Genetics Final Exam part 1 :)

In pet rabbits, brown coat color is recessive to black coat color. A black female rabbit gives birth to four black-coated and three brown-coated baby rabbits. What can be determined about the genotype of the baby rabbits' father?

He could be heterozygous black/brown or homozygous brown

Albinism is a total lack of skin pigment due to an autosomal recessive gene. A man is normally pigmented, but his father was albino. He marries a woman who is albino. What is the probability of this couple having an albino child?

1/2

The process that converts the information in RNA into proteins is known as _______________.

Translation

Meiosis results in diploid cells.

False

In a given family, the father carries a mutation in a mitochondrial gene, but the mother does not. The chance of their children inheriting the mitochondrial mutation is:

0%

Round seeds (R) are dominant to wrinkled seeds (r), and yellow seeds (Y) are dominant to green seeds (y). A true-breeding pea plant with round and yellow seeds is crossed to a true-breeding plant with wrinkled and green seeds. The F1 progeny are allowed to self-fertilize. What is the probability of obtaining a wrinkled, green seed in the F2?

1/16

A new muntjac species that you are studying has 9 different chromosomes. Like all mammals, the muntjac is diploid. How many chromosomes would you expect to see in a normal somatic (non-gamete) cell from this organism?

18

"Dumpy" is a commonly used mutant phenotype in the nematode worm C. elegans. Two "Dumpy" individuals are crossed to each other, and this cross produces 210 "Dumpy" and 70 wild-type individuals. If one of the "Dumpy" individuals used in this cross was mated with a wild type, would be the ratio of "Dumpy": wild-type observed in the offspring?

1:1

If you have a fly with the genotype A/a; B/b, and you cross it with a homozygous recessive individual, what phenotypic ratio would you expect in the progeny?

1:1:1:1

In chickens, the dominant allele Cr produces the creeper phenotype (having extremely short legs). However, the creeper allele is lethal in the homozygous condition. If two creepers are mated, what proportion of the living progeny will be creepers?

2/3

The pedigree below shows the segregation of an autosomal dominant trait. If IV-1 marries IV-5, what is the probability that their first child will be affected? Assume that the homozygous mutant genotype is viable and has the same phenotype as the heterozygote.

3/4

You are analyzing an unusual DNA sequence from a tardigrade, and find that it only contains 10% thymine. In this case, how much of this sequence would you expect to be guanine?

40%

In Mendel's peas, yellow seeds are dominant to green. A pure-breeding yellow plant is crossed with a pure-breeding green plant. All of the offspring are yellow. If one of these yellow offspring is crossed with a green plant, what will be the expected proportion of plants with green seeds in the next generation?

50%

Which of the following statements is TRUE?

A testcross can be used to determine whether an individual is homozygous or heterozygous for a dominant allele

In horses, the black coat color is due to a dominant allele B, and the chestnut coat color is due to a recessive allele b. The trotting gait is due to a dominant allele T, and the pacing gait to the recessive allele t. What gametes will be produced by a homozygous black pacer?

All B; t

The subunits which make up a protein are:

Amino acids

tRNAs play a key role in protein synthesis. One end of a tRNA contains a(n) _________, and a(n) ________ is attached to the other end.

Anticodon, amino acid

Examine the pedigree below. What is the most likely mode of inheritance?

Autosomal recessive

Hair color is determined 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. A black female Labrador retriever was mated with a yellow male. Half of the puppies were black and half were yellow. If the genotype of the black female parent was Bb Ee, then what was the genotype of the other parent?

BB ee

Alleles of genes that cause autosomal recessive disorders must be inherited from _____________ in order for the offspring to be affected by the disorder:

Both parents

Deafness in humans is often an autosomal recessive phenotype. However, it can be caused by mutations in a number of different genes. If two individuals with autosomal recessive deafness have a child together, and the child has normal hearing, what genetic phenomenon is this an example of?

Complementation

Homologous chromosomes always contain the same alleles.

False

Meiosis results in two daughter cells that are identical to the starting cell.

False

Recombination occurs during DNA replication.

False

Which of the following statements is FALSE?

Generally, chromosomes of eukaryotes are circular

If the pedigree below is for an autosomal recessive characteristic, which individuals are definitely heterozygous?

I-1, I-2, II-4, II-5, III-1

In your spare time, you decide to take up breeding guppies. You purchase some guppies from a pure-breeding green line, and some from a pure-breeding yellow line. You cross them, and the resulting F1 progeny are all pale green, unlike either parent. Curious as to what could produce this phenotype, you make an F1 x F1 cross to produce F2 progeny. In the F2, you observe the following ratio: 1/4 yellow, 1/2 pale green, and 1/4 green guppies. What genetic phenomenon is causing this? (simplest possible explanation!)

Incomplete dominance

What is the role of the SRY gene in humans?

It is located on the Y chromosome and initiates the developmental pathway toward the male phenotype.

The following diagram shows a cell, chromosomes, and spindle fibers attached. What process is this cell undergoing?

