X And Y Chromosomes, & Gender linked disorders Flashcards
Is XX Male, or Female?
Female
How many matched pairs of chromosomes are there in every human body cell?
23
Is XY Male, or Female?
Male
What chromosomes do women have?
XX
What chromosomes to Men have?
XY
Why are come characteristics/ disorders sex linked?
Because the gene is located on a sex chromosome.
Which chromosome is smaller and carrier less genes?
The Y Chromosome.
Which chromosome carries the most of the sex linked genes?
The X chromosome, as it’s larger
Why are Men more likely to show recessive characteristics for genes that are sex linked?
Because men only have one allele (on the X chromosome), which is shown even if it’s recessive, due to the fact that the Y chromosome is much shorter and doesn’t cover up the X chromosome.
What are two examples of sex linked genetic disorders?
Colour blindness and haemophilia.
How many copies of the recessive allele do women need to be colour blind?
Two
Why is colourblindness much more common in men that women?
Because women need two recessive genes in order to be colour blind whereas men only need one (as their Y chromosome doesn’t cover up their X chromosome)
A female carrier of colour blindness would have how many recessive alleles?
One.
Give the ratio of the possible outcomes of phenotypes of offspring, from a normal female (Carrier) and a normal male?
(Normal:carrier:colour blind)
2:1:1
