Practice Midterm

Helpfulness: 0
Set Details Share
created 1 year ago by Jonathan_Miranda
44 views
book cover
Molecular Biology of the Cell
Chapters 1, 2, 4-8, 14, 17
updated 1 year ago by Jonathan_Miranda
show moreless
Page to share:
Embed this setcancel
COPY
code changes based on your size selection
Size:
X
Show:
1

1) During interphase (any part of the cell cycle other than M-phase), DNA is packed into the nucleus by

(a) folding it into an alpha (α) helix

(b) condensing it into sister chromatids

(c) storing it bound to the nucleolus

(d) by histones that pull the DNA into nucleosomes and chromatin fibers

D

2

(2) In a DNA double helix

(a) the 2 DNA strands are identical

(b) base pairing matches purines (A & G) with pyrimidines (C & T)

(c) deoxyribose molecules of 1 DNA strand forms hydrogen bonds with the bases of the other DNA strand

(d) the 2 DNA strands run parallel in the 5’ to 3’ direction

B

3

(3) Which of the following is NOT true of a chromosome?

A) it is a single molecule of DNA

B) it contains 2 telomeres, one at each end

C) it contains a single origin of replication

D) it contains a single centromere

C

4

(4) The structure of DNA

A) provides a mechanism for storing and transmitting cellular information

B) is strictly maintained throughout the cell cycle to ensure proper cell function

C) can be described as a polymer of ribose

D) all of the above

A

5

(5) Nucleosomes

A) are a basic unit of chromosome structure found only in eukaryotes

B) have a core of histone proteins

C) are formed into chromatin fibers by the histone protein H1

D) all of the above

D

6

(6) Modification of histone proteins influences chromatin structure and includes

A) polyadenylation

B) binding of small interfering RNAs

C) methylation, acetylation, and phosphorylation of the N-terminal end of the histone

D) none of the above

C

7

(7) DNA replication

(a) is non-conservative

(b) occurs during the M phase of the cell cycle

(c) requires a primase

(d) uses a DNA polymerase that only polymerizes nucleotides in the 3’ to 5’ direction

C

8

(8) Okazaki fragments are short, newly synthesized DNA fragments formed on the lagging strand template during DNA replication. They are:

A) complementary and anti-parallel to the lagging strand template

B) produced because DNA synthesis can only occur in the 5’ to 3’ direction

C) produced because DNA synthesis can only occur in the 3’ to 5’ direction

D) a and b are correct

D

9

(9) Which of the following proteins/enzymes does NOT function in DNA replication?

A) exonuclease

B) helicase

C) sigma (σ) factor

D) DNA ligase

C

10

(10) DNA mutation repair mechanisms include nucleotide excision repair, which is

A) the removal and replacement of single, modified bases

B) the removal and replacement of segments of DNA that contain errors such as pyrimidine dimers

C) the excision and replacement of mismatch errors by DNA polymerase and ligase

D) the repair of a double-strand break in DNA

B

11

(11) CRISPR Cas9

A) allows for experimental manipulation or editing of genomes

B) is a complex of a synthetic guide RNA molecule and Cas9 nuclease

C) is an experimental technique based on bacterial defense against viruses

D) all are correct

D

12

(12) Human DNA has multiple origins of replication that are

A) all activated simultaneously during S-phase so the large number of human genes can be copied quickly

B) located near the telomeres, so replication moves from the ends to the midpoints of chromatids

C) locations where the double-stranded DNA is opened and replication proceeds in 2 directions with 2 replication forks

D) a and b are correct

C

13

(13) Which of the following does NOT occur during M-phase in animal cells?

(a) condensation of chromosomes

(b) breakdown of the nuclear envelope

(c) doubling of DNA

(d) fragmentation of the endoplasmic reticulum

(e) separation of sister chromatids

C

14

(14) The cleavage furrow begins forming in

(a) prophase

(b) prometaphase

(c) anaphase

(d) telophase

(e) interphase

C

15

(15) The cell cycle is regulated by

(a) G1/S-cyclins that commit the cell to division

(b) S-cyclins that help stimulate chromosome duplication or DNA replication

(c) M-cyclins that stimulate entry into mitosis

(d) all are correct

D

16

(16) An event that occurs before M-phase is

(a) the nuclear envelope breaks down

(b) the spindle apparatus forms

(c) centrosomes replicate

(d) chromosomes attach to microtubules

C

17

(17) Kinesin

(a) is a motor protein

(b) functions during mitosis/meiosis to separate chromosomes

(c) moves along microtubules

(d) all of the above

D

18

(18) Which of the following does NOT occur during prophase of mitosis?

