Lecture 29

Question 1

Messenger RNA is a _______. Some how we must associate a triplet of nucleotides (codon) with the amino acid that it stand for in the genetic code. ______ postulated a separate set of molecules that interact with BOTH amino acids and nucleic acids. This is the ______.

Answer 1

1. polynucleotide
2. Crick
3. transferRNA

Question 2

Protein synthesis proceeds from the ______ of the protein to the _______. Amino acids are linked to tRNA by ______-____ synthetases. Most cells have 20 synthetases, one for each amino acid. These enzymes must recognize both the _____ of tRNA and _____ _____. If there is only one synthetaste per amino acid, each synthetase must recognize multiple _____.

Answer 2

1. N-terminus
2. C-terminus
3. aminoacyl-tRNA synthetases
4. anticodon
5. amino acid
6. codons

Question 3

Synthesis of polypeptide chain is directed by the sequence of nucleotides in a _____. Translation of triplet bases into one ____ ____ according to genetic code. Machinery for doing this is the ______. It is a large complex of RNA and protein, but the RNA is the catalytically active part.

Answer 3

1. mRNA
   2.amino acid
2. ribosome
   4.

Question 4

Ribosomes are like tape reader. They proceeds along _____, three bases at a time. This brings together the active triplet from mRNA with ______ of charged _____. This brings amino acid attached to tRNA juxtaposition with growing end of poplypeptide chain. _______ synthesizes peptide bond.

Answer 4

1. mRNA
2. anticodon
3. tRNA
4. ribosome

Question 5

The ribosome contains three sites for binding tRNA + an attached amino acid or polypeptide. These are called the: (3)

Answer 5

1. A-site (acceptor site)
2. P-site (peptidyl site)
3. E-site (exit site)

Question 6

After attaching to the the ribosome at the A-site the tRNA moves from A–>__–>— site during protein synthesis.

Answer 6

A–>P–>E site

Question 7

A-site is occupied by ________-tRNA. This is the first encounter of it with the _______. The ligand in the A-site functions as the acceptor for the growing polypeptide chain.

Answer 7

1. aminoacyl-tRNA

2. ribosome

Question 8

The P-site is occupied by _______-tRNA, i.e. the tRNA carrying the growing peptide chain.

Answer 8

peptidyl-tRNA

Question 9

The E-site binds _______ tRNA ready to exit from the ______.

Answer 9

1. decylated tRNA

2. ribosome