N) 46 chromosomes in humans
Term
Haploid number
Definition
having one of each type of chromosome (respresented as n) eg 23 distinct chromosomes in humans (only gametes - sperm and egg cells)
Term
sex is determined by which chromosomes?
Definition
the 23 set
Term
Autosomes
Definition
non-sex chromosomes (all of them except for the 23 set)
Term
Homologous Chromosomesone
Definition

one set from mom, one set from dad

are similar in size, shape, pattern, and gene location

carry the same genes but alleles may differ

Term
Process of Meiosis
Definition

two consecutive cell divisions which reduce parental chromosome number by half and produce four haploid daughter cells

 

each daughter cell is genetically different from parental cell

 

how sperm and eggs get only one set of chromosomes

Term
Prophase 1 in Meiosis 1
Definition
  • longest phase of meiosis
  • chromosomes condense
  • centrosomes move toward poles
  • spindle forms
  • nuclear envelope breaks down
  • homologous chromosomes pair up and synapsis occurs
  • crossing over occurs between non-sister chromatids; 1 to 3 chiasmata per tetrad
  • spindle microtubules attatch to kinetochores
Term
Telophase 1 and Cytokinesis in Meiosis 1
Definition
  • each pole now has a haploid set of replicated chromosomes
  • furrow forms in animals
  • cell plate forms in plants
Term
Does duplication of chromosomes occur between meiosis 1 and meiosis 2?
Definition
No
Term
sources of genetic variation that sex produces
Definition

Crossing over occurs during prophase 1 and produces recombinant chromosomes

 

 independent assortment of homologs

 

random fertilization of gamets

Term
Number of possible combinations of homologs after crossing over
Definition

2^N- where N= haploid number of chromosomes

 

 

ex:

 

in humans 2^23 = 8 million different possibilities

Term
Genetics: Why we Care
Definition
  • Genetics is the scientific study of inheritance (heredity) - how traits are passed from parents to offspring
  • genetics influence morphology, physiology, behavior, even disease susceptibility
  • understanding life on earth requires an understanding of genetics
  • evolution could not occur if there was no genetic variation within a population
Term
Preformation Hypothesis
Definition
an individual already esists in microscopic form in either the egg or the sperm and only needs to unfold during development
Term
Blending Inheritance Hypothesis
Definition

Sperm and eggs of parent organisms contain a sampling of parent's essence that is blended togehter in the offspring to give an intermediate resulting condition

 

Yellow + Red = Orange

Term
Mendel's Experimental Organism: why study peas?
Definition
  • many true-breeding varieties available
  • can easily control matings
  • peas also self-pollinate
  • short generation time
  • many discrete traits (characters)
    • determined by action of 1 gene
    • phenotypes fall into only a few distinct categories
Term
Mendel's Experiments
Definition
crossing pure lines = true breed lines
Term
Phenotype
Definition

expressed observable characterisitics of organisms

 

Yy- shows dominant trait- dominant phenotype

Term
Genotype
Definition

genetic makeup of the individual (specific alleles it carries)

 

 

Yy- heretozygous genotype

Term
Dominant
Definition

the trait is expressed in the phenotype of the heterozygote

 

denoted by uppercase letter

Term
Recessive
Definition

the trait that is not expressed in the phenotype of a heterozygote

 

denoted by a lowercase letter

Term
Alleles
Definition

alternative molecular versions of the same gene all diploid individuals have 2 alleles for each gene

 

different alleles have different DNA sequences and were created by mutations

Term
Homozygote
Definition

carries 2 of the same alleles

 

RR

 

or

 

rr

Term
Heterozygotes
Definition

Carries 2 different alleles

 

Rr

Term
Mendel's Law of Segregation
Definition
Alleles seperate during gamete formation and each gamete recieves only one allele for each trait
Term

Mendel's Conclusiong from Monohybrid crosses

 

Particulate theory of inheritance

Definition
  • inheritance is determined by discrete factors- now we call them genes
  • each individual has 2 alleles (alternate versions of a gene) for each character/trait
  • 1 allele is inherited from each parent (alleles segregate into gametes) Law of segregation
Term
Sickle-cell anemia
Definition
autosomal recessive disorder
Term
Achondroplasia
Definition
autosomal dominant disorder
Term
Mendel's Lae of Independent Assortment
Definition

now we know that this occurs when genes for 2 or more traits are located on seperate chromosomes or far apart on the same chromosome

