Inheritance part 2 summary notes
21 February 2023 16:55
- Final pair of chromosomes are sex chromosomes
- Females have 2 X chromosomes
- Males have one X and one Y chromosome
Sex inheritance in humans
- All gametes in females are the same as they contain a single X chromosome
- Males produce 2 different types of gamete- half have X chromosome, other half have Y
chromosome
Sex linkage
- Any gene carried on X or Y chromosome is said to be sex linked
- X chromosome longer than Y chromosome- for most of the length of the X chromosom
there is no equivalent homologous portion of the Y chromosome
- Characteristics controlled by recessive alleles that are on the non homologous portion
the X chromosome appear more frequently in males as there is no homologous portio
on the Y chromosome that might have the dominant allele
Example: haemophilia - blood clots slowly- slow and persistent bleeding
- Mostly in males
- Usually a recessive allele with an altered sequence of DNA bases- codes for a faulty
protein that does not function
- Cannot produce functional protein that is required in clotting process
21 February 2023 16:55
- Final pair of chromosomes are sex chromosomes
- Females have 2 X chromosomes
- Males have one X and one Y chromosome
Sex inheritance in humans
- All gametes in females are the same as they contain a single X chromosome
- Males produce 2 different types of gamete- half have X chromosome, other half have Y
chromosome
Sex linkage
- Any gene carried on X or Y chromosome is said to be sex linked
- X chromosome longer than Y chromosome- for most of the length of the X chromosom
there is no equivalent homologous portion of the Y chromosome
- Characteristics controlled by recessive alleles that are on the non homologous portion
the X chromosome appear more frequently in males as there is no homologous portio
on the Y chromosome that might have the dominant allele
Example: haemophilia - blood clots slowly- slow and persistent bleeding
- Mostly in males
- Usually a recessive allele with an altered sequence of DNA bases- codes for a faulty
protein that does not function
- Cannot produce functional protein that is required in clotting process
