sex linkage

Question 1

what is a homologous pair

Answer 1

diploid organisms have pairs of chromosomes same genes different alleles

Question 2

what is sex linkage?

Answer 2

the expression of alleles located on sex chromosomes depends on the sex of the individual

Question 3

what are the two sex chromosomes in humans?

Answer 3

X and Y

Question 4

which sex chromosomes do females have?

Answer 4

XX (x is bigger than y) all the gametes are the same

Question 5

which sex chromosomes do males have?

Answer 5

XY they produce two different types of gamete- half have an X chromosome and half have a Y

Question 6

what does the x chromosome being longer result in

Answer 6

there is no equivalent homologous portion of Y. those characteristics that are controlled by recessive alleles on this non homologous portion of the X chromosome will appear more frequently in the male because no homologous part of Y chromosome that might have the dominant allele

Question 7

what an X linked genetic disorder caused by?

Answer 7

a defective gene on the X chromosome. e.g. haemophilia

Question 8

what is a cause of haemophilia?

Answer 8

a recessive allele with an altered sequence of dna nucleotide based that therefore codes for a faulty protein which does not function. must be homozygous recessive to suffer males only have one x chromosome so if it has the faulty allele they will suffer

Question 9

what is the phenotypic ratio for sex linkage (carrier mum, normal adult)

Answer 9

3:1