Translation

Question 1

What is a codon?

Answer 1

Triplet of DNA that encodes amino acids

Question 2

How many codons are there?

Answer 2

64

Question 3

How many stop codons are there?

Answer 3

3

Question 4

How many amino acid encoding codons are there?

Answer 4

61

Question 5

What is the initiation codon?

Answer 5

AUG

Question 6

What else does AUG encode for, other than being the initiation codon?

Answer 6

Met

Question 7

What is degeneracy?

Answer 7

More than one codon for some amino acids

Question 8

What does UUU code for?

Answer 8

Phe

Question 9

What does CCC code for?

Answer 9

Pro

Question 10

What does GGG code for?

Answer 10

Gly

Question 11

What does AAA code for?

Answer 11

Lys

Question 12

What are the three stop codons?

Answer 12

UGA
UAG
UAA

Question 13

What is the open reading frame (ORF)?

Answer 13

The in-frame sequence between the initiation codon and the termination codon

Question 14

What does the 5’ end of the mRNA correspond to?

Answer 14

The N-terminal of the protein (amino terminus)

Question 15

What does the 3’ end of the mRNA correspond to?

Answer 15

The C-terminal (carboxy terminus)

Question 16

Who discovered that protein synthesis begins at the amino terminal end of the nascent proteins?

Answer 16

Dintzis (1961)

Question 17

What serves as the adapter molecules for specific amino acids, since mRNA templates can’t directly line up amino acids for protein synthesis?

Answer 17

tRNA - bind to specific codons on the RNA template

Question 18

How are amino acids linked to tRNA molecules before being incorporated into the protein?

Answer 18

Amino acids are enzymatically to tRNA

Question 19

Which undergoes more proofreading, translation, transcription or replication?

Answer 19

Replication

Question 20

How many bases are found in tRNA?

Answer 20

73-93 (small)

Question 21

All cells have at least ___ tRNAs.

Answer 21

32

Question 22

What forms the wobble in the “wobble rules”?

Answer 22

The fact that some tRNAs can recognize more than one codon

Question 23

What do most tRNAs have at the 5’ end?

Answer 23

G

Question 24

What does the D arm of tRNA contain?

Answer 24

Dihydrouridine

Question 25

What does the TpsiC arm contain?

Answer 25

The sequence ribothymidine (T) pseudouridin (psi) cytosine (C)

Question 26

What is the anticodon? Where is it found?

Answer 26

A 3 base sequence | In the anticodon loop of tRNA

Question 27

What does the anticodon of tRNA base pair with?

Answer 27

The codon in mRNA

Question 28

What base does inositate contain?

Answer 28

Hypoxanthine

Question 29

Some tRNAs contain what different nucleotide?

Answer 29

Inositate

Question 30

Hypoxanthine can base pair weakly with which bases?

Answer 30

U, C, A

Question 31

How many subunits make up ribosomes?

Answer 31

2 - a large and a small subunit

Question 32

What is each ribosomal subunit made of?

Answer 32

An assembly of one or more rRNA molecules and many different proteins

Question 33

What 3 sites do the ribosomal subunits form?

Answer 33

1. Peptidyl (P) site 2. Aminoacyl (A) site 3. Exit (E) site

Question 34

What occurs at the aminoacyl site?

Answer 34

It is the site where the amino acids come in

Question 35

How big is a large bacterial ribosomal subunit?

Answer 35

50S

Question 36

How big is a large eukaryotic ribosomal subunit?

Answer 36

60S

Question 37

What size is the small bacterial ribosomal subunit?

Answer 37

30S

Question 38

What size is the small eukaryotic ribosomal subunit?

Answer 38

40S

Question 39

What are the 5 major stages of protein synthesis?

Answer 39

1. Activation of amino acids 2. Initiation 3. Elongation 4. Termination and ribosome recycling 5. Folding and posttranslational processing

Question 40

What occurs in stage on o protein synthesis?

