Transcript Why don`t you look like a rhinoceros or any other type of organism?

Heredity &
Punnett Squares
If you look around the room you
share some physical
characteristic with your
classmates.
What do you see that you have
in common?
Genotype
Punnett
Square
Phenotype
Heredity
Probability
Recessive
Trait
Genes
Dominant
Trait
Heredity
• Is the passing on of traits
(characteristics) from parents to
offspring.
What traits were passed on to
these kittens?
Gregor Mendel
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Born 1822 in Austria
Was a monk
Studied and bred pea plants
He wondered why some traits are passed
to other offspring and some are not.
Genes
• Are the set of DNA instructions that carry
hereditary information.
• Passed from parents
• Located on DNA which makes up chromosomes.
Dominate Traits
• The trait that will always appear.
bb
Bb
bB
Recessive Traits
• The trait will that recede or not be shown is
recessive.
bb
bb
bb
Punnett Square
• Used to see all the possible
combinations of genes from a
parent.
bb
b
b
B
Bb
b
Eye Calculator
Alleles
• Are half of the genotype.
Ex.
B b
Probability
• Is the mathematical chance or % chance
of inheriting a gene.
In a Punnett Square….
• If one square contains the gene for brown hair,
there is 25% chance of that child having brown
hair.
• If it’s two squares, it’s 50%.
• If it’s three squares, it’s 75%.
• If it’s four squares, it’s 100%.
Homozygous
• When the gene is purebred.
EX. A rabbit with black fur and the gene FF.
Heterozygous
• The gene is a hybrid.
EX. A rabbit with black fur and the gene Ff.
Incomplete Dominance
• You may hear it called co-dominance,
although that’s a little bit different.
• Is the blending of intermediate traits
Ex. Skin color.
Incomplete Dominance
• Neither allele is dominant or recessive
• Organisms with two different phenotypes
produces offspring with a third phenotype
that is a blending of the parents
From teacherweb.com
Incomplete Dominance
• Ex: Cross a red flower (RR) with a white flower
(WW) and the offspring will be pink (RW)!
From teacherweb.com
So, how does information move
from gene to physical trait?
Genotype
• Is the inherited
combination of genes
from the Punnett
square.
Ex. Bb
Phenotype
• An organism’s
inherited trait.
Ex. Brown
Practice a Punnett using the
blood types A and AB.
Take a moment to create and
then explain a Punnett square to
your partner.