Week 5
What are we crossing in a complementation test? What is the purpose?
Mutant strains; we are trying to determine if the mutations occur in the same gene/locus or if complementation is occurring.
What are the 4 main steps of imprinting?
establishment, maintenance, erasure and reestablishment of the imprint
An adoption study was used to determine nature vs. nurture of depression. The study results are as follows:
Does this indicate stronger genetic (nature) or environmental (nurture) factors?
genetic
Draw the alleles for the following parental genotype if it is in coupling and if it is in repulsion:
FfTt
Coupling: FT/ft
Repulsion: Ft/fT
What is epigenetics?
Non-permanent modifications to a gene/chromosome that affect gene expression
What does a "-" signify on a complementation table?
mutant, same complementation group, not in complementation
The Igf gene promotes growth in mice. A dwarf male mouse is crossed with a normal female and all offspring are small. When a dwarf female mouse is crossed with a normal male, all the offspring are normally sized. Assuming this is a recessive trait, what best explains this phenomenon.
Genomic imprinting
Which of the following traits demonstrates the the a very strong genetic component based on the given concordance rates:
Type I Diabetes
A pea plant with yellow seeds (Yy) and tall stems (Tt) is crossed with another pea plant with green seeds (yy) and short stems (tt). The following types and numbers of offspring were obtained:
22 YyTt
67 Yytt
70 yyTt
21 yytt
What is most likely influencing the frequency of these offspring genes?
a. Independent assortment
b. Coupling
c. Repulsion
d. Complete Linkage
repulsion
Two rabbits with a genetic disease caused by an autosomal recessive mutation have a litter of baby rabbits. None of their 12 offspring have the disease. Which of the following is a valid genetic explanation for this finding?
a. The two rabbit parents carry mutations for the disease in the same gene as one another
b. The two rabbit parents carry mutations for the disease in different genes from one another
c. The disease is an X-linked recessive trait
b
Why is cytoplasmic DNA inherited uniparentally? (HINT: what theory explains why)
Endosymbiotic theory (mito and chloro have their own DNA); only the female gamete passes on it's cytoplasm
What is the most likely mode of inheritence:
x-linked recessive
Sickle Cell Anemia is being studied in twins. In one study, 43 monozygotic twin pairs were identified in which at least one member of the pair had Sickle Cell. In 13 of these twin pairs, the other member of the pair also had Sickle Cell Anemia. What is the concordance rate for Sickle Cell in monozygotic twins
30%
Female tree frogs heterozygous for three recessive mutations f (four toes), s (spots), and r (red eyes) were testcrossed and the following progeny were obtained:
What is the distance from the f and s genes?
29.5%
Which of the following would you expect to have the exact same mitochondrial DNA?
A grandfather and grandson
A woman and her husband
A man and his sister’s daughter
A woman and her brother’s daughter
A man and his sister’s daughter
A female varigated 4-oclock plant is crossed with a male white plant. What are the possible offspring phenotypes?
white, green, variegated
Phil and Claire have three kids (Alex, Hayley and Luke). They are surprised when they find out Hayley has been diagnosed with sickle cell anemia since neither Phil nor Claire have the disease. Claire’s brother, Mitchell also has sickle cell anemia, although neither of their parents (Jay and Dede) have the disease. What is the most likely mode of inheritance for this trait and what are the genotypes of Phil and Claire.
Autosomal recessive; Aa & Aa
In a test-cross between an individual who is AaBb, and an individual who is aabb, the following types and numbers of offspring were obtained:
27 AaBb
30 Aabb
29 aaBb
32 aabb
Which of the following is most likely true?
a. The two genes are located close together on the same chromosome
b. The two genes are located on different chromosomes or far apart on the same
c. The genes show repulsion
d. The genes show coupling
The two genes are located on different chromosomes or far apart on the same
Female tree frogs heterozygous for three recessive mutations f (four toes), s (spots), and r (red eyes) were testcrossed and the following progeny were obtained:
What is the difference between the s and r genes?
23.5%
If there is no recombinant offspring, what can we say about the distance between the two alleles?
They are in the same locus, 0 map units apart, completely linked
Put the following mutant strains in complementation groups. How many genes are there? Are mutations 2 and 9 in complementation?
Mutant 1 3 5 7 9
2 + + + + -
4 + + + - +
6 + - - + +
8 + + + - +
10 + + + + +
G1: 3,5,6
G2: 2,9
G3: 7,8,4
G4: 1
G5: 10
5 genes
No
The direction of shell coiling in a species of snails is determined by the genetic maternal effect. The allele for dextral s+ is dominant to the allele for sinistral s. Squidward has a pet snail named Snellie that is sinistral and reproduces only as a female. Which of the following statements are TRUE regarding Snellie.
Snellie's genotype cannot be s+s+
In a species of fly, smooth wings (W) are dominant to wrinkled wings (w) and red bodies (R) are dominant to yellow bodies (r).
A WwRr and wwrr fly mate and produce the following offspring:
What is the percent recombination frequency for this cross?
17%
Female tree frogs heterozygous for three recessive mutations f (four toes), s (spots), and r (red eyes) were testcrossed and the following progeny were obtained:
What is the distance between the f and r genes?
44%
Determine the order of 4 genes on a chromosome given the following recombination frequencies:
AB 5%
AC 15%
BC 10%
AD 8%
BD 13%
CD 23%
c,b,a,d