Exam 1: Evolution

Question 1

How does evolution occur? (5 mechanisms)

Answer 1

1) Genetic Drift
2) Mutation
3) Heritable Epigenetic Modification
4) Migration
5) Natural Selection
- -basically anything that changes allele frequencies in population or heritable expression of alleles

Question 2

Evolution (defn)

Answer 2

The change in allele frequencies in a population across generations.

Question 3

Genetic drift

Answer 3

totally random changes in allele frequency from generation to generation due to chance (sampling error)

Question 4

mutation

Answer 4

changes in the genetic code such as errors in DNA replication, gene deletions or duplications, etc.

Question 5

epigenetic inheritance

Answer 5

heritable changes that are not due to changes in DNA sequence, such as DNA methylation and histone modifications, etc..

Question 6

migration

Answer 6

alleles moving from one population to another

Question 7

natural selection

Answer 7

when some alleles favored over others due to an increase in fitness (not random) acts on genetic variation within the population

Question 8

HIV

Answer 8

• Retrovirus with 2 single strand RNA genomes
• Uses enzyme reverse transcriptase to replicate RNA–>DNA
• Infects macrophages and helper T cells

Question 9

random fixation (of alleles) (genetic drift)

Answer 9

When an allele frequency becomes 100%, the other alleles are lost by chance

Question 10

Inbreeding depression (genetic drift)

Answer 10

mating between relatives

Question 11

outbreeding depression (genetic drift)

Answer 11

mating between completely different species

Question 12

hybrid vigor (genetic drift)

Answer 12

mating halfway

- optimal state w/ heterozygous offspring

Question 13

Hardy Weinberg Theorem

Answer 13

States:

• In a non-evolving population, the frequencies of alleles and genotypes in a population remains constant from generation to generation.
• When given allele frequencies, genotype frequencies should be the Hardy-Weinberg expectations.

Question 14

gene

Answer 14

• a region of genome sequence (DNA or RNA)

Question 15

locus

Answer 15

location within a genome (can be in a gene)

Question 16

allele

Answer 16

variant forms of a gene

Question 17

There are ____ alleles at a locus

Answer 17

2

Question 18

The frequency of all alleles in a population will add up to ____.

Answer 18

1

Question 19

The 5 Conditions for Non-evolvingPopulations

Answer 19

1) No mutations
2) Random mating
3) No natural selection
4) Extremely large population size
5) No gene flow

Question 20

point mutations

Answer 20

single nucleotide substitutions, insertions , or deletions

- Due to DNA replication error in mitosis or meiosis

Question 21

Gene-level mutations

Answer 21

• Gene insertions (Gene duplications, transposons, horizontal gene transfer)
• Gene deletions (pseudogenoization, transposons)
• Exon shuffling

Question 22

Chromosome-level mutations

Answer 22

• Chromosome duplications
• Deletions
• Inversions
• Fusions

Question 23

Genome-level Mutations

Answer 23

• Autopolyploidization

- Allopolyploidization

Question 24

Horizontal gene transfer

Answer 24

• Transfer of genetic material to another organism that is not its offspring.
• How bacteria evolve.
• Responsible for drug resistance.

Question 25

Transposons

Answer 25

• “Jumping genes”
• DNA sequence that can change is relative position within the genome.
• ‘copy and paste’ = retrotransposons
• ‘cut and paste’ = DNA transposons
• Considered ‘junk DNA’

Question 26

Polyploidy

Answer 26

presence of extra sets of chromosomes due to accidents during cell division

• Autopolyploid
• Allopolyploid

Question 27

Autopolyploid

Answer 27

• Individual with more than 2 chromosome sets.

- Derived from 1 species

Question 28

Allopolyploid

Answer 28

• Species with multiple sets of chromosomes

- Derived from multiple species

Question 29

(T/F) Epigenetic changes can result in phenotypic differences.

Answer 29

True

Question 30

(T/F) Epigenetic modifications change the genetic code.

Answer 30

False

Question 31

types of Chromatin Modification (Epigenetic Modification)

Answer 31

1) Methylation
2) Histone modifications (acetylation, deactylation)
3) Chromatin remodeling

Question 32

DNA Methylation (Epigenetic Modifications)

Answer 32

• Methyl groups are added and removed to DNA using enzyme, with the help of methylates and demethylases.
• Higher levels of methylation in promotor regions will correspond to decreased expression of a gene.

Question 33

Recombination (meiosis)

Answer 33

• Process that involves shuffling of the combination of alleles along the chromatid arm= new DNA combinations

Question 34

Random mating (meiosis)

Answer 34

• Shuffles allelic combinations themselves into new genotypes
• (Independent shuffling of haploid chromosomes or gametes)

Question 35

Genetic recombination

Answer 35

• Process in which a molecule of nucleic acid (DNA/RNA) is broken down and then joined to a new one
• Crossover = new combo. of alleles