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BIO 110- EXAM #4
BIO 110
132
Biology
Undergraduate 2
04/14/2013

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Term
In protein synthysis, where does the process of transcription take place?
Definition
In the nucleus, using DNA as a template
Term
Which of the following bases is NOT found in mRNA?
Definition
Thymine
Term
In DNA, complementary base pairing occurs between:
Definition
adenine and thymine
Term
Each "word" in the mRNA language consists of how many letters?
Definition
3
Term
Replication of DNA:
Definition
produces two molecules, each of which is half new and half old DNA
Term
Who found DNA (deoxyribonucleic acid) in nuclei in the 1800s?
Definition
Miescher
Term
Who transferred hereditary material from dead cells to live cells in the early 1900s?
Definition
Griffith
Term
______ and ______ separated deadly S cells (from Griffith’s experiments) into lipid, protein, and nucleic acid
components in 1940.

What was the conclusion?
Definition
Avery; McCarty

-DNA is the “transforming principle”
Term
______ and ______ experimented with bacteriophages (viruses that infect bacteria)in the 1950s.

Conclusion?
Definition
Hershey; Chase

:DNA, not protein, is the material that stores
hereditary information
Term
What is a Nucleotide?
Definition
A nucleic acid monomer consisting of a five-carbon sugar
(deoxyribose), three phosphate groups, and one of four nitrogencontaining bases
Term
DNA consists of four nucleotide building blocks
• Two pyrimidines: ______ and ______
• Two purines: ______ and ______
Definition
thymine; cytosine

adenine; guanine
Term
Rosalind Franklin’s research in x-ray crystallography revealed
the dimensions and shape of the DNA molecule. What was it?
Definition
an alpha helix
Term
What was the final piece of information Watson and Crick
needed to build their model of DNA?
Definition
the dimensions & shape of DNA (alpha helix)
Term
DNA _____ ________ and ________ correct most replication errors
Definition
repair mechanisms; proofreading
Term
One template builds DNA ________; the other builds DNA ________, in segments.
Definition
continuously; discontinuously
Term
Breaks hydrogen bonds between DNA strands
Definition
DNA helicase
Term
Joins free nucleotides into a new strand of DNA
Definition
DNA polymerase
Term
Joins DNA segments on discontinuous strand
Definition
DNA ligase
Term
DNA polymerases proofread DNA sequences during DNA
replication and repair damaged DNA
Definition
DNA repair mechanisms
Term
When proofreading and repair mechanisms fail, an error becomes a ________– a permanent change in the DNA sequence
Definition
mutation
Term
• Exact copies of a molecule, cell, or individual
• Occur in nature by asexual reproduction or embryo splitting
(identical twins)
Definition
Clones
Term
produces an exact copy (clone) of an individual
Definition
Reproductive cloning technologies
Term
• Nuclear DNA of an adult is transferred to an enucleated egg
• Egg cytoplasm reprograms differentiated (adult) DNA to act like
undifferentiated (egg) DNA
• The hybrid cell develops into an embryo that is genetically
identical to the donor individual
Definition
Somatic cell nuclear transfer (SCNT)
Term
________ ________ uses SCNT to produce human embryos
for research purposes
Definition
Therapeutic cloning
Term
________ _________ was first to discover the molecular structure of DNA, but did not share in the Nobel prize which was given to Watson, Crick, and Wilkins
Definition
Rosalind Franklin
Term
_______ is toxic because it inactivates ribosomes, the organelles which assemble amino acids into proteins, critical to life processes
Definition
Ricin
Term
Enzymes use the nucleotide sequence of a gene to synthesize a complementary strand of RNA
Definition
Transcription
Term
Contains information transcribed from DNA
Definition
Messenger RNA (mRNA)
Term
Main component of ribosomes, where polypeptide chains are built
Definition
Ribosomal RNA (rRNA)
Term
Delivers amino acids to ribosomes
Definition
Transfer RNA (tRNA)
Term
The information carried by mRNA is decoded into a sequence of
amino acids, resulting in a polypeptide chain that folds into a
protein
Definition
Translation
Term
A multistep process including transcription and translation, by
which genetic information encoded by a gene is converted into a structural or functional part of a cell or body
Definition
Gene expression
Term
DNA ________ and ________ both synthesize new molecules by base-pairing
Definition
replication; transcription
Term
___ ________ adds nucleotides to the transcript
Definition
RNA polymerase
Term
[image]
Definition
[image]
Term
RNA transcription steps:
Definition
• RNA polymerase and regulatory proteins attach to a promoter (a specific binding site in DNA close to the start of a gene)

