Transcript 10.2-Heredity (Mendel)

Chapter 10.2
Mendel’s Laws of Heredity
I.
Gregor Mendel
 father of genetics – branch of
biology that studies heredity
 investigated heredity – the
passing of traits from parents
to offspring
 was 1st to predict how traits
are transferred from one
generation to the next
II.
Mendel studied pea plants because . . .
 peas reproduce sexually, with egg & sperm
 sperm is transferred to egg by pollination – he
could control in a lab to do an experiment
A.
Abbreviations in Heredity
1.
P1 = parents
2.
F1 = first filial generation
(filial means offspring)
3.
F2 = second filial generation
(offspring mate w/ each other)
B.
C.
Each organism has 2 genes that control
each of the traits located on its
chromosomes
1.
Allele – a form/copy of a gene
2.
For every trait, there are 2 alleles –
1 from father, 1 from mother
Mendel first worked with purely green
plants (GG) & purely yellow plants (gg) –
when mated, they formed a hybrid:
1.
Offspring were green (but were Gg)
2. Dominant = observed
trait (G)
3. Recessive = hidden trait (g)
4.
5.
6.
7.
Phenotype = the way an organism
looks; what you can physically see
 eye color, hair color, height
Genotype = the genes/alleles an
organism has in its chromosomes
 Tt, Bb, LL, aa
Homozygous = containing 2 of the
same alleles (dominant or recessive)
 TT or tt, BB or bb
Heterozygous = containing 2
different alleles (only dominant)
 Tt, Bb, Ll, Aa
III.
Mendel’s 2 Laws of Heredity
A.
The Law of Segregation - Every organism
has 2 alleles per gene, but when gametes
are created, a gamete gets only 1 allele
1.
During fertilization, 2 gametes
randomly pair to produce 4
combinations of alleles
2. 2 organisms can
look alike, but
have different
allele combinations
B.
The Law of Independent Assortment –
genes for different traits are inherited
independent of each other
1.
You won’t look exactly like either
your mom or your dad – you’re a
mix of both of their traits
2.
Example:
Mom
AaBbCcDd
Dad
aabbccdd
You AabbccDd , aaBbCcdd, etc.
Gregor Mendel rap
Gregor Mendel monk song