4-5-additional

Question 1

In order to code for the 20 amino acids found in living things, a “word” in the genetic code must consist of at least

Answer 1

3 bases ( a “triplet”)

Question 2

how many possible code words are there in the genetic code.

Answer 2

64 (explanation: each word is three bases long, and there are four alternatives for each base, so 4X4X4 = 64)

Question 3

a 3-base sequence on the mRNA codes for either …

Answer 3

a specific amino acid or a control word

Question 4

who broke the genetic code

Answer 4

Nirenberg and Matthaei

Question 5

The genetic code consists of …

Answer 5

(1) 61 amino-acid coding codons

(2) three termination codons that stop the process of translation.

Question 6

what does it mean that the genetic code is redundant (sometimes referred to as degenerate),

Answer 6

there are multiple code words for the same amino acid (for example, glycine coded for by GGU, GGC, GGA, and GGG codons).

Question 7

promoters

Answer 7

sequences of DNA that are the start signals for the transcription of mRNA

Question 8

terminators

Answer 8

the transcription stop signals

Question 9

Ribosomes consist of

Answer 9

a small and a large sub-unit.

Question 10

The smaller sub-unit of a ribosome has a binding site for…

Answer 10

the mRNA.

Question 11

The larger sub-unit has… .

Answer 11

two binding sites for tRNA

Question 12

Transfer RNA (tRNA): shape and function

Answer 12

the shape of a cloverleaf and carries the proper amino acid to the ribosome

Question 13

how many tRNAs and how are they different

Answer 13

61 different tRNAs, each having a different binding site for the amino acid and a different anticodon.

Question 14

Amino acid linkage to the proper tRNA is controlled by ….

Answer 14

aminoacyl-tRNA synthetases.

Question 15

Energy for binding the amino acid to tRNA comes from …

Answer 15

ATP by conversion to Adenosine Monophosphate (AMP).

Question 16

The initiator codon (Which triplet?)

Answer 16

(AUG)

(It codes for the amino acid N-formylmethionine (f-Met). No transcription occurs without the AUG codon. f-Met is always the first amino acid in a polypeptide chain, although it is frequently removed after translation).

Question 17

Initiation complex (translation)

Answer 17

The initiator tRNA, mRNA, and the small ribosomal unit

Question 18

The initiation complex joins with the

Answer 18

large sub-unit of the ribosome

Question 19

the kind of bond that forms between the amino acids

Answer 19

peptide bond

Question 20

What happens when the ribosome moves to the next triplet on the mRNA .

Answer 20

That opens up the A site and a new tRNA enters at the A site

Question 21

What happens when the codon in the A site is a termination codon?

Answer 21

a releasing factor binds to the site, stopping translation and releasing the ribosomal complex and mRNA.

Question 22

polysome

Answer 22

more than one ribosome, sometimes many, reading the same messenger RNA. In this way, a cell may rapidly make many proteins at once.

Question 23

Mutation (revised definition for what mutation is at the molecular level)

Answer 23

a mutation is a change in the DNA base sequence that results in a change of amino acid(s) in the polypeptide coded for by that gene.

Question 24

point mutation

Answer 24

mutation involving the substitution of a single base.

Question 25

frame shift mutation

Answer 25

when the reading frame of the gene is shifted by the addition or deletion of one or more bases

Question 26

powerful evidence for the common ancestry of all living things.

Answer 26

With the exception of mitochondria, all organisms use the same genetic code.