Chapter 6

Question 1

Translation

Answer 1

Production of polypeptides from mRNA

Question 2

Building blocks of polypeptides

Answer 2

Amino acids

Question 3

5 parts of amino acid

Answer 3

Central carbon
Amino group (NH3+)
Carboxyl group (COO-)
Hydrogen atom
R group (side chain)

Question 4

What part of amino acid is “acid”?

Answer 4

Carboxyl group

Question 5

Amino acids are joined by ____ bonds

Answer 5

Peptide

Question 6

Ends of polypeptides

Answer 6

Free amino group (N terminus)
Carboxyl group (C terminus)

Question 7

Which end of polypeptide is the beginning?

Answer 7

N terminus

Question 8

Proteins shape determined by what two things?

Answer 8

Primary amino acid sequence

Cellular conditions that promote necessary folding

Question 9

4 levels of protein organization

Answer 9

Primary
Secondar
Tertiary
Quaternary

Question 10

Primary structure of proteins

Answer 10

Linear sequence of amino acids

Question 11

Secondary structure of proteins

Answer 11

Shape taken by a polypeptide (or region of) by folding as a result of weak bonds like H-bond
Ex: alpha helix and beta sheet

Question 12

Tertiary structure of proteins

Answer 12

3D shape of a polypeptide
Arises from folding of secondary structures
Can contain mixture of alpha helices and beta sheets

Question 13

Quaternary structure of proteins

Answer 13

Only in multi-subunit proteins
Association of polypeptide chains
Ex: hemoglobin has 2 a and 2 b polypeptides

Question 14

How many codons are there?

Answer 14

61 code for amino acids

3 code for stop

Question 15

Is genetic code of amino acids universal?

Answer 15

Yes except for couple exceptions

Question 16

Degeneracy of genetic code

Answer 16

Redundancy
More than one codon is used for each amino acid (except Met and Trp)
Allows wobble pairing

Question 17

tRNA

Answer 17

Transfer correct amino acids to codons
Single stranded
Each carries an anticodon and each can only attach to ONE kind of amino acid
Some tRNAs can recognize more than one codon

Question 18

Anticodon written from

Answer 18

3’ to 5’

Question 19

Wobble pairing

Answer 19

One anticodon can pair with more than one codon
3rd base of anticodon at 5’ end can wobble
This base not as constrained as 1st 2
Inosine can recognize A,U, and C

Question 20

Charging

Answer 20

Process of attaching correct amino acid to tRNA

Carboxyl group attached to 2’ or 3’ carbon

Question 21

Initiation of Translation in Prokaryotes

Answer 21

30S subunit and other IFs bind to ribosome-binding site aka Shine-Dalgarno sequence
tRNA fMet binds to AUG codon
50s subunit binds to 30s subunit

Question 22

Shine-Dalgarno sequence

Answer 22

Complementary to a sequence within the 16S rRNA of the 30S subunit

Question 23

fMet

Answer 23

tRNA attached to a modified form of methionine binds to AUG codon

Question 24

30S + 50S subunits=

Answer 24

70S initiation complex

Question 25

70S initiation complex

Answer 25

Has 3 binding sites for tRNA | Prokaryotes

Question 26

3 binding sites of 70s complex

Answer 26

Aminoacyl (A)- binds incoming aa-tRNA Peptidyl (P)- binds tRNA with growing peptide chain Exit (E)- contains uncharged tRNA to be released

Question 27

Elongation of Translation in Prokaryotes

Answer 27

aa-tRNA binds to A site fMet is transferred from P site to aa in A site by ribozyme Translocation of ribosome to next codon Uncharged tRNA (w/o aa) is released from E site Process repeated until stop codon

Question 28

Termination of translation in prokaryotes

Answer 28

Release factor protein binds to stop codon Triggers ribosome to cleave polypeptide from tRNA Components separate

Question 29

Initiation of Translation in Eukaryotes

Answer 29

No shine-dalgarno sequence 40S ribosomal subunit binds to 5' cap and scans for Kozak sequence Once Kozak is found, 60S subunit binds to complex and AUG in Kozak is used for initiation

Question 30

Simultaneous translations on mRNA in eu or prokaryote?

Answer 30

Both. | Average mRNA has 8-10 ribosomes at any time

Question 31

Each ribosome translates how many amino acids per second?

Answer 31

15

Question 32

Polysome

Answer 32

Complex between an mRNA and ribosomes