Exam Questions Flashcards
How is a gene a code for the production of a polypeptide?
The nucleotide sequence in triplets determine the sequence of amino acids in the primary structure.
How is a phosphodiester bond formed between two nucleotides in a DNA molecule?
Condensation reaction between phosphate group and deoxyribose and is catalysed by DNA polymerase.
Define ‘non-coding base sequences’ and describe where the non-coding
multiple repeats are positioned in the genome.
DNA that does not code for polypeptides positioned between genes.
Why don’t all mutations in the nucleotide sequence of a gene cause a change in the structure of a polypeptide?
DNA codes are degenerate and occurs in introns.
Describe how ONE amino acid is added to a polypeptide that is being formed at a ribosome during translation.
tRNA brings specific amino acids to the ribosome. Anticodon on tRNA binds to codons on mRNA. Amino acids joined by condensation reaction using ATP.
Describe how mRNA is produced from an exposed template strand of
DNA.
Free RNA nucleotides form complementary base pairs.
Phosphodiester bonds form by RNA polymerase.
Give the two types of molecule from which a ribosome is made.
RNA and proteins
What is an exon?
A sequence of DNA that codes for an amino acid.
Suggest one way the structure of the chromosome could differ along its length to result in the stain binding more in some areas.
Difference in base sequences.
What is the proteome of a cell?
The full range of proteins that a cell is able to produce.
Describe the structure of proteins. (5)
1)Proteins are polymers of amino acids that are joined by peptide bonds formed by a condensation reaction.
2)The primary structure is the order of amino acids.
3)The secondary structure is the folding of the polypeptide chain due to hydrogen bonding.
4)The tertiary structure is 3D folding due to hydrogen bonding, ionic bonding and disulfide bridges.
5)Quaternary structure is two or more polypeptide chains.
How do the organic bases help to stabilise the structure of DNA?
Hydrogen bonds between the base pairs hold the two strands together. Many hydrogen bonds provide strength.
Suggest how a mutation can lead to the production of a protein that has one amino acid missing.
Loss of codon can cause an amino acid to be missing.
How can deletion lead to the production of a non-functional protein?
Mutation changes codons causing a frame shift. Amino acid sequence changes after this. This affects hydrogen, ionic and sulfur bonds. This changes the structure of the protein so it is non-functional.
How can single base substitution affect the protein produced?
Prevents splicing so faulty mRNA formed.
