4.2 Protein synthesis

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 range of proteins a cell can produce

Question 3

tRNA

Answer 3

Folded into a clover leaf shape
Hydrogen bonds between base pairs
Shorter
Anticodon
Amino acid binding site

Question 4

mRNA

Answer 4

Linear
No hydrogen bonds
Longer
Codons
No amino acid binding site

Question 5

How is mRNA formed by transcription in eukaryotic cells?

Answer 5

• DNA helicase breaks hydrogen bonds between complementary bases, unwinding double helix
• One strand acts as template
• Free RNA nucleotides join to exposed bases by complementary base pairing
• Uracil is used in place of thymine
• RNA polymerase joins adjacent nucleotides by condensation reactions, forming phosphodiester bonds
• Pre-mRNA is spliced to remove introns, forming mRNA

Question 6

How is a polypeptide formed by translation?

Answer 6

• mRNA attaches to ribosome and ribosome moves to start codon
• tRNA brings specific amino acid to ribosome
• tRNA anticodon binds to complementary mRNA codon
• Ribosome moves along to next codon
• Amino acids join by condensation reaction, forming a peptide bond, using energy from hydrolysis of ATP
• tRNA released
• Ribosome moves along mRNA to form the polypeptide until a stop codon is reached