Chapter 10.1: Mendel

Gregor Mendel•Father of genetics• Studied heredity• Passing on of traits from parent to

offspring

Gregor Mendel cont…

• Genetics—the study of heredity

Gregor Mendel cont…

• Traits—characteristics that are inherited

• Ex: Height, Hair color, breast cancer

Gregor Mendel cont…

• Mendel studied pea plants• Reproduce sexually• Have two sex cells (gametes)• One male, one female

Garden peas cont…• Both sex cells in same flower• Male sex cell = pollen• Female sex cell = ovule

Garden Peas Cont…

• Pollination—how plants reproduce• Transfer pollen to ovule• Fertilization—combining the male

and female sex cells • Result = seed (baby plant)

Garden Peas Cont…

• Plants usually self-pollinate• Male and female gametes of same

flower combine• Mendel used cross pollination• Male of one flower combines with

female of another flower

Punnett Squares

• Hybrid—a child whose parents had different traits

• Ex: Dad is tall and mom is short

• Kid is hybrid for height

Monohybrid Cross

• Punnett square for one trait• Ex: Tt x Tt• Results = 3:1 ratio

Monohybrid Cross cont…

• Traits are found on genes which make up chromosomes

• Alleles—different genes• Ex: T or t (T = tall, t = short)

Rule of Dominance

• All humans have both dominant and recessive alleles

• Dominant—trait that shows up• Ex: T = tall or B = brown hair• Recessive—trait that is normally

hidden• Ex: t = short or b = blonde hair

Rule of Dominance cont.

• Only time you see a recessive trait is when both parents give you the recessive

• Ex: tt = short or bb = blonde hair

Law of Segregation

• Parents don’t control what genes they give their kids

Vocabulary

• Phenotype—in words, what your traits are

• Ex: Tall, short, has breast cancer

Vocab cont…

• Genotype—in letters, what your traits are

• Ex: TT, Tt, tt

Vocab cont…

• Homozygous—2 alleles for a trait are the same

• Could be dominant = TT• Could be recessive = tt

Vocab cont…

• Heterozygous—2 alleles for a trait are different

• Only dominant = Tt

Law of Independent Assortment

• All traits are inherited separately

• Ex: All blonde hairs don’t have blue eyes

Probability

• The likelihood of something happening

• Ex: Chances of having a boy vs. a girl = 50%