Inheritance of sex & sex linkage (Edexcel GCSE Biology): Flashcards
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No. of chromosome pairs in human body cells
No. of chromosome pairs in human body cells
23 pairs
Chromosome pair that determines sex
Chromosome pair that determines sex
23rd pair
No. of chromosome pairs controlling characteristics
No. of chromosome pairs controlling characteristics
22 pairs
Genetic info fraction in gametes vs parent
Genetic info fraction in gametes vs parent
(half)
Sex chromosomes in males
Sex chromosomes in males
XY
Sex chromosomes in females
Sex chromosomes in females
XX
Chance of child being male
Chance of child being male
50%
Why sex-linked disorders more common in men
Why sex-linked disorders more common in men
Only have one X chromosome, so recessive allele is expressed
Cause of colour blindness
Cause of colour blindness
Faulty allele on X chromosome
Copies of recessive allele for women to be colour blind
Copies of recessive allele for women to be colour blind
Two copies
Copies of recessive allele for men to be colour blind
Copies of recessive allele for men to be colour blind
One copy
Carrier (colour blindness) definition
Carrier (colour blindness) definition
Has one copy, not affected, can pass allele on
Haemophilia definition
Haemophilia definition
Disease where blood doesn't clot properly