 

genes that are in close proximity on the same chromoso me are often inherited together (phenomenon of genetic linkage)

Term
Mendel's Major Contributions
Definition
  1. Hereditary units are genes
  2. Each individual has two alleles for each trait
  3. Each gamete contains one allele of each gene (alleles segregate- law of segregation)
  4. Alleles may be dominant or recessive
  5. alleles for one trait assort independently of alleles for another trait (Law of independent assortment)
  6. Used great system, quantitative approach, large samlpe sizes, and followed mulitiple generations
  7. mendel know nothing about chromosomes yet he discovered rules of inheritance
Term

Fly Labs:

Why we use fruit flies as a model system?

Definition

small size and easy to culture in the lab

short generation time

produces lost of offspring per mating

Term
TH Morgan's first mutant
Definition

red eyes designated as w+ or +

 

+ always refers to wild type (common phenotype)

 

white eyes - mutant designated as w

 

in flies, genes named after mutants

Term

heterozygous for eye color female and

 

hemizygous for eye color and genes located on X chromosome male

 

(SEX LINKED)

 

 

Definition

Female     x       Male

Xw+Xw               XwY

Xw+         Xw

 

Xw          Xw+Xw         XwXw                  

 

Y          Xw+Y            XwY          

 

50% of daughters have white eyes 50% of sons will have white eyes      

Term
Morgan's experiment that discovered sex-linked genes
Definition

figured out this gene is located on the X chromosome after Nettie Stevens discovered how sex is determined in beetles: XX and XY system, just like humans-

 

no crossing over occurs between x and y chromosomes in males

Term
Thomas Hunt Morgan's discovery
Definition
Thomas Hunt Morgan proposed that the gene for white eye color in fruit flies resides on the X chromosome and that the Y chromosome does not carry an allele for this gene. This is the hypothesis of X-linked inheritance (X-linkage or sex-linkage) females would then have two copies of the gene and males would have only one. Morgan was first scientist to trace a gene to a specific chromosome (X) this was possible
Term
Sex-linkage
Definition

genes located on the X or Y chromosome are said to be sex-linked

sex-linked traits are inherited differently in males and females


X and Y synapse in meiosis 1 but they are not homologous (X is much bigger- has many genes that Y lack)

Term
Systems of sex determination
Definition
sex is genetically determined in some species
Term
sex determination may be environmental
Definition
some fishes change gender with size or age
Term
red-green color blindness
Definition
X-linked trait
Term
genetic diseases and disorders in humans that display X-linked inheritance
Definition

color blindness

hemophilia

Duchenne's muscular dystophy

male pattern baldness

Term
what happens when genes are located on the same chromosome?
Definition

the law of independent assortment may be violated

 

Term
Linkage (linked genes)
Definition

the physical association of genes that are found on the same chromosome but that influence different traits

 

law of independent assortment may be violated if genes are located in close proximity on one chromosome (they may be inherited as a unit)

 

Remember: linkage is different than sex linkage

Term
Crossing over (recombination) can lead to
Definition
new combination of alleles in the offspring that were not present in the parents
Term
Linkage mapping: Creating a Genetic Map
Definition
genes on a chromosome are arranged in a linear array and the physical distance between them dictates the frequency of crossing over between them. the greater the physical distance, the greater the frequency of crossing over
Term
If two genes are located on the same chromosome will they always be inherited as a unit?
Definition

if two genes are right next to each other expect no recombinants

relative positions of genes on chromosome affect rate of recombination

very close- low RF; far apart- high RF

can use frequency of recombination to map relative positions of genes along the chromosomes

 

Genes 50 or more map units (cM) apart behave as if they were on seperate chromosomes

Term
The type of dominance influences the
Definition
phenotype of a heterozygote
Term
Complete dominance
Definition
dominant allele shows up in phenotype of heterozygotes
Term
incomplete dominance
Definition

phenotype of heterozygotes is intermediate to the two homozygotes

 

red + white = Pink

Term
Codominance
Definition

both alleles are visible in the phenotype of heterozygotes

 

