Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biochemistry: Block 4 > RNA Modification and Protein Synthesis > Flashcards

RNA Modification and Protein Synthesis Flashcards

1
Q

Generally, what posttranscriptional modifications are made to prokaryotic mRNA?

A

None

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

What enzymes transcribe rRNA in eukaryotes?

A

Mostly RNA Pol I but 5S rRNA by RNA Pol III

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

What enzymes act on pre-rRNA to yield final rRNA species?

A

Pre-rRNA is cleaved by a ribonuclease, and exonucleases produce final products

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

Where does eukaryotic rRNA synthesis/processing occur?

A

Nucleolus

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

What is the action of Rnase P?

A

It is an exonuclease that removes a 16 nucleotide sequences at the 5’ end of tRNA

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

What sequence is post-transcriptionally added to the 3’ end of tRNA that forms the acylation site?

A

CCA

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

What is the first modification step that happens to mRNA as it is produced?

A

5’ capping

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

What are the functions of 5’ capping?

A

Stabilizes mRNA and permits efficient initiation of translation; helps ribosome recognize and place mRNA

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

What is the first step of 5’ capping?

A

The gamma phosphate is removed

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

What molecule is first added to the 5’ end of the mRNA transcript in 5’ capping? By what enzyme? Through what kind of linkage?

A

GMP by guanylyl transferase via a 5’ to 5’ linkage

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

What is the final step of 5’ capping? What enzyme catalyzes this step?

A

Methylation of the guanine at the 7 position by guanine-7-methyltransferase

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

Where does 5’ capping occur?

A

Nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the three funtions of polyadenylation?

A

Stabilizes mRNA, promotes exit from the nucleus, aids in translation

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

What enzyme catalyzes polyadenylation?

A

Polyadenylate Polymerase

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

Through what does Polyadenylate Polymerase bind to DNA?

A

The polyadenylation sequence near the 3’ end

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

What complex accomplishes mRNA splicing?

A

Spliceosome

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

What is at the 5’ end of an intron?

A

The splice donor site - GU here

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

What is at the 3’ end of an intron?

A

Splice acceptor site- AG here

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

What base is found at the branch site of an intron?

A

A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is an snRNP? What are they made of?

A

small nuclear ribonucleoprotein complexes; snRNA

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

How do snRNAs facilitate intron removal?

A

By base pairing with consensus sequences at the exon/intron boundary

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

What chemistry results in the formation of the lariat structure in mRNA splicing?

A

The 2’ hydroxyl group of the A at the branch site attacks the phosphate of the G at the 5’ end of the intron forming a 2’-5’ phosphodiester bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Approximately what percentage of genetic diseases result from splice site mutations?

A

15%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What disorder results from incorrect splicing of the beta globin gene?

A

Beta-thalassemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What disease is an autoimmune response to one’s own snRNPs?

A

Systemic lupus erythematosus

26
Q

What is the process of using different splice sites within the same gene to generate different proteins?

A

Alternative Splicing

27
Q

What is the conventional direction for writing codon sequences?

A

5’–> 3’

28
Q

How many codons are possible?

A

64

29
Q

How many potential reading frames can each mRNA transcript have?

A

3

30
Q

What is the intiation codon? What does it code for?

A

AUG; methionine

31
Q

What are the 3 termination codons?

A

UAG, UGA, UAA

32
Q

What are the four characteristics of the genetic code?

A

Specificity; universality; degeneracy; nonoverlapping and commaless

33
Q

What is a missense mutation?

A

A single base pair mutation that results in the changing of the codon for one AA for that of a different AA

34
Q

What is a nonsense mutation?

A

A single base pair mutation that results in the changing of the codon for one AA for that of a stop codon

35
Q

What is a silent mutation?

A

A single base pair mutation that results in a codon that codes for the same AA

36
Q

What is a frameshift mutation?

A

A single or double base pair insertion or deletion that results in a change in the reading frame?

37
Q

What is the process by which a sequence of 3 bases that are noramlly repeated in tandem become amplified due to mistakes in DNA synthesis?

A

Triplet Repeat Expansion

38
Q

What repeat expansion causes Huntington’s

A

CAG

39
Q

How many tRNAs are there in humans?

A

50

40
Q

What enzyme covalently attaches the AA to its respective tRNA?

A

Aminoacyl-tRNA synthetases

41
Q

How many aminoacyl-tRNA synthetases are there?

A

20

42
Q

What ribosomal subunit binds mRNA and ensures correct mRNA-tRNA base pairing?

A

Small Subunit

43
Q

What ribosomal subunit catalyzes peptide bond formation?

A

Large subunit

44
Q

What are the three ribosomal sites?

A

A (acceptor), P (peptidyl transferase), E (exit)

45
Q

What is the energy cost of the addition of a single AA in protein synthesis?

A

2 ATP and 2 GTP

46
Q

What is the directional relatioship of a codon and anticodon?

A

Antiparallel

47
Q

What proposes that the last base of a codon is capable of non-tradiitional base pairing?

A

Wobble Hypothesis

48
Q

In what direction are protein peptides syntheisezed?

A

Amino- to- carboxy terminal direction

49
Q

What molecules assist in regulating and facilitating the formation of the full translational machinery?

A

Initiation factors

50
Q

What prokaryotic mRNA sequence base pairs with the 16S rRNA in translation?

A

Shine-Delgarno sequence

51
Q

What is the only aminoacyl tRNA to be inserted directly into the P site?

A

initiator met-tRNA

52
Q

What is the chemistry of the peptide bond formation during translation elongation?

A

The carboxyl group of the polypeptide attacks the amino group of the AA-tRNA

53
Q

What molecules recognize the stop codons and promote the hydrolysis of the bond between the protein and the final tRNA?

A

Release factors

54
Q

What is a polysome?

A

More than one ribosome translating one mRNA transcript at a time

55
Q

What is the mechanism of streptomycin?

A

Binds to 30S subunit, distorting it

56
Q

What is the mechanism of tetracyclines?

A

Binds to 30S subunit, blocks entry of AA-tRNA to A site

57
Q

What is the mechanism of chloramphenicol?

A

Inhibits peptidyltransferase

58
Q

What is the mechanism of clindamycin/ erthromycin?

A

Binds to 50S subunit, blocks translocation

59
Q

What is the mechanism of diptheria toxin?

A

Inactivates elongation factor, blocks translocation

60
Q

What is the mechanism of cyclohexamide?

A

May bind to E site and block translocation

61
Q

What is the mechanism of puromycin?

A

AA-tRNA analog, causes peptide chain termination

Biochemistry: Block 4 (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions