BIO152H5 Lecture Notes - Lecture 7: Genetic Variation, Monosomy, Pleiotropy

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redmink995

30 Nov 2017

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Genetic variation the basis to which natural selection can work on. Genetic variation means that there is variation in the genetic makeup of the organisms, so that some can survive certain environmental changes and some cannot. Its connection to evolution is that without genetic variation, populations cannot evolve because there would be no change in the population. Epistasis one trait affecting the expression of another trait. For example, in terms of dog"s coat color. There are two different genes, one for disposition and one for darkness. If a dog has the allele for large disposition and darkness, then the coat color will be black. The disposition of that color would influence the darkness of that color. Polygenic inheritance more than one gene making up the overall physical characteristic of that individual. In terms of height, there is not simply one gene for height. There are a number of different genes to dictate how tall someone is.

Related Questions

QUESTION 1

Jim is blood type A, his brother John is type O and his sister Jane is type AB. What are the genotypes of their parents?

Which of the following is true for alleles that show incomplete dominance?

Heterozygotes have a genotype like the dominant allele.

Homozygotes have a genotype like the recessive allele.

Heterozygotes have a phenotype intermediate between the dominant and recessive alleles.

Homozygotes have the same phenotype as the heterozygotes.

QUESTION 3

Which principle of inheritance concluded that when games are formed in meiosis, the two alleles of each gene separate from one another, and each gamete receives only one allele?

independent assortment

Which term best describes a condition in which alleles at one locus can alter the expression of alleles at another locus?

polygenic inheritance

A single unit of genetic information located on a chromosome defines:

The physical expression (appearance or function) of an organism's genes defines:

genotype

a single characteristic

Palomino horses (golden color with a blond mane) are an incompletely dominant trait produced by the combination of the chestnut color allele and the cream color allele. If you wanted to produce as many palominos as possible, which mating strategy below would be the best choice?

Which term best describes the effect of a single gene on multiple aspects of the phenotype?

polygenic inheritance

QUESTION 9

Which term best describes the separate expression of both alleles for a single trait in the same cell?

polygenic inheritance

QUESTION 10

One form of a gene found on a single chromosome defines:

A chocolate lab (whose mother was a yellow lab) is mated with a black lab whose genotype is BbEe. What fraction of the offspring would be expected to be yellow labs?

What type of allele is always expressed regardless of whether the individual is homozygous or heterozygous for it?

Both the dominant and recessive alleles

Given the parents AABBGgHhrr Ã AabbGgHhRr, assume simple dominance and independent assortment. What proportion of the progeny will be expected to have the genotype AaBbggHHrr?

___________________ is defined as having two of the same type of allele for a particular trait.

The physical position of an allele on a single chromosome defines:

Which term best describes two or more genes affecting the phenotype in an additive fashion?

codominance

polygenic inheritance

Canaries: Green (wild-type) Pied phenotype Yellow type

Canaries are popular pets and easy to breed in captivity. Additionally, they display great phenotypic diversity, which allows you to do some interesting genetic investigations with them.

When you take a canary from a true-breeding green strain and cross it with a canary from a true-breeding yellow strain, all offspring display the pied phenotype. Based on this you suspect that this color variation is inherited by a gene with a co-dominant inheritance pattern (showing both phenotypic traits in hybrid phenotypes).

You decide to test this hypothesis. To do so, you take pairs of your hybrid F1 individuals (of pied phenotype), and cross them to produce an F2 generation.

After many dozens of crosses and hundreds of offspring, you arrive at the peculiar ratio of:

3/16 green : 6/16 pied : 7/16 yellow

Which of the following hypotheses are consistent with these data? (Note that not all of these hypotheses are mutually exclusive. Assume that the two genes are independently assorting)

Hint: This problem is very hard to work from the given ratios to what is happening genetically. It is easier to "work backwards" and start with each choice below, and see if you can obtain all or important aspects of the results of your cross when making the assumption that the answer choice is correct.

Select all that apply:

Select one or more:

a. At least one of the genes involved is sex linked.

b. One gene controls production of darker pigment (melanin which appears green when mixed with yellow). A second gene acts as a patterning gene with one allele causing expression and the other non-expression of melanin and when in the heterozygous condition each allele controls melanin expression on different parts of the body so long as the bird's genotype of the first gene allows for the production of melanin.

c. this is a single-gene trait with co-dominance

d. one of the two genes involved displays complete dominance, while the other displays co-dominance.

e. the genes involved are epistatically interacting

f. more than one gene is involved

1. A) Explain how changes in the environment drive evolutionary change. B) Provide and explain an example

2. A) Explain how the Hardy-Weinberg equation allows us to find evidence of evolution. B) Could processes other than Natural Selection result in deviation from the Hardy-Weinberg equilibrium? List and explain each one: C) define what the process is and D) the effect it has on the allele frequency.

3. A gene that is responsible for multiple traits (pleiotropy), for example the same allele causes sickle-cell anemia and provides resistance to malaria. Would a gene that controls these two traits respond equally to natural selection favoring malaria resistance as a non-pleitropic gene that only controls malaria resistance? Explain your answer.

4. A) Explain how lack of genetic variation limits evolution and provide an example. B) Explain how epistasis limits evolution and provide an example

Questions 5-6 are based on the following:

Letâs say you are studying a population of Japanese four oâclock plants. In these plants, the allele for red color flower shows incomplete dominance over the allele for white flowers. This is very convenient for this experiment because you can distinguish the heterozygous (pink flowers) from the homozygous dominant (red flowers). For your experiment, you produced a large number of plants, 25% had red flowers, 25% had white flowers and 50% had pink flowers. You transplanted them into different habitats and left some in the lab (using the same proportions in all the habitats). You waited a few years, while plants reproduce for a few generations and then you go back and resample the populations youâve transplanted.

5. In the lab you ensured that all individuals receive all requirements to grow and reproduce and mate randomly. A) What do you expect the distribution of the phenotypes after a few generations breeding in the lab? B) Is the lab population in Hardy-Weinberg equilibrium? Yes/No, explain

6. In habitat A, you find that you only have red flowering plants and white flowering plants but there are no pink flowering plants. A) Is the population in habitat A in Hardy-Weinberg equilibrium? Yes/No, explain. B) Which one(s) of the five agents of evolutionary change could be responsible for these results? Explain. C) What type(s) of selection (stabilizing, disruptive, directional, oscillating, etc...) could be responsible for the results in habitat A? Explain

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BIO152H5 Lecture Notes - Lecture 7: Genetic Variation, Monosomy, Pleiotropy

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