Part 1: DNA to RNA synthesis Flashcards
1
Q
Reverse transcriptase:
A
- can transcribe DNA from RNA
- therefore DNA ⇔ RNA
2
Q
The three principle classes of RNA molecules:
A
- ribosomal RNA (rRNA)
- messenger RNA (mRNA)
- transfer RNA (tRNA)
3
Q
RNA molecules are transcribed from:
A
- specific regions (genes) of the DNA genome.
4
Q
Ribosomal RNA (rRNA) is the:
A
- structural and catalytic component of ribosomes
- comprises about 80% of cellular RNA
5
Q
The four types of rRNA in humans:
A
- 5S rRNA
- 5.8S rRNA
- 18S rRNA
- 28S rRNA
6
Q
Transfer RNA (tRNA):
A
- comprises about 15% of a cell’s RNA
- “adaptor” molecule that delivers amino acids to the ribosome
7
Q
Messenger RNA (mRNA) is the:
A
- template for protein synthesis
- heterogeneous in size, varying according to the length of the encoded protein.
- less than 5% of the total RNA content (variable)
8
Q
small nuclear RNAs (snRNAs)
A
- involved in mRNA splicing
9
Q
small nucleolar RNAs (snoRNAs)
A
- function in rRNA processing
10
Q
microRNAs
A
- help regulate gene expression
11
Q
Transcription is defined as:
A
- DNA-directed RNA synthesis
12
Q
The RNA synthesis reaction proceeds in what direction?
A
5’ → 3’
13
Q
What is the template−product relationship?
A
- coding strand
- template strand
- RNA product
RNA product is transcribed from the template strand, but is identical to the coding strand (with the exception of ribose and U instead of T)
14
Q
Template strand:
A
- the strand of DNA that is transcribed into RNA
- template read from 3’ → 5’
- RNA synthesized/transcribed 5’ → 3’
15
Q
What is the transcription reaction?
A
- nucleophilic attack
- 3’-OH on the last NTP of the growing RNA chain attacks alpha-phosphate on incoming NTP
- PPi released
16
Q
Is a primer required for RNA transcription from DNA?
A
No
RNA does not need a primer.
17
Q
RNA synthesis is catalyzed by:
A
RNA polymerase
NO PRIMER NEEDED
