ANSC 221 Exam #4

Single-strand DNA binding protein

helps to hold the DNA strands apart while they are being replicated

If the DNA of a mammalian promoter region experiences increased methylation on cytosine which of the following results is most likely to occur?

inactivation of the gene

Which molecules directly participate in the process of translation?

mRNA, tRNA, and rRNA

Which of the following statements correctly describes a nucleotide composition? nitrogenous base nitrogenous base, sugar, and phosphate group nitrogenous base and sugar sugar and phosphate group

nitrogenous base, sugar, and phosphate group

DNA ligase

plays role in the elongation of the lagging strand during DNA replication, joining Okazaki fragments together

Topoisomerase

relieves the strain in the DNA ahead of the replication fork caused by the untwisting of the double helix

DNA polymerase I

removes nucleotides from the RNA primer that is used for initiation DNA synthesis

Which of the following enzymes is required to make complementary DNA (cDNA) from RNA?

reverse transcriptase

Which one of the following conditions would most likely cause allele frequencies to change by chance?

small populations

In large-scale, genome-wide association studies in humans, which of the following types of genetic markers are typically sought by researchers?

specific SNPs found more often in persons with a particular disorder than in healthy controls

At which site of mRNA is the ribosome recruited to initiate the translation process?

start codon

In a Hardy-Weinberg population with two alleles A1 and A2 that are in equilibrium. If the frequency of the allele A2 is 0.3; what is the frequency of individuals that are homozygous for this allele?

0.09

Considering that the environmental variance for body weight in a mouse population is 15, and the genetic variation is 7, what is the heritability of a body weight in this population?

0.32

In a Hardy-Weinberg population with two alleles A1 and A2 that are in equilibrium. If the frequency of allele A2 is 0.2; what is the frequency of individuals that are heterozygous for this allele?

0.32

A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (A2A2), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants. What is the estimated frequency of allele A1 in the gene pool?

0.5

A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (A2A2), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants. What proportion of the population is most likely heterozygous (A1A2) for this trait?

0.5

In a Hardy-Weinberg population with two alleles A1 and A2 that are in equilibrium. If the frequency of allele A2 is 0.1; what is the frequency of individuals with A1A1 genotype?

0.81

A particular triplet of bases in the coding sequence of DNA is 5'-AAA-3'. The anticodon on the tRNA that binds the mRNA codon is:

3′-AAA-5′

During elongation, nucleotides are added in which direction?

5' to 3' direction

Use this model of a eukaryotic primary transcript to answer the following question. Assuming that: E = exon and I = intron. 5′- UTR E1 I1 E2 I2 E3 I3 E4 UTR -3′ If the primary transcript is processed and transported to the cytosol, which of the following molecules best represents the mRNA that will be produced? 5′- UTR I1 I2 I3 UTR -3′ 5′- E1 E2 E3 E4 -3′ 5′- UTR E1 E2 E3 E4 UTR -3′ 5′- E1 I1 E2 I2 E3 I3 E4 -3′

5′- UTR E1 E2 E3 E4 UTR -3′

A sample of double-stranded DNA contains 42% cytosine. Approximately what percent of the nucleotides in this sample will be thymine? 8% 16% 42% 58%

8%

Which of the following combinations of base pairs will be found in a molecule of DNA? A = C A = G and C = T A + C = G + T G + C = T + A

A + C = G + T

During the elongation phase of translation, which site in the ribosome represents the first location where a codon pairs with an anticodon?

A site

Which one is polymerized in 5′→3′ during DNA synthesis? Leading strand Lagging strand Okazaki fragments All of these

All of these

Which of the following statements is accurate with regard to a population in Hardy-Weinberg equilibrium?

Allele frequencies should not change from one generation to the next.

Which of the following is NOT included in the functions of the 5' cap and poly-A tail in mRNA? mRNA protection against degradation. Export of mature mRNA into the cytoplasm. Assistance in the initiation of translation. Assistance in terminating the translation.

