Are you dominate or recessive Tongue rolling Dominate Roller Recessive Non Roller Bent little fingers Dominate Bent Recessive Straight Widows peak Dominate Widows Peak ID: 239677
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Slide1
Genetic Traits
Are you dominate or recessive?Slide2
Tongue rolling
Dominate – Roller
Recessive – Non RollerSlide3
Bent little fingers
Dominate – Bent
Recessive – StraightSlide4
Widow’s peak
Dominate – Widow’s Peak
Recessive – No Widow’s PeakSlide5
Hitchhiker’s Thumb
Dominate – Straight
Recessive – BentSlide6
Hand clasping, left over right thumb
Dominate – Left thumb on top
Recessive – Right thumb on topSlide7
Hair on middle joints of fingers
Dominate – Hair present
Recessive – No hairSlide8
Short big toe (or long 2
nd
toe)
Dominate – Short big toe, long 2
nd
toe
Recessive – Long big toe, short 2
nd
toeSlide9
Dimples
Dominate – Dimples
Recessive – No DimplesSlide10
Free earlobe
Dominate – Detached (free)
Recessive – AttachedSlide11
Curly Hair
Dominate – Curly
Recessive – StraightSlide12
Eye Color
Dominate – Brown
Recessive – Non-brownSlide13Slide14
Genetics
The study of traits and hereditary passed on in different organisms.Slide15Slide16
Mendel
Father of genetics
Austrian monk who did his work in the mid 1800s
Worked with peas which led to the idea of genes, traits, and allelesSlide17
Mendel
Genes – locations on chromosomes that code for particular characteristics
Pea height
Trait – the physical expression of genes
Short and Tall
Allele – the alternate version of genes coding for the same trait
Short or TallSlide18
Mendel
Principle of Dominance
An organism with a dominant allele will always show that trait, but an organism with a recessive allele will only show that trait if there is not a dominate allele presentSlide19
Mendel
Genotype – the description of an organism’s genetic coding for a characteristic
You cannot see a genotype, it’s in the DNA
Homozygous – when an organism carries identical alleles for a trait
Heterozygous – when an organism carries both alleles for a traitSlide20
Mendel
Phenotype – the description of an organism’s physical expression of a trait
You can see it!Slide21
Mendel
Back to Mendel
Used pea plants to make his observations
Tested for traits such as seed shape, seed color, seed coat color, pod shape, pod color, flower position, and plant height
Original plats: P (parental)
1
st
offspring: F
1
2
nd
offspring: F
2Slide22
Mendel
First test cross
Homozygous dominate plant (tall – TT) with a homozygous recessive plant (short – tt)
TT
t t
T
T
t
t
T
T
T
T
t
t
t
tSlide23
Mendel
F
1
GenerationAll the new plants are heterozygous
Tt – genotype
Tall - phenotypeSlide24
Mendel
Punnett Squares – a diagram used to show the gene combinations that might result from a genetic cross
T
t
t
T
T
T
T
T
t
t
t
tSlide25
Monohybrid Cross
A monohybrid cross involves one trait
Example:
Do a monohybrid cross for pea plant seed color. One plant is homozygous dominate (yellow) and the other is homozygous recessive (green).
Use case sensitive friendly letters
Dominate is represented by a capital letter
Recessive is represented by a lower case letterSlide26
Monohybrid Cross
Y
y
y
Y
Genotypes
:
_____% are ______
Phenotypes
:
_____% have __________Slide27
Monohybrid Cross
Cross two of the offspring from the F1 generation to produce the F2 generation.
(Two heterozygous yellow pea plants)
Genotypes
:
_____% are ______
_____% are ______
_____% are ______
Phenotypes
:
_____% have __________
_____% have __________
Slide28
Monohybrid Cross
Mom is homozygous recessive for blue eyes and dad is heterozygous for brown eyes. What is are the chances they will have a blue eyed child?
Phenotypes
:
_____% have __________
_____% have __________
Slide29
Monohybrid Cross
One parent is homozygous dominate for a widow’s peak and the other is recessive. What will the genotype and phenotypes of their children be?
Genotypes
:
Phenotypes
:
Slide30
Dihybrid Cross
A dihybrid cross involves two traits
Independent assortment: genes for different traits can segregate (mix up) independently
Because of crossing over in meiosis
Just make a bigger punnett square (4x4)
Must include all the possibilities
Both traits are represented for each column/rowSlide31
Dihybrid Cross
In a horse, brown hair is dominate and white hair is recessive; a trotter is dominate and a non-trotter is recessive. Cross a heterozygous brown haired homozygous trotter with a recessive white haired non-trotter. (BbTT x bbtt)
BT
bT
BT
bT
bt
bt
bt
bt
Phenotypes
:
Brown/Trotter - ______%
Brown/Non - ______%
White/Trotter - ______%
White/Non - ______%Slide32
Dihybrid Cross
In a plant, tall and red flowers are dominate alleles; short and white flowers are recessive alleles. Cross two heterozygous tall red flowered plants.
Phenotypes
:
Tall/Red - ______%
Tall/White - ______%
Short/Red - ______%
Short/White - ______%Slide33
Dihybrid Cross
Extra Credit:
One parent has the homozygous recessive trait for dimples (none) and is heterozygous for the hand clasping trait. The other parent is heterozygous for the dimple trait and homozygous dominate for the had clasping trait (left thumb on top). What is the probability one of their children will have dimples and clasp their hands with their right thumb on top?