Quiz about PCB 4023 Practice Exam 1

Question 1

Despite the diversity, cells resemble each other to an astonishing degree in their chemistry. For example, only four _____ are used to make DNA.

Accepted Answer

dNTP

Answer

NTP

Answer

amino acid

Answer

monosaccharide

Answer

fatty acid

Question 2

The _____ is made up of two concentric membranes and is continuous with the membrane of the endoplasmic reticulum.

Accepted Answer

nuclear envelope

Answer

plasma membrane

Answer

Golgi network

Answer

mitochondrial membrane

Question 3

Ionic bonds form a ___.

Accepted Answer

Salt

Answer

Molecule

Answer

Polymer

Answer

Lipid bilayer

Question 4

The side chain of the amino acid R under pH 7 is ___.

Accepted Answer

Positively charged

Answer

Nonpolar

Answer

Negatively charged

Answer

Polar but uncharged

Question 5

Which of the following amino acid side chain can be phosphorylated by a protein kinase?

Accepted Answer

Y

Answer

C

Answer

F

Answer

D

Question 6

Hydrogen bonds are essential to form a(n) _____

Accepted Answer

alpha-helix

Answer

lipid bilayer

Answer

salt

Answer

polypeptide

Question 7

Which of the following protein is necessary to stop a mitogenic signaling by dissociating a SH2 domain containing protein (Grb2) from phosphorylated Growth factor receptor?

Accepted Answer

a protein phosphatase

Answer

a lipid kinase

Answer

a protein kinase

Answer

a lipid phosphatase

Question 8

Which of the following is mainly mediated by an ionic bond?

Accepted Answer

Phospho-tyrosine and SH2 domain association

Answer

Grb2 and SOS association

Answer

Growth factor & Receptor Tyrosine Kinase association

Answer

SOS and Ras association

Question 9

Choose an example of a motor protein.

Accepted Answer

Myosin II

Answer

Insulin

Answer

Sodium potassium ATPase

Answer

EGFR

Question 10

Choose an example of a protein that is a signaling molecule (ligand).

Accepted Answer

Insulin

Answer

Sodium potassium ATPase

Answer

Myosin II

Answer

EGFR

Question 11

Choose an example of a protein of which a signaling receptor.

Accepted Answer

EGFR

Answer

Sodium potassium ATPase

Answer

Insulin

Answer

Myosin II

Question 12

A protein _____ is the modular unit from which many larger single-chain proteins are constructed.

Accepted Answer

Domain

Answer

Primary structure

Answer

Secondary structure

Answer

Quaternary structure

Answer

Tertiary structure

Question 13

Which of the following molecule shows a significant conformational change in response to binding to ATP?

Accepted Answer

Myosin II

Answer

Ras

Answer

Grb2

Answer

The heterotrimeric G proteins

Question 14

Which of the following proteins will form a globular protein molecule?

Accepted Answer

Actin

Answer

Keratin

Answer

Elastin

Answer

Collagen

Question 15

In a DNA double helix, ___

Accepted Answer

the two DNA strands run antiparallel.

Answer

the two DNA strands are identical.

Answer

purines pair with purines.

Answer

thymine pairs with cytosine.

Question 16

The N-terminal tail of histone H3 can be extensively modified, and depending on the number, location, and combination of these modifications, these changes may promote the formation of heterochromatin. What is the result of heterochromatin formation?

Accepted Answer

gene silencing

Answer

an increase in gene expression

Answer

recruitment of remodeling complexes

Answer

displacement of histone H1

Question 17

Most eukaryotic cells only express 20-30% of the genes they possess. The formation of heterochromatin maintains the other genes in a transcriptionally silent (unexpressed) state. Which histone modification is associated with the formation of the most common type of heterochromatin?

Accepted Answer

H3 lysine 9 trimethylation

Answer

H3 lysine 4 methylation

Answer

H3 lysine 14 methylation

Answer

H3 lysine 27 methylation

Question 18

RNA in cells differs from DNA in that ___.

Accepted Answer

it is single-stranded and can fold up into a variety of structures.

Answer

it contains the base uracil, which pairs with cytosine.

Answer

it is single-stranded and cannot form base pairs.

Answer

the sugar ribose contains fewer oxygen atoms than does deoxyribose.

Question 19

Transcription is similar to DNA replication in that ___.

