Deck 25: Dna Structure and Gene Expression

Question 1

Hershey and Chase experimented with radioactively labeled phosphorus and sulfur to determine that DNA and not protein is the genetic material. Which of the following was essential to the success of the experiment?

A) Sulfur is present in amino acids in the protein coat of bacteria.
B) Phosphorus is present in high amounts in DNA.
C) Sulfur is not present in DNA.
D) Phosphorus is not present in amino acids in the protein coat of bacteria.
E) All of the answer choices describe information that was necessary for the success of the experiment.

Answer 1

E

Question 2

Chargaff's rules of DNA structure states that

A) A + T = G + C.
B) A = T, C = G
C) A = C, T = G.
D) A = G, T = C.
E) the number of purines in DNA never equals the number of pyrimidines.

Answer 2

B

Question 3

During semiconservative replication, if the parental strand has adenine, which of the following bases will be placed on the new strand?

A) adenine
B) thymine
C) cytosine
D) guanine
E) uracil

Answer 3

B

Question 4

Because every DNA molecule contains one old strand and one new strand, the process of DNA replication is called

A) conservative.
B) semiconservative.
C) mixed.
D) dispersive.

Question 5

After their experiment, Hershey and Chase concluded that the radioactively labeled sulfur, but not the phosphorus, was found within the bacteria.

Question 6

The enzyme that is used to join DNA nucleotides together is

A) DNA polymerase.
B) RNA polymerase.
C) helicase.
D) primase.
E) lipase.

Question 7

Which of the following is true about RNA?

A) The structure is a double helix.
B) The bases are held together by hydrogen bonds.
C) The bases are complementary to each other.
D) It contains deoxyribose sugar.
E) It is composed of the nucleotides adenine, guanine, cytosine, and uracil.

Question 8

Which of the following statements about DNA replication is correct?

A) As hydrogen bonds break, the DNA molecule unwinds.
B) The process is known as semiconservative replication because one old strand is conserved in the new molecule.
C) The enzyme that catalyzes DNA replication is DNA polymerase.
D) Complementary base pairs are held together with hydrogen bonds.
E) All of the answer choices are correct statements about DNA replication.

Question 9

In the Watson-Crick model of DNA, the "sides" of the ladder are composed of

A) sugars.
B) bases.
C) hydrogen bonds.
D) sugar-phosphate molecules.
E) phosphate groups.

Question 10

If the protein coat of a virus that infects a bacterium is labeled with radioactive sulfur while the DNA of the virus is labeled with radioactive phosphorus, over time

A) both the sulfur and the phosphorus will be found within the bacterium.
B) only the sulfur will be found inside the bacterium.
C) only the phosphorus will be found inside the bacterium.
D) both the sulfur and the phosphorus will be found outside the bacterium.
E) the radioactivity of the sulfur and phosphorus will decay very quickly and not be detectable.

Question 11

The X-ray diffraction photography of Rosalind Franklin and Maurice Wilkins was critical to showing that

A) DNA has a double-helix structure.
B) the bases of DNA were held together by hydrogen bonds.
C) DNA has equal numbers of purines and pyrimidines.
D) DNA has deoxyribose sugar rather than ribose sugar.
E) the four bases of DNA are adenine, guanine, cytosine, and thymine.

Question 12

The individual(s) given the most credit for the discovery of the structure of DNA is (are)

A) Alfred Hershey and Martha Chase.
B) James Watson and Francis Crick.
C) Erwin Chargaff.
D) Rosalind Franklin and Maurice Wilkins.
E) Charles Darwin and Gregor Mendel.

Question 13

The hereditary material found in all cells is

A) DNA.
B) rRNA.
C) mRNA.
D) tRNA.
E) ATP.

Question 14

The fact that for a given species the amount of purines in the DNA always matches the number of pyrimidines was first determined by

A) Watson and Crick.
B) Franklin and Wilkins.
C) Hershey and Chase.
D) Chargaff.
E) Mendel.

