Chapter 3 - Pedigree analysis

Question 1

What is a pedigree diagram?

Answer 1

A diagram that uses specific symbols to display information about each individual and a single character being investigated

Question 2

Why do we use pedigree tests instead of test crosses on humans?

Answer 2

Not ethical

Question 3

Why do we use pedigree diagrams?

Answer 3

Often used to analyse the incidence of a genetic disorder in a family
Likelihood to pass it down to the next generation

Question 4

What does it mean to identify the patterns of inheritance?

Answer 4

Whether it is dominant or recessive
Whether it is autosomal or sex-linked

Question 5

What are the key characteristics to identify an autosomal dominant inheritance?

Answer 5

• Both male and female
• Generation is never skipped from the point it is introduced
• Can result in parents with trait, and a child without a trait
• Two parents without the trait cannot pass it on to the child

Question 6

What are the key characteristics to identify an autosomal recessive inheritance?

Answer 6

• for the trait to be seen, the individual must be homozygous recessive
• both males and females affected
• can skip generation
• can result in two parents without the trait and a child with the trait
• if two parents have the trait then all the children have the trait

Question 7

What is the key characteristics to identify a x-linked recessive inheritance

Answer 7

• more common in males than females
• can skip generations
• mother with trait passes it on to their sons
• daughter with trait must have father with trait

Question 8

What are the key characteristics to identify a x-linked dominant inheritance?

Answer 8

• coded by dominant allele
• both male and female only require one copy of the dominant allele
• if father passes it to all of this daughters and not sons

Question 9

What are the key characteristics to identify a y-linked inheritance

Answer 9

all males are affected because it is carried on the y chromosome