Download Final Exam Review Donnelly Part Answers

BSC 2010 Final Exam Review
New Information (Chapters 22-24):
Chapter 22
Main Concepts
History of Evolution of Species
- Jean Baptiste Lamarck
- Hypothesized that acquired traits can be inherited (e.g. thought giraffes
progressively stretched their necks farther and farther and could pass down these
longer necks to their children)
- Charles Darwin
- Wrote On the Origin of Species; sailed to the Galapagos Islands and noticed
profound differences in the finches there, specifically their beaks. He proposed these
finches all came from a common ancestor but had evolved to eat their own type of food
source on the island.
Theory of Evolution
- Change through time.
- Descent with modification.
- Genetic changes in population over time.
- Unifying theory of biology.
Natural Selection
- How does natural selection cause change in a population?
- By selective advantage; certain individuals will have more suitable
characteristics for their environment and will tend to be able to reproduce more
often.
- What does natural selection act on in the population?
- Inherited characteristics that lead to an advantage in the environment.
- Evidence of natural selection - What fields have supported natural selection as a
mechanism of evolution?
- Biology, geology, chemistry, physics.
- What are the differences between the following types of selection: directional,
stabilizing, disruptive?
- Directional selection: the characteristics on one of the sides are selected
for/reproduced more often and thus the graph shifts to one side.
- Stabilizing selection: the in-between characteristics in the middle are selected
for/reproduced more often.
- Disruptive selection: the characteristics on both of the sides are selected
for/reproduced more often and thus the graph grows two camel humps.
- Sexual Selection
- Intrasexual (“among the same sex”) = e.g. Males compete with one another,
one becomes alpha and mates with the female.
- Intersexual (“between different sexes”) = e.g. Females prefer certain mates.
- Sexual Dimorphism
- The differences between males and females of the same species.
- 3 Key Points to Natural Selection
1. Individuals do not evolve, populations evolve.
2. Natural selection only works on heritable traits with variation in the population.
3. Evolution is not working towards a specific goal or “perfect” organisms.
Vocabulary
Homologous structures – Structures that evolved from a common ancestor (e.g.
human hands vs. bat wings).
Vestigial structures – Structures that have lost their ancestral functions but are still
present (e.g. a pelvis in a whale).
Adaptation – Traits with useful roles are selected for in natural selection.
Chapter 23
Main Concepts
- Heterozygote Advantage
- e.g. Sickle-cell anemia heterozygotes do not have full-on sickle-cell anemia and
also have a higher resistance to malaria than do people with normal red blood
cells.
Limits of natural selection
1. Selection can only act on existing variation in a population.
2. Evolution is limited by historical constraints.
3. Adaptations are usually compromises.
4. Natural selection interacts with chance/random events and the environment.
Microevolution
How do the following cause changes in a population?
– Mutations – A permanent change in the DNA sequence of a gene (e.g. having blue
eyes).
– Natural Selection – Selective advantage of those individuals better suited for the
environment.
– Genetic Drift – Change in allele frequency due to random sampling.
– Gene Flow – Moving genes from one population to another.
Hardy-Weinberg Principle
What are the 5 assumptions for a population to be in Hardy-Weinberg
equilibrium?
- The Hardy-Weinberg principle is a “null hypothesis” to check for evolution; it is
almost always violated by real populations.
1. No natural selection.
2. No mutation.
3. No gene flow.
4. Completely random mating.
5. Large population.
Hardy-Weinberg Problems
Equations:
Allele Frequencies: p + q = 1
p = frequency of dominant allele in population
q = frequency of recessive allele in population
Genotype frequencies: p2 + 2pq + q2 = 1
p2 = frequency of homozygous dominant
2pq = frequency of heterozygous
q2 = frequency of homozygous recessive
*Additional practice problems available in document on Webcourses
Examples from Lecture:
A population of 100 butterflies has a dominant brown color and a recessive white
color.
1. If the frequency of the brown allele is 0.8, what is the frequency of the white
allele?
p = 0.8
p+q=1
q= 1 – 0.8 = 0.2
2. Calculate the predicted frequencies of the genotypes if population is at HardyWeinberg equilibrium.
p= 0.8, q= 0.2; Genotype frequency equation= p2 + 2pq + q2 = 1
p2 =(0.8)2 = 0.64
2pq= 2(0.8)(0.2)= 0.32
q2 =(0.2) 2 = 0.04
0.64+0.32+0.04= 1
3. In the butterfly population, 25% are dominant homozygous, 50% are
heterozygous, and 25% are homozygous recessive. Find p and q for this
population.
Frequency of homozygous dominant = p2 = 0.25 p = √0.25 = 0.5
Frequency of homozygous recessive = q2 = 0.25 q = √0.25 = 0.5
Frequency of heterozygous = 2pq = 0.5
Vocabulary
Cline – An ecological gradient of traits.
Bottleneck effect – A population's size is reduced for at least one generation, usually
by some kind of barrier or being squeezed in the middle (e.g. northern elephant seal).
This leads to much less genetic variation, even if the bottleneck only lasts a few
generations.
Founder effect – A new colony is started by a few members of the original population
(e.g. Dutch settlers in South Africa).
Chapter 24
Main Concepts
Speciation – The formation of new, distinct species.
- Allopatric Speciation vs. Sympatric Speciation
- How does allopatric speciation occur?
- Allopatric = “Different country” aka two species developing in separated
areas.
- How does sympatric speciation occur?
- Sympatric = “Same country” aka two species developing in the same
area.
Reproductive Barrier – Anything that inhibits reproduction.
- Pre-zygotic Barriers
What are the different types of pre-zygotic barriers?
- Post-zygotic Barriers
What are the different types of post-zygotic barriers?
Macroevolution – Evolution of taxonomic groups over long periods.
– Adaptive radiation – Organisms diversify quickly due to new resources, food,
and environmental niches opening up; often follows
mass extinctions.
– Mass extinctions – Usually lead to adaptive radiation.
– Continental drift – The movement of Earth's continents.
Old Material (Donnelly Lectures):
Main Concepts
Energy Production
Autotrophs vs. Heterotrophs
Purpose of Cellular Respiration and Fermentation – Create energy from glucose.
Purpose of Photosynthesis – Create glucose from energy (sunlight).
Reproduction
Mitosis vs. Meiosis
- How are they similar?
- How are they different?
Mitosis
- Why do cells do mitosis?
To create cloned versions of themselves.
- What is the final product?
Two cloned cells identical to the parent cell.
Meiosis
- Why do cells do meiosis?
To create gametes that have the correct [haploid] number of
chromosomes in order to combine with another gamete.
- What is the final product?
Four genetically unique daughter cells.
- Processes during meiosis that can further increase genetic diversity
Viruses
- Where and how do viruses reproduce?
Inside of a host cell, hijacking the host cell's reproduction
machinery. “I'm in yo cell, producing mah babies.”
Principles of Inheritance
Punnett Square
- Punnett Square with one trait (monohybrid crosses)
- Punnett Square with two traits (dihybrid crosses)
- Sex-linked characteristics
Gregor Mendel and the particulate hypothesis
Chromosome Theory of Inheritance
Structure of DNA
– Double helix
– Complementary
– Anti-parallel
– Chargaff’s rule about nucleotide bases
– Codons and anticodons
DNA Replication Process
– Which organelle?
- Wherever the DNA is (nucleus in eukaryotes, cytoplasm in prokaryotes).
– What stage of cell cycle?
- S (DNA synthesis phase during interphase).
– Why does it happen?
- To be able to create cloned and daughter cells with the correct amount of
genetic information.
Genetic Code
– Nearly universal for all organisms
– What are the two characteristics about the genetic code important for
decreasing errors?
o Redundant
o Not ambiguous
Flow of Genetic Information
– Central Dogma: DNA to RNA to Protein
– What processes are involved in gene expression?
o Transcription (DNA to RNA)
o Translation (RNA to protein)
Vocabulary
Homozygous dominant – AA.
Heterozygous – Aa.
Homozygous recessive – aa.
Genotype – The gene and its alleles.
Phenotype – The expression of the gene.
Homologous chromosomes
Sister chromatids
Crossing over – Exchange of genetic material during prophase I of meiosis.