Accepted Answer

nucleotide polymerization occurs only in the 5'-to-3' direction.

Answer

an RNA transcript is synthesized discontinuously and the pieces are then joined together.

Answer

it uses the same enzyme as that used to synthesize RNA primers during DNA replication.

Answer

the newly synthesized RNA remains paired to the template DNA.

Question 20

Which of the following statements is FALSE?

Accepted Answer

RNA polymerase adds bases in a 3'-to-5' direction; DNA polymerase adds bases in a 5'-to-3' direction.

Answer

RNA polymerase can start making a new RNA molecule without a primer; DNA polymerase cannot.

Answer

RNA polymerase does not proofread its work; DNA polymerase does.

Answer

RNA polymerase catalyzes the linkage of ribonucleotides while DNA polymerase catalyzes the linkage of deoxyribonucleotides.

Question 21

Which one of the following is the main reason that a typical eukaryotic gene is able to respond to a far greater variety of regulatory signals than a typical prokaryotic gene or operon?

Accepted Answer

The transcription of a eukaryotic gene can be influenced by proteins that bind far from the promoter.

Answer

Eukaryotes have three types of RNA polymerase.

Answer

Eukaryotic RNA polymerases require general transcription factors.

Answer

Prokaryotic genes are packaged into nucleosomes.

Question 22

Which of the following does not occur before a eukaryotic mRNA is exported from the nucleus?

Accepted Answer

The ribosome binds to the mRNA.

Answer

The mRNA is polyadenylated at its 3' end.

Answer

A guanine nucleotide with a methyl group is added to the 5' end of the mRNA.

Answer

RNA polymerase dissociates.

Question 23

30. The correct statement about the genetic code is correct?

Accepted Answer

All codons specify more than one amino acid.

Answer

Most of the genetic code is redundant.

Answer

All amino acids are specified by more than one codon.

Answer

All codons specify an amino acid.

Question 24

A neuron and a white blood cell have very different functions. For example, a neuron can receive and respond to electrical signals, while a white blood cell defends the body against infection. This is because ___

Accepted Answer

the neuron expresses some mRNAs that the white blood cell does not.

Answer

all of the proteins found in a neuron are completely different from the proteins found in a white blood cell.

Answer

the neuron and the white blood cell within an individual have the same genome.

Answer

neurons and white blood cells are differentiated cells and thus no longer need to transcribe and translate genes.

Question 25

The distinct characteristics of different cell types in a multicellular organism result mainly from the differential regulation of the ___.

Accepted Answer

transcription of genes transcribed by RNA polymerase II.

Answer

replication of specific genes.

Answer

transcription of housekeeping genes.

Answer

proteins that directly bind the TATA box of eukaryotic genes.

Question 26

Which of the following statements about differentiated cells is TRUE?

Accepted Answer

Some of the proteins found in differentiated cells are found in all cells of a multicellular organism.

Answer

Cells of distinct types express nonoverlapping sets of transcription regulators.

Answer

Once a cell has differentiated, it can no longer change its gene expression.

Answer

Once a cell has differentiated, it will no longer need to transcribe RNA.

Question 27

Which of the following statements about transcriptional regulators is FALSE?

Accepted Answer

Transcription regulators interact only with the sugar-phosphate backbone on the outside of the double helix to determine where to bind on the DNA helix.

Answer

Transcription regulators will form hydrogen bonds, ionic bonds, and hydrophobic interactions with DNA.

Answer

The DNA-binding motifs of transcription regulators usually bind in the major groove of the DNA helix.

Answer

The binding of transcription regulators generally does not disrupt the hydrogen bonds that hold the double helix together.

Question 28

Which of the following is NOT involved in post-transcriptional control?

Accepted Answer

Mediator

Answer

the spliceosome

Answer

Dicer

Answer

RISC

Question 29

miRNAs, tRNAs, and rRNAs all ___

Accepted Answer

do not code for proteins.

Answer

act in the nucleus.

Answer

are packaged with other proteins to form RISC.

Answer

form base pairs with mRNA molecules.

Question 30

MicroRNAs _.

Accepted Answer

are produced from a precursor miRNA transcript.

Answer

are found only in humans.

Answer

control gene expression by base-pairing with DNA sequences.

Answer

can degrade RNAs by using their intrinsic catalytic activity.

