DNA- Translation

Enzymes are biological catalysts. Lipase is an enzyme involved in the digestion of triglycerides. Lipase is synthesised in cells.

Describe the role of RNA in the synthesis of lipase. (5)

1. mRNA is produced by transcription in the nucleus.

2. mRNA leaves the nucleus and associates with the ribosome.

3. tRNA brings specific amino acid to the ribosome.

4. Anticodons on the tRNA complementary base pair with the codons on the mRNA.

5. Order of amino acids in the lipase molecule is determined by the codons on the mRNA.

The synthesis of mRNA occurs in a process called transcription.

Compare and contrast the process of transcription with the process of DNA replication. (4)

Similarities

1. involve formation of a polynucleotide.

2. involve DNA helicase (unzipping the DNA).

Differences

1. transcription uses RNA nucleotides whereas replication uses DNA nucleotides.

2. transcription uses RNA polymerase whereas replication uses DNA polymerase.

Describe how mRNA is synthesised at a template strand of DNA. (2)

1. RNA nucleotides align with complementary bases on DNA

2. RNA nucleotides joined together by RNA polymerase.

Describe the differences between the structure of DNA and the structure of RNA. (3)

1. DNA is double stranded whereas RNA is single stranded

2. DNA contains deoxyribose whereas RNA contains ribose

3. DNA contains thymine whereas RNA contains uracil

Describe the structure of a mononucleotide found in RNA. (2)

1. contains ribose and phosphate

2. and a nitrogenous base

Describe the process of protein synthesis that occurs in the cytoplasm. (5)

1. ribosome attaches to mRNA

2. tRNA brings specific amino acid to the ribosome

3. the anticodons on the tRNA complementary base pair with the codons on the mRNA

4. hydrogen bonding between tRNA and mRNA

5. peptide bonds between amino acids

6. formed by a condensation reaction

7. tRNA released from ribosome

8. ribosome detaches from mRNA.

Describe the roles of transcription and translation in the synthesis of a globular protein by a muscle cell. (5)

1. the gene for the globular protein is transcribed

2. complementary base pairing between RNA nucleotides and DNA to produce mRNA

3. mRNA leaves the nucleus and attaches to a ribosome

4. the anticodons on the tRNA complementary base pair with the codons on the mRNA

5. tRNA brings specific amino acid

6. the sequence of amino acids in the globular protein is determined by the codons on the mRNA