3.4.2 DNA and Proteinsynthesis

Question 1

What is the Genome?

Answer 1

The complete set of genes in a cell

Question 2

What is the Proteome?

Answer 2

The full set of protiens that a cell is able to produce

Question 3

What are the two main RNA molecules used in proteinsynthesis?

Answer 3

tRNA (transfer)
mRNA (messenger)

Question 4

What is the structure of mRNA?

Answer 4

Constists of thousands of mononucleotides which from a long, single helixed strand

Question 5

What is the function of mRNA?

Answer 5

Carries genetic code from the nucleus to the ribosomes where each 3 nitrogenous base is a codon

Question 6

What is the structure of tRNA?

Answer 6

A molecule made of ∼80 nuclotides arranged in a clover-leaf shape

Question 7

What are the two main parts of the tRNA?

Answer 7

Amino Acid binding site
Anticodon

Question 8

What is the function of tRNA?

Answer 8

To attach itself to a complementary codon while having an amino acid attached to it

Question 9

What is special about tRNA molecule?

Answer 9

Multiple tRNA molecules can carry the same amino acid although their anticodon being different this is due to DNA being degenerate

Question 10

What are the main stages in proteinsythesis?

Answer 10

Transcription and Translation

Question 11

What is the process of transcription?

Answer 11

1. DNA helicase breaks the H-bonds forming two seperate strands
2. The nucleotide bases on the exposed template strand pair up with their complementary RNA nucleotides
3. RNA polymerase then goes along the molecule and joins the nucleotides together to form a pre-mRNA molecule
4. The RNA polyermase then reaches a stop codon where it leaves the pre-mRNA

Question 12

What is the difference between transcription in eukaryotes and transciption in prokaryotes?

Answer 12

In prokaryotes there is no pre-mRNA and DNA is made directly while in eukaryotes the pre-mRNA has to be SPLICED to form mRNA.

Question 13

What is splicing?

Answer 13

Splicing is the removal of introns from the pre-mRNA to form the mRNA

Question 14

What is the process of translation?

Answer 14

1.mRNA attaches itself to the ribosome and a tRNA molecule with a completmenary anticodon attaches to it
2. A second tRNA molecule then attaches to the next codon
3. A peptide bond between the two amino acids for via a condensation reaction
4. The first tRNA molecule then leaves
5. The process then repeats itself until a stop codon is reached
6. A polypeptide is then formed