Answer 40

The tRNA is "charged" with the proper amino acid

Question 41

How and where are amino acids attached to the corresponding tRNA?

Answer 41

Via ester bonds to the 3' OH

Question 42

What is the reaction that attaches the amino acid to the tRNA?

Answer 42

Aminoacylation of the 3' OH

Question 43

What catalyzes the aminoacylation of the amino acid to the tRNA?

Answer 43

Amino acyl-tRNA synthetase

Question 44

tRNA charging is highly ___.

Answer 44

Specific

Question 45

Why is tRNA charging irreversible?

Answer 45

It uses 2 high-energy bonds

Question 46

T or F: The identity of the amino acids attached to the tRNA are checked by the ribosome.

Answer 46

False

Question 47

How do aminoacyl-tRNA synthetases recognize correct tRNAs? (4 ways)

Answer 47

Some recognize the anticodon Some recognize 10 or more bases in tRNA Some recognize one specific base pair

Question 48

After tRNA is charged by a snthetase, the aminoacyl tRNA forms a complex with what molecule that will also bind one GTP molecule?

Answer 48

EF-Tu (elongation factor)

Question 49

How many tRNAs do all organisms have for methionine?

Answer 49

2 - one for initiation, one for methionines within the polypeptide chain

Question 50

In bacteria, how many components are required for initiation?

Answer 50

7

Question 51

How many steps does it take for the 7 bacterial initiation factors to assemble?

Answer 51

3 steps

Question 52

How is the initiation codon distinguished in step 1 of bacterial protein initiation?

Answer 52

By proximity to the Shine-Dalgarno sequence

Question 53

In bacteria protein initiation, where is the P site placed?

Answer 53

Right over the AUG of the start site

Question 54

What is the first step in bacterial mRNA initiation?

Answer 54

Small (30S) subunit positions itself on the mRNA template

Question 55

What is step 2 in the initiation of protein synthesis in bacteria?

Answer 55

Initiator tRNA binds to the P site

Question 56

What is step 3 in protein synthesis initiation in bacteria?

Answer 56

Large (50S) subunit binds to the complex

Question 57

How many initiation factors or involved in the initiation of protein synthesis in eukaryotes?

Answer 57

At least 9

Question 58

What is the Kozak sequence, that is found at many initiation sites?

Answer 58

5'-CCACCAUGG-3'

Question 59

Do eukaryotes have a Shine-Dalgarno sequence?

Answer 59

No

Question 60

How many ribosomes are found bound to each mRNA molecule?

Answer 60

10-100

Question 61

What are the 3 steps of elongation?

Answer 61

Bind next aminoacyl-tRNA Peptide bond formation Translocation

Question 62

Why are 2 steps used to move tRNAs?

Answer 62

Anchors one of of tRNA with the other moves | Prevents premature release of peptidyl-tRNA, enhances processivity

Question 63

Proofreading on ribosomes is limited to what?

Answer 63

Codon-anticodon interactions

Question 64

In termination, how is the peptide chain released from the ribosome?

Answer 64

Induce peptidyl transferase to transfer peptide chain to water

Question 65

How many termination factors do eukaryotes have?

Answer 65

1

Question 66

How much energy does protein synthesis take?

Answer 66

At least 4 high-energy bonds per peptide bond

Question 67

Why is so much energy used in protein synthesis?

Answer 67

To maintain proper alignment of codon, tRNA and the growing end of the chain

Question 68

Tetracycline and chloramphenicol are two drugs that do what?

Answer 68

Inhibit translation

Question 69

What side affects can tetracycline have? (used to treat perio-disease)

Answer 69

Stain teel

Question 70

How do tetracyclines inhibit translation?

Answer 70

Bind the A site | Block aa-tRNA binding

Question 71

How does Ricin inhibit translation?

Answer 71

Inactivates the 60S subunit by depurinating the A residue of 28S rRNA - can't bind TF