exams Questions Flashcards
1
Q
How mRNA is translated into … at the ribosome (4 marks)
A
- codon on mRNA complementary base pairing with anticodon on tRNA
- specific tRNA for each amino acid
- protein formed by condensation reaction
- peptide bond formed
2
Q
Describe how mRNA is produced in the nucleus of the cell (6 marker)
A
- helicase, breaks hydrogen bonds
- only one DNA strand acts as a template
- RNA nucleotides attracted to exposed bases
- attraction according to base pairing rule
- RNA polymerase join RNA nucleotides together
- pre-mRNA spilled to remove introns
3
Q
Describe the structure of proteins (5 mark)
A
- polymer of amino acid
- joined by peptide bond
- formed by condensation reaction
- primary structure is the order of amino acids
- secondary structure is the coding of a polypeptide chin due to hydrogen bonding
- tertiary structure is 3-d folding due to hydrogen bonding and ionic and disulphide bonds
- quaternary structure is 2 or more polypeptide chains
4
Q
Describe how proteins are digested in the human gut (4 marks)
A
- hydrolysis of peptide bonds
- endopeptidases break polypeptide into smaller peptide chains
- exopeptidases removes terminal amino acids
- dipeptidases hydrolyse dipeptides into amino acid
5
Q
Not all mutations in nucleotides sequence of gene cause a change to the structure of a polypeptide give reasons why? (2 marker)
A
- degenerate code = triplet code for same amino acid
- occurs in non - coding sequence
6
Q
3 ways in which DNA in prokaryotes is different from DNA in eukaryotes (3 mark)
A
- DNA shorter
- fewer genes
- not associated with proteins unlike nuclear DNA
- introns absent but present in nuclear DNA
- DNA circular not linear
7
Q
Differences between RNA nucleotide and DNA nucleotide (1 mark)
A
Deoxyribose in DNA and ribose in RNA
