Final Genetics Exam1-4

What concept suggests that cells arise only from preexisting cells and that the cell is the fundamental unit of structure and function in living organisms?

cell theory

Gregor Mendel carried out a cross between two pea plants by taking pollen from a plant that was homozygous for round seeds and dusting the pollen onto the stigma of a plant homozygous for wrinkled seeds. Which of the following would be the reciprocal cross that Mendel had carried out for this experiment?

stigma of a plant homozygous for round seed pollinated with pollen from a plant homozygous for wrinkled-seed plant

Round seeds (R) are dominant to wrinkled seeds (r), and yellow seeds (Y) are dominant to green seeds (y). A plant of unknown genotype is testcrossed to a true-breeding plant with wrinkled, green seeds. The offspring produced were 53 round and yellow, 49 round and green, 44 wrinkled and yellow, and 51 wrinkled and green. What is the likely genotype of the parent in question?

RrYy

A diploid somatic cell from a rat has a total of 42 chromosomes (2n = 42). What is the total number of chromosomes present in the cell during metaphase I of meiosis?

42

In a certain species of plant, flowers occur in three colors: blue, pink, and white. A pure-breeding pink plant is mated with a pure-breeding white plant. All of the F1 are blue. When the blue F1 plants are selfed, the F2 plants occur in the ratio 9 blue : 3 pink : 4 white. What is the name for this type of interaction?

recessive epistasis

A mother with blood type B has a child with blood type O. Give all possible blood types for the father of this child.

A, B, O

Which of the following sequences CORRECTLY shows the flow of genetic information during gene expression?

DNA → RNA → protein

Different versions of the same gene are called a(n)

allele

Kinetochore proteins bind to which of the following chromosomal locations?

centromere

The curly gene determines normal (X+) or curly (Xc) wing development in fruit flies (Drosophila). Select the statement that accurately predicts the F2 progeny created by crossing a heterozygous female fly with a curly-winged male fly.

25% X+Xc, 25% XcXc, 25% X+Y and 25% XcY

The fundamental unit of heredity is the

gene

Select the statement that best predicts the outcome if a single pair of sister chromatids fails to separate properly during meiosis II

One gamete will contain an extra chromosome, one gamete will lack a chromosome, and two gametes will be normal.

The complete genetic makeup of any organism is referred to as a

genome

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

If two heterozygous Aa plants are crossed with each other, what will be the genotypic ratio found in the offspring?

1:2:1

A person with albinism is likely to

be susceptible to sunburn

Women with Turner syndrome (XO) and normal women (XX) are clearly different phenotypically. In addition, the vast majority of XO conceptions abort before birth. However, both XO and XX women have one active X chromosome since the X in XO women remains active and one might expect that they would therefore have similar phenotypes. What is the MOST reasonable explanation for their different phenotypes?

Some genes remain active on the inactive X chromosome, and XX women will have two copies of these

genes expressed and XO women only one copy.

Why are viruses not classified as prokaryotes or eukaryotes?

Viruses do not have cell structures that enable independent replication

Which of the following statements describes genetic maternal effect?

the phenotype of the offspring is determined by the genotype of the mother

You identify an XXX fruit fly (Drosophila) that has three sets of autosomes (AAA). Predict the sex of this fly.

female

A mother with blood type A has a child with blood type AB. Give all possible blood types for the father of this child.

B, AB

The concept of dominance states that

when two different alleles are present in a genotype, only the dominant trait is observed in the phenotype

Which of the following is fundamentally the study of evolution?

population genetics

Select the answer that best describes the conceptual error contained in the following misconception: “Brown eyes are dominant over blue eyes.”

Dominance describes a relationship between alleles, not traits

If a female Drosophila that is heterozygous for a recessive X-linked mutation is crossed to a wild-type male, what proportion of female progeny will have the mutant phenotype?

0%

The experiments of Gregor Mendel can be placed into which subdivision of genetics?

transmission genetics

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 proportion of plants with green seeds in the next generation?

50%

In order to be functional, a eukaryotic chromosome requires all of the following EXCEPT

a plasmid

The sex determination system used by Drosophila is called

the X:A sex determination system

How many Barr bodies does a person with Turner syndrome have?

0

A eukaryotic diploid cell from an organism with the ZZ–ZW sex determination system has two pairs of autosomes and a pair of sex chromosomes, Z and W, shown here. What is the probability of a gamete from this individual that has the following genotype: alleles A and b, chromosome Z?

1/8

What allows different cells of an organism to have different phenotypes?

the regulation of gene expression

Which of the following statements about the sex-linked recessive trait of red–green color blindness in humans is FALSE?

A color-blind daughter can have a normal father

Human males with XY chromosomes are _____ and produce two different kinds of gametes, whereas females with XX chromosomes are _____ and produce only one kind.

heterogametic; homogametic

Which statement best describes the process of binary fission?

