Mechanisms of Evolution
What is "change in the relative frequency in which an allele occurs in a population due to random events"?
genetic drift
how many genes does a dihybrid cross show the inheritance pattern for?
two
a genetic cross between a homozygous recessive and the genotype in question (aabb x AaBb or AABB)
another name for Recombination
crossing over
what is complete dominance?
only one of the dominant alleles need to be present to be expressed (Rr) or (RR).
Define Bottleneck Effect and what it can lead to in a species
population numbers become so low that survivors carry just a proportion of original genes. Inbreeding is inevitable and population is prone to genetic drift
Define the "F.O.I.L" Method and when you use it
First
Outside
Inside
Last
You use it when crossing two parents to determine the gametes in a Punnet Square
what is a diagram that depicts the biological relationships between an organism and its ancestors (a biological family tree)
pedigree chart
What is the difference between a somatic cell and gametic cell mutation on genetic variation?
somatic cell mutations only affect that organism and are not passed down on to the organism like a gametic mutation
what is incomplete dominance? Give an example of genotype and phenotype.
Incomplete dominance is an inheritance pattern whereby neither allele is dominant over the other. If an individual has a heterozygous genotype (carries two different alleles), neither allele is expressed in the phenotype but instead the phenotype is a blend of both alleles.
white (ww) and red (WW), pink (Ww)
Stabilizing, directional and disruptive selection are all types of ?
Natural Selection
What is the phenotypical ratio for an unlinked dihybrid cross between two heterozygous Parents (e.g. RrYy x RrYy)?
9:3:3:1
what is the difference between and allele and a gene
a gene is a piece of dna that codes for a trait
an allele is a different form of the gene
describe crossing over
pieces of chromosomes exchange pieces of their DNA during metaphase
what is codominance? give an example of geno- and phenotype.
Codominance is an inheritance pattern whereby both alleles are equally dominant. If an individual has a heterozygous genotype (carries two different alleles), both alleles are expressed in the phenotype.
Roan cattle (RR = red, Rr = roan, rr = white)
Give an example of Founder Effect
any example where you reference individuals from a population emigrating / become geographically isolated, "founding" their own population.
decreased genetic variation in new population and more subject to genetic drift
Blue eyes are dominate to green (B) and curly hair dominant to straight hair (H) in poodles. You took your purebreeding Blue eyed and curly haired (BBHH) female poodle to a stud for cross breeding so you could get rich selling the puppies. You have your purebreed papers on hand.
The puppies are so cute, however you notice that you have 6 blue eyed and curly hair puppies and one green eyed and curly haired puppie (bbHH) and one blue eyed and straight-haired puppy. (BBcc)
You paid $2k for the insemination at the breeders. Do you have cause to get your money back? Yes or no? Back your up your answer with science.
Yes get your money back!
BBHH x BBHH can never pass on any recessive alleles
what does dihybrid inheritance mean?
What is the only way of permanately creating new alleles
what are the 3 possible alleles for blood type?
B, A, i
"Survival of the fittest" from Natural Selection.
The industrial revolution changed the air quality and soot ended up on the trees in the habitat of the peppered moth. Light coloured moths were eaten and dark coloured survived. They went from 2% of the population to 95% in just a short biological time.
What selection pressure is this an example of?
Directional Selection
(Selects against one extreme of the trait)
You are becoming a horse breeder and Clydesdales are becoming popular. People are paying heaps of money for chestnut with black legs (CCgg Ccgg, as chestnut is dominant to bay and black legs are recessive to white). You have a friend who says he has found success in successfully breeding this particular colour scheme (phenotype). You decide to go into business together. You breed CcGg x CcGg.
after 3 generations of breeding, you have produced 4 offspring. The horses
are either chestnut with white legs or bay with black legs).
What is going on here? Explain the science and what is or isn't happening?
The genes are linked. No independent assortment occurs. Instead of producing 4 phenotypes (9:3:3:1) you are getting (3 chestnut with white: 1 bay with black) which is two phenotypes. Crossing over is not occuring.
you need to get out of business! A smell a liar
human height, skin colour and eye colour are example of what type of variation
Continuous
(Distributed on a continuum)
describe what happens during metaphase that introduces genetic variation
independent assortment - homologous pairs of chromosomes line up randomly at the equator
segregation - chromatids line up randomly at equator
who's the daddy? Determine whether it is possible that the male is the father of the child (use a Punnett square):
the potential father and the mother both hav AB-type blood. The child has O-type blood.
1 IAIA: 2 IAIB: 1 IBIB
1 type A: 2 type AB: 1 type B
the child cannot be either one of theirs, since neither carry the i allele and ii is required to express the O phenotype.