Assistance in terminating the translation

A researcher introduced many copies of a RNA into a culture of mammalian cells and used a fluorescent probe to follow it. She found that the introduced strands separated; double-stranded RNA degraded and the single-stranded RNA remained. She hypothesizes that the remaining strand is acting as a miRNA. The remaining strand is able to do which process?

Bind to complementary regions of target mRNAs

Hershey and Chase set out to determine which type of molecule is used for genetic inheritance. They completed a series of experiments where E. coli was infected by a T2 virus. Which molecular component of the T2 virus ended up inside the cell? protein RNA ribosome DNA

DNA

Which of the following characteristics allowed Hershey and Chase to determine whether the genetic material was made of DNA or protein? DNA contains sulfur, whereas protein does not. DNA contains phosphorus, whereas protein does not. DNA contains nitrogen, whereas protein does not. DNA contains purines, whereas protein includes pyrimidines.

DNA contains phosphorus, whereas protein does not.

Which one is the correct statement about the central dogma of molecular genetics? RNA is reverse transcribed to the DNA which is translated to protein DNA is transcribed to RNA which is translated to proteins Proteins catalyze DNA replication which then controls all activities Protein give rise to RNA which form DNA

DNA is transcribed to RNA which is translated to proteins

Which of the following statements are TRUE regarding DNA synthesis? (select all that apply) Topoisomerase is the main DNA-replicating enzyme DNA replication is necessary for cell division DNA replication takes place inside the nucleus in Eukaryotes DNA replication is always semiconservative

DNA replication is necessary for cell division DNA replication takes place inside the nucleus in Eukaryotes DNA replication is always semiconservative

Identify which of the following are main techniques of biotechnology.

DNA sequencing Expressing genes Gene editing

Which of the following best explains why a neuron and a pancreatic cell isolated from the same individual contain different sets of proteins?

Each cell type contains different regulatory proteins and, therefor, they express different proteins.

Which of the following statements correctly describes the primary difference between enhancers and proximal elements?

Enhancers are located considerable distances from the promoter; proximal control elements are close to the promoter.

Genetic variation is quantified by the percentage of homozygous loci in a population.

FALSE

High heritability indicates that much of the variation can be attributed to the environmental factors.

FALSE

Low heritability means that genetic factors are likely to have great impact on phenotypic variation.

FALSE

Number of eggs is an example of a continuous trait.

FALSE

Identify which of the following are applications of biotechnology.

Forensics Ancestry

Which of the following mechanisms is commonly used to coordinate the expression of multiple, related genes in eukaryotic cells?

Groups of genes that are expressed together have specific combinations of control elements.

Which of the following statements correctly describes the structure of chromatin? Heterochromatin is composed of DNA, whereas euchromatin is made of DNA and RNA. Both heterochromatin and euchromatin are found in the cytoplasm. Heterochromatin is highly condensed, whereas euchromatin is less compact. Euchromatin is not transcribed, whereas heterochromatin is transcribed.

Heterochromatin is highly condensed, whereas euchromatin is less compact.

Which of the following processes is the best way to determine whether alternative splicing of a given gene occurs?

Isolate mRNA from the given gene and compare the sequences.

Which of the following processes correctly describes alternative RNA splicing? It is a mechanism for increasing the rate of translation. It can allow the production of proteins of different sizes and functions from a single mRNA. It can allow the production of similar proteins from different RNAs. It increases the rate of transcription.

It can allow the production of proteins of different sizes and functions from a single mRNA.

Which of the following characteristics of RNA-seq make it particularly suitable to use in genome-wide expression studies?

It does not require knowledge of the genome's sequence before the study begins.

Which of the following statements accurately describes the structure of a eukaryotic chromosome? It is composed of a single strand of DNA. It is constructed as a series of nucleosomes wrapped around two DNA molecules. It has different numbers of genes in different cell types of an organism. It is a single linear molecule of double-stranded DNA plus proteins.

It is a single linear molecule of double-stranded DNA plus proteins.

