More on protein synthesis

Question 1

What are the 2 stages of making proteins?

Answer 1

Transcription and translation

Question 2

Where are proteins made?

Answer 2

In the cell cytoplasm by subcellular structures called ribosomes

Question 3

Where is DNA found? Why can’t it move out?

Answer 3

1) The cell nucleus

2) Because it is really big

Question 4

What is the function of messenger RNA (mRNA)?

Answer 4

Getting information from the DNA to the ribosome in the cytoplasm.

Question 5

What is messenger RNA made of?

Answer 5

A sequence of bases

Question 6

What does messenger RNA use as a base instead of thymine?

Answer 6

Uracil

Question 7

What is RNA polymerase

Answer 7

The enzyme involved in joining together the base sequence to make mRNA.

Question 8

How does transcription work? (5 stages)

Answer 8

1) RNA polymerase binds to the region of non-coding DNA in front of a gene.
2) The 2 DNA strands unzip and the RNA polymerase moves along one of the strands of DNA.
3) It uses coding DNA in the gene as a template to make the mRNA.
4) Base pairing between the DNA and RNA ensures that the mRNA is complementary to the gene.
5) Once made, the mRNA molecule moves out of the nucleus and joins with the ribosome in the cytoplasm.

Question 9

How does translation work? (5 stages)

Answer 9

1) Amino acids are brought to the ribosome by another RNA molecule called transfer RNA.
2) The order in which the amino acids are brought to the ribosome matches the order of codons in mRNA.
3) Part of the tRNA’s structure is called an anticodon - it’s complementary to the codon for the amino acid. The pairing of the codon and anticodon makes sure that the amino acids are brought to the ribosome in the correct order.
4) The amino acids are joined together by the ribosome. This makes a protein.