4.2 - Protein Synthesis

Question 1

What is a genome?

Answer 1

The complete set of genetic information contained in the cells of an organism.

Question 2

What is the proteome?

Answer 2

The complete set of proteins that can be produced by a cell.

Question 3

Describe the structure of messenger RNA (mRNA).

Answer 3

A long, single strand. Its base sequence is complementary to the DNA it was transcribed from.

Question 4

Suggest advantaged of using mRNA rather than DNA for translation.

Answer 4

• Shorter & contains uracil = breaks down quickly so no excess polypeptide forms.
• Single-stranded & linear = ribosome moves along strand and tRNA binds to exposed bases.
• Contains no introns.

Question 5

Describe the structure of tRNA.

Answer 5

A single strand or around 80 nucleotides that is folded over into a clover leaf shape. On one end is an anti-codon, on the opposite end is an amino acid binding site.

Question 6

What is produced by transcription?

Answer 6

mRNA

Question 7

Where does transcription take place?

Answer 7

In the nucleus.

Question 8

Outline the process of transcription

Answer 8

• DNA uncoils into two strands with exposed bases. One used as a template.
• Free nucleotides line up next to their complementary bases, and are joined together by RNA polymerase.

Question 9

What happens to mRNA after transcription?

Answer 9

In eukaryotic cells, pre-mRNA must be spliced to remove introns, leaving only coding regions. Then it moves out of the nucleus and attaches to a ribosome.

Question 10

What is produced in translation?

Answer 10

Proteins

Question 11

Where does translation take place?

Answer 11

In the cytoplasm on ribosomes.

Question 12

Outline the process of translation.

Answer 12

• The anti-codon of tRNA attaches to complementary bases on the mRNA.
• Amino acids bonded to tRNA form peptide bonds, continuing to form a polypeptide chain until a stop codon is reached.
• This process requires ATP.