Life of Proteins

Question 1

monocistronic

Answer 1

one ORF per mRNA

Question 2

polycistronic

Answer 2

mRNA codes several ORFs

Question 3

eukaryotic mRNA is ____, prokaryotic mRNA is _____

Answer 3

monocistronic

polycistronic

Question 4

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

Answer 4

3-base anticodon region

Question 5

what do tRNAs have at acceptor terminus

Answer 5

amino acid

Question 6

how many possible codon sequences are there

Answer 6

64

Question 7

wobble hydpotsis

Answer 7

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

Question 8

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

Answer 8

inosine

Question 9

how are tRNA molcules linked to amin oacid

Answer 9

aminoacyl-tRNA synthases

Question 10

how many aminoacyl tRNA synthetases are there

Answer 10

20

Question 11

where does translation take place

Answer 11

cytosol on ribosomes

Question 12

how many subunits do ribosomes have

Answer 12

2

Question 13

how many RNA molecules are found in ribosomal subunitns

Answer 13

1-3

Question 14

function of cytoplasmic ribosomes

Answer 14

synthesis of the bulk of proteins

Question 15

function of mitochondrial ribosomes

Answer 15

protein sythesis inside of mitochondria

Question 16

where are ribosomal subunits syntehsied

Answer 16

cytosol

Question 17

intiation of translation requires the correct assumbly of waht

Answer 17

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

Question 18

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

Answer 18

binds to large subunit to conclude insitation phase

Question 19

first step of intiation

Answer 19

elF2a activated by binding GTP

Question 20

what does elF2a-GTP do

Answer 20

binds intiator methionine-tRNA met to form ternary compelx

Question 21

what does ternay complex do

Answer 21

bind small ribosomal suunit

Question 22

what happens to the small ribosomal subunit

Answer 22

mRNA binds to it, forming pre-initiation complex

Question 23

what does pre-initaition compelx do

Answer 23

assembles into initation complex by binding large ribosomal subunit

Question 24

how does elongation phase starte

Answer 24

initation methionine tRNA met binds to P site of ribosome

Question 25

what happens after initatior methionine tRNA met binds to P site

Answer 25

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

Question 26

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

Answer 26

peptidyl bond formed btwn 1st and 2nd amino acid

Question 27

what happens after the peptidyl bond forms

Answer 27

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

Question 28

how does termination start

Answer 28

stop codon reaches A site of ribosome

Question 29

what happens after ribosome reaches A site

Answer 29

eRF pairs with stop codon

Question 30

what happens after eRF pairs with stop codon

Answer 30

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

Question 31

how does streptomycin work

Answer 31

binds to small subunit and inhibitis initiation

Question 32

how does neomycin and gentamicin work

Answer 32

bind to ribosomes and cause mistranslation of codonds

Question 33

how does tetracycline work

Answer 33

block A site, prevents tRNA binding

Question 34

how does chloramphenicol work

Answer 34

prevent peptidyl bond formation

Question 35

how does riicin work

Answer 35

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

Question 36

how do you regulate transctation

Answer 36

prevent recognitino of start codon | regulat acitivity of initaiton factors

Question 37

how do chaperones work

Answer 37

binding to hydrophobic regions of the folding peptide

Question 38

where are chaperons foudn

Answer 38

cytosol and ER

Question 39

Charcot Marie Tooth Disease is caused by what

Answer 39

mutation in HSP gene

Question 40

what happens to cells during the unfolded protein response

Answer 40

inhibit global protein translation induce chaperone production apoptosis

Question 41

what does glycosylation do

Answer 41

changes the physical properties of proteins

Question 42

where does glycosylation of proteins take place

Answer 42

begin in ER, continue into golig

Question 43

reaction of glycosylation

Answer 43

glycosyltransferase transfers sugar from activiated sugar nucleotide to acceptor substrate

Question 44

what are the glycosyltransferases specific for

Answer 44

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

Question 45

what happens during N linked glycosylation

Answer 45

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

Question 46

steps of N linked glycosylation

Answer 46

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

Question 47

O-linked glycosylation

Answer 47

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

Question 48

step of O link glycosylation

Answer 48

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

Question 49

what is O linked glycosylation involved in

Answer 49

blood typing

Question 50

how can proline be modified

Answer 50

hydroxylated to function in colalgen triple helix