(a) chromosomes condense and are seen to be composed of 2 chromatids

(b) the mitotic spindle forms

(c) microtubules connect to kinetochores on each chromatid

(d) the nuclear membrane, endoplasmic reticulum (ER), and golgi apparatus fragment

C

19

(19) The mitotic spindle consists of

(a) astral microtubules

(b) interpolar microtubules that project from the spindle pole and overlap in the middle of the spindle

(c) microtubules connected to kinetochores on each chromatid

(d) all are correct

D

20

(20) Which of the following proteins functions in separating chromatids?

(a) dynein

(b) cohesin

(c) actin

(d) condensin

A

21

(21) During meiosis, genetic variability is generated by

(a) crossing over of non-sister chromatids at chiasmata during prophase I

(b) independent assortment of maternal and paternal homologs during meiotic division I

(c) both a and b are correct

(d) none is correct

C

22

(22) Comparing meiotic division I (MDI) and meiotic division II (MDII)

(a) MDI separates sister chromatids and MDII separates homologous chromosomes

(b) MDI reassorts genetic information and MDII recombines genetic information

(c) MDI produces 2 haploid cells and MDII produces 4 haploid cells

(d) MDI has a prometaphase and MDII does not

C

23

(23) Transcription is similar to DNA replication in that

(a) nucleotide polymerization is mediated by a polymerase

(b) the RNA remains paired to the template DNA

(c) it only occurs during S-phase of the cell cycle

(d) it uses the same enzyme to synthesize RNA primers

A

24

(24) The sigma (σ) factor, which functions with the bacterial RNA polymerase,

(a) contains the catalytic activity of the polymerase

(b) remains part of the polymerase throughout transcription

(c) recognizes the promoter site in DNA

(d) recognizes the transcription termination site on DNA

C

25

(25) Which of the following statements about RNA splicing is TRUE?

(a) it occurs in both prokaryotes and eukaryotes

(b) it requires tRNA to designate the splice sites

(c) it is carried out by the splicesome

(d) it occurs in the cytosol

C

26

(26) Prokaryotic and eukaryotic gene transcription both require

(a) RNA polymerase

(b) promoter

(c) chromatin remodeling enzymes

(d) sigma (σ) factor

A

27

(27) The TATA box sequence serves as

(A) the start of translation

(B) binding site for repressors

(C) binding site for activators

(D) promoter

D

28

(28) Translation requires the following type of RNA

(A) snoRNA

(B) snRNA

(C) rRNA

(D) miRNA

C

29

(29) Nucleotides serve as

(A) storage for genetic information and long term energy

(B) storage for genetic information and short term energy storage

(C) storage for genetic information and important structural parts in membranes

(D) building blocks of proteins and DNA

B

30

(30) DNA and RNA polymerases all synthesize nucleotide polymers, but which of the following is NOT a shared characteristic of both these groups of polymerases

(a) binds loosely to DNA

(b) synthesizes polymers by adding nucleoside triphosphates

(c) has a proofreading site to check accuracy of synthesis

(d) polymerizes in the 5’ to 3’ direction

C

31

During interphase (any part of the cell cycle other than M-phase), DNA is packed into the nucleus by

A) folding it into an alpha (α) helix

B) condensing it into sister chromatids

C) storing it bound to the nucleolus

D) by histones that pull the DNA into nucleosomes and chromatin fibers and by folding into higher order structures

D

32

In a DNA double helix

A) the pyrimidine adenine pairs with the purine guanine

B) the purine guanine pairs with the pyrimidine cytosine

C) deoxyribose molecules form hydrogen bonds with nitrogenous bases

D) the 2 DNA strands are held together by hydrogen bonds between paired purines

B

33

Which of the following is TRUE of a chromosome during G1 phase of the cell cycle?

