Homework Questions Exam 3

Question 1

What is the initial target of the RNA polymerase?

Answer 1

The promoter

Question 2

RNA polymerase is guided by the

Answer 2

Template strand of the DNA

Question 3

RNA that has hydrogen bonded to itself forms a

Answer 3

Stem loop

Question 4

How would you increase the concentration of a particular polypeptide in a cell?

Answer 4

Increase the level of transcription

Question 5

During elongation, what direction is RNA synthesized?

Answer 5

5’ to 3’

Question 6

In the process of transcription, promoters are specific sequences of ______________ that are recognized by ___________________.

Answer 6

DNA
Sigma factors.

Question 7

The function of RNA polymerase is to

Answer 7

Catalyze the formation of phosphodiester bonds between ribonucleotides.

Question 8

Polycistronic transcription units are common in

Answer 8

Both Archaea and bacteria

Question 9

Many pharmaceutical drugs specifically inhibit transcription in bacteria but not in archaea or eukarya. Why would drugs that inhibit transcription only affect bacteria and not archaea even though they are both prokaryotes?

Answer 9

Archaea and eukarya have very similar RNA polymerases that are different than bacterial RNA polymerases

Question 10

The template for RNA polymerase is _______________ and the new RNA molecule is _______________ to the template.

Answer 10

DNA
Antiparallel and complimentary

Question 11

termination of RNA synthesis is ultimately determined by

Answer 11

Specific nucleotide sequences on the template strand

Question 12

What is the definition of polycistronic mRNA?

Answer 12

A single piece of mRNA that contains the transcript of multiple genes.

Question 13

True or false: Inverted repeats are common features of transcription termination sequences in all 3 domains of life.

Answer 13

True

Question 14

What results in the process of bacterial translation?

Answer 14

A polypeptide

Question 15

How is bacterial translation different from eukaryotic translation?

Answer 15

Bacteria can begin translation before transcription has terminated

Question 16

Ribosomes move along the mRNA in which direction?

Answer 16

5’ to 3’

Question 17

How do prokaryotes determine where to begin translation so the correct protein is synthesized?

Answer 17

The rRNA recognizes the correct start codon with the aid of upstream Shine-Dalgarno sequence.

Question 18

The process of synthesizing proteins involves translation one “language,” nucleic acid sequences, into another “language” amino acid sequence. the cellular component that does the actual translating from codons to amino acids is the ________________.

Answer 18

tRNA

Question 19

Transfer RNA molecules function

Answer 19

to transfer the correct amino acids to the ribosome during translation

Question 20

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 20

MRNA
TRNA

Question 21

A triplet of bases on an mRNA molecule is known as a(n)

Answer 21

Codon

Question 22

True or false: Aminoacyl-tRNA synthetase catalyzes the action between the appropriate amino acids and ATP to form an activated amino acid: AA + ATP <—-> aminoacyl-AMP + P-P

Answer 22

True

Question 23

What are the products of semiconservative replication for a double stranded DNA molecule?

Answer 23

Two double stranded DNA molecules, each consisting of one parental stand and one daughter strand.

Question 24

Why is DNA replication essential for a cell?

Answer 24

An organism must copy its DNA to pass genetic information to its offspring

Question 25

What is the function of the parental DNA in replication?

Answer 25

It serves as the template for DNA replication.

Question 26

Supercoiling is important for DNA structure because

Answer 26

It condenses the DNA so that it can fit inside the cell.

Question 27

The two strands of the DNA double helix are held together by

Answer 27

Hydrogen bonds between nucleotide bases

Question 28

In complementary base pairing of DNA, adenine pairs with ____ (or _______ in RNA) and cytosine always pairs with __________.

Answer 28

Thymine Uracil Guanine

Question 29

Each adenine-thymine base pair has ________ hydrogen bonds while each cytosine-guanine base pair has ___________ hydrogen bonds.

Answer 29

2 3

Question 30

DNA-binding proteins interact predominantly within which portion of a double stranded DNA helix?

Answer 30

Major groove

Question 31

Given the following DNA sequence (5’ to 3’) what would be the DNA sequence on the complimentary strand (3’ to 5’) of the double stranded helix molecule? DNA sequence: AGTCCGA

Answer 31

TCAGGCT

Question 32

What genetic element is transcribed into a single mRNA?

