Transcription

Question 1

Describe the primary and secondary structure of RNA

Answer 1

primary structure is generally single stranded, but RNA can also form some 3-D secondary structures if it is complementary with itself

Question 2

What is rRNA?

Answer 2

RNA molecule that is a structural component of the ribosome, which is involved in protein synthesis

Question 3

What is pre-mRNA?

Answer 3

immediate products of transcription in eukaryotes that is processed to mRNA; not in bacteria

Question 4

What is mRNA?

Answer 4

messenger RNA; RNA molecule that carries the coding instructions for a polypeptide chain from DNA to a ribosome

Question 5

What is tRNA?

Answer 5

transfer RNA; RNA molecule that carries an amino acid to the ribosome and transfers it to the growing polypeptide chain

Question 6

What three things does transcription require?

Answer 6

1. A DNA template
2. raw materials (ribonucleotide triphosphates)
3. a transcription apparatus (associated proteins and enzymes)

Question 7

What is the template strand?

Answer 7

The DNA nucleotide strand that is used as the template during transcription; the RNA synthesized during transcription is complementary and antiparallel to the template strand

Question 8

What is the coding strand?

Answer 8

The DNA strand that is complementary to the template strand; the RNA transcript will match this strand, except T will be replaced with U

aka the nontemplate strand

Question 9

What is a transcriptional unit and what are its parts?

Answer 9

A sequence of nucleotides in DNA that encodes a single RNA molecule and the sequences necessary for its transcription

Normally contains a promoter, an RNA-coding region, and a terminator

Question 10

What is the promoter?

Answer 10

A DNA sequence that the transcription apparatus recognizes and binds to; indicates the direction of transcription, which DNA strand will be the template, and the starting point of transcription

often upstream of the transcription start site

Question 11

What is a consensus sequence?

Answer 11

A group of common nucleotides (often A and T) in a stretch within the promoter

Question 12

What is the RNA coding region?

Answer 12

The sequence of DNA nucleotides that is copied into an RNA molecule

Question 13

What is the terminator?

Answer 13

sequence of DNA nucleotides that brings about the end of transcription

Question 14

How do rNTPs differ from dNTPs?

Answer 14

rNTPs have a hydroxyl at the 2’ carbon of their sugar (ribose), making it less stable than DNA

RNA nucleotides also utilize U (uracil) instead of T

Question 15

What is RNA Polymerase and in what direction does it transcribe?

Answer 15

The enzyme that synthesized RNA from a DNA template

works from 5’ to 3’

Question 16

What is a sigma factor?

Answer 16

molecule that aids in the binding of RNA polymerase to the promoter and aids in initiation

Question 17

What are rifamycins?

Answer 17

a class of antibiotics that prevent RNA polymerase from binding to DNA; does not affect eukaryotic RNA pol

Question 18

What does RNA Pol I synthesize

Answer 18

rRNA

Question 19

What does RNA Pol II synthesize

Answer 19

pre-mRNA

Question 20

What does RNA Pol III synthesize

Answer 20

tRNA

Question 21

Does RNA Polymerase require a primer to begin transcription?

Answer 21

no

Question 22

What are the stages of transcription?

Answer 22

1. Initiation
2. Elongation
3. Termination

Question 23

What are exons?

Answer 23

regions of RNA that code for a protein

Question 24

What are introns?

Answer 24

sequences in RNA that do not code for proteins and are spliced out

Question 25

What processing the eukaryotic pre-mRNA undergo?

Answer 25

1. addition of the 5’ cap (modified G)
2. addition of a poly-A tail to the 3’ end
3. splicing (removal of introns)