A) it is a single molecule of DNA

B) it contains a telomere at the end of the leading strand

C) it contains a single origin of replication at the centromere

D) it contains a several centromeres

A

34

Which of the following lists gives TRUE important characteristics of DNA structure?

A) 2 polymers of ribose, running anti-parallel to one another, and hydrogen bonded together by nitrogenous bases

B) 2 complementary strands, joined together by covalent bonds between nitrogenous bases, and coiled into a helix

C) 2 polymers of nucleotides, each polymer covalently linked through phosphates and sugars of the nucleotides, and the 2 polymers linked by hydrogen bonds between opposing nitrogenous bases

D) 2 complementary strands, running anti-parallel to one another, and held together by histones

C

35

Nucleosomes

A) are a chromosome structure seen only when DNA is replicating during S phase

B) have a core of 16 non-histone proteins

C) are formed into 30 nm chromatin fibers by the association of histone protein H1

D) are a substructure of the nucleus where ribosomes are synthesized

C

36

Modification of histone proteins influences chromatin structure and includes

A) polyadenylylation

B) methylation, acetylation, and phosphorylation of the N-terminal end of the histone

C) binding of small interfering RNAs

D) end-capping of the histone tail with the amino acid methionine

B

37

Epigenetic inheritance is

A) alteration of gene expression due to nucleosome remodeling

B) inheritance of chromatin structure rather than DNA sequence

C) due to the persistence, through meiosis, of histone tags on the conserved strand of DNA

D) the transmission of exogenous genetic information due to foreign genes attaching to native DNA

B

38

DNA replication is a duplication of DNA that

A) is completely non-conservative

B) occurs during the M phase of the cell cycle

C) requires a primase

D) uses a DNA polymerase that join nucleotides in the 3’ to 5’ direction

C

39

Okazaki fragments are short, newly synthesized DNA fragments that are

A) formed on the lagging strand template during DNA replication, and are complementary and anti-parallel to the lagging strand template

B) formed at the start of DNA synthesis when the polymerase is getting properly oriented on the template strand

C) produced because DNA synthesis can only occur in the 3’ to 5’ direction

D) joined into a single strand by DNA joinase

A

40

Which of the following enzymes is NOT part of the elaborate DNA replication machine?

A) DNA primase

B) helicase

C) DNA polymerase

D) telomerase

D

41

DNA mutation repair mechanisms

A) include 4 processes that all require 2 copies of the DNA

B) include nucleotide excision repair, which is the removal and replacement of segments of DNA that contain errors such as pyrimidine dimers

C) include mismatch repair, which is the proofreading function of DNA polymerase and its exonuclease site

D) are suppressed in pre-cancer cells which leads to higher mutation rates and conversion of the pre-cancer cells to metastatic cancer cells

B

42

CRISPR Cas9

A) is a therapeutic technique that locates and repairs mutated genes in human embryos

B) is a molecular complex, composed of a synthetic guide RNA molecule and Cas9 nuclease, and used for experimental gene editing

C) is based a natural process that allows bacteria to exchange genetic material with one another and bring about genetic recombination

D) is an evolutionally conserved process of post-transcriptional gene silencing through mRNA degradation

B

43

Origins of replication in human DNA are

A) multiple per chromatid and are activated sequentially during S-phase so the large number of human genes can be copied in a controlled manner

B) located at opposite ends of sister chromatids to avoid mixing the DNA content of sister chromatids during mitosis

C) locations where the double-stranded DNA is opened and replication proceeds in 2 directions with 2 replication forks

D) located at the centromeres of chromosomes

C

44

Which of the following statements about DNA replication is FALSE?

A) DNA replication is semi-conservative; DNA strands remain intact and serve as templates during replication

B) DNA replication proceeds 5’ to 3’; nucleotides are added only at the 3’ end of a DNA strand

C) helicase, DNA primase, and DNA polymerase are key enzymes in DNA replication

D) telomerase initiates DNA replication, which begins at the ends of the chromosomes

D

45

Which of the following is FALSE about the cell cycle?

A) it is controlled by constantly active cyclin-dependent kinases (Cdks)

B) it usually consists of 4 phases in eukaryotic cells

C) it has checkpoints that ensure the cell cycle does not progress unless all conditions are favorable

D) it includes a phase of DNA replication that precedes cell division

A

46

Which of the following occurs during M-phase but is NOT controlled by M-Cdk?