Answer 32

the structural genes

Question 33

Which operons are always transcribed unless deactivated?

Answer 33

Repressible operons

Question 34

Which operons are never transcribed unless activated?

Answer 34

Inducible operons

Question 35

Where on the DNA strand does a repressor bind?

Answer 35

the operator

Question 36

When the cell is not in the presence of tryptophan,

Answer 36

RNA polymerase can transcribe mRNA

Question 37

When is the repressor protein transcribed?

Answer 37

It is always transcribed

Question 38

Why is the tryptophan operon turned off in the presence of tryptophan?

Answer 38

tryptophan binds to and activates the repressor proteins; the repressor proteins, in turn, bind to the operator, preventing transcription.

Question 39

What is the overall function of the trp operon?

Answer 39

to ensure that the cell has a supply of tryptophan at all times.

Question 40

How do the repressor proteins block the transcriptions of the structural genes?

Answer 40

It binds to the operator when activated.

Question 41

What is the inducer molecule in the lac operon?

Answer 41

Allolactose

Question 42

With which genetic region do the repressor proteins interact?

Answer 42

The operator region

Question 43

When the cell in not in the presence of lactose,

Answer 43

The repressor proteins bind to the operator.

Question 44

What is the basic function of the lac operon?

Answer 44

To code for enzymes involved in catabolizing lactose

Question 45

To what genetic element does the RNA polymerase bind?

Answer 45

The promoter

Question 46

A recombinant cell

Answer 46

Is a cell that receive DNA from an outside source and incorporates it into its own

Question 47

What is the hallmark of all horizontal gene transfers

Answer 47

Transfer of. DNA between organisms of the same generation

Question 48

What are the 3 types of horizontal gene transfer in bacteria?

Answer 48

Transduction, conjugation and transformation

Question 49

What is the function of the conjugation pilus?

Answer 49

It pulls the F+ and F- cells together

Question 50

What is required by an F- cell to become an F+ cell?

Answer 50

F plasmid

Question 51

What is the key difference between donor cells and recipient cells?

Answer 51

An F plasmid

Question 52

What cellular macromolecule is the fertility factor comprised of?

Answer 52

Nucleic acid

Question 53

At which point does the recipient cell become an F+ cell?

Answer 53

During the formation of the complimentary strand of the F factor

Question 54

How does an F+ cell different from an Hfr cell?

Answer 54

Hfr strains have the F plasmid integrated into the chromosome.

Question 55

Why does conjugation between an Hfr strain and an F- strain not result in 2 Hfr strains?

Answer 55

Conjugation is typically disrupted before the fertility factor can be transferred.

Question 56

What is a characteristic of a F+ cell?

Answer 56

Ability to synthesize sex pili, presence of fertility factor and ability to mate with an F- cell.

Question 57

What benefits does the F- strain receive from mating with an Hfr strain?

Answer 57

It acquires new, potentially beneficial genes from the Hfr strain

Question 58

What base is not found in DNA?

Answer 58

Uracil

Question 59

DNA replication always proceeds in only one direction because the _________ of the incoming nucleotide is attached to the free _________ of the growing DNA strand .

Answer 59

5’-phosphate 3’-hydroxyl group

Question 60

What is formed on the lagging strand during DNA synthesis?

Answer 60

Okazaki fragments

Question 61

the function of the DNA polymerase is to catalyze

Answer 61

The addition of Deoxynucleotides

Question 62

During DNA replication, Okazaki fragments are linked together by ___________, an enzyme that creates phosphodiester bonds between nicked fragments of DNA.

Answer 62

DNA ligase

Question 63

In DNA replication, there are leading and lagging strands because

Answer 63

DNA replication is semiconservative and each strand is copied simultaneously in opposite directions.

Question 64

Which statement illustrates why DNA polymerase cannot initiate a new DNA strand?

Answer 64

DNA polymerase requires a preexisting 3’ hydroxyl group in order to add nucleotides

Question 65

true or false: DNA replication is bidirectional in prokaryotes with circular chromosomes?

Answer 65

true