Exam 2

Question 1

A viral capsid is composed of individual units of ____ called _____

Answer 1

proteins; capsomeres

Question 2

Which is not true regarding temperate phages?

Answer 2

They always kill their host once infection begins

Question 3

A single base substitution happens to cause a nonsense mutation early in the gene for a protein. What will be the result?

Answer 3

The protein will be truncated so much that it is unlikely to function normally.

Question 4

To be retained permanently in the bacterial chromosome, a piece of DNA that has been transferred into the cell must ______.

Answer 4

recombine into the chromosome

Question 5

Transposons are used in research to create random mutations in an organism’s genome. Transposons create mutations by

Answer 5

inserting into a gene

Question 6

The presence of the F plasmid in a cell alters all the following properties of a cell EXCEPT

Answer 6

the ability to replicate DNA

Question 7

Frameshift mutations can be very severe. What is one reason why they are often so serious?

Answer 7

When a frameshift mutation occurs, it causes changes in many bases downstream and can affect many of the amino acids in the protein

Question 8

The isolation of a single mutant from a population containing millions of wild-type cells is done by using

Answer 8

selection

Question 9

RNA genomes have a higher mutation rate than DNA genomes. This is because

Answer 9

RNA repair mechanisms do not exist

Question 10

A mutation in the genome of an organism can affect

Answer 10

both the genotype and the phenotype of the organism

Question 11

Which of the following events happens in specialized transduction?

Answer 11

Bacterial genes adjacent to the site where the phage DNA integrates are transduced

Question 12

Increasing genetic variability by the uptake of DNA from the environment is

Answer 12

transformation

Question 13

An organism that cannot synthesize methionine is an example of

Answer 13

An auxotroph

Question 14

How are the individual strands of DNA arranged in a double-stranded molecule?

Answer 14

Antiparallel; that is to say, a 5’ to 3’ strand is on the bottom and a 3’ to 5’ strand is on the top

Question 15

Which of the following molecules is NOT involved in transcription?

Answer 15

amino acids

Question 16

In DNA replication, where is the location of the 3’ hydroxyl to which an incoming nucleotide is attached?

Answer 16

on a deoxyribose suar

Question 17

In E. coli, what two promoter regions are recognized by the σ70 subunit

Answer 17

the -10 and -35 regions

Question 18

How would you describe the proofreading activities of DNA Pol I and Pol III?

Answer 18

3’ -> 5’ exonuclease

Question 19

On which strand(s) of newly formed DNA are Okazaki fragments found?

Answer 19

lagging strand

Question 20

Which of the following genetic elements encodes genes that are essential to a cell?

Answer 20

Chromosome

Question 21

Which of the following functions is NOT conferred by a plasmid?

Answer 21

tRNA gene(s)

Question 22

What are groups of genes called that are transcribed into a single polycistronic mRNA?

Answer 22

Operon

Question 23

In addition to an inverted repeat sequence in the DNA that leads to a stem-loop structure in RNA, what is the other primary feature of an intrinsic transcriptional terminator?

Answer 23

a series of A residues

Question 24

Polypeptides and proteins must fold properly to be functional. Hydrogen bonds between the oxygen and nitrogen atoms of the peptide bonds are crucial to which level of protein structure?

Answer 24

secondary structure

Question 25

How many bases make up a codon

Answer 25

three

Question 26

The codon on the _____ matches with the anticodon on the _____ to direct the addition of the correct amino acid to the growing polypeptide chain

Answer 26

mRNA/tRNA

Question 27

The Tat system is involved in

Answer 27

protein secretion

Question 28

What type of enzyme links an amino acid to its specific tRNA

Answer 28

aminoacyl-tRNA synthetases

Question 29

In all cells a gene encodes for

Answer 29

a protein, tRNA or rRNA depending on the specific gene

Question 30

Transcription of chaperones is greatly accelerated when a cell is stressed by

Answer 30

excessive heat

Question 31

Tetracycline is added to the medium. It binds to the 30s ribosome, blocking the A site and preventing the binding of aminoacyl tRNAs. What effect would this have on translation?

Answer 31

Polypeptide synthesis would be inhibited

Question 32

Transfer RNA (tRNA) molecules

Answer 32

function to transfer the correct amino acid to the ribosome during translation

Question 33

The first step of translation begins with

Answer 33

the ribosome binding site (RBS) on the mRNA binds to the 16S rRNA to begin the formation of the initiation complex

Question 34

Binding of an activator protein to an upstream region of the promoter enhances transcription by which of the following?

Answer 34

bending of DNA to allow contact between RNA polymerase and the activator

Question 35

When multiple unrelated genes are regulated simultaneously in response to a change in the environment, that is known as

Answer 35

global control of gene expression

Question 36

Which of the following is NOT true of DNA-binding proteins?

Answer 36

Most bind to DNA in a nonspecific manner

Question 37

A system that is used in bacteria to control the regulation of several operons that encodes enzymes that metabolize different carbon sources is called

Answer 37

catabolite repression

Question 38

Expression of a structural gene is controlled by

Answer 38

binding of specific proteins to DNA sequences in its upstream region

Question 39

A common motif in proteins that bind DNA in Bacteria is the

Answer 39

helix-turn-helix

Question 40

Where do transcriptional regulators most commonly bind to?

Answer 40

major grooves in dsDNA

Question 41

A cluster of genes arranged in a linear, consecutive manner that is under the control of a single operator is called

Answer 41

operon

Question 42

In quorum sensing, the small signal molecule that is released into the environment by bacterial cells is called a(n)

Answer 42

auto-inducer

Question 43

Consider the following:
I Quorum sensing is only seen in gram-positive organisms
II. Molecules called autoinducers spread freely across the microbial membrane

Answer 43

Only the second statement is true

Question 44

Bacterial cells that can naturally take up DNA from the environment are known as

Answer 44

competent

Question 45

Which of the following events happens in specialized transduction?

Answer 45

Bacterial genes adjacent to the site where the phage DNA integrates are transduced

Question 46

Increasing genetic variability by the uptake of DNA from the environment is

Answer 46

transformation

Question 47

The enzyme required to carry out transposition is known as

Answer 47

transposase