Mn blood groups in humans

NM homozygoted have only M molecules on surface of red blood cells

NN homozygotes have only N molecules on surface of red blood cells

MN heterozygotes have both M and N moecules on surface of red blood cells (both alleles are expressed simultaneously) - humans with AB blood type

Term
Type of dominance and scale
Definition

the phenotype of a heterozygote can be observed at a variety of levels (scales): whole organisms, biochemical, or molecular. Conclusions about type of dominance vary with the level of analysis

Tay Sachs allele (t) and normal allele (T)

consider heterozygotes:

 

Individual organism level- Tt don't have disease- complete dominance

Biochemical Level: Tt has intermediate enzyme activity level - incomplete dominance

Molecular level: Tt produces equal amounts of functional and dysfunctional enzymes- codominance

Term
dominanat traits are not necessarily the most common in a population:
Definition

polydactyly- extra fingers and toes- dominant trait

Achondroplasia- a form of dwarfism- dominant trait

Huntington's disease- dominant trait

 

most humans are homozygous recessive for these three genes- whether a triat is common or rare in a population will depend on the evolutionary processes at work

Term
Epistasis
Definition

one gene alters the expression of another gene(or genes) - genes interact

 

ex: coat color in Labs

gene B codes for melanin production B= black coat bb=chocolate coat

gene E determines how much pigment is depositied in each individual hair

E= full deposition of pigment ee= blocked deposition of pigment= yellow coat

Term
id you have two dogs who have genotypes BbEe and BbEe what are the their phenotypes?
Definition
both black
Term
if you have two parents that have genotypes that are BbEe and BbEe what are their Gamete Genotypes?
Definition

BE

Be

bE

be

Term
with epistasis- BbEe and BbEe what do their offspring look like and what are the phenotypic ratios???
Definition

          BE          Be            bE             be

 

BE        BBEE       BBEe       BbEE         BbEe  

 

     Be         BBEe      BBee        BbEe         Bbee       

 

bE        bBEE        bBEe        bbEE        bbEe  

      

be        bBeE        bBee        bbeE        bbee  

 

phenotypic rations- 9B:4Y:3CH

Term
Epistasis at the molecular level
Definition

Epistasis occurs when one gene alters the expression of another gene

 

this happens often in gene regulation: one gene may code for a protein that prevent transcription of another gene

Term
Pleiotropy
Definition

one gene affects several traits (2 or more)

period gene in fruit flies affects a fly's biological clock and it affects the male's courtship dance

defective fibrillin protein leads to Marfan syndrome

Term
Polygenic inheritance
Definition

two or more genes affect one trait

 

no 3:1 phenotypic ratio in the F2 offspring

 

instead there is a continuum of colors- that is a clear indication of plygenic inheritance

Term
quantitative traits
Definition
show a full range of phenotypes- a normal distribution
Term

you cross two shrimps with orange claws and you observe the following offspring phenotypes:

8 red clawed shrimp

15 orange clawed shring

6 yellow clawed shrimp

 

what is the simplest explanation for this pattern of inheritance?

Definition

incomplete dominance

 

 

1:2:1 ratio implies one gene is affecting it

Term
Multiple Alleles
Definition

more than 2 alleles for a gene exist in a population

 

but each individual has only two alleless for each geme gamete has only one allele for each gene

 

ABO blood groups in humans

Term
Multiple Alleles: ABO blood groups in humans
Definition

3 alleles in population

1 gene codes for enzyme that attaches carbohydrates to surface of red blood cells

6 genotypes

4 phenotypes

Genotype- IAIA or IAI phenotype- A

Genotype- IBIB or IBI phenotype- B

Genotype- IAIB phenotype- AB

Genotype- ii phenotype O

Term

Gene x Environment (G x E)

interactions

Definition

the effect of a gene depends upon the environment in which it is expressed

 

caot color in siamese cats and himalayan rabbits- enzymes can function in a certain temp

flower color in hydrangeas- pH changes the color

Term
Abnormal Chromosome Numbers
Definition

Errors in meiosis = non-disjunctions, may result in gametes that have missing or extra chromosomes

 

