Genetics – study of variation and inheritance.
Gene – Basic unit of inheritance; a heritable factor that controls a specific character
- 30,000-40,000 genes in humans
- genome– the whole of the genetic information of an organism; all of the genes of an organism collectively
- genes are made of DNA
Chromosomes – organized structure of DNA + protein found in cells
- eukaryotic chromosome is made of DNA and protein.
- typical animal/plant chromosome contains: about 1000 genes
- arranged in linear sequence
- gene locus – specific position of a gene on a chromosome
- homologous – when 2 chromosomes have the same sequence of genes; chromosomes usually not identical (alleles differ)
- allele – a form of a gene, differing from other alleles of the gene by a few bases at most and occupying the same locus as the other alleles of that gene
- eukaryote chromosomes – DNA molecules associated with protein
- visible during mitosis/meiosis
- condensed (become shorter and fatter by coiling process of histone proteins)
- in body cells of most eukaryotes: 2 chromosomes of each type – 2 homologous chromosomes = DIPLOID
- only one chromossome of each type passed on in a gamete
- Gametes = HAPLOID
- Meiosis: a special type of division of the nucleus to produce haploid gametes
Gene mutation – genes changing when passed from parent to offspring; a change to the base sewuence of a gene
Base mutation – when one base in a gnee is replaced by another base.
- Results to diseases
- e.g. sickle cell anemia