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OntoGeneticsNature vs. Nurture
Eye color
Hair color
Skin color
freckles
Widows peak
• DNA means ______________________
• Make up your ____________________.– Consists of many _____________ that
genetically code for each of your _________.
Deoxyribonucleic Acid
chromosomes
genes
traits
What happens if the “code” fails or is changed???
______________________Mutation
Copies DNA gene code
PROTEIN that makes your eyes blue!!
Determines everything else!!
• Located on the sex chromosome (usually the X since it’s much larger than the Y).
• Called “sex-linked” genes
• popular examples are Color Blindness, Fragile X syndrome, Muscular Dystrophy, and Hemophilia
Mom Dad
MALE
FEMALE
Determines NOT ONLY SEX, but also many sex characteristics!!
Mom Dad
Color Blindness
Carrier female
Normal male
Carrier Female
Normal male
Why can Dad NOT pass on the defect to his sons???
Mom Dad
Color Blindness
Carrier female
affected male
Normal Female
Normal male
Which gender does Mom pass the defect on to??
• A female with a defective X has a 2nd “good X” to compensate for the problem
• A male, on the other hand, only has one X, so if he gets a defective one, he’s stuck with the disorder!
• Males can not pass on their defect to a son. Why?
_____________________________________________________
What is the only way for a female to have the disorder?
______________________________________________________
Males do not pass on an X to a son, only a Y
If she gets 2 BAD X’s, one from each parent!
Sex-Limited Genes
• Genes that are present in both sexes, but influences only one.
• Found on autosomes (not sex), but has effect on only one sex.– Ex: Chest hair, baldness, and breast size in humans.
Since only men go bald, you might think the balding gene is on the sex chromosome, but it’s not. It’s found on the 11th. Why then, don’t more women show baldness?
Is a trait inherited or is it learned from experience…..
Are you a good singer because of your genes, or because you practice a lot?
Heritability is a mathematical proportion indicating the extent of inheritance and/or the extent of non-inheritable factors (such as environment).
SCALE
100% environmental
“low heritability”
100% inherited
“high heritability”
NATURE vs. NURTURE
Heritability
• Adopted children
– Resembling their adoptive parents would indicate...
– Resembling their biological parents would indicate…
HERITABLITY (cont.)
“Monozygotic twins ” Identical twins (same DNA)
“Dizygotic twins” Fraternal twins (different DNA)
Where on the heritability scale would these scenarios fall?
Strong resemblance in monozygotic twins?? High heritability
Equal resemblance in both sets of twins?? Low heritablity
Phenylketonuria (PKU)
• Genetics condition characterized by mental retardation. It is caused by diet.
• Inability to metabolize the amino acid Phenylalanine. It builds up to toxic levels in people with the disorder.
• Eliminate the amino acid from the diet, and eliminate its effects!
• It is heritable, but can be modified by following a particular diet!!
You do not carry your genes around as a way of reproducing yourself…
Your genes carry you around as a way of reproducing themselves.
A cat quick enough to snatch a bird successfully today might not be speedy enough to catch the next generation of birds, because only the swiftest of yesterday’s birds remain to provide offspring.
Black Headed Gull Kittywake
Ground Nest Cliff dweller
High Predation Low Predation
Drops food in nest Feeds food directly to young
Camouflaged nest Full, deep nest
Mate standing up Mate sitting down
Offspring jump high into wind to learn to fly
Offspring do not jump
Can wander from nest Restricted to nest until flight
Primates grooming
Ants working
Bees die after stinging
Reciprocal Altruism
• I’ll scratch your back if you scratch mine.
These primates help others with the understanding that that help will be returned.
Kin Selection Altruism toward a relative.
Although it may be dangerous for a mother to protect her young, it ensures the passing of her genes…including the altruistic gene!!
Therefore, it helps the spread of altruism within the species.
Altruism Video
Battle at Krueger