biol 117 lecture 1 study questions

How can you determine if a trait is genetic?

Look into the family history and take genetic tests/ it runs in families ex: twins

What is an autosomal dominant or dominant inheritance?

Concepts:

• Only one defective copy of allele causes phenotype to be expressed

• Both females and males can pass phenotype to either sex of children

  Pedigree Observations:

• Equal and both females and males

• Happens in most generations

• Children of affected parents will have 50% chance risk for inheriting phenotype

• Unaffected parent will not produce affected children

What is autosomal recessive inhheritance?

Concepts:

• Must have mutant copy in both alleles for phenotype to be expressed

Pedigree Observations

• Tends to “disappear” in generations

• Equal in both females and males

• If both parents are carriers their children will have 25% chance risk for inheriting phenotype

What is Pseudo-Dominant Inheritance

Concepts:

• Both copies of allele have to be mutant to cause phenotype

• Carrier rate is high

  Pedigree Observations:

• Equal and both females and males

• Tend to “skip” in most generations

• Both parents affected, all children will be affected

• Could be dominant with reduced penetrance

What is X-linked inheritance?

Concepts:

• Only one X- linked chromosome from men will always express a mutation

• Usually recessive

• No male to male transmission

Pedigree Observations:

• Happens mostly in males

• Daughters of affected male will always be carriers

• Tend to “skip” a generation

Why are recessive traits difficult to identify as “genetic”?

are rare and hard to find, only can be found in large families

Why are pseudo-dominant traits difficult to identify as “recessive”?

They follow a autosomal dominant inheritance pattern

What are some complicating factors in pedigree analysis?

Risks modified by:

Mosaicism, environmental factors, De Novo mutation, incomplete penetrance, age-related penetrance (ex: Alzheimers)

Data collection complicated by:

small families, adoptions, divorce, early death