Which of the following statements best describes the significance of the TATA box in the promoters of eukaryotes? It is the recognition site for the binding of a specific transcription factor. It sets the reading frame of the mRNA during translation. It is the recognition site for ribosomal binding during translation. It is the recognition site for ribosomal binding during transcription.

It is the recognition site for the binding of a specific transcription factor.

Why is it important to identify the promoter region first before the transcription process can start? It is where the RNA polymerase binds to so the reading of the bases can start It provides the necessary enzyme needed for the transcription to proceed It removes the cap that regulates the transcription process It provides the template that will serve as the pattern to be transcribed

It is where the RNA polymerase binds to so the reading of the bases can start

Which of the following best describes the redundancy in the genetic code? A single codon can specify the addition of more than one amino acid. The genetic code is different for different domains of organisms. The genetic code is universal (the same for all organisms). More than one codon can specify the addition of the same amino acid.

More than one codon can specify the addition of the same amino acid.

The heritability for egg weight in a group of chickens on a farm in Maine is 0.95. Which of the following statements regarding this heritability are TRUE?

Nearly all of the phenotypic variance for this trait in this group of chickens is due to genetic variance. The environment in Maine has low effect on the outcome of this trait.

In analyzing the number of different bases in a DNA sample, all of the following are true regarding the base pairing rule. (select all that apply) Purines are always equal in amount to pyrimidines Adenine forms three hydrogen bonds with Thymine Adenine always pairs with Thymine Cytosine always pairs with Guanine

Purines are always equal in amount to pyrimidines Adenine always pairs with Thymine Cytosine always pairs with Guanine

Which process occurs as part of transcription?

RNA is synthesized

In eukaryotes, there are several different types of RNA polymerase. Which type is involved in transcription of mRNA for a protein?

RNA polymerase II

A technique that can examine the quantity and sequences of RNA in a sample using next-generation sequencing is called:

RNA sequencing

Which of the following is a reason that the low error rate of DNA replication is important to evolution? Replication with a high error rate is likely to kill the cell. Fixing replication errors provides a cellular role for mismatch repair enzymes. Rare errors are the source of variation. Most mutations have no effect on phenotype.

Rare errors are the source of variation

A single nucleotide polymorphism, or SNP, is a variation at a single position in a DNA sequence among individuals.

TRUE

Complex traits are controlled by more than one gene.

TRUE

Genetic variation is quantified by comparing the nucleotide sequences of two or more individuals.

TRUE

Height is an example of a polygenic trait.

TRUE

Heritability is highly used in the fields of animal and plant breeding.

TRUE

Heritability is the proportion of phenotypic variance due to genetic variance.

TRUE

Phenotypic variation observed in a population can be divided into genetic and environmental components.

TRUE

The multiple-gene hypothesis states that each gene contributes to the phenotype in a cumulative way.

TRUE

Two different traits can have the same mean but different amounts of variation.

TRUE

A cell is considered to be differentiated if it has which of the following characteristics?

The cell produces proteins specific to a particular cell type.

Which of the following statements correctly describes the difference between the leading strand and the lagging strand in DNA replication? The leading strand is synthesized in the 3'→ 5' direction in a discontinuous fashion, while the lagging strand is synthesized in the 5'→ 3' direction in a continuous fashion. The leading strand is synthesized continuously in the 5'→ 3' direction, while the lagging strand is synthesized discontinuously in the 5'→ 3' direction. The leading strand requires an RNA primer, whereas the lagging strand does not. There are different DNA polymerases involved in elongation of the leading strand and the lagging strand.

The leading strand is synthesized continuously in the 5'→ 3' direction, while the lagging strand is synthesized discontinuously in the 5'→ 3' direction

Which of the following statements correctly describes the difference between the leading and the lagging strands of DNA in DNA replication? The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction. The leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end. The lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together. The leading strand is synthesized at twice the rate of the lagging strand.