• RNA polymerase moves over the gene in a 5' to 3' direction, unwinds the DNA helix, reads the base sequence, and joins free RNA nucleotides into a complementary strand of mRNA
Term
Many RNA polymerases can transcribe a gene at the same time
Definition
Term
Base ________ in an mRNA are words in a protein-building
message
Definition
triplets
Term
In eukaryotes, RNA is modified before it leaves the _______ as a mature mRNA
Definition
nucleus
Term
Nucleotide sequences that are removed from a new RNA
Definition
Introns
Term
Sequences that stay in the RNA
Definition
Exons
Term
• Allows one gene to encode different proteins

• Some exons are removed from RNA and others are spliced together in various combinations
Definition
Alternative splicing
Term
After splicing, transcripts are finished with a modified guanine
______ at the 5' end and a poly-A tail at the 3' end
Definition
“cap”
Term
[image]
Definition
[image]
Term
mRNA carries protein-building information to ribosomes and tRNA for ________.
Definition
translation
Term
• A sequence of three mRNA nucleotides that codes for a specific amino acid
• The order of codons in mRNA determines the order of amino acids in a polypeptide chain
Definition
Codon
Term
[image]
Definition
[image]
Term
• Consists of 64 mRNA codons (triplets)
• Some amino acids can be coded by more than one codon
Definition
Genetic code
Term
Some codons signal the start or end of a gene
• ___ (methionine) is a start codon
• UAA, UAG, and UGA are stop codons
Definition
AUG
Term
tRNA has an _________ complementary to an mRNA codon, and a binding site for the amino acid specified by that codon
Definition
anticodon
Term
________, which link amino acids into polypeptide chains, consist of two subunits of rRNA and proteins
Definition
Ribosomes
Term
__________ converts genetic information carried by an mRNA
into a new polypeptide chain
Definition
Translation
Term
The order of the codons in the mRNA determines the order of the amino acids in the polypeptide chain
Definition
Term
Translation occurs in the ________ of cells
Definition
cytoplasm
Term
What are the 3 stages of translation?
Definition
1) Initiation
2) Elongation
3) Termination
Term
• A small ribosomal subunit binds to mRNA
• The anticodon of initiator tRNA base-pairs with the start codon
(AUG) of mRNA
• A large ribosomal subunit joins the small ribosomal subunit
Definition
Initiation
Term
The ribosome assembles a polypeptide chain as it moves
along the mRNA
• Initiator tRNA carries methionine, the first amino acid of the
chain
• The ribosome joins each amino acid to the polypeptide chain
with a peptide bond
Definition
Elongation
Term
When the ribosome encounters a stop codon, polypeptide
synthesis ends
• Release factors bind to the ribosome
• Enzymes detach the mRNA and polypeptide chain from the ribosome
Definition
Termination
Term
Many ribosomes may simultaneously translate the same mRNA, forming ________.
Definition
polysomes
Term
Small-scale changes in the nucleotide sequence of a cell’s DNA
that alter the genetic code
Definition
Mutations
Term
May result in a premature stop codon or a different amino acid in a protein product

• Example:sickle-cell anemia
Definition
Base-pair-substitution
Term
Can cause the reading frame of mRNA codons to shift, changing the genetic message

