Genetics Flashcards
In what stage can a protein be functional? What can occur if the protein was modified?
quaternary
protein would change function or be disabled
What does DNA translation and transcription accomplish?
transcription = turns RNA into mRNA
translation = turns mRNA into protein
What roles do RNA have?
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
What is the molecular clock hypothesis?
neutral mutations should occur in a predictable clock-like fashion
What molecule can affect a phenotype?
microRNA (binds to mRNA)
What is alternate splicing?
trimming different parts of an RNA out to make different mRNA which translate into various proteins
What makes up non-coding sections of the genome?
- pseudogenes
- RNA genes (remnants of viruses)
- microsatellites (highly mutable repeating segments)
What is a point mutation/base substitution?
change in a single base
What is an insertion mutation?
addition of a base/bases
What is a deletion mutation?
removal of a base/bases
What is a gene duplication?
addition of an identical gene
What is an inversion mutation?
reversal of the gene order
What is a chromosome fusion mutation?
combining two chromosomes
What is a genome duplication mutation?
increasing the ploidy by copying chromosomes
What are some examples of human point mutations?
- albinism
- polydactyly
- fused limbs
- piebaldism
What protein is responsible for albinism?
tyrosinase (point mutation prevents its production)
In what stage of meiosis are mutations most likely to occur?
prophase 1 (crossing over)
What is polyphenism?
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
What conditions were laid out in the Hardy-Weinberg theorem?
- 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
How did a mutation affect mosquitos in France?
- 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
What effect does genetic drift have on a population?
randomly changes frequency of some alleles (can increase or decrease)
What effect does bottlenecking have on a population
sudden reduction in population changes the frequency of alleles present, allele diversity can decrease –> can lead to inbreeding or genetic drift
What is a human example of the founder effect?
Norfolk Island: colonizers had a higher representation of migraine-inducing gene
Define an inbreeding depression
reduced fitness/reproductive success in an individual as a result of inherited deleterious genes from inbreeding
What is antagonistic pleiotropy?
when a mutation in one gene has negative effects on other genes
How does having less Eda expression (i.e is homozygous recessive) benefit freshwater sticklebacks?
less bony plates produced = more energy directed towards growth and earlier reproduction
What is directional selection and provide an example
population phenotypes favour one extreme end
i.e oil content in cultivated corn
What is stabilizing selection and provide an example
population phenotypes favour the intermediate
i.e human baby sizes, gall fly gall sizes
What is disruptive selection and provide an example
population phenotype favours both extremes
i.e limnetic + benthic sticklebacks, high and low bristle flies
What process can cause identical twins to have different phenotypes?
methylation (addition of CH3) can silence a gene
What is negative frequency dependent selection?
when a phenotype has a higher fitness when its considered rare
What is a heterozygote advantage?
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
What possible advantage do kermode bears have over normal black bears?
possibly better at hunting (harder for fish to see)
What are additive alleles?
multiple genes contributing to a phenotype, and the phenotype is stronger when more copies are present
What is the difference between broad and narrow sense heritability?
broad (H2) = total genetic variance
narrow (h2) = additive genetic variance
What does the equation R = h2 x S mean?
R (phenotypic response) = h2 (narrow sense) x S (selection strength)
aka the breeder’s equation
Why was one hypothesis rejected regarding mice colours?
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
What mutation of the BRCA1 gene can be traced back to a common ancestor?
point mutation of G base to T
What type of genes are used in genetic tracing?
conserved (slow to change) genes (i.e metabolic) for distant relatives and mitochondrial (accumulates mutations) for close relatives
What methods are used in building molecular phylogenetic trees?
- maximum parsimony (shortest pathway explanation)
- genetic distance
- maximum likelihood
- probability models
What are the two hypotheses for human evolution?
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
Where would you expect a higher percentage of neanderthaal DNA?
eurasia
Where was HIV hypothesized to be sourced from?
- 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
