lecture 27

Question 1

how homopolypeptides produced

Answer 1

Synthetic mRNAs of repeated sequence (homopolymers) were
tested in vitro for protein synthesis: produced homopolypeptides

Question 2

how many possible reading frames are for synthetic mRNA?

Answer 2

There are 3 possible reading
frames for this synthetic mRNA
(random co-polymer) depending
on where the ribosome in the cell
extract starts translation

Question 3

read the experiment slide 7

Question 4

how many possible types of amino acid are there

Answer 4

• Of the 43 = 64 possible
  triplets, 61 specify amino
  acids, while 3 specify stop
  codon

Question 5

what is The genetic code is
degenerate

Answer 5

The genetic code is
degenerate: some amino
acids are specified by more
than one codon

Question 6

The genetic code is……….

Answer 6

The genetic code is comma-
free

Question 7

The genetic code contains
……..and …….codons (non-
sense).

Answer 7

The genetic code contains
start and stop codons (non-
sense).

Question 8

what is the wobble position

Answer 8

Base-pairing between mRNA codons
and aminoacyl tRNAs is “anti-parallel”,
but there is flexibility in binding at the 3 rd
codon position (1 st anti-codon position).
This is known as the Wobble position

Question 9

what is the degeneracy feature

Answer 9

Oftentimes, the base in the 3 rd codon position can be changed and still
specify the same amino acid, (i.e., UCC and UCU both specify serine; GCU,
GCA, GCG, GCC specify alanine). This feature of the genetic code
explains degeneracy.

Question 10

which amino acids are specified by more than one codon

Answer 10

all the amino acids except methionine and tryptophan are specified by
more than one codon