Happy Tuesday! Get prepared for the quiz on Mitosis vs Meiosis it 10 minutes to look over notes Clear your desks! Good luck

Life’s Biggest Question Solved! Why we are the way we are…

An Inventory of your Traits! Take this survey on different traits on your body Even the littlest of traits makes you different from your classmates This is all due to your genetic make-up and the genes you inherited from your parents!

Mark Yes or No, I have… Detached earlobes Can roll my tongue Dimples Freckles Naturally curly hair Cleft chin allergies I cross my left thumb over my right thumb when I clasp my hands I can see the colors red and green The hairline on my forehead is straight

Traits Traits are observable characteristics we inherit from our parents –Some are common while some are not –Every person has a different combination of traits that make them unique from anyone else!

Where do these traits come from? Today we’re going to learn about how our genetic information (inherited from our mom and dad) turn in to observable traits on our body!

How do you know if someone is a boy or a girl? You look in their genes!

How many chromosomes do humans have in their body cells? 46 total or 23 sets How many chromosomes come from mom? 23 total Where are the genes?

Homologous Chromosome: Every organism has 2 of each chromosome, one inherited from mom and one from dad Chromosomes contains the same gene that code for a trait Mom & Dad may have different versions of the genes, and that difference in DNA causes different versions of the same trait to be expressed.

MomDad Homologous Chromsomes Gene for Eye color Different version for the same gene Allele: Different versions of the same gene leading to a difference in the trait expressed

Alleles are represented by letters in the alphabet, and there are always two letters together since you have one from mom AND one from dad Ex: cc, aa, Aa, GG

Vocabulary Definitions Phenotype : the observable traits of an organism Ex: Brown eyes, curly hair, short Genotype : the genetic combination of alleles present in an organisms chromosomes Ex: Bb; bb; BB

Mom Dad Let’s look at the offspring these two parents made! Phenotype is blue Phenotype is brown But Genotype (genetic makeup) is Blue and Brown!  Bb

Phenotype vs. Genotype detached ear lobes Homozygous zz

Bb Dominant – phenotype always represented Recessive – loses to the dominant allele

Genotype StrongestPhenotype BB bb Bb B b B

Heterozygous: 2 different alleles for a single trait –Bb or Cc or Dd –**Always a capital letter and a lower case letter Homozygous: identical alleles for a single trait –BB or CC or dd –**Always either all capital letters of lowercase letters –Homozygous dominant: DD –Homozygous recessive: dd

Point to remember: usually the dominant allele is what determines the letter of the alphabet –Example: if Straight hair is dominant over curly hair –SS – straight hair –Ss – straight hair –Ss – curly hair

Finish questions #1-#3 with a partner and we’ll go over it Then, we’ll build our own bunnies using genetics!

An Introduction to Punnett Squares Punnett Square : a mathematical way to predict the genotype ratios of offspring from 2 parents Parent #1 alleles Parent #2 alleles

Albinism Dominant: melanin is produced normally: AA or Aa Recessive: melanin produced is messed up: aa

2 parents: Aa and Aa

Calculating Ratios Ratio = # of offspring with trait # of possible offspring Wanted: Ratio of expected Heterozygous Dominant offspring Ratio = # offspring with Aa = 1/2 4 total offspring

**These ratios are what we EXPECT to happen!** Let’s look at what actually happens in our bodies and what the punnett squares predict will happen

Sex Determination Whether you are a boy or a girl all depends upon the presence of a Y chromosome, inherited from your father!