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Flashcards in Life of Proteins Deck (50):
1

monocistronic

one ORF per mRNA

2

polycistronic

mRNA codes several ORFs

3

eukaryotic mRNA is ____, prokaryotic mRNA is _____

monocistronic
polycistronic

4

where do tRNA anneal to 3-base codons on the mRNA

3-base anticodon region

5

what do tRNAs have at acceptor terminus

amino acid

6

how many possible codon sequences are there

64

7

wobble hydpotsis

position of of the anticodon is flexible and can wobble to pair with different nucletodies in the 3rd position of the codon

8

what does tRNA have that isn't found in DNA or mRNA

inosine

9

how are tRNA molcules linked to amin oacid

aminoacyl-tRNA synthases

10

how many aminoacyl tRNA synthetases are there

20

11

where does translation take place

cytosol on ribosomes

12

how many subunits do ribosomes have

2

13

how many RNA molecules are found in ribosomal subunitns

1-3

14

function of cytoplasmic ribosomes

synthesis of the bulk of proteins

15

function of mitochondrial ribosomes

protein sythesis inside of mitochondria

16

where are ribosomal subunits syntehsied

cytosol

17

intiation of translation requires the correct assumbly of waht

-small ribosomal subunit
-mRNA
-tRNA that binds the first codon

18

what happens once the small subunit is laoded with tRNA and mRNA

binds to large subunit to conclude insitation phase

19

first step of intiation

elF2a activated by binding GTP

20

what does elF2a-GTP do

binds intiator methionine-tRNA met to form ternary compelx

21

what does ternay complex do

bind small ribosomal suunit

22

what happens to the small ribosomal subunit

mRNA binds to it, forming pre-initiation complex

23

what does pre-initaition compelx do

assembles into initation complex by binding large ribosomal subunit

24

how does elongation phase starte

initation methionine tRNA met binds to P site of ribosome

25

what happens after initatior methionine tRNA met binds to P site

second aminoactyl-tRNA placed into A site which requies EF-1

26

what happens after the aminoacyl-tRNA is placed on the A site

peptidyl bond formed btwn 1st and 2nd amino acid

27

what happens after the peptidyl bond forms

ribosome moves one codon further on mRNA with help from EF-2. now mRNA-peptidyl complex is in P site and A site is empty. uncharged tRNA levels through E site

28

how does termination start

stop codon reaches A site of ribosome

29

what happens after ribosome reaches A site

eRF pairs with stop codon

30

what happens after eRF pairs with stop codon

eRF bound GTP is hydrolyzes and peptides is released from P site

31

how does streptomycin work

binds to small subunit and inhibitis initiation

32

how does neomycin and gentamicin work

bind to ribosomes and cause mistranslation of codonds

33

how does tetracycline work

block A site, prevents tRNA binding

34

how does chloramphenicol work

prevent peptidyl bond formation

35

how does riicin work

removes adenine bases from various positions of the rRNA in the alrge subunit

36

how do you regulate transctation

prevent recognitino of start codon
regulat acitivity of initaiton factors

37

how do chaperones work

binding to hydrophobic regions of the folding peptide

38

where are chaperons foudn

cytosol and ER

39

Charcot Marie Tooth Disease is caused by what

mutation in HSP gene

40

what happens to cells during the unfolded protein response

inhibit global protein translation
induce chaperone production
apoptosis

41

what does glycosylation do

changes the physical properties of proteins

42

where does glycosylation of proteins take place

begin in ER, continue into golig

43

reaction of glycosylation

glycosyltransferase transfers sugar from activiated sugar nucleotide to acceptor substrate

44

what are the glycosyltransferases specific for

-the sugar donor
-the acceptor molecule
-type of glycosidic bond formed

45

what happens during N linked glycosylation

an oligosaccharide molecule is added to tha mino group of an aspargine residue

46

steps of N linked glycosylation

1) synthesis of univeral oligosaccharide on dolichol phostate in ER
2) transfer of univeral oligosaccharide to nascent polypeptide chain
3) modification of univeral oligosaccharide in golgi

47

O-linked glycosylation

post translation event, only occurs on fully folded proteins. only occurs after protein has reached golgi

48

step of O link glycosylation

glycosyltransferases of goligi transfer N-acetyl-galactosamine to hydroxyl group of serine or threonine rediues on surface of protein

49

what is O linked glycosylation involved in

blood typing

50

how can proline be modified

hydroxylated to function in colalgen triple helix