Practice Final

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Molecular Biology of the Cell
Chapters 1-8, 10-20
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1

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

2

In nucleic acids, nitrogenous bases are linked by ________ bonds, which are ________

A) hydrogen; strong

B) phosphodiester; strong

C) hydrogen; weak

D) tertiary; weak

C

3

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

4

What is a limiting factor on the rate of replication?

A) the rate of initiation

B) the phase of the cell cycle

C) the distance between origins of replication

D) the nucleotides within the gene

A

5

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

6

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

7

The cell cycle is regulated by

A) G1/S-cyclins that commits 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 of the above

D

8

When in the cell cycle does the centrosome cycle begin?

A) S-phase

B) M-phase

C) G1-phase

D) G2-phase

A

9

Which of the following does NOT occur during prophase of mitosis?

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

B) the mitotic spindle forms

C) microtubules connect to kinetochores on each chromatid

D) the nuclear membrane, endoplasmic reticulum (ER), and golgi complexes fragment

C

10

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 of the above

C

11

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

A) dynein

B) kinesin

C) actin

D) condensin

A

12

During meiosis, genetic variability is generated by

A) crossing over of sister chromatids at chiasmata during metaphase

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 chromosomes

C

13

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

14

Which of the following is NOT a function of the sigma (σ) factor in prokaryotic RNA synthesis?

A) recognize the transcription start site

B) unwind the DNA for transcription to occur

C) increase affinity of RNA polymerase for the DNA start site

D) recognize different start sites

B

15

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

16

RNAi functions in

A) post-transcriptional gene silencing

B) pre-replicational gene silencing

C) transcription

D) DNA degradation

A

17

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

18

Proteins are synthesized starting at the

A) 5’ end of the protein

B) N-terminus of the protein

C) 3’ end of the protein

D) C-terminus of the protein

B

19

a-helices are stabilized by

A) ionic bonds

B) non-covalent bonds

C) covalent

D) hydrogen bonds

D

20

Tertiary protein structure is stabilized by

A) only weak noncovalent interactions between R groups

B) many covalent interactions and fewer weak noncovalent interactions

C) many weak noncovalent interactions and fewer covalent interactions

D) only covalent interactions between R groups

C

21

Which of the following statements about enzymes is TRUE?

A) catalysis of an energetically unfavorable reaction by an enzyme will enable that reaction to occur

B) enzymes decrease the activation energy of a reaction

C) an enzyme can be a polymer of monosaccharides

D) enzymes are permanently altered after catalyzing a reaction

B

22

Which of the following is NOT a way in which cells regulate enzyme activity?

A) allostery

B) phosphorylation/GTP binding

C) changing amino acid sequence of the protein

D) location of enzymes; co-locating enzymes that contribute to the same pathway

C

23

Heat shock proteins are an example of what type of proteins?

A) antibodies

B) transporter proteins

C) chaperones

D) structural proteins

C

24

Acetyl CoA

A) is oxidized to CO2and NADH/FADH2through the Krebs cycle

B) is an electron carrier

C) is a form of cellular energy because it has a phosphate group

D) contains about 7.4 kcal/mol

A

25

What is the NET yield of glycolysis?

A) 4 ATP, 2 NADH, and 2 Pyruvate

B) 2 ATP, 2 NADH, and 2 Pyruvate

C) 2 ATP, 2 NADH, and Acetyl CoA

D) 3 NADH, 1 GTP, 1 FADH2, and 2 CO2

B

26

Which of the following statements about complex I of the electron transport chain is TRUE?

A) it receives electrons from NADH, passes them to ubiquinone, and all electrons that contribute to ATP synthesis must pass through it

B) it receives electrons from FADH2, passes them to ubiquinone, and contains heme proteins

C) it receives electrons from NADH, passes them to cytochrome c, and does not pump protons (H+)

D) it receives electrons from NADH, passes them to ubiquinone, and pumps protons (H+)

D

27

Which of the following statements about ATP synthase is TRUE?

A) it is a transmembrane protein and an enzyme

B) it is the final electron acceptor in the electron transport chain

C) protons pass through it from the matrix into the cytosol

D) it catalyzes a substrate-level phosphorylation

A

28

In what complex is succinate reduced to fumarate?

A) complex I

B) complex II

C) complex III

D) complex IV

B

29

Transport through nuclear pores

A) is unidirectional from the nucleus to the cytosol

B) requires a nuclear signal sequence, a receptor, and GTP

C) requires a nuclear signal sequence, a receptor, and ATP

D) requires nuclear signal sequences that are amino acid sequences at the C-terminal end of the protein

B

30

Mitochondrial proteins

A) are synthesized inside the mitochondria, because it has its own genome

B) are synthesized in the cytosol and transported into mitochondria in a folded state

C) pass easily through the outer mitochondrial membrane, which is a very porous membrane that allows most molecules to pass through

D) are transported unfolded by a process that requires ATP and chaperones

D

31

Which of the following is a function of the cell membrane?

A) maintain distinctive cell/organelle chemistry

B) regulate import and export of materials into and out of the cell

C) sense changes in the environment through cell surface receptors.

D) all of the above

D

32

Which of the following is NOT a possible function of membrane proteins?

A) act as a receptor

B) provide catalysis as an enzyme

C) act as an anchor

D) convert the chemical energy stored in ATP into membrane movement

D

33

Which of the following is best describes the composition of cell membrane?

A) cell membranes are composed of 2 layers: a layer of phospholipids and a layer of proteins

B) cell membranes are composed of equal numbers of phospholipids, proteins, and carbohydrates

C) cell membranes are bilayers of proteins with associated lipids and carbohydrates

D) cell membranes are bilayers of phospholipids with associated proteins and carbohydrates

D

34

Cell membranes are stabilized by which molecular interactions?

