Chapter 8

Question 1

characteristics of mRNA

Answer 1

• moves genetic info out of nucleus into cytoplasm

- read in codons

Question 2

characteristics of rRNA

Answer 2

• joins amino acids by peptide bonds

- makes up part of ribosome

Question 3

characteristics of tRNA

Answer 3

• delivers amino acids to site of protein synthesis

- has an anticodon that interacts with a specific codon from another molecule

Question 4

steps of DNA transcription

Answer 4

1. RNA poly binds to DNA strand upstream from gene
2. RNA poly pairs RNA bases with DNA bases on template strand
3. RNA breaks away from RNA poly and they both leave the DNA strand

Question 5

characteristics of transcription (DNA -> RNA)

Answer 5

• only one strand serves as the template for a given gene (oriented in 3’ to 5’)
• catalyzed by RNA poly

Question 6

characteristics of DNA replication (DNA -> DNA)

Answer 6

• catalyzed by DNA poly

- requires a primer

Question 7

characteristics of promoters

Answer 7

• contains -35 and -10 region upstream of transcription start site
• contains TATA box
• located at 5’, upstream

Question 8

function of sigma factor in prokaryotic transcription

Answer 8

facilitates the binding of RNA poly to promoter to initiate transcription

Question 9

prokaryotic transcription

Answer 9

• can be terminated by rho helicase or intrinsic termination (hair-pin loop)
• includes -10 sequence

Question 10

eukaryotic transcription

Answer 10

• includes 5’ cap
• requires TFIID to recognize TATA box
• promoter includes TATA box
• polyadenylation occurs at 3’ end to form poly-A tail
• splicesome removes introns and joins exons

Question 11

steps of eukaryotic transcription

Answer 11

1. RNA poly II binds DNA promoter element (initiation)
2. Ribonucleotide align with complementary DNA nucleotides
3. RNA poly links triphosphate ribonucleotides together (elongation)
4. 5’ cap is added
5. RNA poly is released from DNA (termination)
6. mRNA gains poly-A tail and is spliced
7. mRNA leaves nucleus

Question 12

function of 5’ cap

Answer 12

• stabilizes mRNA near start codon
• assists in RNA splicing
• signals
• protection

Question 13

function of poly-A tail

Answer 13

• assists mRNA in binding to large ribosomal subunit

- transports mRNA out

Question 14

function of RNA splicing

Answer 14

• removes introns
• constructs multiple products from single gene
• facilitates transport of mRNA into cytoplasm

Question 15

who won the nobel prize for reverse transcription?

Answer 15

Howard Temin and David Baltimore