FRIDAY, Nov. 4FRIDAY, Nov. 4thth

You are homozygous dominant for a hairy You are homozygous dominant for a hairy chest and your sweetie’s chest and your sweetie’s heterozygous. heterozygous.

Hairy (H) is dominant to not hairy (h).Hairy (H) is dominant to not hairy (h).• Draw a punnett square to determine Draw a punnett square to determine

the amount of chest hair your offspring the amount of chest hair your offspring may have!may have!

• Tell the possible genotypes and Tell the possible genotypes and phenotypes of your babies!!!phenotypes of your babies!!!

You are homozygous dominant for a hairy chest and You are homozygous dominant for a hairy chest and your sweetie’s heterozygous. your sweetie’s heterozygous. Hairy (H) is dominant Hairy (H) is dominant to not hairy (h).to not hairy (h).

• HH x HhHH x Hh• punnet square punnet square

• Tell the possible genotypes and phenotypes of your Tell the possible genotypes and phenotypes of your babies!!!babies!!!

• Genotypes: 50% HH; 50% Hh (1:1)Genotypes: 50% HH; 50% Hh (1:1)• Phenotypes: 100% hairy-chested, 0% Phenotypes: 100% hairy-chested, 0%

not hairy not hairy

(1:0)(1:0)

H H

H HH HH

h Hh Hh

Tongue-Rolling: Rolling up edges (dominant trait) vs not rolling (recessive

Longer 2nd toe is dominant Longer 2nd toe is dominant over 2nd toe shorter than big over 2nd toe shorter than big toe.toe.

Mid-digit hair: Mid-digit hair

(dominant trait) vs. No mid-digit hair (recessive trait)

Pinky: Straight pinky (recessive

trait) vs. Bent pinky (dominant

trait)

Thumbs: Thumbs: Straight thumb (dominant trait) Straight thumb (dominant trait)

vs. Curved thumb (recessive vs. Curved thumb (recessive trait)trait)

Dimples: Dimples: Dimples (dominant trait) Dimples (dominant trait)

vs. vs. No dimples (recessive No dimples (recessive

trait)trait)

Forelock: White Forelock: White forelock (dominant forelock (dominant trait) vs. No white trait) vs. No white forelock (recessive forelock (recessive trait)trait)A white forelock is a A white forelock is a patch of white hair, patch of white hair, usually located at the usually located at the hairline.hairline.

Widow's Peak (left) is Widow's Peak (left) is dominant over no dominant over no widow's peak hairline.widow's peak hairline.

Earlobes: Free ear Earlobes: Free ear lobes (dominant lobes (dominant trait) vs. Attached trait) vs. Attached ear lobes (recessive ear lobes (recessive trait)trait)

6.6 KEY CONCEPT 6.6 KEY CONCEPT Independent assortment and crossing over during meiosis result in genetic diversity!!

Genetic diversity!! How Genetic diversity!! How the heck does it happen?the heck does it happen?

Random, increases unique Random, increases unique combos of genes! 64 trillion combos of genes! 64 trillion combos in humans!!!combos in humans!!!

Indep. asstmt. of chromos Indep. asstmt. of chromos increasesincreases unique gene combos…8 unique gene combos…8 million diff. combos of chromos in million diff. combos of chromos in gametes!!!gametes!!!

Exchange of chromo segments Exchange of chromo segments between hom. chromos during between hom. chromos during prophase I, new combos of genes, prophase I, new combos of genes, from mom and dad!from mom and dad!

So, what’s this crossing over thing?So, what’s this crossing over thing?

• exchange of chromo. segments between homologous chromos!

• during prophase I (meiosis I)• results in new combinations of

genes

Pair up!!!Pair up!!!Segments Segments

cross!!cross!!

Remember, Remember,

chromosomes contain chromosomes contain

MANY genes!!MANY genes!!

– Genes located near each other on same chromo usually inherited together!!!

– farther apart usually separated by crossing over– Researchers use this to calculate distances on

chromosomes…(but you don’t need to know how!)

PHUN Punnett Practice PHUN Punnett Practice

Let’s check your answers…Let’s check your answers…

Then the Quiz!!Then the Quiz!!