The following links offer some useful revision on Cell Structure to support your learning:
The Higher Biology Podcast – Mutations
At Higher, you will need to know the following:
- Proteins are held in a three dimensional shape by peptide bonds, hydrogen bonds, interactions between individual amino acids.
- Proteins have a large variety of structures and shapes resulting in a wide range of functions.
- Polypeptide chains fold to form the three dimensional shape of the protein.
- Amino acids are linked by peptide bonds to form polypeptides.
- Mutations result in no protein or a faulty protein being expressed.
- Genetic disorders are caused by changes to genes or chromosomes that result in the proteins not being expressed or the proteins expressed not functioning correctly
- Single gene mutations involve the alteration of a DNA nucleotide sequence as a result of the substitution, insertion or deletion of nucleotides.
- Nature of single-nucleotide substitutions including: missense, nonsense and splice-site mutations. Missense (replacing one amino acid codon with another), nonsense (replacing an amino acid codon with a premature stop codon — no amino acid is made and the process stops) and splice-site mutations (creating or destroying the codons for exon/intron splicing).
- Nucleotide insertions or deletions result in frame-shift mutations or an expansion of a nucleotide sequence repeat.
- The effect of these mutations on the structure and function of the protein synthesised and the resulting effects on health.
- Chromosome structure mutations. The structure of a chromosome can be altered. These mutations can take the form of a deletion (loss of a segment of a chromosome), duplication (repeat of as egment of a chromosome) or translocation (the rearrangement of chromosomal material involving two or more chromosomes).
