5.4

Question 1

1. What are linked genes?

Answer 1

*Genes that are adjacent and close to one another on the same chromosome and that are inherited together are known as linked genes.

Question 2

2. What does map distance tell you about a pair of linked genes?

Answer 2

2. Map distance tells you how close together a pair of linked genes is. The smaller the map distance, the closer together the genes are on the chromosome and the more likely those genes will be inherited together.

Question 3

3. What are sex-linked traits?

Answer 3

• Traits that are determined by genes located on sex chromosomes are known as sex-linked traits.

Question 4

4. How do sex-linked traits differ from Mendelian traits?

Answer 4

4. Sex-linked traits differ from Mendelian traits because each parent does not contribute sex-linked alleles to every biological offspring. like with Mendelian inheritance; biological sex will determine which sex-linked alleles are inherited.

Question 5

What’s special about linked traits and sex-linked traits, and how can one identify them?

Answer 5

Linked genes and sex-linked traits do not follow predicted ratios associated with Mendel’s laws and can be identified by quantitative analysis.

Question 6

Tell me about linked genes

Answer 6

Typically inherited together
Less likely to be separated during crossing over in meiosis (prophase I)

Question 7

How can the distance between linked traits be calculated?

Answer 7

The probability that genetically linked genes will segregate as a unit can be used to calculate the map distance between them.

More likely to be inherited together = closer on the chromosome

Question 8

How is the probability that genetically linked traits will segregate together calculated?

Answer 8

• Determined by how frequently a pair of genes participates in a single crossover event
• Linked genes have a recombination frequency of less than 50%

Question 9

5% is how many map units apart?

Answer 9

5

Question 10

Which is further, 30 map units or 2 map units?

Answer 10

30

Question 11

Are sex chromosomes homologous?

Answer 11

No

Question 12

Why are most genetic diseases X linked?

Answer 12

Because the y chromosome carries very little genetic informtion