2.2.3 An Inheritance Story

2.2.3 An Inheritance Story

PBS

Recap

What is Kai's diagnosis?

What are the 2 ways that you could have this genetic disease?

Familial Inheritance

• What is a gene?

Trace the Path

• Kai's parents do not have NF1 – no other known individuals with NF1 in the family.

They have 3 questions for you:

1. How did Kai get NF1?
2. What are the chances that he'll pass it to his (potential) future children?
3. What are the chances that they'll have another child with NF1?

Familial Inheritance

• Genes are inherited

• 2 copies of each gene:

• Allele 

Family Inheritance: Alleles

• Each allele represented by a letter
• Dominant

• Recessive

• Genotype is represented by 2 letters (1 from each allele)
• Homozygous dominant

• Homozygous recessive

• Heterozygous

Family Inheritance: Neurofibromin Gene

Neurofibromin gene represented by -> n Functional = n (recessive) Dysfunctional = N (dominant) Possible genotypes for neurofibromin gene: What are the phenotypes for each genotype?

Inheritance Patterns

Some genes are on autosomes; others are on sex chromosomes Autosomal Recessive Autosomal Dominant

It's Your Turn

2.2.3 > Familial Inheritance

• Complete Step 1

• Then complete the Check for Understanding in step 2

Discuss

It's Your Turn Again!

• Complete step 3 – include all terms in your explanation

Pedigrees

• What is a pedigree?

Diagramming Generations

• Each row = 1 generation
• Connecting lines = direct relationship 
• For children, birth order goes from left to right
• Determine the inheritance pattern below:

Calculating the Chances

Genotype?

Phenotype?

Autosomal dominant or autosomal recessive?

How can we determine the chances of Kai passing NF1 to his offspring?

Punnett Squares! Let’s go over how to set one up and predict offspring genotypes

Class Discussion

• Should an individual have children if they know there is a chance they could pass on a trait that could have negative health consequences? Should individuals screen their genes through their health care provider before deciding to have children?

It's Your Turn!

Complete the Punnett Squares Assignment then Complete the Pedigrees Assignment