A) condensation of chromosomes

B) phosphorylation of lamins leading to breakdown of the nuclear envelope

C) formation of the mitotic spindle apparatus

D) activation of proteolytic enzymes that break cohesin and allow separation of sister chromatids

D

47

Chromosomes are aligned on the equator of the mitotic spindle and attached, via kinetochore microtubules, to the centrosomes

A) prophase

B) metaphase

C) anaphase

D) telophase

B

48

Which of the following does NOT occur during anaphase?

A) centromeres split and chromatids separate

B) chromosomes move to opposite poles of the mitotic spindle

C) fragments of nuclear envelopes begin associating with chromosomes

D) poles of the mitotic spindle move farther apart

C

49

Reformation of the nuclear envelop (or nuclear membrane) at the end of mitosis is regulated by

A) S-Cdk

B) M-CdK

C) ubiquitin

D) protein phosphatases

D

50

Chromosomes are moved by microtubules and motor proteins toward the spindle equator during

A) prophase

B) prometaphase

C) metaphase

D) telophase

B

51

The centrosome is

A) a pair of centrioles positioned at right angles to one another

B) an amorphous sphere of proteins that initiate polymerization of microtubules

C) formed when M-Cdk brings about dephosphorylation of tubulin proteins allowing them to assemble into the microtubules of the mitotic spindle

D) centrioles and the amorphous sphere of proteins together form the centrosome

D

52

A cell cycle event that precedes M-phase is

A) breakdown the nuclear envelope

B) formation of microtubules in the spindle apparatus

C) replication of centrosomes

D) condensation of chromosomes

C

53

Cytokinesis

A) begins during anaphase

B) begins with formation of the cleavage furrow

C) involves a contractile ring of actin filaments and myosin proteins in plant cells

D) is the division of the cytoplasm by M-Cdk controlled movements of the cell membrane

B

54

Dynein

A) is a motor protein

B) functions during mitosis to breakdown cohesion and separate sister chromatids

C) breaks down microtubules to shorten them as chromosomes are pulled apart

D) pushes centrosomes along interpolar microtubules to spread the mitotic spindle across the full diameter of the cell

A

55

Which of the following occurs during prometaphase of mitosis?

A) chromosomes condense and are seen to be composed of 2 chromatids

B) the mitotic spindle forms

C) microtubules connect to kinetochores on each chromatid

D) the nuclear membrane fragments

C

56

The mitotic spindle consists of

A) astral microtubules that extend from one centrosome past chromosomes to the centrosome at the opposite pole

B) interpolar microtubules that project from the spindle pole and overlap in the middle of the spindle

C) microtubules directly connected to centromeres of chromosomes

D) highly specialized chromosomal microtubules, one for each chromosome, that serve as tracks for the motor proteins that transport chromosomes

B

57

Which of the following proteins functions in separating centrosomes, pulling apart the poles of the mitotic spindle?

A) dynein

B) cohesin

C) actin

D) condensin

A

58

During meiosis, genetic variability is generated by

A) crossing over of sister chromatids at chiasmata during prometaphase

B) dividing the DNA in half to create haploid cells

C) independent assortment of maternal and paternal homologs during meiotic division I

D) recombination, the exchange of chromatids between maternal and paternal homologous chromosome

C

59

Comparing meiotic division I (MDI) and meiotic division II (MDII)

A) MDI separates sister chromatids and MDII separates homologous chromosomes

B) MDI reassorts genetic information and MDII recombines genetic information

C) MDI has a prometaphase and MDII does not

D) MDI produces 2 haploid cells and MDII produces 4 haploid cells

D

60

Which of the following does NOT occur during telophase?

  1. chromosomes cluster at opposite poles of the mitotic spindle
  2. nuclear envelope assembles around chromosomes
  3. Golgi bodies migrates to opposite sides of the cell
  4. chromosomes begin to disperse

(31) nd an rRNA of the ribosome

C

61

Transcription is similar to DNA replication in that

A) it is the formation of a nucleotide strand guided by a complementary strand of DNA

B) the nucleotides incorporated into the new polymer are the same

C) it is performed by a polymerase with proofreading capability

D) it produces a single type of nucleotide polymer

A

62

The sigma (σ) factor, which functions during bacterial transcription, does NOT

A) increase the affinity of the RNA polymerase for the transcription start site

B) interact with the RNA polymerase

C) recognize the transcription start site in DNA

D) recognize the transcription termination site on DNA

D

63

Which of the following statements about RNA splicing is FALSE?