Question 31

Which of the following statements about miRNAs is FALSE?

Accepted Answer

miRNAs are produced from rRNAs.

Answer

One miRNA can regulate the expression of many genes.

Answer

miRNAs are transcribed in the nucleus from genomic DNA.

Answer

miRNAs are made by RNA polymerase.

Question 32

Which of the following statements about RNAi is TRUE?

Accepted Answer

RNAi is induced when double-stranded, foreign RNA is present in the cell.

Answer

The RNAi mechanism is found only in plants and animals.

Answer

RISC uses the siRNA duplex to locate complementary foreign RNA molecules.

Answer

siRNAs bind to miRNAs to induce RNAi.

Question 33

Which one of the followings proteins contains a single Transmembrane (TM) region?

Accepted Answer

Growth factor receptor (Receptor Tyrosine Kinase)

Answer

Sos

Answer

Ras

Question 34

Which of the following events is necessary for establishing lipid anchor of a membrane protein on the extracellular side?

Accepted Answer

Glycosylphosphatidylinositol (GPI) anchor

Answer

Myristoylation

Answer

Prenylation

Answer

Ubiquitylation

Question 35

Some proteins are almost as mobile as lipids, whereas others are virtually immobile. Which of the following proteins would be the fastest moving membrane protein?

Accepted Answer

Bacterial rhodopsin a 7-TM protein

Answer

fibronectin, a peripheral glycoprotein that interacts with the extracellular matrix.

Answer

E-Cadherin at the cell-cell junction linked to the F-Actin

Question 36

Which of the following statement on SRP (Signal Recognition Particle) is NOT true?

Accepted Answer

SRP binding to the start transfer sequence will inhibit the Ribosome binding to the ER

Answer

An ER signal sequence and an SRP direct a ribosome to the SRP Receptor on the ER membrane.

Answer

SRP binding to the ER signal sequence on a Ribosome pauses translation

Answer

SRP receptor localizes on the ER membrane

Question 37

Which of the following is one of the features of RPTK?

Accepted Answer

kinase domain

Answer

an intracellular ligand binding domain

Answer

seven transmembrane domain

Answer

GEF activity

Question 38

Which of the following type of molecules associate with activated RPTK?

Accepted Answer

an SH2 domain containing adaptor protein

Answer

MAPK

Answer

Ras

Answer

heterotrimeric G proteins

Question 39

MAP Kinase stands for ___?

Accepted Answer

Mitogen Activated Protein Kinase

Answer

Mono Amino Phosphate Kinase

Answer

Mitochondrial Associated Protein Kinase

Answer

Microtubule Assembly Protein Kinase

Question 40

In response to mitogenic signal, cells induce immediate early response genes. Which of the following is one of them?

Accepted Answer

c-Myc

Answer

RPTK

Answer

GPCR

Answer

MAPK

Question 41

Under certain situation, cells interpret the same molecular ligand to a RPTK differently through selective downstream signal transduction. For example, RPTK can activate PI3K, Ras, or PLC pathways. Which of the following pathway is most critical for RPTK to suppress programmed cell death?

Accepted Answer

PI3K/PKB(Akt)

Answer

Ras/MAPK

Answer

PLC

Question 42

There are eight members of phosphatidylinositol. Which of the following is the target (or substrate) for PLC?

Accepted Answer

PI(4,5)P2

Answer

PIP3

Answer

PI(3)P

Question 43

There are eight members of phosphatidylinositol. Which of the following is the target (or substrate) for PI3K?

Accepted Answer

PI(4,5)P2

Answer

PIP3

Answer

PI(3)P

Question 44

In response to a survival signal, the activated PKB(Akt) phosphorylates BAD protein. Does Bad protein suppress or promote apoptosis?

Accepted Answer

promotes

Answer

suppresses

Question 45

In response to a survival signal, the activated PKB(Akt) phosphorylates BAD protein. Upon phosphorylation, BAD protein does one of the following:

Accepted Answer

dissociating from Bcl-2

Answer

directly promoting apoptosis

Answer

inactivating Bcl-2

Question 46

Which of the following statements is true?

Accepted Answer

Bcl2 inhibits apoptosis.

Answer

Akt kinase inhibits Bcl2.

Answer

Akt kinase activates BAD protein.

Question 47

Which of the following is not regulated by the PI3K/PKB/mTOR signaling?

