chapter 6; translation

Question 1

describe the structure of aa

Answer 1

-R group: specific for each aa, can be acidic, basic, neutral, polar, nonpolar
-amino group: NH2
-carboxyl: COOH

Question 2

what is a polypeptide and the type of bonds it has?

Answer 2

chain of aa
-formed by peptide bonds between carboxyl group and amino group

Question 3

describe determinants of order

Answer 3

1.DNA sequence
2.RNA message (transcription)
3. order of protein (made on ribsome complex)
4. shape
-structural
-enzymatic: changes shape

Question 4

what are the structures of proteins?

Answer 4

-primary
-secondary
-tertiary
-quaternary

Question 5

a.a sequence

Answer 5

primary structure

Question 6

folding and twisting of a single polypeptide chain, H-O bonds in the polypeptide backbone.
-alpha helix: right handed coil
-beta pleated sheet: two or more chains stacked

Answer 6

secondary structure

Question 7

tertiary structure

Answer 7

3D folding, interactions between R groups, disulfide bonds, H bonds, ionic bonds, hydrophobic interactions.

Question 8

quaternary structure

Answer 8

two or more tertiary structures, multisubunits

Question 9

describe the tRNA structure of

Answer 9

-cloverleaf
-5-3 antiparallel
-acceptor stem: ends in ACC-3’
-anticodon: vary

Question 10

characteristics of the code system

Answer 10

-triplet code
-table: almost universal
-start codon: AUG
-stop codon:UAA, UAG, UGA
-start and stop codons help define ORFS

Question 11

what enzyme “charges” a tRNA

Answer 11

aminoacyl-tRNA synthase

Question 12

give the steps of the charging process of tRNA

Answer 12

1. aa and ATP bind to enzyme
2. hydrolysis: AMP, then joins a.a
3. tRNA binds to enzyme, transfers aa, AMP displaced

Question 13

describe ribosomes

Answer 13

-2 subunits, one large and one small
-contain rRNA and ribosomal proteins
-eukaryotic: 60s and 40s
-s represents suedberg units
-mRNA passes through small unit

Question 14

what are the structures needed for initiation in translation? (scanning model)

Answer 14

• eIF-3 and 40s ribosome subunit
  -eIF-2 with charged tRNA
  -eIF-4 on RNA 5’ cap

Question 15

after scanning model, follows

Answer 15

-eIF-1 removes 2 and 3
-eIF-5 brings large subunit 60s.

Question 16

elongation is triggered by

Answer 16

poly-A binding proteins hitting complex

Question 17

A site:

Answer 17

-aminoacyl, where an incoming aminoacyl- tRNA bind

Question 18

P site:

Answer 18

the peptidyl site, tRNA carrying the growing peptide is located

Question 19

E site:

Answer 19

exit site; where tRNA binds on its path from P site to leaving the ribosome

Question 20

EF-TU function

Answer 20

brings one tRNA after another with correct anticodon

Question 21

what carries out the formation of peptide bonds between aa. aa releases from tRNA, tRNA then leaves P site

Answer 21

peptidyl transferase

Question 22

EF-G function

Answer 22

shifts ribosome

Question 23

codon move to the _____ side

Answer 23

left

Question 24

what triggers termination

Answer 24

encounter of UAA codon, eukaryotes do not have anticodon for it

Question 25

describe the termination process (translation)

Answer 25

RF-1 ( on A site) and RF-3 ( protein complex) bind and aa rips of tRNA.

Question 26

signal peptide

Answer 26

specific protein sequence

Question 27

signal recognition particle (SRP)

Answer 27

bind to SRP receptor and is located on the ribosome

Question 28

SRP receptor

Answer 28

on ER, binds with SRP

Question 29

signal peptide fills into ER, once inside it is ________

Answer 29

modified

Question 30

if a protein is made in the ER: it ends up in

Answer 30

membrane, surface protein, or outside the cell membrane

Question 31

if a protein is made in the cytoplasm

Answer 31

it stays in the cyto