Translation

Question 0

______ three nucleotide codons in mRNA encode 20 amino acids + start and stop codons; most amino acids have multiple codons; codons are read in the _____ direction with the ___ terminal nucleotide at the left

Answer 0

64 codons; 5’ to 3’, 5’ at left

Question 1

The conversion of information in RNA to protein = ______

Answer 1

Translation (of one language to another)

Question 2

one codon– _____ – acts as both initiation signal and methionine

Answer 2

AUG

Question 3

There are three possible reading frames in protein synthesis; RNA can be translated 3 different ways. What can go wrong..?

Answer 3

(one base pair mutation), single deletion, single addition= shifted reading frame

*as long as non multiple of 3

Question 4

______ match amino acids to codons in mRNA

Answer 4

tRNA

Question 5

tRNA recognizes 5’ codon on mRNA and binds/recognizes a specific _______ at the 3’

Answer 5

amino acid

Question 6

The Anticodon of tRNA is :

Answer 6

set of 3 consecutive nucleotides that pairs with the complementary codon on the mRNA

Question 7

the short, single stranded region on the 3’ end of tRNA….

Answer 7

recognizes and binds a SPECIFIC amino acid that corresponds to the condon

Question 8

Some tRNAs only require accurate base-pairing only …..position of the codon and can tolerate a mismatch (WOBBLE) at the _____ position

Answer 8

first two positions must be accurate, third can wobble

Question 9

Wobble base-pairing explains….

Answer 9

why so many alternative codons for AA differ only in their third nucleotide

Question 10

Recognition and attachment of the correct AA to a tRNA depends on enzymes called _________ which:

Answer 10

amionacyl-tRNA synthetases: covalently couple AA to appropriate tRNA

**one for each AA (20)

Question 11

Synthetases use ______ to produce a high-energy bond between the ____ end of the tRNA and an amino acid. The energy of this bond is used at a later step to link…

Answer 11

ATP hydrolysis ; 3’ end

NRG used to link AA covalently to growing peptide chain

Question 12

Amino acids are added to the ____-terminal end of a growing polypeptide chain

Answer 12

C-terminal

Question 13

Fundamental Reaction of Translation:

Answer 13

Formation of peptide bond between Carboxyl-group (o-c=o) at the end of the growing polypeptide chain and the free amino group (NH2) on the incoming amino acid

**nucleophilic attack

Question 14

A protein is synthesized from its _____ end to its ______ end

Answer 14

N to C

Question 15

Each amino acid carries within it the activation energy for the addition of the next amino acid from the breaking of the….

Answer 15

covalent linkage between the tRNA and the carboxyl end of the polypeptide chain

Question 16

The formation of each peptide bond is energetically favorable because…

Answer 16

the growing C-terminus has been activated by the covalent attachment of the tRNA molecule

Question 17

The ______ subunit of ribosomes recognizes mRNA and only once correctly position, the ____ subunit is added

Answer 17

Small recognizes, then large is added

Question 18

Ribosomes are made of:

Answer 18

proteins (1/3) ++++ RNA molecules (rRNA) (2/3)

Question 19

The small subunit of ribosomes:

Answer 19

matches tRNA to the codon of the mRNA

Question 20

The large subunit of ribosomes:

Answer 20

catalyzes formation of peptide bonds

Question 21

_______ form the E, P, and A tRNA binding sites

Answer 21

rRNA

Question 22

Prokaryotic Ribosome (70S)
Large subunit (50s) ------ Small subunit (30S)
5S+23S+ proteins= 50S
16S+ proteins=30S

Answer 22

Look at a picture

Question 23

Eukaryotic Ribosome= 80S
Large subunit=60S ——- Small subunit= 40S
5S+28S+5.8S+ proteins= 60S
18S+ proteins= 40S

Answer 23

Look at picture

Question 24

Three tRNA binding site: A= P= E=

Answer 24

``` A= incoming aminoacyl-tRNA ===tRNA + amino acid P= existing peptidyl-tRNA bond E= exiting of tRNA ```

Question 25

Translation begins with the ____ codon, thus all new proteins have ______ at their _____ terminal (which is usually removed)

Answer 25

AUG--> Methionine which is at N terminus

Question 26

(eukaryotes) the initiator tRNA is first loaded onto the small subunit with proteins called ______

Answer 26

eukaryotic initiation factors (eiFs)

Question 27

After tRNAi binds with eiFs, the small subunit binds the 5' end of mRNA which is recognized by....and it then proceeds to look for first AUG (assisted by helicases)

Answer 27

the 5' cap and eiFs

Question 28

After the small subunit finds AUG start site.....

Answer 28

eiFs dissociate, allowing for large subunit to join ****tRNAi now occupies P site, A site awaits next aminoacyl-tRNA

Question 29

The start codon selection in bacteria is different since bacterial mRNA don't have a 5' cap, instead they....

Answer 29

have a specific sequence called the Shine-Delgarno sequence

Question 30

bacterial mRNAS are ________ whereas eukaryotic mRNAS generally only encode for a single protein

Answer 30

polycistronic

Question 31

Three major steps of Elongation: 1) 2) 3)

Answer 31

1) new tRNA binds to A site (codon base pairing) 2) carboxyl end (o-c=o) of peptide chain released from it's tRNA (in P site) by breaking high energy bond-->followed by joining peptide chain to free AA linked to tRNA in A site (peptidyl transferase) 3) conformational change moves mRNA exactly 3 nucleotides through ribosome to prepare ribosome for next aminoacyl-tRNA REPEAT

Question 32

_________ are necessary for moving the mRNA forward through the ribosome in translation

Answer 32

elongation factors (EFS)

Question 33

The end of the protein-coding message is signaled by the presence of one of three stop codons:

Answer 33

UAA, UAG, UGA

Question 34

Release factors bind the ribosome with the stop codon in the A site and forces peptidyl transferase to....

Answer 34

add a water molecule instead of an amino acid to the peptidyl tRNA (c terminal) thereby freeing the carboxyl end of the chain * **released into cytoplasm * ****Large and small subunits separate with the help of a divorce attorney

Question 35

Protein synthesis can occur in the _______ in addition to the ________

Answer 35

Rough Endoplasmic Reticulum (RER) + cytosol **translation in RER allows for quick packaging and transportation in vesicles

Question 36

Tetracycline

Answer 36

blocks binding of aminoacyl-tRNA to A site of ribosome

Question 37

Streptomycin

Answer 37

prevents the transition from translation initiation to chain elongation and also causes miscoding

Question 38

Chloramphenicol

Answer 38

blocks the peptidyl transferase reaction on ribosome

Question 39

Erythromycin

Answer 39

binds in the exit channel of the ribosome (E) and thereby inhibits elongation of peptide chain

Question 40

Rifamycin

Answer 40

block initiation of RNA chains by binding to RNA polymerase thus preventing RNA synthesis