Variation and inheritance
- Created by: GraceLong
- Created on: 23-05-16 16:36
View mindmap
- Variation and inheritance
- Inherited characteristics
- Inherited characteristics can be dominant or recessive
- Alleles are different versions of the same gene
- There are debates about how much 'nature or nurture' effects intelligence, health and sporting ability
- Dominant and recessive characteristics depend on dominant and recessive alleles
- Dominant alleles are expressed when present but recessive alleles are expressed in the absence of the dominant allele
- Monohybrid corss
- Involves one pair of characteristics controlled by single gene - one dominant and one recessive allele
- Homozygous has identical alleles and hetrozygous has different alleles
- A persons genotype is their genetic make up whereas a persons phenotype is the allele expressed
- Chromosomes
- Sex chromosomes in mammals determine sex. Females have ** and male have XY
- There is a random chance of which sperm fertilises an egg... therefore an equal chance of male or female
- A sperm will carry either an X or a Y. The egg always contains the X chromosome
- Most cells have the same number of chromosomes depending on the species. Humans have 23 pairs
- Inherited disorders
- Usually caused by faulty alleles that are recessive
- Ethical issues raised about having screening for genetic disorders and knowing the risks of passing on a genetic disorder
- Caused by faulty genes
- It is possible to predict the probability of inheriting orders using genetic diagrams
- Genetic variation
- Caused by: fertilisation resulting in zygote from father and mother
- Caused by: mutations which randomly change genes or chromosomes
- Caused by: rearrangement during formation of gametes
- Inherited characteristics
Comments
No comments have yet been made