Transcript Simple Geneticsx - Petal School District

Genetics:
the study of heredity
I. Heredity-_____________________
Father of Genetics? _______________
II. Genetics Terms
A. Basic terms
1. trait-__________________
2. allele-_________________
ex: eye color alleles=
brown, blue
Alleles are either dominant or
recessive.
3. dominant-___________
ex: B, T
4. recessive-____________
ex: b, t
5. phenotype-________________
ex: tall, short
6. genotype-_________________
ex: Dd, aa, RR
Genotypes are described as:
7. homozygous-(pure)-________
ex: BB, gg
8. heterozygous-(hybrid)-______
ex: Bb, Gg, Hh
B. Punnett square—used to predict the
possible genotypes of offspring
*Why does the Punnett square have 4
boxes in it? Each parent has 2
alleles for each trait. Do the MATH!
2 parents X 2 alleles=4 possible
combinations
of alleles
C. Generations
1. P generation means parents.
2. F1 generation means the
offspring. F1 stands for first filial
generation.
3. F2 is the offspring of the
offspring. (like the
grandchildren!)
III.Gregor MendelA. Father of Genetics
B. Monk who tended the
garden
C. Crossed pea plants
(thousands) and carefully
recorded data
D. Work led to Laws of
Heredity
E. Mendel’s Laws of Heredity:
1. Law of segregationOnly one version (allele) of a
gene is passed on to each sex cell
[instead of both alleles].
2. Law of independent
assortmentDifferent genes are passed on
independently of one another
[because chromosomes are
randomly placed into each sex
cell].
IV. Types of Crosses
A. Monohybrid—predicts the
inheritance of ONE trait
Ex: eye color
B. Dihybrid—predicts the
inheritance of TWO traits together
Ex: dark hair and brown eyes;
dark hair and blue eyes
Dihybrid Cross
Practice Questions