The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction

A researcher introduced many copies of a RNA into a culture of mammalian cells and used a fluorescent probe to follow it. She found that the introduced strands separated; double-stranded RNA degraded and the single-stranded RNA remained. She hypothesizes that the remaining strand is acting as a miRNA. Which piece of evidence would support her claim?

The rate of accumulation of the polypeptide encoded by the target mRNA is reduced

Which of the following statements about RNA processing is FALSE? Introns are removed before mRNA leaves the nucleus The 5' end will be capped Poly-A tail will be added at the 3' end The spliceosomes remove the exon in pre-mRNA

The spliceosomes remove the exon in pre-mRNA

Which of the following statements is TRUE regarding Okazaki fragments? They are not synthesized by DNA polymerase They are synthesized by DNA polymerase on the leading strand They are synthesized by DNA polymerase on the lagging strand They are synthesized by DNA ligase the leading strand

They are synthesized by DNA polymerase on the lagging strand

Which of the following functions are characteristic of general transcription factors in eukaryotes?

They bind to the other proteins or to the TATA box.

A single base substitution mutation is likely to have a less harmful effect when the base change results in which of the following? a stop codon a codon that specifies the same amino acid as the original codon an amino acid substitution that alters the tertiary structure of the protein an amino acid substitution at the active site of an enzyme

a codon that specifies the same amino acid as the original codon

Translation termination occurs when a ribosome interacts with which of the following structures? the end of the mRNA molecule a stop codon the 5′ cap the poly-A tail

a stop codon

DNA polymerase III

adds nucleotides to the 3' end of a growing DNA strand

Which of the following results is most likely to occur if acetylation of histone tails in the chromatin embryonic cells is increased?

decreased chromatin condensation

DNA methylation and histone acetylation are examples of which process?

epigenetic phenomena

Muscle cells differ from nerve cells mainly because they

express different genes

A section of DNA has the base sequence shown in #1. A mutation in this DNA strand results in the base sequence shown in #2. What type of mutation does this change represent? #1 5' - AGCGTTACCGT-3' #2 5'-AGGCGTTACCGT-3' a missense mutation a point mutation a silent mutation frameshift mutation

frameshift mutation

The effect of which Hardy-Weinberg condition is affected by population size?

genetic drift

Which of the following statements correctly describes pyrimidines? (select all that apply) includes cytosine and thymine includes guanine and adenine nitrogenous base composed of a single organic ring nitrogenous bases with two organic rings Pair together by hydrogen bonds

includes cytosine and thymine nitrogenous base composed of a single organic ring

Which of the following statements correctly describes purines? (select all that apply) includes cytosine and thymine includes guanine and adenine nitrogenous base composed of a single organic ring nitrogenous bases with two organic rings pair together by hydrogen bonds

includes guanine and adenine nitrogenous bases with two organic rings

Which of the following molecular structures contains codons? a protein mRNA tRNA rRNA

mRNA

Which answer correctly compares the primary transcript in the nucleus of a eukaryotic cell with the functional mRNA? the primary transcript is the same size as the mRNA the primary transcript is larger than the mRNA the primary transcript is smaller than the mRNA both the primary transcript and mRNA contain introns

the primary transcript is larger than the mRNA

In eukaryotes, which of the following is the first step in translation? base pairing of activated methionine-tRNA to AUG of the messenger RNA binding of the larger ribosomal subunit to smaller ribosomal subunits the ribosome reaches a stop codon the small subunit of the ribosome recognizes and attaches to the 5′ cap of mRNA

the small subunit of the ribosome recognizes and attaches to the 5′ cap of mRNA

In the structure of many eukaryotic genes, individual exons parallel which of the following? the sequence of the intron that immediately precedes each exon the number of polypeptides making up the functional protein the various domains of the protein product the number of start sites for transcription

the various domains of the protein product

Transcription in eukaryotes requires which molecules in addition to RNA polymerase?

transcription factors

The function of enhancers is an example of:

transcriptional control of gene expression

Helicase

unwinds the DNA double helix at the replication fork