Down syndrome- extra copy of chromosome 21

Term
Modern View of Inheritance
Definition
  • Mendel's laws and rules still provide the backbone for understanding the particulate nature of inheritace adn the segregation of alleles during meiosis
  • we now recognize that pleiotropy, epistasis, and plygenic inheritance are common feaures of organisms
  • moreover, the environment has a major impact on how genes are expressed. Phenotypes often represent the combined effects of genes and environment
Term
Multifactoral genetic disorders
Definition

heart disease

type II diabetes

cancer

alcoholism

Bipolar Disorder

Depression

Term
Multiple Allelism
Definition
in a population more than two alleles present at a locus
Term
why is there a controversy about bilogical evolution in US but not in many other countries?
Definition

poor undersanding of genetics

literal interpretation of the Bible

conservative political ideology

Term
Science is profoundly material discipline
Definition

science is a formal process of generating new knowledge that uses evidence to construct testable explanantions and predictions of natural phenomena as well as the body of knowledge generated through this process

scientists used observations, experiments and reasoning to develop explanation for natural phenomena but science differs from other ways of knowing by its dependece on empirical evidence and testable explanations

all scientific knowledge is subject to revision in light of new discoveries; scientists never claim absolute knowledge

Term
Religion is profoundly metaphysica discipline
Definition
a framework of beliefs relationg to supernatural beings or forces that transcend the everday material world. Religious knowledge can be gained from a religious leader, a sacred text, and or personal revelation it is not limited in scope, can try to answer any question, and is often used to erect moral codes of behavior. Religious knowledge is often viewed as being absolute and infallible, but this tends to vary from religion to religion from sect to sect, and from individual to individual
Term
Science as a discipline has
Definition
no opinion on the existence of god. Individual scientists may be religious, agnostic, or atheist
Term
Mixing science and religion incorporation of religious principles into science?
Definition

logically impossible- supernatural entities, by definition, cannot be measure, weighed, manipulated, added to or subtracted from controlled experiments

the supernatural is simply not tractable scientifically

science cannot address existential questions such as what is the meaning of life or how does one lead a moral life? in general scientific consensus is that religiously-themed topics such as intelligent design do not belong in science curriculum. A more appropriate venue for this topic vouw be courses on philosophy or theology

Term
What is Evolution?
Definition
today evolution is most accurately dfeined by biologists as a change in the genetic makeup of populations can lead to speciation (the formation of new species)
Term
Linnaeus
Definition

developed a nested classification of species by grouping species by morphological similarities

 

father of taxonomy

hierarchical classification

Term
Hutton
Definition

Scottish geologist- promoted gradualism- the idea that small changes occuring over long period of time can accumulate to cause large transformations of the earth

 

principles of Geol;ogy

 

Term
Cuvier
Definition

a pioneer of paleontology- showed that extinctions were common however he believed in catastrophism rather than gradualism

 

father of paleontology

described many fossil species

showed that extinction had occured

Term
Lyell
Definition
built of Hutton's thinking to promote uniformitarianism- te idea that the geological mechanisms that operated during the Earth's history continue to operate today and at the same rate
Term
Early ideas about Evolution
Definition

species are immutable- they were created by a divine being and they don't change

the earth is young

Term
Malthus
Definition

populations have the potential to grow exponentially and will therefore compete for resources; many individuals will die

 

observed that in nature many species produce far more offspring than can survive. this promoted Darwin to focus on differential survival as a key mechanism in evolution

Term
Lamarck
Definition

promoted the idea that species change over time

 

proposed that species evolve as environments change prior to Darwin..but his mechanism turned out to be wrong

 

Lamarck's ideas: species change, species are related, use and disuse, inheritance of acquired characterisitics

acquired traits cannot be inherited

(body building)

Term
Wallace
Definition
independently arrived at the idea of descent by modification and hastened Darwin's publication of Origin of Species
Term
Artificial Selection
Definition

Darwin knew a great deal about artificial selection

humans had been selecting on specific traits in many different species for thousands of years

this process can change the genetic makeup of a population- it can cause evolution

 

ex: dog breeds

Term

Darwin and Wallace's Big Ideas

Descent with Modification

Definition

life on earth had a single origin and all the diverse organisms around today are descendants, modified by evolutionary prcesses of this common ancestor

 

Term

Darwin's and Wallace's Big Ideas

Mechanism to explain evolution: Natural Selection

 

