Genetics Final: Midterm #2 Questions

Question 1

Suppose that extra fingers and toes are caused by a recessive trait, but it appears in only 40% of homozygous recessive individuals. Two heterozygotes conceive a child. What is the probability that this child will have extra fingers and toes?

Answer 1

.10

Question 2

In humans, blood types A and B are codominant to each other and each is dominant to O. What blood types are possible among the offspring of a couple of blood types AB and B?

Answer 2

A, B, and AB only

Question 3

Refer to question 3

Answer 3

:)

Question 4

Hair color is determine in Labrador retrievers by alleles at the B and E loci. A dominant allele B encodes black pigment, whereas a recessive allele b encodes brown pigment.
Alleles at a second locus affect the deposition of the pigment in the shaft of the hair; dominant allele E allows dark pigment (black or brown) to be deposited, whereas recessive allele e prevents the deposition of dark pigment, causing the hair to be yellow.
What type of gene interaction does this represent?

Answer 4

Recessive epistasis

Furthermore, if a black female with the genotype Bb Ee was mated with a yellow male and half of the puppies were yellow, 1/4 were black and 1/4 were brown.
What is the genotype of the yellow male?
bb ee
All recessive

Question 5

Look up 6-8 on exam.

Answer 5

:)

Question 6

Linked genes are _____

Answer 6

on the same chromosome

Question 7

recombination occurs through:

Answer 7

Crossing over and independent assortment

Question 8

A testcross includes:

Answer 8

One parent who shows the dominant phenotype for one or more genes and a second parent who is homozygous recessive for these genes.

Question 9

Review linkage and formulas for linkage.

Also, interference values.

Answer 9

:)

Question 10

The image of the complete set of chromosomes possessed by an organism is called a

Answer 10

karyotype.

Question 11

Know chromosome rearrangement images.

Answer 11

review on 19-21

Question 12

What is not true about chromosomal inversions?

Answer 12

The inversion mutations will not likely have pronounced phenotypic effects since there is no loss of genetic material.

Question 13

These are true statements of chromosomal inversions:

Answer 13

• The individual organisms have neither lost nor gained any genetic material.
• An inversion can break a gene into two parts and separate each to different locations.
• The expression of the genes may be altered due to the positional effect.
• Individuals heterozygous for inversions may end up producing abnormal gametes

Question 14

What form of aneuploidy describes and organism that has an extra copy of a single chromosome?

Answer 14

Trisomy

Question 15

What form of aneuploidy causes primary down syndrome?

Answer 15

Trisomy

Question 16

Which type of chromosome mutation is responsible for familial down syndrome?

Answer 16

Robertsonian translocation

Question 17

A man has a condition where all of his gamete undergo meiosis I normally, but have a nondisjunction of the x chromosome during meiosis II. He mates with a woman who produces all normal gametes. What is the probability that the fertilized egg will develop into a child with Turner syndrome (XO)? Assume that all gametes and zygotes are viable.

Answer 17

1/4

Question 18

A man has a condition where all of his gametes undergo nondisjunction of the sex chromosomes in meiosis I, but meiosis II proceeds normally. He mates with a woman who produces all normal gametes. What is the probability that the fertilized egg will develop into a child with Klinefelter syndrome (XXY)? Assume that all gametes and zygotes are viable

Answer 18

1/2

Question 19

What type of organism results from the hybridization of a haploid gamete from one species with a diploid gamete from a different species?

Answer 19

allotriploid

Question 20

A newly discovered species of dung beetle has 2n=16 chromosomes. It mates with a closely related beetles species that has 2n=12 chromosomes.
How many chromosomes would there be in an allotriploid beetle produced from this cross?

Answer 20

20 or 22

Question 21

What do nonsense mutations do?

Answer 21

Convert a codon for a particular amino acid within a gene into a stop codon.

Question 22

Huntington’s disease is an example of a disease caused by what type of mutation?

Answer 22

Expanding nucleotide repeat

Question 23

Insertion or removal of one or more nucleotide base pairs in DNA within a gene often results in a _____ mutation.

Answer 23

Frameshift

Question 24

Transposable elements are found:

Answer 24

in practically all organisms

Question 25

This is a characteristic of retrotransposons:

Answer 25

They transpose through an RNA intermediate

- They also create a duplication of a target sequence on each side of them when they reach a new site

Question 26

When the f factor integrate into the E. coli chromosome, the result is an ____ strain

Answer 26

Hfr

Question 27

Cotransformation between two genes is more likely if they are ______________-

Answer 27

close to each other.

Question 28

The process of transferring DNA from one bacterium to another through a bacteriophage is called:

Answer 28

transduction