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Flashcards in Molecular Biochem Deck (21):
1

What are the different types of RNA?

rRNA= most abundant
mRNA= longest
tRNA= smallest

Rampant, Massive, Tiny

2

Compare prokaryotic vs eukaryotic RNA polymerases

Eukaryotes:
RNA Polymerase I makes rRNA
RNA Polymerase II makes mRNA; opens DNA @ promoter site
RNA Polymerase III makes tRNA

Prokaryotes: 1 RNA polymerase (multisubunit complex) makes all 3 kinds of RNA

3

Alpha-amanitin

Found in death cap mushrooms

Inhibits RNA polymerase II & causes liver failure if ingested

4

Name the start & stop codons

Start: AUG (methionine in eukaryotes, formyl-methionine in prokaryotes)

Stop: UGA, UAA, UAG

5

Origin of replication

Particular sequence in genome where DNA replication begins.

Single in prokaryotes, multiple in eukaryotes

6

Helicase

Unwinds DNA template at replication fork

7

Single-stranded binding proteins

Prevent strands from reannealing

8

DNA topoisomerases

Crease a nick in the helix to relieve supercoils created during replication

*Fluoroquinolones inhibit DNA gyrase (prokaryotic topoisomerase II)

9

Primase

Makes an RNA primer on which DNA polymerase III can initiate replication

10

DNA polymerase III

Prokaryotic only.

Elongates leading strand by adding deoxynucleotides to the 3' end. Elongates lagging strand until it reaches primer of preceding fragment.

11

Exonuclease

3'-5' proofreading activity in prokaryotes.
Also excises RNA primer during DNA polymerase I activity.

*Missing from Hepatitis C

12

DNA polymerase I

Prokaryotic only.

Degrades RNA primer and fills in the gap with DNA.

13

DNA ligase

Seals.

14

Telomerase

Enzyme adds DNA to 3' ends of chromosomes to avoid loss of genetic material with every duplication.

15

Which direction does mRNA reading vs protein synthesis proceed?

mRNA: 5' --> 3'

Protein synthesis: N to C

16

Shine-Dalgarno sequence

Ribosomal binding site in prokaryotic mRNA upstream from start codon

Helps to recruit ribosome to mRNA

17

Kozak consensus sequence

Occurs on eukaryotic mRNA. Surrounds methionine to serve as initiator for translation.

(gcc)gccRccAUGG [R = adenine or guanine]

18

Capped, tailed, and spliced transcript is called:

mRNA

19

What 3 processing steps occur in the nucleus after transcription?

1. Capping on 5' end (addition of 7-methylguanosine occurs in cytosol)

2. Polyadenylation on 3' end (~200 As)

3. Splicing out of introns

20

snRNPs are involved in. . .

splicing of pre-mRNA

21

tRNA has _ _ _ at the 3' end and binds ___

tRNA has CCA at the 3' end and covalently binds amino acids