-Offspring are identical to the original cell or organism

Involves inheritance of all genes from one parent

-Offspring are similar to parents, but show variations in traits

-Involves inheritance of unique sets of genes from two parents

-Reproduction of an entire single-celled organism

-Growth of a multicellular organism

-Growth from a fertalized egg into an adult

-Repair and replacement of cells in an adult

DNA+Proteins

--To prepare for cell division, the chromatin becomes highly compact, and the chromosomes are visible with a microscope

-Each chromosome appears as 2 sister chromatids

-Contains identical DNA molecules

-Joined at centromere

An ordered sequence of events for cell division

-Consists of 2 stages:

    *interphase and mitotic phase

-G1-growth, increase in cytoplasm--preparation for S stage

-S-Duplication of chromosomes

-G2- Growth, preparation for cell division (mitosis)

-Mitosis-division of the nucleus

-Cytokinesis-division of cytoplasm

-Cytoplasm growth, normal cell activities, most of cell's time

a. G1 Phase (Gap  1)

b. S Phase (synthesis)

c. G2 Phase (Gap 2): energy buildup

1) two identical copies of DNA needed

2) semiconservative replication

a. DNA polymerase unzips DNA entirely and permanently

b. DNA polymerase matches exposed nitrogenous bases with complementary bases: A,G,C,T

c. Each new chromosome has one new and one old DNA strand

d. Strands stay attached to each other at centromere

e. The 3rd benefit of double stranded DNA: easy to copy

-Prophase

-Metaphase

-Anaphase

Telophase

---cytokinesis often overlaps telophase

-Occurs in the nucleus

-Chromosomes coil become compact

-Nuclear membrane breaks down

-Sister chromatids separate at the centromeres

-Daughter chromosomes are moved to opposite poles of the cell

-The nuclear envelope forms around chromosomes at each pole, establishing daughter nuclei

-chromosomes stop moving

-Chromatin UNCOILS

CLEAVAGE

-A cleavage furrow forms from the contracting ring of microfilaments, interacting with myosin

-The cleavage furrow deepens to separate the contents into two cells

CELL PLATE

-A cell plate forms in the middle from vesicles containing cell wall material

-The cell plate grows outward to reach the edges, dividing the contents into two cells

-Each cell has a plasma membrane and cell wall

-Presence of essential nutrients

-Growth factors, proteins that stimulate division

-Presence of other cells causes density-dependent inhibition

-Length

-Centromere position

-Gene location

process that converts dipolid nuclei to haploid nuclei

-Occurs in the sex organs, producing gametes-sperm and eggs

union of sperm and egg

- The zygote has a diploid chromosome number, one set from each parent

Meiosis I: homologous chromosomes separate

-Chromosome number is reduced by half

Meiosis II: sister chromatids separate

-The chromosome number remains the same

a. nuclear membrane disintegrates, spindle forms

b. chromosomes condense

c. sister chromosomes pair

d. crossover occurs

a. PAIRS align at equator

b. independent assortment

(=independent orientation)

a. members of each pair separate

b. no breakage of centromeres

Telophase I

follows meiosis I without chromosome duplication

-each of the 2 haploid products enters meiosis II

-Chromosomes have reached the poles of the cell

-A nuclear envelope forms around each set of chromosomes

-With cytokinesis, four haploid cells are produced

- Two divisions of chromosomes

-Pairing of homologous chromosomes

-Exchange of genetic material by crossing over

-Each pair of chromosomes independently aligns at the cell equator during metaphase I

-two pairs chromosomes (2n=4)--> 4 different assortments

-people: 2n=46, n=23---> 223 combinations

The combination of each unique sperm with each unique egg increases genetic variability

8.4 million genetically different gametes!

involves exchange of genetic materials between homologous chromosomes

1) prophase I

2)sister chromosomes swap genes

3) usually at least one crossover per pair

4) so even more gamete types are possible

-Discovered principles of genetics in experiments with the garden pea

- Mendel showed that parents pass heritable factors to offspring (heritable factors are now called genes)

-Controlled matings

-Self-fertilization or cross- fertilization

-Observable characteristics with two distinct forms

-True-breeding strains (varieties with self- fertilization produces offspring all identical to the parent)

The offspring of 2 different varieties

-the cross fertilization aka the hybridization

Describes the inheritance of a single character

-parental generation: purple flowers x white flowers

-F1 generation: all plants with purple flowers

-F2 generation: 3/4 of plants with purple flowers

-F2 generation:1/4 of plants with white flowers

3:1!

1. Genes are found in alternative versions called alleles; a genotype is the listing of alleles an individual carries for a specific gene

2. For each characteristic, an organism inherits two alleles, one from each parent; the alleles can be the same or different

3. If the alleles differ, the dominant allele determines the organism's appearance, and the recessive allele has no noticeable effect

4. Law of segregation: Allele pairs separate (segregate) from each other during the production of gametes so that a sperm or egg carries only one allele for each gene

revealed by tracking two characters at once (law #2)

-each pair of alleles segregates independently of the other pairs of alleles during gamete formation

9:3:3:1

-The probability of a specific event is the number of ways that event can occur out of the total possible outcomes

-Rule of Multiplication: Multiply the probabilities of events that must occur together

-Rule of Addition: Add probabilities of events that can happen in alternate ways

-Shows the inheritance of a trait in a family through multiple generations

-Demonstrates dominant or recessive inheritance

-can be used to deduce genotypes of family members

-Two recessive alleles are needed to show disease

-Heterozygous parents are carriers of the disease- causing allele

-Probablility of inheritance increases with inbreeding, mating between close relatives

-One dominant allele is needed to show disease

-Dominant lethal alleles are usually eliminated from the population

-Neither allele is dominant over the other

- Expression of both alleles is observed as an intermediate phenotype in the heterozygous individual

ex. red and white flowers make PINK

-More than 2 alleles are found in the population

-A diploid individual can carry any two of these alleles

-The ABO blood group has three alleles, leading to four phenotypes

-Neither allele is dominant over the other

-Expression of both alleles is observed as a distinct phenotype in the hterozygous individual

-Observed for type AB blood

-One gene influences many characteristics

Many genes influence one trait

-Skin color is affected by several genes

-Skin color is affected by exposure to the sunlight

- Susceptibility to diseases, such as cancer, has hereditary and environmental components

-The law of segregation depends on separation of homologous chromosomes in anaphase I

- The law of independent assortment depends on alternative orientations of chromosomes in metaphase I

-Are located close together on the same chromosome

-Tend to be inherited together

-Most F2 individuals had purple flowers, long pollen or red flowers, round pollen

-Recombinant chromosomes are formedd

-Geneticist measure genetic distance by recombination frequency

-Show the order of genes on chromosomes

-Arrange genes into linkage groups representing individual chromosomes

mammals

XX= Female; XY= Male

located on either of the sex chromosomes

-X-linked genes are passed from mother to son and mother to daughter

-X-linked genes are passed from father to daughter

Y-linked genes are passed from father to son

-Males express X-linked disorders such as the following when recessive alleles are present in one copy

--Hemophilia

similarities in Y chromosome sequences

-Show significant percentage of men related to the same male parent

-Demonstrate a connection between people living in distant locations

Group of individuals of the same species living in the same place at the same time

-Populations may be isolated from one another (with little interbreeding), or individuals within populations may interbreed

changes in the nucleotide sequence of DNA, is the ultimate source of new alleles

-Occasionally, mutant alleles improve the adaptation of an individual to its environment and increase its survival and reproductive success (ex. DDT resistance in insects)

-Homologous chromosomes sort independently as they separate during anaphase I of meiosis

-During prophase I of meiosis, pairs of homologous chromosomes cross over and exchange genes

-Further variation arises when sperm randomly unite with eggs in fertilization

-Sexual reproduction alone does not lead to evolutionary change in a population

-both allele and genotype frequencies in a population remein constant from generation to generation unless specific disturbing influences are introduced

1. Very large population

2. No gene flow between populations

3. No mutations

4. Random mating

5. No natural or artificial selection

-Behavioral adaptations

-Structural adaptations

-Biochemical adaptations

-Physiological adaptations

-Organisms produce more offspring then the environment can support

-Organism vary in many traits

-Darwin reasoned that traits that increase their chance of surviving and reproducing in their environment tend to leave more offspring than others

-As a result, favorable traits accumulate in a population over genterations

-Individuals do not evolve: populations evolve

-Natural selection can amplify or diminish only heritable traits; acquired characteristics cannot be passed on to offspring

-Evolution is not goal directed and does not lead to perfection; favorable traits vary as environments change

rare and random and have little effect on the gene pool

-new alleles

-favors intermediate phenotypes, acting against extreme phenotypes

-stabilizing selection is very common, especially when environments are stable

acts against individuals at one of the phenotypic extremes

- common during periods of environmental change, or when a population migrates to a new and different habitat

the emergence of new species

-everytime speciation occurs, the diversity of life increases

Major changes over evolutionary time (like origin of wings)

-all three wings evolved from the same ancestral tetrapod limb by natural selection

-DNA coding for conservative sequences (like rRNA genes) is useful for investigating relationships between taxa that diverged hundreds of millions of years ago

-mtDNA evolves rapidly and has been used to study the relationships between different groups of Native Americans who have diverged since they crossed the Berlin Land Bridge 13,000 years ago

Homologous genes have been found in organisms separated by huge evolutionary distances

-gene duplication has increased the number of genes in many genomes

can be calibrated in real time by graphing the number of nucleotide differences against the dates of evolutionary branch points known from the fossil record

-used to estimate dates of divergences without a good fossil record

---a molecular clock has been used to estimate the date that HIV jumped from apes to humans

Construcing the tree of life is a work in progress

-an evolutionary tree for living things has been developed, using rRNA genes

1. gene transfer between a mitochondrial ancestor and the ancestor of eukaryotes

2. gene transfer between a chloroplast ancestor and the ancestor of green plants

--we are the decendents of Bacteria AND Archaea