Question 15

If a species contains 23% A in its DNA, what is the percentage of guanine it would contain?

A) 23%
B) 46%
C) 25%
D) 44%
E) 27%

Question 16

Which scientist(s) is/are noted for their X-ray diffraction photo of DNA?

A) Chargaff
B) Griffith
C) Messelson and Stahl
D) Franklin
E) Hershey and Chase

Question 17

A nucleotide contains

A) DNA and RNA.
B) a sugar and a phosphate.
C) complementary purines and pyrimidines.
D) RNA, protein, and lipids.
E) a sugar, a phosphate, and a nitrogen-containing base.

Question 18

Which of the following describes a function of the DNA helicase?

A) connects the Okazaki fragments and seals any breaks in the sugar-phosphate backbone
B) adds nucleotides to the growing 3' end of the new DNA strand
C) creates the lagging strand in semiconservative replication
D) unwinds and "unzips" the double-stranded DNA by breaking the weak hydrogen bonds between the paired bases
E) re-creates the broken hydrogen bonds so that DNA becomes double-stranded again

Question 19

In semiconservative DNA replication, each new double helix formed will have

A) two new strands and two old strands.
B) one new and one old strand in each helix.
C) three new strands in one helix and three old strands in the second helix.
D) two new and one old strand in one helix and two old and one new strand in the second helix.
E) two new strands in one helix and two old strands in the other helix.

Question 20

In DNA, the amount of adenine is always equal to the amount of

A) cytosine.
B) uracil.
C) guanine.
D) thymine.
E) ATP.

Question 21

The addition of a poly-A tail to mRNA occurs after which of the following?

A) replication
B) transcription
C) translation
D) translocation
E) termination

Question 22

How many bases on a DNA molecule equal one codon?

A) 1
B) 2
C) 3
D) 4
E) 20

Question 23

If one strand of DNA has the base sequence AAGCAA, the complementary strand has which of the following sequences?

A) UUCGUU
B) TTCGTT
C) AAGCAA
D) UTCGTU
E) TTCGTG

Question 24

Which of the following nucleotide bases is found only in RNA?

A) guanine
B) adenine
C) thymine
D) uracil
E) cytosine

Question 25

During translation, which of the following is involved in translation?

A) mRNA
B) tRNA
C) rRNA
D) ribosome
E) All of the answer choices are involved in translation.

Question 26

Which of the classes of RNA molecules has an anticodon?

A) ribosomal RNA
B) transfer RNA
C) messenger RNA
D) primary mRNA transcript
E) ribozyme

Question 27

Transcription of part of a DNA molecule with a nucleotide sequence of AAACAACTT results in a mRNA molecule with the complementary sequence of

A) GGGAGAACC.
B) UUUGUUGAA.
C) TTTGAAGCC.
D) CCCACCTCC.
E) AAACAACTT.

Question 28

Which of the following describes the flow of information in protein synthesis?

A) protein → RNA → DNA
B) DNA → RNA → protein
C) DNA → protein → RNA
D) RNA → DNA → protein
E) RNA → protein → DNA

Question 29

A sequence of mRNA that is removed during processing is a(n)

A) exon.
B) intron.
C) replicon.
D) promoter.
E) gene.

Question 30

Which of the following bases pairs with adenine in DNA?

A) guanine
B) adenine
C) thymine
D) uracil
E) cytosine

Question 31

Which of the classes of RNA molecules is produced in the nucleolus?

A) ribosomal RNA
B) transfer RNA
C) messenger RNA
D) primary mRNA transcript
E) ribozymes

Question 32

Which of the following is part of DNA replication?

A) transcription
B) lagging strand
C) translation
D) amino acids
E) protein synthesis

Question 33

Prior to protein synthesis, the DNA

A) attracts tRNAs with appropriate amino acids.
B) serves as a template for the production of mRNA.
C) adheres to ribosomes for protein synthesis.
D) contains anticodons that become codons.
E) must first undergo replication.

