DR Medhat MRCP

Autosomal
dominant
Autosomal
recessive
Homozygote
Heterozygote
Natural
selection
Gene flow OR
g. migration
Genetic drift
Linkage
disequilibirium
Mutation
Requires only one copy of the mutation to produce the disease
Requires two copies of the mutation to produce disease
Alleles at a locus are the same
Alleles at a locus are different
- The process whereby organisms possessing certain characteristics
that make them better adjusted to the environment tend to
survive and reproduce in greater numbers, and are therefore able
to transmit their qualities to succeeding generations e.g It has been
suggested that cystic fibrosis (CF) (autosomal recessive) has a high
prevalence in some populations because heterozygotes are
resistant to the effects of chloride-secreting diarrhoea
- The transfer of alleles or genes from one population to another. In
humans it usually happens following migration (e.g. West African
population with European in USA).
- The statistical drift over time of gene frequencies in a population,
due to random sampling effects in subsequent generations
- the occurence of some combinations of alleles more or less often
than would be expected from a random formation of haplotypes
- Is a change in genetic sequence
• Chemical structure of nucleic acid
- All nucleic acids are poly nucleotides .
- A nucleotide is composed of 3 components :
1) A base
2) A pentose sugar.
3) 1-3 phosphate group.
- There are 2 kinds of nucleic acids :
Deoxyribonucleic acid (DNA).
Ribonucleic acid (RNA).
35