1. The Legacy of Gregor Mendel
Genetics Intro
The Legacy of Gregor Mendel

2. The Big Question
Why do children look like their parents?

3. That’s GENETICS!
The scientific study of heredity
Heredity: the passing down of traits from parents to offspring via genes and chromosomes

4. Who started genetics? Gregor Mendel of course!!!
Austrian monk in 1860’s
Studied different traits of the garden pea
Discovered the basic laws of genetics
“Father of Genetics”

5. More Mendel!!!
1st person to succeed in predicting how traits are passed from one generation to next
Trait: what an organism looks or behaves like

6. Why is Mendel SO important?
Studied one trait at a time
Analyzed his data mathematically
Looked at multiple traits
Used multiple trials

7. Why peas?
Quick growing
Lots of different traits

8. So what did Mendel find out?
Genes and Alleles
GENE: section of DNA that determines a trait (Mendel called them factors)
ALLELE: particular form of a trait (represented by letters).
We have TWO alleles for every gene. One from mom, one from dad.
EX: plant size
“T” is the tall allele
“t” is the short allele
Each plant can either be TT, Tt, or tt

9. Dominant vs Recessive Genes
Dominant-genes that keep other genes from showing their traits. Uppercase letters.
Ex: plant size- “T” is for the tall gene for a tree. It is also the dominant gene over “t” for short. If a plant has the T gene, it will be tall. It can either have TT or Tt. The T masks the t.
Recessive-the genes that do not show their traits when dominant genes are present. Lowercase letters.
Ex: t is the recessive gene, so it is masked in Tt, but if it’s tt then the plant will be short

10. Combinations of Alleles
We get one allele from each parent
Three possible combinations
TT: homozygous/pure dominant
Tt: heterozygous/hybrid
tt: homozygous/pure recessive
NOTE: We use a variety of letters to represent alleles: B, b, C, c, F, f, and so on.

11. More New Vocabulary
Genotype – describes the combination of alleles that an individual has. (TT, tt, Tt)
Phenotype – describes the physical appearance of a trait (Tall, Short, Tall)