BIOC15H3 Lecture Notes - Lecture 9: Dihybrid Cross, Eosin, Black Fly

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ivoryhorse944

18 Nov 2013

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Bioc15fall2013 lecture 9 notes: sex linkage maps and inheritance and lecture 10: linkage and chromosomes. Seed coat pattern in lentils are determined by a gene with 5 alleles spotted (cs), dotted, clear, marbled-1 (cm1) and marbled-2 (cm2) Sorting out the dominance relations by select crosses of lentils: f2 phenotypes from dihybrid crosses ill be 9:3:3:1 ratio only when dominance of alleles of both genes is complete. Complementary gene action generates purple flower colour in sweet peas: dihybrid cross generates a 9:7 ratio in f2 progeny 9 purple and 7 white. B_ee(3) and bbee(1) were golden (so 4 golden in total: epistasis 2 or more genes interact to control a phenotype. Genetic heterogeneity in humans: mutations in many genes can cause deafness. 3 two deaf parents can have hearing offspring due to genetic complementation (homozygous when parents carry mutations in the same gene, complementation does not occur and thus the child will be deaf.

Related Questions

1. Codominance results in:

a) joint expression of two alleles
b) intermediate expression of two alleles
c) sometimes dominance , sometimes recessiveness
d) none of the above

(I am stuck between A or B. Why is A or B the answer? TYSM!)

CAN you please explain how to get these two following questions? I am kind of confused. TYSM!-->

2) In drosophila, fused veins is inherited as an X-linked recessive. If a fused vein male is crossed with a wild type female, the phenotypes of the F1 offspring will be:

A) All fused vein
B) All wild type
c) 1/2 wild type females, 1/2 fused vein males
D) 1/2 fused vein females, and 1/2 wild type males
E) 1/2 wild type famels: 1/4 wild type males: 1/4 fused vein males

3) The recessive muations curved wing and sepai eye are located on different autosomal chromosomes in drosophila. A curved wing female is crossed to a sepia eye male to produce the F1. If an F1 female is then crossed to a curved wing, sepia male, what phenotypic ratio will be expected in their offspring?

A) 1/4 WT ; 1/4 sepia; 1/4 curved; 1/4 sepia, curved
B) 2/4 WT; 1/4 Sepia; 1/4 curved
C) 9/16 WT; 3/16 sepia; 3/16 curved; 1/16 sepia, curved
D) 1/2 sepia; 1/2 curved

___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).

BIOC15H3 Lecture Notes - Lecture 9: Dihybrid Cross, Eosin, Black Fly

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