Genetics Chapter 8

Question 1

RNA ribonucleotides are composed of a […], […], and one or more […], with two critical differences compared to DNA nucleotides.

Answer 1

sugar; nucleotide base; phosphate groups

Question 2

The bases adenine, guanine, and cytosine are the same, but thymine is replaced by […]. The sugar […] is used rather than […]

Answer 2

uracil; ribose; deoxyribose

Question 3

In the late 1950s, researchers used the […] technique to follow the trail of newly synthesized RNA in cells. The pulse exposed cells to […] nucleotides followed by a chase of nonradioactive nucleotides.

Answer 3

pulse-chase; radioactive

Question 4

The […] R N A molecules were then traced in the cells

Answer 4

radiolabeled

Question 5

[…] and […] (1957) examined transcription this way in bacteria, immediately after bacteriophage infection. Infection stimulated a burst of […] , which quickly dissipated, indicating rapid breakdown of the RNA molecules. They concluded that RNA transcription was necessary for formation of […].

Answer 5

Volkin; Astrachan; transcriptional activity; new phage proteins

Question 6

Over a short period of time, the radioactivity moved to the […] and then dissipated after some time. This led researchers to conclude that RNA synthesized in the […] carried its information to the […] for translation into protein

Answer 6

cytoplasm; nucleus; cytoplasm

Question 7

The similar sugars in RNA and DNA lead to formation of nearly identical […] in the molecules. RNA strands are assembled by formation of […] bonds between adjacent nucleotides. RNA is synthesized from a […] using complementary base pairing (A with U and C with G)

Answer 7

sugar-phosphate backbones; phosphodiester; DNA template

Question 8

[…] catalyzes the addition of each ribonucleotide to the 3′ end of the nascent strand, and forms phosphodiester bonds between nucleotides. Two phosphates are […] in the process, as in DNA synthesis. RNA polymerases make about one mistake for every […]nucleotides copied into RNA

Answer 8

RNA polymerase; eliminated; 104

Question 9

Messenger RNA (mRNA) is produced by […] genes and is a short-lived intermediary between DNA and protein. It is the only type of RNA that undergoes […]. Transcription of mRNA is often followed by […] processing

Answer 9

protein-producing; translation; posttranscriptional

Question 10

Functional RNAs do not encode proteins, but instead perform […] roles in the cell. Ribosomal RNA (rRNA) combines with numerous proteins to form […]. Transfer RNAs (tRNAs) are encoded in dozens of forms and are responsible for binding an […] and depositing it for inclusion into a growing protein chain.

Answer 10

functional; ribosomes; amino acid

Question 11

Telomerase RNA provides a […] for synthesis of repetitive DNA telomere sequences. Small nuclear RNA (snRNA) of various types is found in the […] of eukaryotes and plays a role in mRNA processing. Micro RNA (miRNA) and small interfering RNA (siRNA) are active in […] and […] cells and are involved in posttranscriptional regulation of mRNA.

Answer 11

template; nucleus; plant; animal

Question 12

Transcription is the synthesis of a […] RNA molecule by RNA polymerase. There are four stages of transcription in bacteria: [..], […], […], and […]

Answer 12

single-stranded; Promoter recognition, Transcription initiation, Chain elongation; Chain termination

Question 13

The […] uses the template strand of the DNA to assemble a complementary, antiparallel strand of ribonucleotides (The 3’ to 5’ strand). The […] strand of DNA, also called the nontemplate strand, is […] to the template strand. (The 5’ to 3’ strand)

Answer 13

polymerase; coding; complementary

Question 14

The gene contains several […] with distinct functions. The promoter is immediately […] (5′) to the start of transcription, referred to as the […] nucleotide. The promoter controls the access of RNA polymerase to the […].