A) hydrophilic interactions and covalent bonds

B) hydrophobic interactions and ionic bonds

C) hydrophobic interactions and van der Waals forces

D) hydrophilic interactions and hydrogen bonds

C

35

Phospholipids have a ________ head and a ________ tail

A) hydrophilic; hydrophilic

B) hydrophobic; hydrophobic

C) hydrophilic, hydrophobic

D) hydrophobic; hydrophilic

C

36

Which of the following are membrane lipids?

A) phospholipids

B) sphingolipids

C) cholesterol

D) all of the above

D

37

What is an antiporter?

A) an integral membrane protein that transports two types of molecules across the cell membrane

B) a peripheral membrane protein that transports multiple types of molecules across the cell membrane

C) an integral membrane protein that transports a single type of molecule across the cell membrane

D) an integral membrane protein transport two different molecules across the cell membrane in opposite directions

D

38

Which of the following statements about membrane transport is FALSE?

A) passive transport is dependent on concentration gradients and membrane potential

B) electrical and chemical gradients can work with or work against passive transport

C) facilitated diffusion moves molecules up their concentration gradient

D) all of the above

C

39

What is a symporter?

A) an integral membrane protein that transports two types of molecules across the cell membrane

B) a peripheral membrane protein that transports a single type of molecule across the cell membrane

C) an integral membrane protein that transports a single substance across the membrane

D) a protein that is involved with moving ions across the cell membrane in opposite directions

A

40

Which membrane transporters select molecules by size and charge and do not bind the molecules they transport?

A) carrier proteins

B) channel proteins

C) protein vesicles

D) G-protein-coupled receptors

B

41

During an action potential, voltage-gated Na+ ion channels open and cause

A) membrane depolarization

B) membrane repolarization

C) balancing of the membrane potential

D) membrane polarization

A

42

During an action potential, voltage-gated K+ ion channels open and cause

A) membrane depolarization

B) membrane repolarization

C) balancing of the membrane potential

D) membrane polarization

B

43

Which type of signaling occurs when cells release a molecule into the bloodstream, it is carried long distances throughout the body, and influences target cells far away

A) autocrine

B) paracrine

C) endocrine

D) synaptic

C

44

When cell signaling induces a fast response, it typically occurs through

A) protein modifications

B) altered protein synthesis

C) both a and b

D) none of the above

A

45

G-protein coupled receptors

A) require no energy

B) stimulate the activity of a heterotrimeric G protein

C) stimulate gene expression

D) are found throughout the cytosol

B

46

How is glycogen metabolism regulated by cAMP?

A) increased cAMP leads to glycogen synthesis and decreased cAMP leads to glycogen breakdown

B) Increased cAMP leads to glycogen breakdown and decreased cAMP leads to glycogen synthesis

C) cAMP synthesizes glycogen from glucose

D) cAMP breaks down glycogen into glucose

B

47

Which of the following activates Ras proteins?

A) phospholipase C

B) protein phosphatase

C) receptor tyrosine kinase

D) protein kinase C (PKC)

C

48

In the signaling pathway that includes cyclic AMP (cAMP), a G protein activates

A)guanalyl cyclase

B) phospholipase C

C) adenylyl cyclase

D) calmodulin

C

49

Caspases are activated by

A) signaling from the extracellular environment only

B) signaling from the intracellular environment only

C) signaling from the extracellular and intracellular environment

D) none of the above

C

50

Which of the following is an extracellular survival factor that can inhibit apoptosis?

A) increased production of Bcl2 family protein

B) inactivation of BH3-only protein

C) inactivation of anti-IAPs

D) all of the above are correct

D

51

The intrinsic pathway of apoptosis depends on

A) mitochondria

B) endoplasmic reticulum

C) golgi complexes

D) the nucleolus

A

52

Necrotic cells characteristically

A) swell, burst, and spill their contents over neighboring cells

B) neatly split into smaller pieces that can be phagocytosed by other cells

C) undergo autophagy

D) cause other cells in the nearby area to die off

A

53

Increased production of which proteins inhibits apoptosis?

A) Bcl2 family proteins

B) BH3-only proteins

C) Anti-IPAs

D) FADDs

A

54

In the intrinsic pathway of apoptosis, which of the following comes before the other steps?

A) assembly of apoptosome

B) activation of Apaf1

C) release of cytochrome c

D) activation of caspase 9

C

55

Oncogenes can transform a normal cell into a cancer cell through

A) deletion or point mutation in coding sequence

B) mutation of proteins that regulate cell growth or the cell cycle

C) gene amplification

D) all of the above

D

56

A benign tumor

A) is invasive

B) can spread to other tissues and affect them

C) is not yet invasive

D) is a small mass of unmutated cells

C

57

What is a malignant tumor?

A) a tumor that is cancerous and can invade neighboring tissues

B) a tumor that is not yet invasive

C) a tumor that can become benign

D) a tumor that cannot give rise to metastasis

A

58

Which of the following is FALSE?

A) most cancers derive from a single cell

B) a single mutation is enough to transform a normal cell to a cancer cell

C) a non-invasive tumor is ‘benign’

D) an invasive tumor is ‘malignant’

B

59

Cancer cells show abnormality in which of the following?

A) motility

B) shape

C) growth factors in culture medium

D) all of the above

D

60

Carbon atoms derived from ___________ are used as raw materials for the synthesis of proteins and lipids needed for tumor growth

A) glucose

B) fats

C) proteins

D) none of the above

A