Transcript sex linked 1

Sex Linked and
Codominant Genes.
Tongue Roll
Attached Earlobe
Tongue Flip
Unattached Earlobe
Tongue Fold
Hitchhiker’s Thumb
Ear Diagram
Ear Wax
Bent Pinky
Hand Fold
Dimples
Mid-digital hair
PTC Tasting
Bent Little
Finger
Widow’s Peak
Short Hallux
Finger
Length
female
marriage
proband
consanguineous
marriage
diseased
male
Dizygotic twins
Affected
individuals
Extra-marital
mating
progeny
carrier
?
Unknown
phenotype
identical
Female carrier of
an x-linked trait
Stillborn
or abortion
(monozygotic)
twins
PEDIGREE
GENERATIONS
Generations are numbered w/Roman
numerals. Within each generation,
individuals are numbered from oldest to
youngest.
More affected males
than females.
Affected grandfather to grandson thru carrier
female.
SEX-LINKED
RECESSIVE TRAITS
Females do not
manifest the
disorder.
Examples of sex-linked
recessive traits:
COLOR BLINDNESS
Examples of sex-linked
recessive traits:
COLOR
BLINDNESS
How it works…
• Female XX and Male XY.
• Traits can be carried on either the
X or Y chromosomes. ( Mostly on
the X).
• Dominant and recessive laws still
apply.
Problems…
1. Baldness: Mother XBXb x Father XBY
bXb x Father XBY
2. Color Blindness
:
Mother
X
X
3. Hemophilia: Mother XBXB x Father XbY
Sex Linked Traits – Punnett Squares
DOMINANT Allele DISEASES
Huntington’s Disease
• Woody Guthrie
• Arlo Guthrie
• Children
Lobster Foot
Dominant allele -- you have the disease or you don’t
Examples of Simple Dominant Disorders
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Dwarfism
Polydactyly and Syndactyly
Hypertension
Hereditary Edema
•
Chronic Simple Glaucoma – Drainage system for fluid in the eye does not work
and pressure builds up, leading to damage of the optic nerve which can result in
blindness.
Huntington’s Disease – Nervous system degeneration resulting in certain and early
death. Onset in middle age.
Neurofibromatosis – Benign tumors in skin or deeper
Familial Hypercholesterolemia – High blood cholesterol and propensity for heart
disease
Progeria – Drastic premature aging, rare, die by age 13. Symptoms include limited
growth, alopecia, small face and jaw, wrinkled skin, atherosclerosis, and
cardiovascular problems but mental development not affected.
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RECESSIVE Allele
DISEASE
• Albinism
• Achondroplasia
• Both parents can be
carriers to have an
affected child
• 2 affected parents will
usually produce an
affected
• Dominant doesn’t necessarily
meanchild
commonplace
Examples of Simple Recessive Disorders
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Congenital Deafness
Diabetes Mellitus
Sickle Cell anemia
Albinism
Phenylketoneuria (PKU) – Inability to break down
the amino acid phenylalanine. Requires
elimination of this amino acid from the diet or
results in serious mental retardation.
•
Galactosemia – enlarged liver, kidney failure,
brain and eye damage because can’t digest milk
sugar
Cystic Fibrosis – affects mucus and sweat glands,
thick mucus in lungs and digestive tract that
interferes with gas exchange, lethal.
Tay Sachs Disease – Nervous system destruction
due to lack of enzyme needed to break down
lipids necessary for normal brain function. Early
onset and common in Ashkenazi Jews; results in
blindness, seizures, paralysis, and early death.
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Polygenic Inheritance in
Humans
• includes skin, eye, and hair color
• light-skinned X dark-skinned
• F1: offspring have intermediate
skin colors
• F2: skin color range from light to
dark skin color of the grandparents
• Children have intermediate skin
color.
Polygenic
Traits…
• Eye color is determined by more than one
gene
• Thus eye color appears to vary on an almost
continuous scale from brown to green to
gray to blue
• Eye color is determined by two genes, one
controls texture of the iris which refracts
light to make blue. A second determines
relative abundance of melanin. When a
small amount of melanin is present, green
eyes result while brown and black eyes
result from relatively increasing amounts of
melanin
Polygenic
Traits…
• Hair color is determined by more
than one gene
• Thus hair color appears to vary
on an almost continuous scale
from black to brown to blond to
red
• The brown and black pigment is
melanin
• The red pigment is an iron
containing molecule
CHROMOSOME 1
Cataracts
Glaucoma
Hereditary deafness
Retinitis pigmentosa
Schizophrenia
Migrane Headahes
Prostate cancer
Acute Leukemia
Brain cancer
Muscular dystrophy
Colon cancer
Alzheimer’s disease
Fish odor syndrome
CHROMOSOME 2
Colon cancer
Obesity
Liver cancer
Diabetes mellitus
Cleft palate
Cataracts
Epilepsy
Parkinson’s disease
Muscular dystrophy
Pseudohermaphroditism
Ovarian cancer
Micropenis
CHROMOSOME 4
Huntington’s disease
Night blindness
Phenylketonuria
Parkinson’s disease
Alcoholism
Red hair
Mast cell leukemia
Achondroplasia
Dopamine receptor
Retinitis pigmentosa
Hip dysplasia
Blood Type
• 4 Types A,B,ABand O
Parent 1 Allele
Parent 2 Allele
Genotype
Phenotype
A
A
A
B
B
B
O
A
B
O
A
B
O
O
AA
AB
AO
AB
BB
BO
OO
A
AB
A
AB
B
B
O
I Am My Own Grandpa
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Many, many years ago when I was twenty-three
I was married to a widow who was pretty as could be.
This widow had a grown-up daughter who had hair of red.
My father fell in love with her and soon the two were wed.
This made my dad my son-in-law and changed my very life
For my daughter was my mother, 'cause she was my father's wife.
To complicate the matter even though it brought me joy
I soon became the father of a bouncing baby boy.
My little baby then became a brother-in-law to dad
And so he became my uncle though it made me very sad
For if he is my uncle then that also makes him brother,
To the widow's lovely daughter who, of course, was my step-mother.
Father's wife then had a child which kept them on the run,
And he became my grandchild, 'cause he was my daughter's son;
My wife she is my mother's mother and it makes me blue,
Because although she is my wife, she's my grandmother too.
Now if she is my grandmother than I'm her grandchild
And every time I think of it, it nearly drives me wild;
For now I have become the strangest case you ever saw
As husband of my grandmother I am my own grandpa.
Chorus:
Oh, I'm my own grandpa, I'm my own grandpa
It sounds funny, I know, but it really is so
Oh, I'm my own grandpa.
Below is a link to the song that can be played in class:
http://www.ziplo.com/grandpa.htm