Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

2) Biochemistry II > RNA Metabolism > Flashcards

RNA Metabolism Flashcards

(83 cards)

Start Studying
1
Q

What is the first step in gene expression?

A

Transcribe a gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How does RNA differ from DNA? (3)

A

o RNA contains a hydroxyl group on C2
o RNA contains Uracil, instead of Thymine in DNA
o RNA is mostly single-stranded

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

RNA is both a ______ and _______ molecule

A

genetic

catalytic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the three major classes of RNA?

A
  • mRNA (messenger)
  • tRNA (transfer)
  • rRNA (ribosomes)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

RNA is the only macromolecule that functions as both an _______________ and ___________

A

information transmitter

catalyst

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is transcription?

A

DNA-dependent RNA synthesis (DNA template is needed to synthesize RNA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is translation?

A

RNA-dependent protein synthesis (mRNA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is transcriptome?

A

Collection of all transcripts (or mRNAs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the function of mRNAs?

A

Encode the amino acid sequences of all the polypeptides found in the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the function of tRNAs?

A

Match specific amino acids to triplet codons in mRNA during protein synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the function of rRNAs?

A

Constituents of ribosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the function of microRNAs? What must they have?

A
  • Regulate the expression of genes via binding to specific nucleotide sequences
  • Must have a complementary sequence for their target RNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are similarities between DNA replication and RNA synthesis? (3)

A

o Addition of complementary nucleotides
o Requirement of template
o Direction of synthesis: 5’ to 3’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are differences between DNA replication and RNA synthesis?

A

o RNA synthesis does not require a PRIMER, unlike DNA synthesis
o While DNA replication includes the whole genome as a template, RNA synthesis only uses a SMALL SEGMENT of DNA as a template
o For any given segment of DNA, only ONE STRAND acts as a template in RNA synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

RNA must distinguish between which DNA strands?

A
  • DNA coding strand

- DNA template strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Which DNA strand is the ALMOST the same as the RNA transcript? What is the minor difference?

A
  • DNA coding strand

- The Ts are replaced by Us

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Where does RNA synthesis occur? What must be done for synthesis to occur?

A
  • At RNA polymerase

- DNA strand must be unwound, which creates a coding and template strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is created for a short period of time during RNA synthesis?

A

DNA/RNA hybrid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What did Watson and Crick determine in terms of complementarity of RNA?

A

Can either be:

  • 2 pyrimidines
  • 1 purine and 1 pyrimidine
  • 2 purines
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the width of DNA? What is type of bonding between nucleotides?

A
  • Width: 1.08 nm

- Hydrogen bonding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

During RNA synthesis, an incoming nucleotide arrives as a ________

A

triphosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What does RNA polymerase require?

A
  • DNA template
  • All 4 types of nucleotides
  • Magnesium (cofactor)
  • Zinc (cofactor)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the catalytic mechanism of RNA polymerase?

A
  • OH- group at the 3 position of the existing nucleotide attacks the first phosphate group (alpha phosphate)
  • Forms a 3’-> 5’ phosphodiester bond
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

The phosphate groups are always present at which carbon?

