Two types?
Small scale @ protein coding genes
Large scale due to chromosomal aberrations @ chromosomal level
Small scale gene mutation is due to?
- Substitution
2. Insertion/ deletion
3 consequences of substitution
- Nonsense
- Missense
- Silent
Insertion/ deletion results in?
Frameshift mutation
2 types of chromosomal aberrations
- Numerical
2. Structural
Numerical chromosomal abbreviation is?
Change in no of chromosome
Numerical abbreviations can be?
- Aneuploid
- monosomic (2n-1)
- trisomic (2n+1) - Polyploid
- 3n/4n - Euploid
- 23 complete sets of chromosome
Causes of aneuploidy
Failure of Sister chromatids to separate during anaphase;
Failure of homologous chromosome to separate during anaphase I
Failure of non-sister chromatids to separate during anaphase II
Def mutation
permanent change in DNA that can involve large chromosomal regions or single nucleotide pair
Explain the difference bt somatic and germline mutations
Somatic:
- occur in non-reproductive cells;
- not transmitted to the next generation
Germline:
- germ cells giving rise to gametes;
- transmitted to the offspring and a succession of future generations
4 types of structural mutations
- Translocation
- Inversion
- Deletion
- Duplication
Explain translocation
movement of a group of genes bt non-homologous chromosomes;
a section breaks and attaches to another;
chromosome becomes deficient in genes
Explain inversion
chromosomes break into two pieces;
middle piece falls out;
inverts itself and reattaches;
Explain deletion
Break at two points;
Middle piece falls apart;
two rejoin->chromosome deficient
Explain duplication
Either
- section of a chromosome is replicated OR
- segment is deleted from a chromosome and added to its homologue