Answer 14

segments; upstream (5′); +1; gene

Question 15

The coding region of the gene is the portion that contains the information needed to synthesize the […]. The termination region of the gene regulates […] of transcription. The termination region is immediately […] (3′) to the coding segment of the gene

Answer 15

protein product; cessation; downstream

Question 16

The bacterial RNA polymerase is composed of a […] RNA polymerase core that binds a sixth subunit, called the […] (σ) subunit. Binding of the RNA polymerase core with the sigma subunit forms the […]. The large core enzyme is composed of two […] subunits, two […] subunits, and an […] subunit. The core enzyme can transcribe RNA from a DNA template but cannot efficiently bind the promoter or initiate RNA synthesis without the […] subunit.

Answer 16

pentameric; sigma (σ); holoenzyme; α; β; ω; σ

Question 17

Several different types of sigma subunits, called […] , are produced. These alter core enzyme conformation in slightly different ways to facilitate association with different […] regions.

Answer 17

alternative sigma subunits; promoter

Question 18

A promoter is a […] DNA sequence that is the RNA polymerase […]site; promoters also bind other transcription proteins.
The promoter is located a […] distance upstream of the coding sequence, within a few nucleotides of +1. RNA polymerase is attracted to promoters by the presence of […].

Answer 18

double-stranded; binding site; short; consensus sequences

Question 19

Consensus sequences are written in […] shorthand form, 5′ to 3′ on the coding strand. At the −10 position is the […] box, or −10 consensus sequence, […]′. At −35 is a 6-b p region, the −35 consensus sequence, […]. RNA polymerase binds to −10 and −35 sequences and occupies the […] between and around them.

Answer 19

single-stranded; Pribnow; 5′-T A T A A T-3′; 5′-T T G A C A-3′; space

Question 20

RNA polymerase initiates through a two-step process. First, the holoenzyme makes a […] attachment to the promoter sequence, then binds tightly to form the closed […] . Then, the holoenzyme unwinds about 18 bp of […] around the −10 position to form the open promoter complex.

Answer 20

loose; promoter complex; DNA

Question 21

Next, the holoenzyme progresses downstream to initiate […] at the +1 site. Considerable sequence variation exists among promoters; alternative sigma subunits recognize different consensus sequences, allowing for holoenzyme binding to […] promoters

Answer 21

RNA synthesis; variant

Question 22

The holoenzyme initiates R N A synthesis at the […] site. It remains intact until the first 8 to 10 R N A nucleotides have been joined, at which point the sigma subunit dissociates from the […] enzyme. DNA is unwound ahead of the enzyme to maintain about 18 base pairs of unwound DNA; the double helix […] behind the DNA polymerase

Answer 22

+1 site; core enzyme; reforms

Question 23

When transcription of the gene is completed, the 5′ end of the RNA […] off the core enzyme. The core enzyme […] from the DNA. Shortly after one round of transcription is initiated, a second round […].

Answer 23

trails; dissociates; begins

Question 24

Termination of transcription in bacteria is signaled by a DNA termination sequence that usually contains a […] sequence. In intrinsic termination, a mechanism dependent only on the presence of the repeat induces a […] structure needed for termination. […] termination requires a different termination sequence and the rho protein

Answer 24

repeating; secondary; Rho-dependent

Question 25

Most […] termination occurs via […] termination. Termination sequences include an inverted repeat followed by a string of […] mRNA containing the inverted repeats form into a short stem-loop structure, called a […].

Answer 25

bacterial; intrinsic; adenines; hairpin

Question 26

The hairpin followed by a series of U’s in the mRNA causes the RNA polymerase to […] and […]. The instability caused by the […] polymerase and the U-A base pairs induces the polymerase to release the transcript and […] from the DNA.

Answer 26

slow down; destabilize; slowing; separate

Question 27

Certain bacterial genes require the action of […] protein to bind to the […] mRNA and catalyze the separation of the mRNA from the RNA polymerase. Rho-dependent termination sequences are different for those used in intrinsic termination; instead they have a […] (or rut) site

Answer 27

rho; nascent; rho utilization

Question 28

After transcription of the rut site, rho protein […] to the rut site. Rho then moves along the transcript to […] and catalyzes the release of […] from […], which triggers the release of the […] from the DNA

Answer 28

attaches; RNA polymerase; mRNA; RNA polymerase; polymerase