Practice questions set #13

Question 1

Review the figure relating to the cross with Morgan’s flies pr pr vg vg and pr+pr+vg+vg+. Do
not memorize the figure. Explain the difference between the two predicted ratios.

Answer 1

The difference is that the male will only produce 1 possiblity that is 1 purple and 1 vestigial allele without other possibilities regardless if is in the same chromosome or not because is a homozygote double mutant, and there is no more alleles.However the female If the female chromosomes are in the same chromosomes there are 2 possibilities and 4 if they are in different chromosomes.

Question 2

What does a frequency of recombination of 50% indicate?

Answer 2

It indicates that there is 50% chance of recombination(that genes that weren’t linked to the parental chromosomes), that means that is equal chance of chromosomes to assort through independent assortment when there is 2 genes in different chromosomes,we expect to see the same when there are 2 genes but they are really apart.

The further apart the genes are in the same chromosome the higher the recombination frequency.

Question 3

Define euploidy and aneuploidy.

Answer 3

• Euploidy:an individual with the right chromosomes number for it’s species.
• Aneuploidy:and individual with an error in their chromosome number;it can be duplication or deletion of a chromosome segment error.

Question 4

Uniparental disomy of chromosome 15 can lead to AS or PWS. What will determine which
syndrome the individual will have?

Answer 4

What determines what syndrome the child will have is that if the child inherits either 2 copies of chromosome of a section of chromosome 15 from the mother or father.

Also, it can occur if a section of chromosome 15 gets deleted from the mother in AS,and from the father in PWS.