Metaphase I of meiosis

The pedigree below shows the inheritance of a rare disease. What is the most likely mode of inheritance of this disease?

Mitochondrial

Probabilities are calculated using the addition (sum) rule when they are:

Mutually exclusive

In the diploid cells of an organism, there can be ____________ different allele(s) of a given single copy nuclear gene

One or two

Round seeds (R) are dominant to wrinkled seeds (r), and yellow seeds (Y) are dominant to green seeds (y). A true-breeding plant with round and yellow seeds is crossed to a true-breeding plant with wrinkled and green seeds. What is the genotype of the F1 progeny?

R/r; Y/y

The ability to roll up your tongue on the sides (T, tongue rolling) is dominant to the inability to roll your tongue (t). A woman who can roll her tongue has a child with a man who cannot roll his tongue. The child has his father's phenotype. What is the mother's genotype?

T/t

An individual displays a dominant phenotype. What is the best way to determine if the individual is homozygous dominant or heterozygous at that locus?

Testcross

In Labrador retrievers, black coat color is dominant to brown. Suppose that a black Lab is mated with a brown one and the offspring are four black puppies and one brown puppy. What can you conclude about the genotype of the black parent?

The genotype must be Bb

A researcher working on zebrafish is interested in the genetics of eye development. She isolates a series of mutant fish that all show a failure of retina development. She then breeds them, determines that the mutations are recessive, and develops pure-breeding strains from each original mutant. What would be a logical next step in her study of these mutations?

To perform a complementation test by crossing the mutant strains with one another.

Homologous chromosomes always contain the same genes

True

If a woman has red-green colorblindness (an X-linked recessive trait), her father must have also had the disorder.

True

The phenotype of the heterozygote determines if a given mutant allele is dominant, recessive, or incompletely dominant.

True

Incomplete penetrance is:

When a given genotype does not always generate the expected phenotype.

An example of a phenotype is:

White eyes in Drosophila

If a human trait is never passed from father to son, it is likely that this trait is:

X-linked

Which of the following human genotypes is associated with Klinefelter syndrome?

XXY

If an organism of genotype Aa was used for a testcross, what was the genotype of the other individual used in the cross?

aa

The following figure shows chromosomal separation taking place. The letters stand for genes; capital and lowercase letters stand for different alleles. The diploid chromosome number in this organism is four. What process is shown?

anaphase of meiosis II

The ability to curl one's tongue into a U-shape is a genetic trait. Curlers always have at least one curler parent but noncurlers can have one or both parents who are curlers. Using C and c to symbolize the alleles that control this trait, what is the genotype of a noncurler?

cc

The attachment point on the chromosome for spindle microtubules is the:

centromere

While doing fieldwork in Madagascar, you discover a new dragonfly species that has either red (R) or clear (r) wings. Initial crosses indicate that R is dominant to r. You perform three crosses using three different sets of red-winged parents with unknown genotype and observe the following data: Cross Phenotypes 1 72 red-winged, 24 clear-winged 2 12 red-winged 3 96 red-winged Which cross is likely to have at least one parent with the genotype RR?

crosses 2 and 3

The process of splitting the cytoplasm, which separates one cell into two, is termed:

cytokinesis

Freckles are caused by a dominant allele. A man has freckles but one of his parents does not have freckles. What is the man's genotype?

heterozygous

Coat color is determined by two loci in large cats. Two pink panthers fall in love and produce a large litter of baby panthers with the following phenotypic ratios: 12/16 pink; 3/16 black; and 1/16 white. What kind of gene interaction is this?

dominant epistasis

In Drosophila, flies that are XXY but have a normal diploid set of autosomes have been found. Such XXY chromosome constitutions have also been found in humans. The sex of such individuals is expected to be:

female in Drosophila but male in humans.

A deletion of a small region on the long arm of chromosome 15 causes a developmental disorder in children called Prader-Willi syndrome when the deletion is inherited from the father. However, the deletion of this same region of chromosome 15 can also be inherited from the mother, but this inheritance results in a completely different set of symptoms, called Angelman syndrome. What type of genetic phenomenon does this represent?

genomic imprinting

A Barr body is a(n):

inactivated X chromosome, visible in the nucleus of a cell that is normally from a female mammal.

In pedigree analysis, consanguinity refers to:

mating between two closely related parents.

The centromere divides a chromosome into two sections or "arms." A chromosome is found to have two arms of equal lengths. Such a chromosome can be BEST described as:

metacentric.

Polydactyly is the condition of having extra fingers or toes. Some polydactylous persons possess extra fingers or toes that are fully functional, whereas others possess only a small tag of extra skin. This is an example of:

variable expressivity.

Which of the following are NOT prokaryotes?

viruses

With regard to the ABO blood types in humans, determine the possible blood types and proportions of offspring of the following parents: Female parent: Blood type A, whose father was blood type B Male parent: Blood type B, whose mother was blood type O

¼ A, ¼ B, ¼ AB, ¼ O