Protein synthesis and sorting

Question 1

ribosomes

Answer 1

carry out the process of polypeptide synthesis

Question 2

tRNA molecules

Answer 2

align the amino acids in the correct order

Question 3

aminoacyl-tRNA synthetases

Answer 3

attach amino acids to their appropriate tRNA molecules

Question 4

mRNA molecules

Answer 4

encode the amino acid sequence information

Question 5

facilitate some of the steps of translation

Answer 5

protein factors

Question 6

made up of two dissociable subunits that resemble rRNA and proteins

Answer 6

bacterial ribosome

Question 7

(A) aminoacyl site

Answer 7

binds each newly arriving tRNA with its attached amino acid

Question 8

(P) peptidyl site

Answer 8

where the tRNA carrying the growing polypeptide chain resides

Question 9

(E) exit site

Answer 9

from which tRNAs leave the ribosomes after they have discharged their amino acids

Question 10

what directs the order of amino acids in a polypeptide?

Answer 10

sequence of codons in mRNA

Question 11

nuclear export signals

Answer 11

for transport of mRNA through the nuclear pores

Question 12

start codon

Answer 12

first to be translated

-usually AUG

Question 13

step 1 of translation in bacteria

Answer 13

IF1,2,3 and GTP bind to small ribosomal subunit

Question 14

step 2 of translation in bacteria

Answer 14

aminoacyl tRNA and mRNA are attached and bind to small ribosomal units

Question 15

step 3 of translation in bacteria

Answer 15

large subunit joins and complex resulting 70S ignition complex and GTP is hydrolyzed

Question 16

tRNA met

Answer 16

imitator in eukaryotes that carries methionine

-doesn’t become formylated

Question 17

cap-binding initiation factor, eIF4F

Answer 17

recognizes the 5’ end of the mRNA

Question 18

kozak sequence

Answer 18

AUG, start codon sequence

Question 19

what must be attached to the start codon for the large subunit to bind to the complex and start initiating?

Answer 19

initiator tRNA met

Question 20

aminoacyl tRNA binding

Answer 20

the ribosome bringing a new amino acid

Question 21

peptide bond formation

Answer 21

links this amino acid to the growing polypeptide chain

Question 22

translocation

Answer 22

moving the mRNA 3 nucleotides ahead to bring the next codon into position for translation

Question 23

release factors

Answer 23

protein that recognizes a stop codon in the A site

Question 24

hydrolysis

Answer 24

releases the polypeptide

Question 25

chemical modification in bacteria so to return to normal function after translation

Answer 25

N-formyl group and Met are removed

Question 26

chemical modification in eukaryotes so to return to normal function after translation

Answer 26

Met is removed

Question 27

internal stretches of amino acids

Answer 27

removed to produce an active protein

Question 28

two types of splicing

Answer 28

intermolecular and intramolecular

Question 29

inteins

Answer 29

remove certain amino acid sequences from poylpeptides

Question 30

cotranslational import

Answer 30

movement of the polypeptide across or into the ER membrane

-directly coupled to the translational process

Question 31

post translational import

Answer 31

polypeptides which are destined to cell organelles, required a special targeting signal

Question 32

molecular chaperones

Answer 32

facilitate protein folding and assembly

Question 33

protein folding is accompanied by the formation of what?

Answer 33

disulphide bonds between Cys in the pp chain

Question 34

unfolded protein response (UPR)

Answer 34

detects misfiled proteins and enhances pathways for protein folding

Question 35

ER-associated degradation (ERAD)

Answer 35

recognizes misfiled proteins and exports them back to cytosol for degradtion

Question 36

glycoproteins

Answer 36

proteins synthesized on rough ER

Question 37

where does initial glycosylation take place?

Answer 37

ER

Question 38

where does further glycosylation occur?

Answer 38

golgi complex

Question 39

what is the default pathway for soluble proteins?

Answer 39

golgi complex- secretory vesicles

-move to cell surface and fuse with palm membrane for secretion from the cell