Punnet squares, pedigrees

Question 1

What is a punnet square?

Answer 1

a method used to find expected genotype and phenotype ratios of offspring when parental genotypes and/or phenotypes are unknown.

Question 2

How do you construct a punnet square?

Answer 2

• write down parental genotypes (choose letters)
• write possible alleles able to be passed on
• construct square
• fill potential genotypes of offspiring
• determine ratio of offspring
• determine phenotype of offspring

Question 3

What does a pedigree chart show?

Answer 3

members of family and how they are related to each other.

Question 4

What is a pedigree?

Answer 4

A genetic family tree used to study inheritance of characteristics.

Question 5

What do circles represent on a pedigree chart?

Answer 5

females

Question 6

What do squares represent on a pedigree chart?

Answer 6

males

Question 7

What does shading represent on a pedigree chart?

Answer 7

affected individuals

Question 8

How are children represented on a pedigree chart?

Answer 8

vertical lines running down from parents

Question 9

How are parents represented on a pedigree chart?

Answer 9

linked by a horisonal line

Question 10

how are siblings represented on a pedigree chart?

Answer 10

line linked by a horisontal line above.

Question 11

What can pedigree charts be used to find?

Answer 11

• if a characteristic is dominant or recessive
• if a characteristic is sex-linked or autosomal.

Question 12

What are things to look for on a pedigree chart?

Answer 12

• gender bias of affected individuals males:females
• affected offspring from unaffected parents
• affected sons from affected fathers

Question 13

What does affected offspring from unaffected parents show?

Answer 13

That the condition is recessive