Definition
a process by which individuals with certain heritable traits produce more offspring than individuals lacking those traits; alleles associated with favored trats increase in frequency from one generation to the next
Term
structural homology
Definition
refers to similarity of morphological traits such as the same general limb structure in vertebrates. Darwin interpreted structural homologies as a product of descent with modification
Term
Developmental homology
Definition
refers to similarity in embryo morphology and or pattern of tissue differentiation. For example all vertebrates have gill pouches and tais early in embryonic development
Term
genetic homology
Definition
similarity in the DNA sequences of genes from different species- structural homologies and developmental homologies result from this
Term
requirement for evolution by natural selection
Definition
  1. must be variation in phenotypes of individuals in a population
  2. variation must have a genetic basis
  3. unequal survival and reproduction among individuals in the population; depends upon the heritable traits that individuals possess and environmental conditions
Term

Field studies of evolution:

Galapagos Finches-

Definition

Variation in environment over a few years

in dry years few plants would reproduce, seeds were scarece and large seeds were predominante- birds with deep beeaks are favored (directional selection for deeper beaks)

in wet years, most plant reproduce, seeds are abundant especially small seeds and small beaked fincehs do better (directional selection for smaller beaks)

natural selection can change direction in short time spans

Term
natural selection depends on..
Definition

biotic and abiotic environment

 

traits that are favored in one generation may no longer be favored in the next generation as the environment changes

Term
Timescale for evolution to occur by natural selection
Definition
depends upon generation time of organisms
Term
Population Genetics
Definition
study of the genetic variation within and among natural populations and the evolutionary processes that generate and maintain this variation
Term
population
Definition
group of individuals living in the same area that are capable of interbreeding
Term
gene pool
Definition
all the alleles in the population
Term
population genetics
Definition
study of genetic variation within and among natural populations and the evolutionary processes that generate and maitnain this variation
Term
biological evolution
Definition
change in genetic makeup (allele and genotype frequencies) of a population
Term
Genetic Variation in Natural Populations of Eukaryotes stems from the itneraction of two very different processes:
Definition
mutation and sexual reproduction
Term
Mutation
Definition
rare and random process resulting from errors in DNA replication and or cell division; original source of new alleles; new mutations are often slightly deleterious or neutral, rarely advantageous
Term
Sexual Reproduction
Definition
meiosis and random fertilization constantly reshuffle allelic combinations but cannot change the frequency of alleles in a population only evolutionary processes change allele and or genotype frequencies
Term
Measure of A Population's Genetic Makeup
Definition

1. Genotype Frequencies- proportion of one particular genotype relative to total # of individuals in a population

 

2. Allele frequencies- proportion of one particular allele relative to total # of alleles (for gene under study) in a population

Term

Population of 1000 butterflies in a field

 

490 dark blue wings = B1B1

420 medium blue wings = B1B2

90 white wings = B2B2

 

what are the geotype frequencies?

what are the allele frequencies?

Definition

Genotype frequencies-

B1B1 = 490/1000 = .49

B1B2 = 420/1000 = .42

B2B2 = 90/1000 = .09

 

Allele Frequencies

B1 = .49 + 1/2(.42) = .49 +.21 = .7

B2 = .09 + 1/2(.42) = .09 + .21 = .3

Term
Allele frequencies- another method for counting
Definition

490 B1B1 = 490 x 2 = 980 B1

420 B1B2 = 420 B1 and 420 B2

90 B2B2 = 90 x 2 = 180 B2

 

1400 B1 alleles and 600 B2 alleles

B1 = 1400/2000 = .7

B2 = 600/2000 = .3

Term
The suffling of alleles due to meiosis and random fertilization of gametes has no effect on
Definition

the overall gene pool of a population

 

useful analogy: meiosis and random fertilixation are like shuffling a deck of cards- the proportion of hearts, spades, clubs, and diamonds in the deck does not change

 

a population's gene pool will remain constant unless evolutionary process (mutation, selection, gene flow or genetic drift) are acting on the population

Term
genotype frequencies will be given by
Definition

p2: 2pq : q2

 

if the both the parents have heterozygous alleles

Term
if population is not evolving then
Definition

genotype and allele frequencies in the population will be stable (will not change over time) this is known as the Hardy Weinberg Principle

after one generation of random mating genotype frequencies for 2 alleles at one locys will be

p2 + 2pq + q2

where p=freq dominant allele and q= freq recessive allele and p+q=1

genotype and allele frequencies will remain constant in successive generation as long as specific assumptions are met

