Ch.12: Gene transcription and RNA modification

Question 1

Not all RNA is…? mRNA is..?

Answer 1

mRNA; translated into proteins

Question 2

Regulatory sequences

Answer 2

sites for the binding of
regulatory proteins that influence the rate of
transcription

Question 3

Promoter

Answer 3

site for RNA polymerase binding which
signals the beginning of transcription

Question 4

Ribosomes

Answer 4

binding site: site for ribosome binding to
mRNA in bacteria which begins the translation of
mRNA into a protein

Question 5

Codons

Answer 5

3 nucleotide sequences within the mRNA that specify
particular amino acids. The sequence of codons within mRNA determines the sequence of amino acids within a polypeptide

Question 6

Start Codon

Answer 6

specifies the first amino acid in a polypeptide sequence, usually a formylmethionine (in bacteria) and a methionine (in eukaryotes)

Question 7

The base sequence in mRNA is…?

Answer 7

identical to the coding or
sense strand of DNA, except for the substitution of uracil in RNA for thymine in DNA

Question 8

RNA polymerase is the…?

Answer 8

enzyme that catalyzes the synthesis of RNA; core enzyme binds loosely to the DNA\ until it encounters a promoter. A region within the sigma factor
that contains a helix-turn-helix structure is involved in the binding to DNA.

Question 9

What 2 mechanism does E.coli use for termination?

Answer 9

-rho-dependent termination
requires a protein known as r (rho)

• rho-independent termination: Utilizes proteins other than r

Question 10

Enhancers and Silencers

Answer 10

stimulate transcription; inhibit transcription

Question 11

Cis-acting elements

Answer 11

DNA sequences that exert their effect only over a particular gene, such as the TATA box, enhancers and silencers- cis-acting elements are usually found near the gene that they regulate and always on the same chromosome that contains the regulated gene

Question 12

trans-acting factors

Answer 12

Regulatory proteins that bind to the promoter regions of genes- trans-acting factors
can control many genes and the genes that encode them are not located near the gene that they regulate.

Question 13

RNA polymerase II

Answer 13

-Five different proteins called general transcription factors (GTFs)
-A protein complex called mediator

Question 14

What is processed from a larger precursor in bacteria?

Answer 14

Bacterial tRNA and ribosomal RNA

Question 15

Splicing using a spliceosome only occurs in?

Answer 15

eukaryotes

Question 16

Bacterial mRNA does not contain…?

Answer 16

7-methyl-guanosine caps at their 5’ end