• Example: Huntington’s disease
Definition
Deletion or insertion
Term
Segments of DNA that can insert themselves anywhere in a chromosomes
Definition
Transposable elements
Term
Uncorrected errors in DNA replication
Definition
Spontaneous mutations
Term
Ionizing radiation, UV radiation, chemicals
Definition
Harmful environmental agents
Term
________ _________ damages chromosomes, nonionizing (UV) radiation forms thymine dimers
Definition
Ionizing radiation
Term
• Mutations in somatic cells of sexually reproducing species are not inherited
• Mutations in a germ cell or gamete may be inherited, with evolutionary consequences
Definition
Term
Aristotle was one of first ________– people who observe life from a scientific perspective
Definition
naturalists
Term
In the late 1800s, Alfred Wallace and others were pioneers in ________– the study of patterns in the observation of species
Definition
biogeography
Term
________ ________ study body plans and structures among groups of organisms
• Some organisms are outwardly similar, but different internally; others differ outwardly, but have similar internal structures
• Some organisms have vestigial parts with no apparent function
Definition
Comparative morphologists
Term
Georges Cuvier proposed that many species that once existed became extinct due to catastrophic geological events unlike those known today
Definition
Catastrophism
Term
Jean-Baptiste Lamarck proposed that individuals changed in response to their environment, and passed those changes on to their descendents
Definition
Gradualism
Term
• Lyell’s book, Principles of Geology, proposed that gradual, repetitive geological processes shaped the Earth over great spans of time
• Lyell’s insights shaped Charles Darwin’s thinking during his fiveyear voyage on the Beagle
Definition
Theory of uniformity
Term
Darwin’s observations of species in different parts of the world helped him understand a driving force of evolution – ________
Definition
natural selection
Term
Darwin’s observations:
Definition
Populations can produce more individuals than their environment
can support
• Some versions of a trait might enhance an individual’s ability to
survive and reproduce in its particular environment
• Example: Finches in the Galapagos Islands
Term
Differential survival and reproduction among individuals of a population that vary in details of shared, inherited traits
Definition
Natural selection
Term
Any trait that enhances an individual’s fitness (ability to survive and reproduce in a particular environment)
Definition
Adaptive trait
Term
_______ ________ Wallace drew on his own observations of plant and animal
species and proposed that natural selection is a driving force of evolution
Definition
Alfred Wallace
Term
Remains of bones, teeth, shells, seeds, spores, or other body parts
Definition
Fossils
Term
Evidence of an organism’s activities (nests, trails, footprints, burrows, bore holes, eggshells, feces)
Definition
Trace fossils
Term
Substantial enough to help reconstruct patterns and trends in the history of life, and establish some lines of descent
Definition
lineages
Term
Reveals the age of a material by determining its radioisotope and daughter element content
Definition
Radiometric dating
Term
• A form of an element with an unstable nucleus
• Decays into atoms of another element
• Example: uranium 238 →lead 206
Definition
Radioisotope
Term
The time it takes for half of a radioisotope’s atoms to decay into a
daughter element
Definition
Half-life
Term
[image]
Definition
[image]
Term
• The chronology of Earth’s history

• Measured by radiometric dating and fossils in similar sequences of sedimentary rock layers around the world
Definition
Geologic time scale
Term
All continents were once part of a supercontinent – Pangea – that split and drifted apart
• Evidence: Magnetic rocks
Definition
Continental drift
Term
• The mechanisms of continental drift
• Plate grow from ridges and sink into trenches
Definition
Plate tectonics
Term
• Ancient supercontinent, older than Pangea
• Similar fossils and geologic formations in Africa, India, South
America and Australia
Definition
Gondwana
Term
Individuals of the same species in the same area
Definition
Population
Term
• All individuals of a species share certain traits
• Individuals of a population vary in the details of their shared traits
Definition
Term
All genes found in one population
Definition
• Gene pool
Term
• Different forms of the same gene
• Determine genotype and phenotype
• Dimorphism and polymorphism
Definition
Alleles
Term
Mutations are the source of new alleles that give rise to differences
in details of shared traits

• ______ mutations usually result in death
• ________ mutations have no effect on survival or reproduction
• ________ mutations convey an advantage
Definition
-Lethal
-Neutral
-Beneficial
Term
Relative abundance of alleles of a given gene in a population
Definition
Allele frequencies
Term
Natural populations are never in _______ ________
• A theoretical state which occurs when a population is not evolving
Definition
genetic equilibrium
Term
Four processes of ________ (small-scale changes in a population's allele frequencies) prevent genetic equilibrium
• Mutation
• Natural selection
• Genetic drift
• Gene flow
Definition
microevolution
Term
Five conditions required for a stable gene pool:
Definition
1) Mutations do not occur
2) Population is infinitely large
3) No gene flow
4) Random mating
5) All individuals survive and reproduce equally
Term
The Hardy-Weinberg formula can be used to determine if a
population is in genetic equilibrium
p
2
(AA) + 2pq (Aa) +q
2
(aa) = 1.0
• The frequency of the dominant allele (A) plus the recessive allele (a)
equals 1.0
p + q = 1.0
Definition
Term
• The differential survival and reproduction among individuals of a
population that vary in details of their shared traits
• A driving force of evolution
• Occurs in recognizable patterns depending on the organisms and their
environment
Definition
Natural selection
Term
• Changing environmental conditions can shift allele frequencies in a
consistent direction
• Forms of traits at one end of a range of phenotypic variation become more common
Definition
Directional selection
Term
Natural selection that favors an intermediate phenotype and eliminates
extreme forms
Definition
Stabilizing selection
Term
Natural selection that favors extreme forms of a trait and eliminates
the intermediate forms
Definition
Disruptive selection
Term
With ______ ________, some version of a trait gives an individual an advantage over others in attracting mates
Definition
sexual selection
Term
Distinct male and female phenotypes (______ _________) is one outcome of sexual selection