Term
Hardy Weinberg Equilibrium
Definition

p= freq B1 and q = freq B2

p2 = freq B1B1

q2 = freq B2B2

2pq = freq B1B2 + freq B2B1

Hardy Weinberg Equilibrium

p2 + 2pq + q2 = 1

Term
Requirements for HWE
Definition
  1. population size is very large (no genetic drift affecting gene under study)
  2. Population is closed (no gene flow)
  3. No mutations are occuring at gene under study
  4. Mating is random with respect to trait under study ( no sexual selection, no inbreeding at gene under study)
  5. All genotypes in populations have equal chance of surviving and reproducing (no selection at the gene under study)
Term
Deviation from HWE is evidence that
Definition
population is evolving with respect to gene (trait) under study
Term
Evolutionary Processes
Definition

Natural Selection

Sexual Selection

Genetic Drift

Gene Flow

Mutation

 

biologists are especially interested in selection, other processes are also important - lead to change in genetic makeup of a population

Term
Natural Selection
Definition
process by which individuals with certain heritable traits survive and reproduce at a higher rate than individuals lacking those traits
Term
Sexual Selection
Definition
Process by which individuals that possess certain heritable traits are more successful at obtaining mates and thus reproduce at a higher rate
Term
Genetic Drift
Definition
process by which chance events lead to changes in allele or geotype frequencies in a population
Term
Gene Flow
Definition

Process by which alleles are transferred from one population to another

due to immigration or emigration of individuals/gametes

gene flow acts to homogenize populations

Term
Mutation
Definition

process by which new alleles arise in a population

due to errors in DNA replication or cell division

Term
How can Biologists use HWE?
Definition

PKU in humans

genetic diease

autosomal recessive disorder

inability to break down phenylalanine due to defective enzyme

leads to severe cogniticve impairment

symptoms can be totally prevented is diagnosis is made at birth and a special diet prescribed

Term

How can Biologists use HWE:

Sickle Cell Disease

Definition

Autosomal recessive disorder

defective hemoglobin molecule

leads to a variety of health problems

 

frequency is .02

frequency of carriers= 2pq - 2 x .098 x .02 = .0392

frequency of homozygous dominant genotypes = p2 - .98 x .98 = .9604

 

Term
heterozygote advantage
Definition
carriers of sickle-cell anemia are more resistant to malaria than HH genotypes
Term
Tree of life Based on rRNA gene
Definition
Humans are not the pinnacle of evolution but rather one tiny twig among many twigs on the tree of life
Term
Modern Synthesis
Definition

the integration of discoveries and ideas from population genetics, paleontology, systematics, zoology, botany, ecologym and biogeography

 

according to the morden synthesis, genetic variation in populations arises from random mutations and is constantly reshuffled into new allelic combos by meiosos and fertilization

the gentic makeup of a population changes when evolutionary processes such as natural, sexual, or artifical selection, genetic drift, gene flow or mutation occur

Term
Natural Selection in Action
Definition
  • most biologists think that small evolutionary changes accumulate over long time periodsto generate large evolutionary changes like speciation
  • even if its difficult to watch speciation taking place, natural selection works fast enough that we can often observe rapid phenotypic and genotypic change in populations in nature and lab
  • focus on three examples- galapagos finches, Trinidadian guppies and HIV evolution within three patients
Term
Evolution by natural selection
Definition
  • Evolution by natural selection does not push organisms forward toward some ideal form; it is not progressive
  • natural selection is more passive and reduces by killing or low reproduction the representation of those traits that are less advantageous in the current environment
  • as environmental conditions change, the traitsthat lead to increases reproductiove success in the environment can also change as you saw in the natural experiments with finches during drought and flood years
  • natural selection can move populations away from Hardy weinberg equilibrium
  • of the prcesses that can cange the gene pool, selection is the only process that produces adaptations: heritable traits that increase survival and or reproductive success
  • alleles increase or decrease in frequency based upon their influence in an individuals fitness
Term
Guppies in Trinidad
Definition

studied guppies in pools with two different predatory fish

guppies in pools with small predators were large and matured later in life

guppies in pools with large predators where smaller and matured earlier

transferred some guppies from each- over 11 years guppies became larger and matured later when exposed to killfish predators that selectively feel on smaller prey

this suggests that predators act as selective forces on the size of prey and over quite short periods of time