Question 34

Which is the process by which a protein is constructed in the cytoplasm of eukaryotic cells?

A) translation
B) transcription
C) replication
D) transformation
E) translocation

Question 35

Which of the following is true about DNA?

A) transfers messages to the ribosomes
B) contains the sugar ribose
C) contains adenine, guanine, uracil, and cytosine
D) is single stranded
E) forms a helix

Question 36

Which type of RNA carries the genetic information from the nucleus to the ribosome?

A) ribosomal RNA
B) transfer RNA
C) messenger RNA
D) All types of RNA can carry the information from the nucleus to the ribosome.

Question 37

A gene is physically located on a(n)

A) chromosome.
B) transfer RNA.
C) enzyme.
D) protein.
E) nucleus.

Question 38

What part of the mRNA contain(s) the information for the structure of the protein?

A) introns
B) exons
C) promoter
D) ribosomes
E) nucleoli

Question 39

During the process of transcription, the information in

A) a protein is converted into RNA.
B) RNA is converted into a protein.
C) RNA is converted into DNA.
D) DNA is converted into RNA.
E) DNA is converted into a protein.

Question 40

The function of transfer RNA is to

A) carry amino acids to ribosomes.
B) transfer nucleotides to the nucleus.
C) transmit coded information to the cytoplasm.
D) turn DNA on and off.
E) act as the site for protein synthesis.

Question 41

Sometimes a newly folded protein must be modified before becoming functional. What level of gene control is this?

A) transcriptional
B) posttranscriptional
C) translational
D) posttranslational
E) operon

Question 42

Specific DNA sequences that have the ability to move within and out of chromosomes are called

A) transposons.
B) introns.
C) exons.
D) operators.
E) ribozymes.

Question 43

Which level of primary control in eukaryotic gene activity involves the speed of transport of mRNA from the nucleus into the cytoplasm?

A) pretranscriptional
B) transcriptional control
C) posttranscriptional control
D) translational control
E) posttranslational control

Question 44

Gene mutations are

A) always deleterious.
B) always beneficial.
C) radiation-induced changes only.
D) alterations in the normal sequence of bases within a gene.
E) alterations to cell cycle.

Question 45

Which of the following levels of control involves the use of a poly-A tail?

A) pretranscriptional
B) transcriptional
C) posttranscriptional
D) transcriptional control
E) translational

Question 46

Initiation, elongation, and termination are three stages in

A) DNA replication.
B) error correction by proofreading enzymes.
C) mRNA processing.
D) translation.
E) intron removal.

Question 47

Which part of a mRNA molecule is edited out?

A) exons.
B) introns.
C) transposons.
D) inducers.
E) promoters.

Question 48

Which of the following processes takes place during transcription?

A) attachment of a ribosome to mRNA
B) growth of a polypeptide chain
C) binding of two tRNA molecules/ribosome
D) liberation of polypeptide from ribosome
E) production of mRNA

Question 49

In eukaryotes, control of gene expression is accomplished by

A) translational control in cytoplasm after mRNA leaves the nucleus and before protein is produced.
B) transcriptional control in the nucleus based on which genes are transcribed and how fast they are transcribed.
C) posttranscriptional control in the nucleus after DNA is transcribed, including the speed with which mRNA leaves the nucleus.
D) posttranslational control in the cytoplasm that occurs after protein synthesis.
E) All of the answer choices are correct.

Question 50

Which is most directly responsible for the sequence of amino acids in a protein?

A) the sequence of the anticodons
B) the number of codons in mRNA
C) the enzyme that attaches the amino acid to tRNA
D) the proteins associated with rRNA
E) the sequence of codons in mRNA

Question 51

The function of the regulator gene is to

A) code for enzymes in a metabolic pathway.
B) serve as an on/off switch for transcription.
C) code for a repressor molecule that can bind to the operator.
D) bind to the RNA polymerase molecule.
E) bind to the promoter.

