FORMAL GENETICS - MENDEL
I. HOW ARE GENES INHERITED?

A. ACTUALLY, HOW CHROMOSOMES ARE INHERITED IN SEXUALLY REPRODUCING ORGANISMS.
B. MITOSIS - ASEXUAL
C. MEIOSIS - SEXUAL
D. REPRODUCTION AND TRANSMISSION OF THE GENETIC CODE FROM ONE GENERATION TO THE NEXT.
ASEXUAL SEXUAL
Male Female
(identical ìdaughterî cells) (combination of male and female)
MITOSIS MEIOSIS

1. ASEXUAL REPRODUCTION AND SOMATIC (body) CELL REPRODUCTION ARE SIMILAR

a. DNA replicates etc. - cell divides
b. New, daughter cells are identical

2. SEXUAL REPRODUCTION REQUIRES THE DNA (chromosomes) TO BE HALVED

II. MENDELIAN GENETICS

A. EXPLAINS INHERITANCE OF SIMPLE TRAITS IN SEXUAL REPRODUCTION
B. MONOGENIC TRAITS

1. One locus on the chromosome
2. Allele - one or more variants of the gene
at a particular locus
3. Alleles can be dominant, recessive, or codominant.to each other.
4. Traits can be homozygous, or heterozygous,
5. e.g.

Y = dominant
y = recessive
YY Yy yy
homozygous heterozygous homozygous
(dominant) (recessive)

C. MENDELíS FIRST LAW

Y = green = dominant
y = yellow = recessive
F1 - FIRST GENERATION CROSS
F2 - SECOND GENERATION CROSS
Y = green = dominant
y = yellow = recessive
1. TRAITS

YY = green
Yy = green
yY = green (same as Yy)
yy = yellow
1:2:1 Genotypic Ratio
3:1 Phenotypic Ratio

2. MENDELíS LAW OF SEGREGATION IS THAT GENES (Alleles) ARE INHERITED INDEPENDENTLY

D. MENDELíS SECOND LAW

1. INDEPENDENT ASSORTMENT
2. Two traits, two alleles each
3. Y,y (COLOR) and R,r (FORM)
4. What happens with the PUNNETTís SQUARE?
5. TRAITS ALSO SEGREGATE INDEPENDENTLY
6. GREEN/YELLOW - COLOR
7. ROUND/WRINKLED - FORM
8. EXCEPTIONS

a. Linkage
b. Crossing-Over