Binary fission is the process by which prokaryotic cells divide.

Wild-type Arabidopsis has five chromosomes (2n=10). Trisomic plants are designated as "Tr" followed by the trisomic chromosome number—that is, Tr1 is trisomic for chromosome 1. Assuming that trisomy is fully viable and that all possible pairing configurations (including nonpairing) are possible at meiosis, what proportion of the progeny from the cross Tr1;Tr2 × Tr1;Tr2 will have a wild-type chromosomal complement?

1/81

While doing research on deep-sea vents, you discover a very simple new life form. After some initial analysis, you find that this life form contains small fragments of DNA, small complementary RNA fragments, and proteins. Fortuitously, you collected two strains, one that is purple and one that is yellow. You wish to discover which of those three molecules could be the genetic material. The classic experiment of which of the following scientists would be the MOST appropriate to mimic?

Avery, MacLeod, and McCarty

DNA strands grow in the 5′ to 3′ direction. This means that the _____ of an incoming nucleotide attaches to the _____ of the growing strand.

5′ phosphate; 3′ hydroxyl

Which statement does NOT describe a difference between DNA and proteins?

DNA is located in the nucleus, whereas proteins are only located in the cytoplasm of cells.

Which scenario generates nonviable products during meiosis?

single crossover in the inverted region in a cell heterozygous for a paracentric inversion

June has two brothers with Becker muscular dystrophy (BMD), an X-linked recessive condition that allows affected males to survive into adulthood. Her parents are phenotypically normal. She marries Sheldon, who also has BMD. June and Sheldon have a daughter. What is the probability that this daughter will have BMD?

1/4

Which term refers to mating between closely related people?

consanguinity

Which DNA modification is the addition of a –CH3 group?

methylation

Which of the following would NOT necessarily be true for a DNA molecule?

A + T = G + C

How does histone acetylation affect chromatin?

It loosens the chromatin and allows increased transcription.

Which statement is INCORRECT concerning an X-linked recessive trait in humans?

An affected woman almost always has an affected mother.

You are a research assistant in a lab that studies nucleic acids. Your advisor gave you four tubes for analysis. Each of these tubes differs in its contents by the source of its nucleic acids: mouse cytoplasm (single-stranded RNA), yeast nuclei (double-stranded DNA), rotavirus (double-stranded RNA), and parvovirus (single-stranded DNA). The approximate nucleotide base composition of each sample is given in the table below.

tubes 1 and 3

Which of these sequences could form a hairpin?

5′-GGGGTTTTCCCC-3′

Enzyme X is an RNase, a molecule that breaks down RNA molecules. Enzyme Y is a DNase, an enzyme that breaks down DNA molecules. Which of the choices describes a likely similarity between enzyme X and enzyme Y?

Both enzymes break phosphodiester bonds.

Most strains of cultivated bananas were created by crossing plants within and between two diploid species: Musa acuminata (genome = AA) and Musa balbisiana (genome = BB). Some bananas have genome AAB, which is an example of which kind of polyploidy?

allotriploid

You are a researcher studying the genetic basis of colon cancer. You have been working with a colon cancer cell line to determine the expression levels of different genes that might contribute to cancer formation. You obtain the DNA methylation status of five genes of interest (the data are shown in the table below). The plus (+) sign indicates the level of DNA methylation; more plus signs correlate with increased methylation levels.

gene 2

Why do telomeres in somatic cells shorten each time the cell divides?

DNA polymerases cannot replicate the ends of chromosomes.

Pedigrees showing the hypothetical human trait have the following characteristics:

- Only males are affected.

- Affected fathers always pass the trait to sons.

What is the MOST likely mode of inheritance for this disorder?

Y-linked

Two chromosomes have the following segments, where · represents the centromere:

K L M · N O P Q R

S T U V · W X Y Z

What type of chromosome mutation would result in the following chromosomes?

K L M · N O P Q R

S T X Y U V · W X Y Z

displaced duplication

Which of the following is represented in the figure?

reciprocal translocation

Which of the following is attached to the 2′ carbon of a ribose sugar in an RNA molecule?

a hydroxyl group

Species I has 2n=18 and species II has 2n=22. How many chromosomes will be found in an autotetraploid of species II?

44

Which of the following descriptions is NOT true of heterochromatin?

It makes up most chromosomal material and is where most transcription occurs.

What statement best describes supercoiling?

Supercoiling occurs when the DNA helix is subjected to strain.

How did Alfred Hershey and Martha Chase contribute to our understanding of DNA?

They found that the phosphorus-containing components are the genetic material of phages.

Which circle shows a noncovalent bond?

circle b

What is the MOST likely mode of inheritance for the trait segregating in the pedigree below?

autosomal recessive

How did Fred Griffith contribute to our understanding of DNA?

