Biochemistry. Just kill me now. Flashcards Preview

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Flashcards in Biochemistry. Just kill me now. Deck (154)
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1

mRNA start codon:

AUG
AUG AUGments protein synthesis

2

What does AUG code for in prokaryotes?
Eukaryotes?

Prokaryotes = formylmethionine
Eukaryotes = methionine

3

mRNA stop codons (3):

UGA
UAA
UAG
U Go Away, U Are Away, U Are Gone

4

What is an operon (3 components)?

Structural genes to be transcribed
Regulatory regions
Promoter region

5

Four common structural features shared by proteins that interact with DNA:

helix-loop-helix
helix-turn-helix
Zn fingers
leucine zippers

6

What are the three types of RNA?

rRNA
mRNA
tRNA
Rampant, massive, and tiny.

7

T/F: Enhancers and repressors control whether a gene is transcribed.

F. Response elements control the RATE of transcription, not whether it happens.

8

Features of promoter sequences (3):

Upstream
Rich in AT
TATA or CAAT box

9

What is an operator region?

It is where inducers and repressors bind, usually located between the promoter region and start.

10

Briefly review the function of the lac operon.
- Transcription factor
- Repressor
- Conditions

lac = codes for b-galactosidase (lactose -> glucose + galactose).
Tx factor CAP is bound when there is no glucose.
Repressor lac is bound when there is no lactose.
Make product only when the repressor is gone (there is lactose) and when CAP is unbound (there is glucose).

11

What are the three eukaryotic RNA polymerases and what do they do?

RNA pol I makes rRNA
RNA pol II makes mRNA
RNA pol III makes tRNA

12

This substance inhibits eukaryotic RNA polymerase II:
Main manifestation of its toxicity?

a-amanitin.
Hepatotoxic.

13

The two ways in which transcription can be terminated in prokaryotes:

rho-dependent ATPase
rho-indepedent (GC-rich hairpin turn followed by a weak point rich in UUUUUUfall right off)

14

T/F: Prokaryotes have more than one polymerase:

F. They just have the one, it makes all three kinds of RNA.

15

Drug that inhibits prokaryotic RNA polymerase and turns your pee red:

Rifampin

16

Where is rRNA made?
mRNA?
tRNA?

rRNA is made in the nucleolus.
mRNA and tRNA are made in the nucleoplasm.

17

Before RNA leaves the nucleus it needs to be processed to become mRNA and gain the ability to leave. Three major processing events:

1. 5' cap addition (SAM needed)
2. Poly-A tail
3. Introns spliced out (by spliceosome)

18

What is the co-factor required for adding a 5' cap to hnRNA?

SAM

19

Poly-A polymerase recognizes this polyadenylation signal:

AAUAAA

20

Patients with lupus make antibodies against this piece of pre-mRNA processing machinery:

Spliceosomal snRNPs.
These are part of the spliceosome used to remove introns.

21

Which part of a transcript gets to leave the nucleus: Intron or exon?

EXon is EXpressed and EXits the nucleus

22

Does tRNA synthetase work at the 5' or 3' end of tRNA? What special marker is at this end?

tRNA synthetase works at the 3' end.
This end always has CCA.

23

T/F: Amino acids destined for transfer are bound hydrostatically to the 5' end of tRNA.

F. The bond is covalent, and it is found at the 3' end.

24

The ribosome in prokaryotes is a __S ribosome composed of these two subunits:

30S + 50S -> 70S
PrOkaryotic = Odd numbers

25

The ribosome in eukaryotes is a __S ribosome composed of these two subunits:

40S + 60S -> 80S
Eukaryotic = Even numbers

26

Where is the prokaryotic ribozme?

It is a 23S rRNA Inside the 50S subunit.

27

tRNA bound with ATP is in what state?
tRNA bound with GTP is in what state?

ATP bound tRNA is "charged" with its amino acid.
GTP bound tRNA is in the process of translocation.

28

Initiation of protein synthesis is activated by this hydrolytic reaction:

GTP hydrolysis

29

This enzyme catalyzes peptide bond formation during protein synthesis. It has two names:

Ribozyme = peptidyltransferase

30

Where are ribosomes made?

In the nucleus.