Genetics

Question 1

In what stage can a protein be functional? What can occur if the protein was modified?

Answer 1

quaternary

protein would change function or be disabled

Question 2

What does DNA translation and transcription accomplish?

Answer 2

transcription = turns RNA into mRNA

translation = turns mRNA into protein

Question 3

What roles do RNA have?

Answer 3

mRNA = creates a template of DNA for protein synthesis
RNA = makes up ribosomes where amino acids are synthesized
microRNA = can regulate genes and silence them

Question 4

What is the molecular clock hypothesis?

Answer 4

neutral mutations should occur in a predictable clock-like fashion

Question 5

What molecule can affect a phenotype?

Answer 5

microRNA (binds to mRNA)

Question 6

What is alternate splicing?

Answer 6

trimming different parts of an RNA out to make different mRNA which translate into various proteins

Question 7

What makes up non-coding sections of the genome?

Answer 7

• pseudogenes
• RNA genes (remnants of viruses)
• microsatellites (highly mutable repeating segments)

Question 8

What is a point mutation/base substitution?

Answer 8

change in a single base

Question 9

What is an insertion mutation?

Answer 9

addition of a base/bases

Question 10

What is a deletion mutation?

Answer 10

removal of a base/bases

Question 11

What is a gene duplication?

Answer 11

addition of an identical gene

Question 12

What is an inversion mutation?

Answer 12

reversal of the gene order

Question 13

What is a chromosome fusion mutation?

Answer 13

combining two chromosomes

Question 14

What is a genome duplication mutation?

Answer 14

increasing the ploidy by copying chromosomes

Question 15

What are some examples of human point mutations?

Answer 15

• albinism
• polydactyly
• fused limbs
• piebaldism

Question 16

What protein is responsible for albinism?

Answer 16

tyrosinase (point mutation prevents its production)

Question 17

In what stage of meiosis are mutations most likely to occur?

Answer 17

prophase 1 (crossing over)

Question 18

What is polyphenism?

Answer 18

when multiple (discrete) phenotypes can be expressed through a single gene in response to environmental conditions –> caused by phenotypic plasticity

i.e wings in beetles when population is crowded, horns on beetles when food is abundant

Question 19

What conditions were laid out in the Hardy-Weinberg theorem?

Answer 19

• no mutations occur
• population is genetically isolated/no drift
• all genotypes are equally fit
• population is infinitely large/no K
• mating is random
• population is diploid
• population reproduces sexually
• no overlap in generations

Question 20

How did a mutation affect mosquitos in France?

Answer 20

• gene called Ester produces esterase, which has detox properties
• mosquitos that had a mutated Ester gene (Ester 1) produces more esterase than usual
• Ester 1 mosquitos were highly resistant to pesticides and survived, reproduced and gene spread throughout population

Question 21

What effect does genetic drift have on a population?

Answer 21

randomly changes frequency of some alleles (can increase or decrease)

Question 22

What effect does bottlenecking have on a population

Answer 22

sudden reduction in population changes the frequency of alleles present, allele diversity can decrease –> can lead to inbreeding or genetic drift

Question 23

What is a human example of the founder effect?

Answer 23

Norfolk Island: colonizers had a higher representation of migraine-inducing gene

Question 24

Define an inbreeding depression

Answer 24

reduced fitness/reproductive success in an individual as a result of inherited deleterious genes from inbreeding

Question 25

What is antagonistic pleiotropy?

Answer 25

when a mutation in one gene has negative effects on other genes

Question 26

How does having less Eda expression (i.e is homozygous recessive) benefit freshwater sticklebacks?

Answer 26

less bony plates produced = more energy directed towards growth and earlier reproduction

Question 27

What is directional selection and provide an example

Answer 27

population phenotypes favour one extreme end i.e oil content in cultivated corn

Question 28

What is stabilizing selection and provide an example

Answer 28

population phenotypes favour the intermediate i.e human baby sizes, gall fly gall sizes

Question 29

What is disruptive selection and provide an example

Answer 29

population phenotype favours both extremes i.e limnetic + benthic sticklebacks, high and low bristle flies

Question 30

What process can cause identical twins to have different phenotypes?

Answer 30

methylation (addition of CH3) can silence a gene

Question 31

What is negative frequency dependent selection?

Answer 31

when a phenotype has a higher fitness when its considered rare

Question 32

What is a heterozygote advantage?

Answer 32

when being heterozygous has a higher fitness over homozygous i.e being heterozygous for sickle cell anemia produces both mutant and normal RBC, has a lower risk of malaria

Question 33

What possible advantage do kermode bears have over normal black bears?

Answer 33

possibly better at hunting (harder for fish to see)

Question 34

What are additive alleles?

Answer 34

multiple genes contributing to a phenotype, and the phenotype is stronger when more copies are present

Question 35

What is the difference between broad and narrow sense heritability?

Answer 35

broad (H2) = total genetic variance narrow (h2) = additive genetic variance

Question 36

What does the equation R = h2 x S mean?

Answer 36

R (phenotypic response) = h2 (narrow sense) x S (selection strength) aka the breeder's equation

Question 37

Why was one hypothesis rejected regarding mice colours?

Answer 37

although both MC1R and Agouti genes can affect pigments, Gulf and Atlantic mice did not share the MC1R mutation so this is rejected proper hypothesis: both populations have lighter pigment from Agouti gene variations

Question 38

What mutation of the BRCA1 gene can be traced back to a common ancestor?

Answer 38

point mutation of G base to T

Question 39

What type of genes are used in genetic tracing?

Answer 39

conserved (slow to change) genes (i.e metabolic) for distant relatives and mitochondrial (accumulates mutations) for close relatives

Question 40

What methods are used in building molecular phylogenetic trees?

Answer 40

- maximum parsimony (shortest pathway explanation) - genetic distance - maximum likelihood - probability models

Question 41

What are the two hypotheses for human evolution?

Answer 41

out of africa - all populations sourced from an origin population in africa - tested by observing genetic differences in populations --> highest variation in old populations in/around africa multiregional distribution - regional homo erectus populations interbred to derive homo sapiens multiple times

Question 42

Where would you expect a higher percentage of neanderthaal DNA?

Answer 42

eurasia

Question 43

Where was HIV hypothesized to be sourced from?

Answer 43

- primate related viruses jumped to humans in Africa from bushmeat practices - SIV mutated to allow it to to target human white blood cells - M and N strains evolved directly in humans - O and P strains developed during spread from gorillas to primates to humans