HMB265H1 Lecture Notes - Lecture 13: Epistasis, Selective Breeding, Twin

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rosebadger889

10 Nov 2017

School

UTSG

Department

Human Biology

Course

HMB265H1

Professor

Maria Papaconstantinou

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HMB265H1 Full Course Notes

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Heritability = statistical measure that helps us measure. Quantitative traits = interaction of many traits, also effects of environment. Have to tease apart which are genetic and which are environment attributes. Need measure of distribution of that trait in the population. Take difference between every individual compared to mean and square it. Square root of phenotypic variance = how variable that population is in terms of phenotype. Try to tease apart genetic from environmental components. If have more than 1 variable, have to keep all other variables constant. If want genetic variance have to keep environment constnat. Need genetically identical seeds and plant them in 2 different envronments. Even though grow plants in greenhouse, variance is not 0. But can still compare the 2 different environments and get idea. Growth of genetically identical and genetically diverse dandelions in a greenhouse. Take identical seeds and genetically diverse seeds and plant them in same environment. Contribution of genes to that particular trait.

Related Questions

1. (Problem 2) Why is the relation between genotype and phenotype frequently complex for quantitative characteristics?

Multiple genes are involved.
The alleles are usually recessive.
The environment often influences the phenotype.
Answers A and B are both correct.
Answers A and C are both correct.

2. (Problem 6) How is the standard deviation related to the variance?

The standard deviation is the difference between the mean and the variance.
The standard deviation is the square of the variance.
The standard deviation is the square root of the variance.
The standard deviation is the square root of the difference between the mean and the variance.
The standard deviation is the square of the difference between the mean and the variance.

3. (Problem 7) What information does the correlation coefficient provide about the association between two variables?

How strongly two variables are associated
The difference in the mean values of two variables
The magnitude of the difference between two variables
The difference in standard deviation between two variables
The extent to which each variable deviates from its mean

4. (Problem 10) Narrow-sense heritability is due to what type of genetic variance?

Additive
Environmental
Genic interaction
Dominance
Genetic by environment interaction

pearcat127

___1. Nationally, the most common cause of Down Syndrome is
a. nondisjunction of Chromosome 21 during meiosis
b. translocation of Chromosome 21 onto another chromosome
c. inversion of a large section of Chromosome 21
d. deletion of the Down Syndrome gene
___2. In humans, sex is determined by
a. The presence or absence of the Y chromosome
b. The ratio of X chromosomes to sets of autosomes
c. The temperature during fetal development
d. Which parent is stronger at the time of conception
___3. A translocation is
a. a chromosomal abnormality in which a piece of one chromosome breaks off and attaches to a different chromosome
b. an abnormality in which the chromosomes are translocated out of the nucleus
c. a condition in which the chromosome has broken in two places and come back together with the middle segment backward
d. an abnormality in which there is an extra copy of one chromosome
___ 4. In snapdragons, a red-flowered plant crossed with a white-flowered plant produces all pink-flowered offspring. But crossing two pink-flowered plants produces red, pink, and white in a 1:2:1 ratio. This is a good example of
a. Incomplete dominance
b. Dominance of the red allele over the white allele
c. Lethal effects of the pink allele
d. Sex-linkage of the flower-color alleles
___ 5. If a person with type AB blood marries a person with Type O blood, what blood types are possible in their children? (Assume this trait is a single-gene trait, not complicated by interaction with other genes).
a. A, B, AB, or O
b. A or B only
c. AB or O only
d. AB only 2
___6. In what phase of meiosis are haploid nuclei first formed? a. Anaphase I b. Metaphase II c. Telophase II d. Metaphase I e. Telophase I
___7. What is the phenotype of a heterozygous tall pea plant? a. tall b. Tt c. TT d. tt e. dominant
___ 8. If genes A and B are far apart on a chromosome, and A and C are close together, which of the following observations is expected?
a. Crossing over will occur more often between A and C than between A and B
b. Crossing over will occur at equal frequencies between A and C, and between A and B
c. Crossing over will occur more often between A and B than between A and C
___9. Sometimes an organismâs genotype for one gene masks the effect of a different gene. This phenomenon is called
a. Dominance
b. Incomplete dominance
c. Co-dominance
d. Epistasis
e. Variable expressivity
___10. The dominant allele of a gene is
a. The one that is expressed most often in a population
b. The one that is expressed most often in any particular cross
c. The one that is expressed in an individual that has two different alleles
d. The one that is most healthy to have, that gives the greatest fitness
___11. In human cells, DNA replication occurs
a. In S phase of interphase
b. In G1 phase of interphase
c. In G2 phase of interphase
d. In prophase of mitosis
e. Whenever the cell needs to read the DNA to make proteins
___ 12. A process in which recipient cells take up genes from DNA molecules floating free in the surrounding medium is called
a. conjugation
b. specialized transduction
c. generalized transduction
d. transformation 3
___ 13. Most calico cats are female. However, a few rare males are observed. What is the genotype of a male calico cat?
a. X BX 0
b. X OY
c. X BY
d. X BYY
e. X BX OY
___ 14. A type of red-green color-blindness is a sex-linked (X-linked) recessive trait in humans. Can a woman have this type of color-blindness?
a. Yes, a woman could be color-blind if her mother and father were both heterozygous.
b. Yes, a woman could be color-blind but only if she has an abnormal number of sex chromosomes.
c. No, women can't show sex-linked traits because they lack a Y chromosome.
d. No, women can't show sex-linked traits because they have two X chromosomes.
e. Yes, a woman could be color-blind if her father was color-blind and her mother was a carrier (heterozygous).

HMB265H1 Lecture Notes - Lecture 13: Epistasis, Selective Breeding, Twin

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