-can easily tell the difference between males & females
Definition
sexual dimorphism
Term
• A state in which natural selection maintains two or more alleles at
relatively high frequencies
• Occurs when environmental conditions favor heterozygotes
• Example: Sickle cell anemia and malaria
• HbA/HbS heterozygotes survive malaria more often than people who make only normal hemoglobin
Definition
Balanced polymorphism
Term
• A random change in allele frequencies over time
• Can lead to a loss of genetic diversity, especially in small populations
Definition
Genetic drift
Term
________ has occurred when all individuals in a population are
homozygous for one allele
Definition
Fixation
Term
• A drastic reduction in population size brought about by severe pressure
• After a bottleneck, genetic drift is pronounced when a few individuals
rebuild a population
• Example: Northern elephant seals, cheetahs

-severe, environmental, catastrophic
Definition
Bottleneck
Term
Genetic drift is pronounced when a few individuals start a new
population
Definition
Founder effect
Term
• Breeding or mating between close relatives who share a large number of
alleles
• Example: Old Order Amish in Lancaster County, Pennsylvania (Ellis-van
Creveld syndrome)
Definition
Inbreeding
Term
• Physical movement of alleles caused by individuals moving into and
away from populations
• Tends to counter the evolutionary effects of mutation, natural
selection, and genetic drift on a population
• Example: Movement of acorns by blue jays

-good thing = more diversity
Definition
Gene flow
Term
• Evolutionary process by which new species form
• Reproductive isolating mechanisms are always part of the process
Definition
Speciation
Term
• The end of gene exchange between populations
• Beginning of speciation

-occurs when the gene flow stops
Definition
Reproductive isolation
Term
Reproductive isolating mechanisms prevent interbreeding among
species
Definition
• Heritable aspects of body form, function, or behavior that arise as
populations diverge
• Prezygotic isolating mechanisms prevent pollination or mating
• Postzygotic isolating mechanisms result in weak or infertile hybrids
Term
• Reduced hybrid viability (ligers, tigons)
• Extra or missing genes

• Reduced hybrid fertility (mules)
• Robust but sterile offspring

• Hybrid breakdown
• Lower fitness with successive generations
Definition
Term
• A physical barrier arises and ends gene flow between populations
• Genetic divergence results in speciation
• Example: llamas, vicunas, and camels
Definition
Allopatric speciation
Term
new species form within a home range of an existing species, in the absence of a physical barrier

-does not happen very often
-occurs more frequently in plants, not animals
Definition
sympatric speciation
Term
A change in chromosome number (________) can cause instant speciation
Definition
polyploidy
Term
populations in contact along a common
border evolve into distinct species

-2 species that live near/border eachother
Definition
parapatric speciation
Term
• Large-scale patterns of evolutioary change
• Includes patterns of change such as one species giving rise to multiple
species, the origin of major groups, and major extinction events
Definition
Macroevolution
Term
Two species in close ecological contact act as agents of selection on
each other (_______)
• Predator and prey
• Host and parasite
• Pollinator and flower
Definition
coevolution
Term
A lineage exists for millions of years with little or no change (e.g.
coelacanth)
Definition
Stasis
Term
Some complex traits in modern species held different adaptive value in
ancestral lineages (e.g. feathers in birds and dinosaurs)
Definition
Exaptation (preadaptation)
Term
A burst of speciation that occurs when a lineage encounters a new set of
niches
Definition
Adaptive radiation
Term
A structural or functional adaptation that allows individuals to exploit
their habitat in a new way
Definition
Key innovation
Term
The irrevocable loss of a species from Earth
Definition
Extinction
Term
• Extinctions of many lineages, followed by adaptive radiations
• Five catastrophic events in which the majority of species on Earth disappeared
Definition
Mass extinctions
Term
-normally copied from left to right

-reversed DNa, not parallel

-this copies in segments from end to beginning
Definition
Term
-Adenine & Thymine

-Deoxyribose

-Double strand
Definition
DNA
Term
-Adedine and Uracil

-ribose

-single strand
Definition
RNA
Term
How do translation and transcription differ?
Definition
Transcription- involves a promoter, occurs in the nucleus

Translation- begins with a start codon
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