He discovered the "transforming principle" that could genetically alter bacteria.

The bonds that connect nucleotides in a single strand are called _____ bonds.

phosphodiester

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

allotriploid

Which statement describes the structure of a nucleotide?

a phosphate and base attached to a sugar

What typically happens to the small fragment generated by a Robertsonian translocation?

The small fragment often gets lost.

Which diagram shows a nucleotide with a purine base?

diagram D

What is the MOST likely mode of inheritance in the pedigree below?

autosomal dominant

What statement about monozygotic and dizygotic twins is true?

Dizygotic twins share an average of 50% of their genes.

During initiation of translation in bacteria:

specific rRNA base pairs with a sequence in mRNA to position a ribosome at the start codon.

Which enzyme is capable of degrading RNA in the 5′ → 3′ direction?

exonuclease

A ________is a complex structure consisting of several rRNA molecules and many proteins.

ribosome

When codons that code for the same amino acid differ in their _____, a single tRNA might bind both of them

through wobble base pairing.

3′ base

Suppose that some cells are grown in culture in the presence of radioactive nucleotides for many generations so that

both strands of every DNA molecule include radioactive nucleotides. The cells are then harvested and placed in new

medium with nucleotides that are not radioactive so that newly synthesized DNA will not be radioactive. What

proportion of DNA molecules will contain radioactivity after two rounds of replication?

1/2

What is the Shine–Dalgarno sequence?

a consensus sequence that is complementary to a sequence of nucleotides at the 3′ end of 16S rRNA

What term best describes codons that specify the same amino acid?

synonymous

Below is a list of steps in the processing of ribosomal RNAs. Please select the choice that lists the steps in the

CORRECT sequential order.

1. Methyl groups added to specific bases and the 2′-carbon atom of some ribose sugars

2. Transcription of the rRNA precursors from DNA

3. Cleavage of precursor rRNA

4. Individual rRNA molecules ready for ribosome assembly

5. Trimming of precursor rRNA

2,1,3,5,4

Which of the following nitrogenous bases is frequently modified enzymatically to become a rare type of

nitrogenous base in tRNA?

uracil

What would be a likely result of expressing telomerase in somatic cells?

cancer

_____ are tandemly repeated DNA sequences located at the ends of eukaryotic chromosomes.

Telomeres

What protein is key to the specificity between an amino acid and its tRNA?

aminoacyl-tRNA synthetase

Below is a list of steps of intron removal and splicing during pre-mRNA processing. Please select the choice that

lists the steps in the CORRECT sequential order.

1. Attachment of snRNP U1 to the 5′ splice site

2. Transcription of the DNA template into the pre-mRNA molecule

3. Release of lariat structure

4. Splicing together of exons

5. Transesterification reaction at the branch point adenine

2,1,5,3,4

Given the figure below, within which of the following would the 5' untranslated region be located? The sequences in red and light gray are included in the mature mRNA. The sequences in light gray make up the protein-coding sequence of the gene. (PICTURE)

promoter

How many common amino acids are found in proteins?

32

DNA polymerases require all of the following for DNA replication EXCEPT

free 3′ OH

The _________ promoter is upstream of the core promoter.

consensus

An in vitro transcription system that contains a bacterial gene does not initiate transcription. What is one possible problem?

There is a mutation in the inverted repeat sequence that prevents a hairpin secondary structure from forming.

Which of the following is observed in prokaryotes but not in eukaryotes?

The 5' end of a prokaryotic mRNA can be translated while the 3' end is still being transcribed.

What may be the consequence of a mutation in the gene that encodes eukaryotic Rat1 exonuclease for eukaryotic

transcription mediated by RNA polymerase II?

The transcription may not be properly terminated, and RNA polymerase II may not be released.

The diagram shown below is one half of a replication bubble. As the DNA template strands unwind toward the

right, new strands of DNA get synthesized. Which of the following represents a lagging strand? (PICTURE)

B

Which of the following elements would NOT be found in an mRNA molecule?

promoter

Which one of the following statements is NOT true for all E. coli DNA polymerases?

They possess 5′ → 3′ exonuclease activity.

If the sequence of an RNA molecule is 5'–GGCAUCGACG–3', what is the sequence of the nontemplate strand of DNA?

5'–GGCATCGACG–3'

Suppose a mutation occurred that prevented a eukaryotic pre-mRNA from receiving a 5' cap. What would be an expected result?

Translation would not occur as the ribosome would not be able to bind to the mRNA

Translating an mRNA requires two other types of RNA:

tRNA and rRNA.

Which of the following small RNA types is unique to prokaryotes?

crRNA

What kind of RNA molecule can be found in eukaryotes but not in bacteria?

pre-mRNA

Which process is illustrated in the diagram below? (PICTURE)

transcription

Which of the following statements is FALSE regarding TFIID?

It is a transcriptional activator protein.