4.2- DNA & Protein Synthesis

Question 1

What is the 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 at any specific time

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 advantages 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 & tRNA binds to exposed bases
• contains no introns

Question 5

Describe the structure of transfer RNA (tRNA)

Answer 5

A single strand of 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 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 the coding regions. Then it moves out of the nucleus and attaches to a ribosome

Question 10

What is produced by translation?

Answer 10

Proteins

Question 11

Where does translation take place?

Answer 11

In the cytoplasm (on ribosomes)

Question 12

Outline 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