A) it allows 1 gene to code for different proteins

B) it occurs in both prokaryotes and eukaryotes

C) it is carried out by the splicesome

D) it occurs in the nucleus

B

64

Prokaryotic and eukaryotic gene transcription both require

A) sigma (σ) factors or transcription factors, respectively

B) enhancers upstream of the gene

C) chromatin remodeling enzymes

D) activator proteins

A

65

The TATA box sequence

A) serves as the start of translation

B) occurs in prokaryotes

C) serves as the binding site for activator proteins

D) occurs in eukaryotic DNA

D

66

Eukaryotic mRNAs are modified or processed in which 3 ways before exiting the nucleus

A) splicing, methylation, and addition of a 5’ polyadenine tail

B) splicing, 5’ capping, and 3’ polyadenylation

C) splicing, 5’ capping with a phosphate group, and recognition by the nuclear export receptor

D) splicing, addition of a 5’ polyadenine tail, binding of polyA proteins

B

67

Which of the following function in the nucleus to help process mRNA?

A) snoRNAs (small nucleolar RNAs

B) snRNAs (small nuclear RNAs)

C) rRNAs (ribosomal RNAs)

D) tRNAs (transfer RNAs)

B

68

The _____________ attaches an amino acid to an individual tRNA, matching the amino acid and the anticodon

A) peptidyl transferase

B) aminoacyl tRNA synthetase

C) ribozyme

D) RNA polymerase

B

69

Which of the following is not a binding site of ribosomes?

A) peptidyl-tRNA site

B) aminoacyl-tRNA site

C) entrance site

D) mRNA-binding site

C

70

DNA and RNA polymerases are all enzyme complexes that synthesize nucleotide polymers, but which of the following is NOT a shared characteristic of both these groups of polymerases

A) binds loosely to DNA

B) synthesizes polymers by adding nucleoside triphosphates

C) has a proofreading site to check accuracy of synthesis

D) polymerizes in the 5’ to 3’ direction

C

71

Which of the following correctly characterizes a fundamental difference between DNA and RNA?

A) DNA is single stranded, while RNA is double stranded

B) DNA is found only in the nucleus, while RNA is found only in the cytoplasm

C) DNA is a long polymer with a ribose and phosphate backbone and 4 nucleotide bases (adenine, guanine, cytosine, and uracil), while RNA is a polymer with a deoxyribose and phosphate backbone and 4 nucleotide bases (adenine, guanine, cytosine, and thyamine)

D) DNA functions in long-term storage and transmission of genetic information, while RNA deploys the genetic code to processes such as protein synthesis, ribonucleoprotein synthesis, and mRNA modification

D

72

Which of the following statements about RNA is FALSE?

A) RNA is the result of the process of transcription

B) RNA is synthesized in the 5’ to 3’ direction, and then translated in the 3’ to 5’ direction

C) DNA can be synthesized from an RNA template in a process called reverse transcription

D) RNA synthesis is part of gene expression, as is protein synthesis

B

73

Which of the following statements about the genetic code is FALSE?

A) the genetic code consists of codons, which all code for an amino acid

B) the genetic code is redundant because 64 codons code for 20 amino acids

C) the genetic code has 3 possible reading frames but only one is correct

D) the genetic code consists of codons, which are all composed of 3 nucleotides

A

74

Ribosomes are the site and enzyme catalyst of protein synthesis, which occurs in the following 3 steps:

A) initiation, peptidylation, and termination

B) attachment, peptidylation, and detachment

C) initiation, elongation, and termination

D) initiation, elongation, and arrest

C

75

Which of the following statements about wobble base pairing is TRUE?

A) wobble base pairing occurs between codons and anticodons of mRNA and tRNA, respectively

B) wobble base pairing creates variation in protein structure and function

C) wobble base pairing occurs in the exit site of the ribosome

D) wobble base pairing occurs between mRNA a

A