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redity and Genetics
Heredity
e passing of traits from parent to offspr
Traits - physical characteristics
Genetics
The study of how traits are inherited
through the interactions of alleles.
Genes
nherited factors that control traits.
special section of DNA found as a sectio
a chromosome.
he different forms of a gene are called alle
Chromosomes
ructure in a cell’s nucleus that contains
eredity material.
(23 pairs)
Gregor Mendel
The father of genetics
Studies the passing of traits through pea pla
obability
•  The odds that something will happen.
•  Geneticist use Punnett squares to sho
the possibilities of genetic outcomes
Punnett Square
hart that shows all of the possible combinat
alleles that can result.
100/0
Male alleles
= black
T
t
= white
T
T T
T t
T
T T
T t
female
100% black
0% white
= black
Male
T
= white
female
t
T
T T
T t
t
T t
t t
75% black
25% white
= black
Male
t
= white
female
T
t
t
T t
T t
t t
t t
50% black
50% white
alleles
Matching pairs of genes
ere are 2 alleles(genes) for each trait
e is dominant and one is recessive.
ominant is written with a capital letter
cessive is written with lower case letter
ake 2 recessive genes for the trait to sho
d only one dominant gene for the trait to
ow.
genotype -An organism’s genetic makeup
(Combination of alleles)
eterogeneous = Dd dominate and recess
(hybrid)
omogeneous = DD dominate and domin
or rr recessive/ recessiv
phenotype - An organism’s physical appeara
Sex Linked Traits
The female has 2 X chromosome and
the male has an X and a Y chromosome
he female passes a recessive gene
at has no corresponding gene from the m
he recessive trait will still show with only
cessive gene.
Pedigree Chart
d by genealogists to study the inheritance
ern of a trait.
mily tree)