Question 52

The site of translation is the

A) nucleus.
B) nucleolus.
C) ribosome.
D) ribozyme.
E) mitochondria.

Question 53

Messenger RNA is produced in the

A) cytoplasm.
B) ribosomes.
C) nucleus.
D) endoplasmic reticulum.
E) lysosome.

Question 54

Which of the following occurs when lactose is present in the environment of E. coli?

A) The lac repressor binds to the promoter.
B) RNA polymerase binds to the operator.
C) No genes are transcribed.
D) RNA polymerase binds to the promotor.
E) Lactose binds to the promotor.

Question 55

Which of the following is a true statement about the genetic code?

A) The genetic code is composed triplet codes.
B) The genetic code produces 64 different possibilities of codon sequences.
C) Some amino acids are coded for by more than one codon.
D) The genetic code contains start and stop codons.
E) All of the answer choices are true of the genetic code.

Question 56

What part of a tRNA molecule will base pair with the codon of a mRNA molecule?

A) DNA sequence
B) anticodon
C) amino acid binding site
D) amino acid
E) promoter site

Question 57

Active genes are found in the

A) heterochromatin.
B) euchromatin.
C) Barr bodies.
D) promoters.
E) operons.

Question 58

Which of the following is a frameshift mutation of the nucleotide sequence CATUAUCCC?

A) CATTUAUCCC
B) ATUAUCCC
C) CTUAUCCC
D) CATUAUCGC
E) All of the answer choices are frameshift mutations.

Question 59

Two strains of E. coli-one of which can turn on its lactase production and one that cannot-are grown together with lactose in the medium. If all other conditions are equal, what will occur?

A) Both strains will continue to be present in equal amounts.
B) The two strains will kill each other off.
C) The strain that can turn on lactase production will outcompete the other strain.
D) The strain that cannot turn on lactase production will outcompete the other strain.
E) The two strains will work cooperatively and share the lactose.

Question 60

The correct sequence of events in the production of a polypeptide is

A) initiation → termination → elongation.
B) elongation → termination → initiation.
C) termination → elongation → initiation.
D) elongation → initiation → termination.
E) initiation → elongation → termination.

Question 61

Which level of primary control in eukaryotic gene activity involves methylation and chromatin packing as a way to keep genes turned off?

A) pretranscriptional control
B) transcriptional control
C) posttranscriptional control
D) translational control
E) posttranslational control

Question 62

An oncogene is

A) a viral gene with no relation to the host cell's genes.
B) a mutated form of a proto-oncogene.
C) a bacterial gene that causes cancer in the host.
D) always seen in human cancer cells.
E) a gene that turns off cellular reproduction.

Question 63

Which of the following factors is likely to a mutation and possibly cancer?

A) X-rays
B) ultraviolet radiation
C) cigarette smoke
D) pesticides
E) All of the answer choices can lead to cancer.

Question 64

A cell of the pancreas specializes in producing insulin, while a muscle cell specializes in the production of the protein myosin. This means that

A) the pancreas and muscle cells are both actively using the genes for insulin and myosin.
B) the pancreas cells are actively using the insulin gene, while the muscle cells are actively using both the insulin and myosin genes.
C) the pancreas cells are actively using the gene that produces insulin, while muscle cells are actively using the gene that produces myosin.
D) neither the pancreas cells nor the muscle cells are specialized.
E) only muscle cells can produce proteins.

Question 65

Which of the following is true about oncogenes?

A) Oncogenes are normal genes that have undergone a mutation.
B) Oncogenes cause cell division to slow down.
C) When mutated, oncogenes turn into proto-oncogenes.
D) Oncogenes increase apoptosis in surrounding cells.
E) All of the answer choices are true statements about oncogenes.

Question 66

When the sheep Dolly was successfully cloned, it was produced by growing an in vitro fertilized egg where the normal egg nucleus had been removed and replaced by a nucleus from an adult. Since this nucleus was from an older mature animal, which of the following would be a reasonable expectation?

