8C Pedigree Analysis

Question 1

What are pedigree charts?

Answer 1

Pedigree charts are family trees used to analysis patterns of inheritance, and show the expressions of a trait over multiple generations

Question 2

What can pedigree charts be used for?

Answer 2

Pedigree charts can be used to find out the probability of a child having a disorder in a particular family

Question 3

On a pedigree chart, what does a square represent

Answer 3

Represents a male

Question 4

On a pedigree chart, what does a circle represent

Answer 4

Represents a female

Question 5

On a pedigree chart, what does being white represent?

Answer 5

Represents unaffected

Question 6

On a pedigree chart, what does being coloured represent

Answer 6

Represents affected

Question 7

What does a square/circle with a small coloured-in version in the centre represent?

Answer 7

Represents a carrier

Question 8

What does a diamond represent?

Answer 8

Represents unknown sex

Question 9

How do you use pedigree chart references?

Answer 9

The generation of an individual is noted with Roman numerals, ascending from oldest to youngest. The location of an individual in a generation is noted using numbers, ascending from left to right.

Question 10

What are the steps to interpret a pedigree chart?

Answer 10

First determine if the pedigree charts shows as autosomal or x-liked disease, Then determine is the disorder dominate or recessive

Question 11

How do you determine if the pedigree charts shows as autosomal or x linked disease

Answer 11

If most of the males in the pedigree are affected the disorder is x linked, if it is a 50/50 ratio between the men and women the disorder is autosomal

Question 12

How do you determine if the pedigree charts shows is dominate or recessive

Answer 12

If the disorder is dominate, one of the parents must have the disorder, if the disorder is recessive neither parent has to have the disorder because they can be heterozygous

Question 13

Looking at the flowchart for analysing pedigree charts, explain it

Answer 13

Explain it – the 5 options of
- Y linked,
- X linked dominant,
- autosomal dominate,
- x linked recessive and
- autosomal recessive

Question 14

Looking at the inheritance patterns explain the 5 different ones

Answer 14

• Autosomal dominant – where the gene for a trait or condition is dominant, and is on a non-sex chromosome
• Autosomal recessive – where the gene for a trait or condition is recessive, and is on a non-sex chromosome
• X-linked dominant – where the gene for a trait or condition is dominant, and is on the X-chromosome
• X-linked recessive – where the gene for a trait or condition is recessive, and is on the X-chromosome
• Y-linked – where the gene for a trait or condition is on the Y-chromosome