Many types of color blindness are what are called X linked, thatis determined by
ID: 1858 • Letter: M
Question
Many types of color blindness are what are called X linked, thatis determined by genes on the X chromosome. Suppose a woman iscarrying one X chromosome with the gene for a particular type ofcolor blindness; her other X chromosome does not have this gene. Ifshe is married to a man who does not have this gene on his Xchromosome. You may remember that color blindness is X linkedrecessive.
A. What is the probability that her first child will carry the Xchromosome with the gene associated with color blindness?
B. Suppose amniocentesis reveals that the child is male.What is the probability that the child is color blind. Hint: thisinvolves conditional probability
Explanation / Answer
Color blindness - X linkedTRAIT
NORMAL FATHER XY CARRIERMOTHER XXC
GAMETES
X
XXC
X
XX NORMAL
XXC CARRIER
Y
XY NORMAL
YXC AFFECTED
50%
B. Suppose amniocentesis reveals that the child is male. What isthe probability that the child is color blind.
50%
GAMETES
X
XXC
X
XX NORMAL
XXC CARRIER
Y
XY NORMAL
YXC AFFECTED