Term
Drug- resistant HIV
Definition

when humans target pathogens with drugs we impose very strong selection pressures

any rare pathogen individuals with drug resistance are at a tremendous advantage and will replicate rapidly

because pathogens reproduce so quickly, resistant strains can dominate the population extremely quickly

 

makes drug development and delivery a real challange in the fight against infectious diseases

Term
Directional selection
Definition

changes the average value of a trait

one tail of phenotypic distribution is favored. if directional selection continues long enough, the favored allele(s) eventually reach a frequency of 1.0 or 100% and are siad to be fixed; those alleles that are no longer found in the population are lost freq = 0 and overtime genetic diversity is reduced

Term
Directional Natural Selection Caused by humans
Definition

antibiotic resistence- evolved resistance to antibiotics

perticide resistance

herbicide resistance

 

 

Term
Balancing selection
Definition

= heterozygous advantage

a pattern of natural selection in which heterozygous individuals have higher fitness than homozygous individuals

 

 

Term
stabalizing selection
Definition
individuals with intermediate phenotypes are favored (population mean stays the same) over time this type of selection reduces both tails of phenotypic distribution and tends to reduce genetic variation in the trait
Term
Disruptive Selection
Definition

occurs when intermediate phenotypes are selected against and extrene phenotypes are favored. Disruptive selection maintains genetic variation but does not change the mean value of a trait

 

opposite of stabalizing selection

Term
regressive evolution
Definition

loss of complex structures- if having a reduced complexity leads to higher reproductive success then the frequency of the alleles associate with that phenotype will increase in the population

 

- eye loss in darkness

-parasitic worms

Term
sexual selection
Definition
process by which individuals that possess certain heritable traits are more successful at attracting and obtaining mates and thus reproduce at a higher rate relative to other individuals in the population
Term
pattern with sexual selection
Definition

males compete more intensely for mates than do females and females are choosier about their mates than are males

 

anisogamy- defined by the occurrence of gametes of different sizes

 

eggs are expensive whereas sperm are energetically cheap

Term
Bateman and Trivers' principle
Definition

difference in gametic investment between males and females leads to three predictions

Prediction 1- male fitness will be limited by the number of mates, whereas female fitness will not

Bateman's rule- only male fitness improves with # of mates

female fitness is limited by resources

Prediction 2- because females invest more into each gamete, they should invest more in parental care of an offspring

in nature females generally invest more in parental care

Prediction 3- given greater investment in gametes and in care of offspring, females should be choosier about who they mate with and males should compete more for mates than do females- we generally see both patterns

Term
Sexual Dimorphism
Definition

differences between sexes in traits related to attracting and obtaining mates

- males have exaggerated traits that they use in fighting or courtship

Term
intrasexual selection
Definition

competition within a sex

 

competition between males selects for male reproductive traits

Term
intersexual selection
Definition

one sex select among variants of opposite sex

 

female mate choice selects for male reproductive traits

Term

Intrasexual selection:

Male-male competition

Definition

male combat- males fight over access to mates

ritualized displays- males use displays to gauge strength of opponent- reduces risk of serious injury

sperm competition- males do not physically compete but their spern do. competition for fertilization

Term
Disruptive Intrasexual selection
Definition
intrasexual selection selects for fighter and sneaker morphs in many animal species
Term
Sperm competition
Definition

males have evolved- claspers to clutch female, a new penis with a scrub brush

 

female places her genitalia over the new penis. male then scrubs the old perm from the females sperm storage organ and deposits sperm

Term

intersexual selection

cryptic hidden female choice

Definition

females not picky about mating

females are promiscuous = mate with many males

after mating females control which fertilize their eggs

females may remove or reject unwanted sperm

Term
benefits of mate choice
Definition

Direct benefits- males offer resources in addition to sperm: access to food and nest sites, gifts, parental care

Indirect benefits- males offer only sperm good genes and sexy sons

Term
why do females sometimes show preferences for males that offer nothing but sperm?
Definition

good genes model- females choose mates whose genes improve tiehr offsprings survival and reproduction

 

sexy sons- fisherian runaway model- females preference can initally be arbitrary but as females choose mates with certain traits both the male trait nad the female preference co-evolve

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