A) The nucleus from the older mature animal would have additional Barr bodies.
B) The nucleus from the older mature animal would contain DNA with many mutations.
C) The nucleus from the older mature animal would contain chromosomes with shorter telomeres.
D) The nucleus from the older mature animal would have chromosomes with longer telomeres.
E) The nucleus from the older mature animal would have a higher concentration of mRNA.

Question 67

Which of the following proteins speed up transcription dramatically?

A) repressors
B) RNA polymerases
C) promoters
D) transcription activators
E) DNA polymerases

Question 68

Which of the following is true of ribosomes?

A) Ribosomes are produced in the nucleolus of a eukaryotic cell.
B) Ribosomes are made of RNA and proteins.
C) Ribsomes are composed of two subunits that join together just as protein synthesis begins.
D) Each ribsome has a binding site for mRNA, as well as binding sites for three tRNA molecules.
E) All of the answer choices are true statements about ribosomes.

Question 69

DNA segments at the ends of chromosomes that shorten every time a cell divides are called

A) transposons.
B) mutagens.
C) activated chromatin.
D) operons.
E) telomeres.

Question 70

What are transcription factors?

A) Transcription factors are proteins that help the repressor bind to the operator.
B) Transcription factors are proteins that help RNA polymerase bind to the promoter.
C) Transcription factors are proteins that help DNA polymerase bind to the promoter.
D) Transcription factors are proteins that help helicases bind to the operator.
E) Transcription factors are proteins that help the operator bind to the repressor.

Question 71

Which of the following is associated with cancer?

A) It can establish new tumors distant from the site of the primary tumor.
B) It forms new blood vessels and brings nutrients and oxygen to the tumor.
C) Cancer cells can undergo cell division repeatedly and indefinitely.
D) Tumors invade surrounding tissues and are filtered by lymph nodes.
E) All of the answer choices describe cancer.

Question 72

Which of the following is associated with a higher cancer risk?

A) hormone therapy
B) smoking
C) use of alcohol
D) exposure to certain hazardous chemicals in the workplace
E) All of the answer choices describe things that increase the risk of cancer.

Question 73

Apoptosis refers to cell death and

A) is always biologically detrimental to an organism.
B) can be programmed and is essential to normal development.
C) is the accumulation of genetic errors.
D) is a failure in the translation or transcription mechanism.
E) is any failure of the genetic machinery to work correctly.

Question 74

A cluster of prokaryotic genes under the control of one regulatory sequence is called a(n)

A) repressor.
B) promoter.
C) operon.
D) operator.
E) regulator gene.

Question 75

Which of the following is true about cancer cells?

A) They exhibit uncontrolled growth.
B) They can form benign or malignant tumors.
C) They exhibit disorganized growth.
D) They may undergo metastasis.
E) All of the answer choices are true statements about cancer.

Question 76

Which level of primary control in eukaryotic gene activity involves using differences in the poly-A tail or the guanine cap to determine how long a particular transcript remains active before it is destroyed?

A) pretranscriptional control
B) transcriptional control
C) posttranscriptional control
D) translational control
E) posttranslational control

Question 77

Tumor-suppressor genes are

A) oncogenes that code for proteins that inhibit cell division.
B) genes that code for proteins that inhibit cell division.
C) oncogenes that code for proteins that stimulate cell division.
D) anti-oncogenes that code for proteins that stimulate cell division.
E) transposons that can be used as cancer therapy.

Question 78

Which of the following behaviors could help prevent cancer?

A) avoiding carcinogenic chemicals
B) avoiding excessive sunlight
C) lowering total fat intake
D) increasing your consumption of broccoli
E) All of the answer choices describe behaviors that can reduce your risk of cancer.

Question 79

Indicate the complementary nucleotide sequence for the following section of DNA: AATGCGTATACG

Question 80

Which of the following serve to directly accelerate the cell cycle?

A) tumor-suppressor genes
B) carcinogens
C) repressors
D) oncogenes
E) p53 gene