A

At the 5th carbon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Which strand of DNA becomes the coding strand?
The coding strand may be either; when one acts as a coding strand, the other is a template strand
26
In Prokaryotes, where are promoters located?
Upstream (left)
27
In Prokaryotes, what are -10 and -35 regions called? Why?
- TATA boxes | - Mostly made of Thymine and Adenosine
28
What are the promoter regions composed of in Prokaryotes?
- 2 TATA boxes | - 1 regulatory regions
29
What does RNA polymerase recognize?
The TATA boxes
30
What is the transcription cycle called in Prokaryotes?
Sigma cycle
31
What is the function of the Sigma domain?
- Helps the RNA polymerase find the TATA box - Begins the unwinding of DNA (initiation of transcription) - Recognition and initiation
32
What happens once transcription begins in Prokaryotes?
- Sigma domain leaves | - NusA subunit comes in
33
What is the function of the NusA subunit?
- Helps the RNA polymerase move forward | - Elongation and termination
34
When is synthesis terminated in the transcription cycle of Prokaryotes?
When a terminator sequence is present, which causes the departure of NusA
35
In Eukaryotes, what is upstream of the initiator sequence? And, what is upstream of that?
o Upstream: TATA box | o Upstream of the TATA box: several regulatory sequences (complex)
36
Prokaryotes have ____ type of RNA polymerase, while Eukaryotes have _____
one | three
37
What does "Y" mean in terms of nucleic acids? What does "N" mean?
- “Y” means any pyrimidine (C or G) | - “N” means any of the four
38
What is the function RNA polymerase I?
Synthesis of rRNA
39
What is the function to RNA polymerase II?
Synthesis of mRNA and specialized RNA
40
Which eukaryotic RNA polymerase is similar to the prokaryotic RNA polymerase? How many subunits does it contain in Eukaryotes?
- RNA Pol II | - 12 subunits
41
What is the function to RNA polymerase III?
- Synthesis of tRNA - Synthesis of 5s rRNA - Synthesis of specialized RNA
42
In Pol II, what binds to the TATA box? What is the TATA box often associated with?
- TBP binds to the TATA box | - TATA box is often associated with TFIIA
43
What happens when TBP binds to the TATA box?
- TFIIB binds to the complex - RNA Pol II is brought in, which is bound to TFIIF - Recognizes the initiator sequence and binds
44
Once Pol II binds to the initiator sequence, what is brought in?
TFIIE comes in, which causes TFIIH to enter
45
What is important about the CTD domain in Pol II?
- Contains heptad AA repeats (52 in humans) | - CTD needs to be phosphorylated to function
46
What happens when the pre-initiation complex is formed?
- When TFs are added, pre-initiation complex is formed - DNA unwinding beings - CTD domain of Pol II is phosphorylated
47
The unwinding of DNA and the phosphorylation of the CTD domain is regulated by what?
TFIIH
48
What allows promoter escape? What is the consequence?
- When the CTD domain is phosphorylated (RNA Pol II can leave the promoter region) - Allows it to move forward into the gene region, while synthesizing RNA strands
49
What happens when promoter escape takes place?
- TFIIH and TFIIE leave | - Elongation factors arrive
50
What happens when a termination sequence arrives?
Causes Pol II release and dephosphorylation
51
What specifically recognizes the TATA box
TBP
52
What stabilizes binding of TFIIB and TBP to the promoter?
TFIIA
53
What unwinds DNA at the promoter and phosphorylates Pol II (within the CTD)?
TFIIH
54
What recruits TFIIH?
TFIIE
55
What binds to TBP and recruits Pol II-TFIIF complex?
TFIIB
56
What binds tightly to Pol II and binds to TFIIB?
TFIIF
57
What are three important processes on synthesized RNA?
- 5' capping - Intron deletion (splicing) - Polyadenylation (Poly-A tail) synthesis
58
When does 5' capping occur?
Very early in the synthesis of RNA (after 20-30 bases)
59
What occurs in association with RNA polymerase?
5' capping
60
What is the unusual linkage in 5' capping?
- 5' to 5' phosphodiester bond | - 7-methyl-guanosine
61
What is the function of the 5' cap?
Protects from ribonuclease, which specifically cleave RNA
62
Transcription always occurs with a ______ attached to RNA polymerase II
5’ cap
63
Differentiate introns and exons.
Exons code for proteins, and introns are intermediate sequences
64
What must be spliced out for an mRNA to be synthesized? What is the exception?
- Introns | - Exception: histone genes do not have introns
65
How do introns and exons differentiate in terms of length?
Exons are short (< 1000 bases); Introns are long (up to 20 000 bases)
66
What are the two types of splicing?
- Self-splicing mRNA | - Splicing by spliceosome
67
Give an example of self-splicing mRNA.
Mitochondrial genes
68
Do self-splicing mRNA require ATP?
No since it is non-enzymatic
69
How do self-splicing mRNAs function? What is at the 5' end and what is at the 3' end?
- 5': UpA - 3': GpU 1) OH group of guanosine acts as a nucleophile and attacks the phosphate at the 5' end 2) The 3' OH of the 5' exon becomes a nucleophile, which completes the reaction 3) pGpA - G-OH (spliced intron) UpU (exon)
70
Group 1 and 2 introns are _________, while group 3 introns are ________
self-splicing | spliced by spliceosomes
71
Group 3 introns occur in which types of mRNA?
Most types of mRNA
72
What is a spliceosome? How many types are they?
- RNA-proteins called snRNP’s (small nuclear RN proteins) | - 5 snRNPs: U1, U2, U4, U5, and U6
73
Group 3 and 4 introns (ex: tRNA) require what?
ATP
74
What is the typical sequence that forms boundaries in splicing by spliceosome?
- 5': GU | - 3': AG
75
Where is the splicing sequence in splicing by spliceosome?
Upstream of AG
76
The snRNPs are complementary to what?
mRNA
77
What are the steps to spliceosome splicing?
1) U1 and U2 bind to the sequence (energy dependent) 2) U4/U6 and U5 arrive, but the complex is still inactive 3) U1 and U4 leave, which frees up the GU at the 5' end 4) G (5') interacts with A (3'), which creates a loop
78
The creation of a loop by a spliceosome is called what?
Lariat formation
79
What is one of the cleavage signals in polyadenylation?
AAUAAA
80
Which proteins assemble at cleavage sequences?
- Polyadenylate polymerase | - Endonuclease
81
What are the steps to polyadenylation (poly-A tail)?
1) Cleavage: endonuclease comes in and cleaves the long, extra sequence of mRNA 2) Synthesis of Poly-A tail: addition of a sequence of A-repeats
82
What is the function of polyadenylation? When is it performed?
- At the end of transcription - Protects the mRNA molecule from enzymatic degradation in the cytoplasm - Aids in transcription termination
83
What does alternative splicing lead to?
Multiple mRNAs from one gene

2) Biochemistry II (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions