genetics. what do bart, lisa & maggie all have in common? why?
TRANSCRIPT
Genetics
What do Bart,
Lisa & Maggie
all have in
common?
Why?
Traits can be…DOMINANT
More likely to be seen
Dominant overpowers the recessive traits.
recessive
Less likely to be seen
Can sometimes be
“hidden” within your genes.
or
Most of
these
characters
are the
same
species.
But how
are they
different?
Genes – the instructions for traits
We inherit our traits from our parents
We get 23 chromosomes from Mom and 23 from Dad.
This equals 46 chromosomes.
Alleles
every trait is decided by two alleles (one from Mom, and one from Dad)
They can be dominant or recessive
We represent these alleles with letters.
Brown hair- dominant allele - B
Blond hair- recessive allele - b
Alleles
• Examples – Curly hair – Dominant – C – Straight hair – recessive – c
• Examples – Dimples – Dominant – D – No dimples – recessive – d
PhenotypeThe appearance of the organism.
PHENO is like PHOTO
What you would be able to see in a photo?
brown hair, curly hair, brown eyes, freckles, dimples, face shape
spotted coat, short hair, long hair, floppy ears short ears
Genotype
The genetic makeup of an organism.This is not visible, but inside their genes
(DNA).Tongue rolling – dominant allele – TNot able to roll tongue- recessive - t
Can roll tongue – TT, Tt Cannot roll tongue - tt
PUNNETT SQUARES
• First, make a box with 4 squares inside it
• Second, put both parents Alleles in the right spot. – Mom, Rr, can roll
tongue– Dad, rr, can’t roll
tongue
R r
r
r
• Bring down each letter
• Bring over each letter
• This will make 4 possible combinations
R r
r
r
Rr
Rr
rr
rr
PUNNETT SQUARES
• What are the possible Genotypes?
• What are the possible phenotypes?
• Give a ratio for each
PUNNETT SQUARES
R r
r
r
Rr
Rr
rr
rr
Mutations