Chapter 17

Question 1

Transcription creates an RNA molecule that is _______ to the DNA template.

Answer 1

complementary

Question 2

what is the polymerase that makes RNA from DNA in bacteria?

Answer 2

RNA polymerase
DNA dependent

Question 3

Template strand definition

Answer 3

the DNA that serve as the template for transcription (the one that RNA polymerase will read)

Question 4

Non-template strand definition

Answer 4

coding strand, have the same sequence as the RNA, will not get copied

Question 5

promoter definition

Answer 5

site where RNA polymerase binds to the gene

Question 6

Sigma definition

Answer 6

binds to the promoter region of the DNa- helps RNA polymerase bind to the gene

Question 7

Holoenzyme contains what?

Answer 7

Sigma and RNA polymerase

Question 8

steps for initiating transcription in bacteria

Answer 8

1. initiation begins- sigma binds to promoter region of DNA
2. initiation continues- RNA polymerase opens the DNA helix; transcription begins
3. initiation is complete- sigma is released from the promoter; RNA synthesis continues from DNA

Question 9

steps for ending transcription in bacteria

Answer 9

1. Hairpin forms- RNA polymerase transcribed a transcription- termination signal, which codes for RNA that forms a hairpin.
2. Termination- the RNA hairpin causes the RNA to separate from the RNA polymerase, terminating transcription.

Question 10

what are the three enzymes used for transcription in Eukaryotes?

Answer 10

RNA polymerase 1, 2, and 3

Question 11

RNA polymerase I

Answer 11

genes that code for most of the large RNA molecules found in ribosomes

Question 12

RNA polymerase II

Answer 12

protein- coding genes; also, genes that code for RNAs that function in ribosome assembly, and in processing and regulation of mRNAs

Question 13

RNA polymerase III

Answer 13

genes that code for transfer RNAs, for one of the small rRNAs found in ribosomes, and for noncoding RNAs; also, genes that code for RNAs that function in ribosome assembly, and in processing and regulation of mRNAs

Question 14

intron definition

Answer 14

contains no genetic information

Question 15

exon definition

Answer 15

contains genetic information

Question 15

when is the RNA functional?
- after being cut
- after going through RNA splicing

Answer 15

after going through RNA splicing

Question 15

what is RNA splicing?

Answer 15

process that removes introns in Eukaryotes

Question 16

what are the steps in splicing?

Answer 16

1. snRNPs bind to start of intron and an A base within the intron.
2. snRNPs assemble to form the spliceosome
3. intron is cut; loop forms
4. intron is released as a lariat; exons are joined together

Question 17

what is the last step to making the final mRNA?

Answer 17

adding a 5’ cap and 3’ poly(A) tail to each spliced transcript

Question 18

What is transcription?
a) Synthesis of protein, with tRNA used as template.
b) Synthesis of DNA, with RNA used as template.
c) Sythesis of protein, with mRNA used as template.
d) Synthesis of RNA, with DNA used as template.

Answer 18

d) Synthesis of RNA, with DNA used as template.

Question 19

Which of the following would not create a frameshift in the final mRNA?
a) Deleting 2 bases from the exon of a gene.
b) Adding an extra base to the exon of a gene.
c) Deleting 1 base from the exon of a gene.
d) Deleting 6 bases from the exon of a gene.

Answer 19

d) Deleting 6 bases from the exon of a gene.

Question 20

In what way is RNA polymerase similar to DNA polymerase?
a) Both read template DNA in the 5’-3’ direction.
b) Both read template DNA in the 3’-5’ direction.
c) Both use DNA as a template to make RNA.
d) Both use RNA as a template to make DNA.

Answer 20

b) Both read template DNA in the 3’-5’ direction.

Question 21

What is the correct order of initiating translation?
I. mRNA binds to small ribosomal subunit
II. Met-tRNA binds to start codon
III. large ribosomal subunit binds to mRNA
IV. tRNAs enter the “A” spot
a) II, III, I, IV.
b) I, III, II, IV.
c) I, II, III, IV.
d) II, I, III, IV.

Answer 21

c) I, II, III, IV.

Question 22

You are studying tropomyosin, a gene that is expressed in both skeletal muscle and smooth muscle. During your experiments you discover that the tropomyosin protein isolated from smooth muscle is almost twice as large as tropomyosin protein isolated from skeletal muscle. Why are the proteins different in size even though they come from the same gene?
a) Genetic recombination.
b) Unequal crossing over.
c) Differences in histone acetylation.
d) Alternative splicing.

Answer 22

d) Alternative splicing.

Question 23

aminoacyl definition

Answer 23

amino acid attached to tRNA

Question 24

what is a tRNA

Answer 24

transporter RNA

Question 25

aminoacyl-tRNA synthetase

Answer 25

enzyme- binds to tRNA and attaches amino acid to the 3’ end

Question 26

steps for initiating translation in bacteria

Answer 26

1. mRNA binds to small subunit
2. initiator aminoacyl tRNA binds to start codon
3. large subunit of ribosome binds, completing ribosome assembly

Question 27

steps for elongation polypeptides during translation

Answer 27

1. incoming aminoacyl tRNA
2. peptide-bond formation
3. translocation
4. incoming aminoacyl tRNA
5. peptide-bond formation
6. translocation

Question 28

steps for termination of translation

Answer 28

1. release factor binds to stop codon
2. polypeptide and uncharges tRNAs are released
3. ribosome subunits separate

Question 29

polycistronic definition

Answer 29

multiple reading frames each with their own ribosome binding sites and stop & start codons
single gene synthesizes at three parts

Question 30

alternative splicing

Answer 30

exons can be spliced out