Welcome back! We have a lot of work to do every day. Remember your materials and have them out at the beginning of class. Don’t wait for me to remind you!

All of these animals don’t look alike, but you recognize them as dogs All of these animals don’t look alike, but you recognize them as dogs. What do they have in common?

Genetics SPI determine the probability of a particular trait in an offspring based on the genotype of the parents and the particular mode of inheritance.

Genetics is... The study of the passing on of traits from parent to offspring http://www.youtube.com/watch?v=bVk0twJYL6Y&list=PL05EB0E51EF56E24B&index=10

Chromosomes In the nucleus In pairs Carry genes Controls all traits of an organism controls the production of proteins

Chromosomes are made of DNA DNA is made of genes DNA / genes codes for proteins Proteins give you your traits!

genes - are the units of heredity Represented with letters You have 2 genes for each trait (1 from mom & 1 from dad) Also Called ALLELES

Mendel’s Experiments Mendel is the father of modern genetics. http://www.youtube.com/watch?v=GTiOETaZg4w

Experiment 1 Experiment 2 Experiment 3 Experiment 4 Short + Short = Short Called this “True breeding” Also called “purebred” Experiment 2 Tall + Tall = Short & Tall Called “not true breeding Also called hybrid Experiment 3 Purebred TALL + purebred short = all hybrid TALL Discovered some genes dominant, others recessive Experiment 4 Crossed two hybrid TALL and got 3 TALL & 1 short When 2 hybrids are crossed, the result is a Dominant to recessive ratio of 3:1

Dominant vs. Recessive Expressed trait capital letter Hidden trait lower case letter

Cheat Sheet Dominant + Dominant = Dominant Dominant + Recessive = Dominant Recessive + Recessive = Recessive

Class activity Example Dominant vs. Recessive Class activity Example

New Vocab

Genotype What you look like on the inside Your letters Examples: BB, Bb, or bb

What you look like on the outside Phenotype What you look like on the outside Ex. Tall or short

Homozygous Heterozygous

Homozygous The same 2 upper case OR 2 lower case Ex. TT or tt Purebred Dominant or recessive Heterozygous Different Letters 1 upper case & 1 lower case Ex. Tt or Bb Hybrid Shows the dominant trait

Genetics with a smile activity

Dragon Genetics Activity

Probability Chances of something happening written as a percentage or fraction or a ratio ex. The chances of you being a girl or boy is 50% or 1/2

Punnett Squares A chart used to show the possible gene combinations of offspring for two parents.

Steps for making a Punnett Square 1- choose a letter to represent the gene in the cross (the first letter of the dominant trait)

2 - Write the genotypes of the parents outside, on top & on the side of the Punnett square (1 letter for each box) 3- Fill in the squares by writing the gene combinations in the boxes

4- Determine the phenotypes of the offspring and calculate probability Each box of 4 represents 25% chance

1 allele from Parent 2 1 allele from Parent 2 1 allele from Parent 1 Genotype Of Offspring 2 letters (25% chance) 1 allele from Parent 2 1 allele from Parent 2