DNA and protein synthesis

Question 1

Genome

Answer 1

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

Question 2

Proteome

Answer 2

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

Question 3

Describe the structure of messenger RNA

Answer 3

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

Question 4

Suggests 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 = rinosomes moves along strand & tRNA binds to exposed bases

Contains no introns

Question 5

Describe the structure of transfer RNA

Answer 5

A single strand of around 80 nucleotides that is folded over into a clover leaf shape. One 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

uncoils

Answer 8

1. DNA uncoils into two strands with exposed bases. One used as a template.
2. 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. Thenit 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 the process of translation

2

Answer 12

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

This process requires ATP

Question 13

Transcription stages

6 points

1. H
2. Line forming..
3. Something re-forms once something happens
4. . RNA reaches..
5. Then something moves out. Then a process takes place

Answer 13

1. H bonds between break causing DNA to uncoil into two strands one acting as a template
2. Free nucleotides line up with complementary bases and is then joined up with RNA polymerase forming an mRNA molecule.
3. H-bonds between the uncoiled strands of DNA re-form once the RNA polymerase has passed by the the strands coil back into a double-helix
4. RNA reaches a stop codon then stops making mRNA and detached from the DNA
5. mRNA moves out of the nucleus and then attached to a ribsome and protein synthesis takes place

Question 14

Translation stages

Answer 14

1. Anti-codon of tRNA binds to complementary bases on mRNA.
2. Amino acids bonded to tRNA and form a peptide bond, continuing to form polypeptide chains until a stop codon is reached.