The parents Homer has straight hair Marge has curly hair The families Is hair curliness controlled by genes or by the environment Homer Homer has straight hair Every cell in Homer has two sets of genes ID: 254026
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Slide1
How are genes inherited? Slide2
The parents
Homer has straight hair
Marge has curly hairSlide3
The families
Is hair curliness controlled by genes or by the environment?Slide4
Homer
Homer has straight hair
Every cell in Homer has two sets of genes
Homer’s has two straight hair genes
We can show the straight hair gene with a capital S
Homer’s genes: SSSlide5
Marge
Marge has curly hair
Every cell in Marge has two sets of genes
Marge has two curly hair genes
We can show the curly hair gene with a small s
Marge’s genes:
ssSlide6
Making a new Simpson
Homer makes sperm
Each sperm has one gene for hair type
Homer only has straight hair genes
So all of his sperm have straight hair genes
Homer’s Sperm
S
SSlide7
Making a new Simpson
Marge makes eggs
Each
egg has
one gene for hair type
Marge only has curly
hair genes
So all of
her eggs have curly hair
genes
Marge’s Eggs
s
sSlide8
Making a new Simpson
s
s
S
S
S
S
S
S
s
s
s
sSlide9
Making a new Simpson
Ss
Ss
Ss
Ss
All of the Simpson babies have one gene for curly hair and one gene for straight hair
So what type of hair do they have? Slide10
Making a new Simpson
Ss
THEY ALL HAVE STRAIGHT HAIR!
The straight hair gene is DOMINANT
Just one copy of this gene will give you that characteristic
The curly hair gene is RECESSIVE
You need two copies of the gene to have that characteristicSlide11
Liking donuts
Homer likes donuts
Every cell in his body has two donut genes.
His genes are: D
D
Homer’s sperm
D
DSlide12
Liking donuts
Marge doesn’t like donuts.
Every cell in her body has two no donut genes
Her genes are: d
d
Marge’s Eggs
d
dSlide13
Making a new Simpson
d
d
D
D
D
D
D
D
d
d
d
dSlide14
Making a new Simpson
Dd
Dd
Dd
Dd
Liking donuts is dominant
D
o the Simpson children like donuts?Slide15
Weight
Marge has normal weight.
Both of her weight gens are for normal genes
Her genes are: N
N
Marge’s Eggs
N
NSlide16
Weight
Homer does not have normal weight. He is obese.
Both of his weight genes are for obesity (not normal weight)
His genes are: n
n
Homer’s sperm
n
nSlide17
Making a new Simpson
Nn
Nn
Nn
Nn
Normal weight is dominant
What weight do all the Simpson children have?Slide18
Practice
Homer’s characteristic
Homer’s genes
Marge’s characteristic
Marge’s genes
Likes beer
BB
Doesn’t like
beer
bb
Plays sports
SS
Doesn’t play sports
ss
Burps
BB
Doesn’t burp
bb
Lazy
LL
Not
lazy
ll
Can’t dance
dd
Can dance
DD
No musical ability
mm
Musical ability
MMSlide19
The next generation?
Lisa has straight hair
Every cell in
Lisa has
two sets of genes
Lisa has one gene for straight hair, which is dominant.
She also has one gene for curly hair, which is recessive.
Lisa’s genes:
SsSlide20
The next generation?
Milhouse
has
straight hair
Every cell in
Milhouse has two sets of genesMilhouse
has one gene for straight hair, which is dominant.
He also has one gene for curly hair, which is recessive.
Milhouse’s
genes:
SsSlide21
The next generation?
Milhouse’s
genes:
Ss
S
s
S
s
Lisa’s genes:
SsSlide22
The next generation?
S
s
s
S
s
S
s
S
s
s
S
SSlide23
The next generation
SS
s
s
Ss
Ss
Straight hair is dominant
How many children have straight hair?
How many have curly hair?Slide24
The next generation
Lisa’s characteristic
Lisa’s genes
Milhouse’s
characteristic
Milhouse’s
genes
Likes School
Ss
Like School
Ss
Good eyesight
EE
Bad
eyesight
ee
Brave
Bb
Not brave
bb