Accepted Answer

Inhibition of Rb phosphorylation.

Answer

Stimulation of protein synthesis.

Answer

Inhibition of Protein degradation.

Question 48

______ signal transduction pathway inhibits cell cycle progression.

Accepted Answer

TGF-beta

Answer

Mitogenic

Answer

Apoptotic

Question 49

p53 can induce cell cycle arrest. What is the p53 mediated cell cycle arrest?

Accepted Answer

generating CDK inhibitors such as p21.

Answer

activating ERK2

Answer

degrading E2F

Answer

stabilizing Rb

Question 50

Which of the following processes occur only in S phase of the cell cycle?

Accepted Answer

DNA replication

Answer

Organelle replication

Answer

Cell growth

Answer

Chromosome segregation

Question 51

The period between one M phase and the subsequent M phase is called:

Accepted Answer

interphase

Answer

S phase

Answer

anaphase

Answer

G2 phase

Question 52

If the Rb protein binds to transcription regulators, the cell will move from G1 phase to S phase.

Accepted Answer

False

Answer

True

Question 53

What inhibits Rb?

Accepted Answer

CyclinD/Cdk

Answer

Ras

Answer

Cdc6

Answer

Myc

Question 54

Transcription factor E2F is inhibited by ____.

Accepted Answer

(a) Rb

Answer

(b) Cyclin D

Answer

(c) p53

Answer

(d) CDK2

Question 55

The signal to commence DNA replication comes from:

Accepted Answer

S-Cdk.

Answer

ORC.

Answer

the destruction of Cdc25.

Answer

the destruction of M-Cdk.

Question 56

RPTK can activate multiple downstream signaling pathways such as PI3K, Ras, or PLC. Which of the following pathway is usually activated for RPTK to induce cells to proliferate?

Accepted Answer

Ras/MAPK/Myc

Answer

PI3K/PKB/Bcl2

Answer

PLC/IP3/Calcium

Question 57

Which of the following statements about the newly synthesized strand of a human chromosome is TRUE?

Accepted Answer

It was synthesized from multiple origins by a mixture of continuous and discontinuous DNA synthesis.

Answer

It was synthesized from a single origin solely by continuous DNA synthesis.

Answer

It was synthesized from a single origin by a mixture of continuous and discontinuous DNA synthesis.

Answer

It was synthesized from multiple origins solely by discontinuous DNA synthesis.

Question 58

A telomerase is best described as a

Accepted Answer

DNA polymerase with its bound RNA template

Answer

RNA polymerase.

Answer

ligase.

Answer

topoisomerase.

Answer

exonuclease.

Question 59

Where does the initiator protein bind DNA at the start of replication?

Accepted Answer

At an origin of replication

Answer

At a replication fork

Answer

At any AT-rich region

Answer

At a promoter region

Answer

At a start codon

Question 60

Helicase induces DNA supercoiling as the replication fork migrates during replication. Which kind of enzyme reduces Helicase-induced supercoiling as the replication fork migrates during replication?

Accepted Answer

Topoisomerase

Answer

Telomerase

Answer

Ligase

Answer

DNA polymerase I

Answer

DNA polymerase III

Question 61

Homologous recombination (HR) is an important mechanism in which organisms use a "backup" copy of the DNA as a template to fix double-strand breaks without loss of genetic information. Which of the following is NOT necessary for homologous recombination to occur?

Accepted Answer

The cell should be at the G1 phase

Answer

The cell should be at the G2 phase

Answer

3' DNA strand overhang

Answer

a long stretch of sequence similarity

Question 62

Sometimes replication errors escape proofreading of DNA Polymerase and generate a DNA mismatch. Which of the following mechanism will fix this kind of error?

Accepted Answer

Mismatch Repair (MMR)

Answer

NHEJ

Answer

HR

Question 63

Which of the following would promote cancer development?

Accepted Answer

upregulating telomerase

Answer

by activating DNA repair system

Answer

by activating TGF-beta signaling

Answer

by activating p53

Question 64

The properties of a lipid bilayer are determined by the structures of its lipid molecules. Predict the properties of the lipid bilayers that would result if the following was the case: phospholipids had only one hydrocarbon chain instead of two.

Accepted Answer

form micelles rather than bilayers.

Answer

still form bilayers

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