Transcript Mendellian Madness! - Effingham County Schools

Mendellian
Madness!
Father of Genetics
Karyotype
Karyo . . . what!?
 Karyotype: set of photographs of
chromosomes grouped together in
pairs.
 Often
used in genetic screening
 Allows scientists to determine if there are
errors
 Useful in determining gender
A he or a she?
Why females are smarter . . .?
SMART
 Born 1822
 Before chromosomes known
 Pea plants are what he loved!
Self-polinating
Sperm cells on flower
fertilize egg on same
flower
True
breeding
egg
Offspring
would be
identical to
itself
Mendel the Austrian Monk
Cross pollination
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
trait - specific characteristic..
Ex: height
Ex: seed color
hybrid - offspring of crosses b/w parents w/ diff
traits.
 monohybrid cross uses a pair of contrasting
traits. Ex: yellow/green
 dihybrid cross involves 2 characters, such as
seed color and seed shape.


generation is a group of offspring from a given
group of parents.

heredity the passing of traits to the next
generation:.

Scientific study
of heredity:
genetics.

Modern genetics
is based on
Mendel’s
explanations.
Genes!!!
Sequence of DNA that codes for a
protein thus determines a trait
Gene
Mom
Dad
Gene
Allele
TT
Tt
tt
T
t
Principle of Dominance
Some alleles are dominant,
some are recessive
AA
Aa
aa
A
a
Dominant vs. recessive
 Dominant allele:
 Shows if there. Masks recessive traits
 Symbolized by CAPITAL LETTERS
 Shows up most commonly in a population

Why?
 Recessive allele:
 Masked by dominant trait
 Symbolized by lower case letters
 Less common in pop. Why?
Class Poll: Dominant or recessive?
Which do they show?
 Laser beam eyes are recessive:
 Dolphin nose is dominant:
dd
Ll
yellow:green
Y Y
y Yy Yy
y Yy Yy
All Yy … all yellow
Y y
Y YY Yy
y Yy yy
Geno-Pheno-What?
 Genotype: Genetic makeup of an
organism
TT
Tt
tt
 Phenotype: Physical characteristics of
an organism
Tall
short
SMART
tt
t
t
Mendel’s Ideas
Law of Segregation
TT
T
T
 Each adult has two copies of each gene
- one from each parent
 These genes are segregated from each
other when gametes are formed
Mendel’s Ideas
Law of Independent
Assortment
 Genes for more than one trait can
segregate independently during the
formation of gametes
 Genes that segregate independently do
not influence other genes inheritance
 Ind. Assortment: helps account for the
many genetic variations seen in things
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Dihybrid Cross