AP Biology Discussion Thursday 3/19/2015

Goals for the day Be able to predict patterns of inheritance and interpret pedigrees. Be able to use probabilities to predict the likelihood of different outcomes Be able to work with Sex-linked traits in genetics problems & pedigrees

Question of the day 3/19 What is the probability of getting “tails” when you flip a two-sided fair coin?

Probability Probability is the likeliness that an event will occur. When talk about a probability we might think of it as a percentage or fraction. Let’s think about it as a fraction first: The number of possible outcomes The number of outcomes you want 1 2

Probability Practice If I have 2 fair coins, what are the chances of getting heads on both coins when thrown simultaneously?

Probability If you say “AND” – multiply If you say “OR” - add

Probability Practice If I have 2 fair coins, what are the chances of getting heads on both coins when thrown simultaneously?

Probability Practice If I have 2 fair coins, what are the chances of getting one head and one tails?

Probability Practice Let’s think genotypes & gametes now… What is the probability of a heterozygote parent giving their offspring a recessive allele?

Probability Practice Let’s think genotypes & gametes now… What is the probability that parents who were both heterozygous ( )for a trait would have a homozygous dominant ( )offspring?

It will get harder… What is the probability of a parent who has the genotype: AaBBCcDdEeff will produce a gamete that has aBcdef? Just remember you can break the question into pieces! Make it managable!

Sex-linked vs Autosomal

Karyotype #1

Sex-linked vs Autosomal Trait/gene on one of your 22 pairs of Autosomes (non- sex chromosomes) Possible genotypes:

Sex-linked vs Autosomal Trait/gene linked to sex chromosomes (X or Y) X-linked trait – only found on the X chromosome Possible genotypes: Females: Males: (HEMIzygous

Sex-linked vs Autosomal What kind of traits have we been dealing with?

= = = = Pedigrees

Pedigree Conventions

STEP 1: Find parents that match each other, but don’t match their children From this you will be able to determine whether a trait is dominant or recessive by answering the following questions.

Can affected parents have unaffected children Yes = ___________ How probable is it? It is impossible?

Can affected parents have unaffected children Yes = ___________

Can unaffected parents have affected children? Yes = ___________

Can unaffected parents have affected children Yes = ___________

Sex-linked vs. Autosomal

STEP 2: Determine whether this trait might be Autosomal or Sex-linked. If it is recessive ask yourself…. If it is dominant ask yourself…

Do only Men Have it? Yes COULD = ___________

If it is a recessive trait, can affected mothers have unaffected sons? Yes = ___________

Do men have the trait more often than women? Yes COULD = ___________

If it is dominant, are the daughters of affected dads also affected? No = ___________

Pedigrees & Probabilities Practice