Protein Translation and Post-Translational Processing Flashcards Preview

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Flashcards in Protein Translation and Post-Translational Processing Deck (37)
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1

Do both subunits of ribosomes have enzymatic function? If not, which one does?

No, only large subunit does

2

What is the ternary complex?

eIF2a-GTP bound to initiator methionine-tRNA

3

What is the pre-initiation complex?

ternary complex bound to small subunit + mRNA

4

What is the initiation complex?

pre-initiation complex bound to large subunit

5

The energy needed to bind to large subunit comes from what?

hydrolysis of eIF2a-GTP

6

What site is methionine-tRNA in?

P site of large ribosomal subunit

7

How much energy is required to elongate one amino acid?

2 GTP is needed: one to bind tRNA to the A site (charged tRNA) and another to move ribosome one codon over

8

When does translation terminate?

once a stop codon has reached the A site

9

What pairs with the stop codon in termination of translation?

a protein, eRF (eukaryotic release factor)

10

Does termination of translation require energy?

yes, when the peptide is release from the P site, provided by the hydrolysis of eRF-GTP
- ribosomal subunits separate from each other

11

Which antibiotic binds to ribosomes and causes mistranslation of codons?

neomycin and gentamicin

12

Which antibiotic binds to small subunit and inhibits initiation?

streptomycin
- also causes mistranslation

13

What anitibiotic prevents peptidyl bond formation?

chloramphenicol

14

Which antibiotic blocks the A site and prevents rRNA binding?

tetracycline

15

Which toxin removes adenine bases from various positions of the rRNA in the large subunit?

ricin

16

Which toxin inactivates EF-2 by ADP-ribosylation?

Diptheria toxin

17

What are two ways to regulate translation (gene expression)?

1) prevent recognition of start codon by binding a protein to the 5' UTR of mRNA
2) phosphorylate eIF-2a (initiating factor), becomes inactive

18

Where does protein folding occur (organelle)?

cytosol and ER

19

Where does N-linked glycosylation occur?

ER, before protein folding is complete

20

In N-linked glycosylation, sugar is added to what residue in protein?

asparagine

21

Where is dolichol phosphate located (organelle)?

ER

22

Where does modification of oligosaccharide occur?

Golgi
1) high mannose type (bulky)
2) complex type

23

What disorder affects N-linked glycosylation?

congenital disorder of glycosylation (CDG)

24

Which disorder has defective trimming of oligosaccharide chain?

CDG II

25

Which disorder has defective synthesis of lipid-linked oligosaccharide precursor?

CDG I

26

Where does O-linked glycosylation occur?

Golgi

27

Which residues are sugar added to in O-linked glycosylation?

glycosyltransferases transfer sugars to serine or threonine of fully folded proteins

28

What is the first sugar of O-linked glycosylatoin?

N-acetylgalactosamine

29

What sugar does the H-antigen of the A type RBC?

GalNac

30

What sugar does the H-antigen of the B type RBC?

Gal