Ch 3: Genes, Environment, and Development Flashcards
Natural Selection
Involves the notion that some genes aid in adaptation more than other genes do, and thus are more likely to be passed on in future generations.
Conception
Defined as the (magic) moment when the egg is fertilized by the sperm.
At conception the _____ material of the mom’s ____ (egg) & Dad’s sperm unite to form a _____.
Genetic, ovum, zygote.
Chromosomes
Consist of thousands of genes. Scientists estimate the average human cell contains 20-2500 genes.
Identical Twins
Occur when a fertilized ovum (egg) divides to form 2 separate individual cells. (1 in 250 births)
Fraternal Twins (“dizygotic”)
Involve any 2 individual ova being released and each of the two is fertilized by different sperm cells. (1 in 125 births)
Identical twins share 100% of genes, therefore any differences between them must be due to ________.
Environment (pre- and post-natal).
i.e. 48% chance both twins get schizophrenia.
Fraternal twins share ABOUT __% of genes.
50%.
On average, this is true about biological siblings born years apart.
The __ chromosome is stubbier and has more genes than the __ chromosome.
X, Y.
X about 11000 genes and Y about 80
Genetic Expression
Involves the ACTIVATION of particular genes in particular cells, at particular times. Genetic expression may be linked to environmental events, so that environmental occurrences may turn genes on or off.
Polygenic Inheritance
The result of several genes in a combination, interacting with one another in environmental triggers. Causes most behavior and personality traits as well as mental illnesses.
Phenotype & Genotype
Genotype: inherited genes (like genes on the X chromosome).
Phenotype: Involves overt expression of genes/genetic influence (like having blue eyes)
Recessive Traits
Matching pair of genes needed to express (overtly show) a characteristic carried by a pair of genes. (2 recessive needed for trait to show).
Incomplete Dominance
When there is a compromise between the effect of 2 genes (blending of two traits).
Co-dominance
2 characteristic coexist.
The Period of the Zygote begins with ______. A developing human traveling through the fallopian tube to the uterus.
Fertilization.
Tina is in her 5th week of pregnancy. She is carrying an ____.
Embryo.
Embryo
When a developing child has just become completely embedded in the wall of the uterus, about 2 weeks into the pregnancy. Lasts week 3 to 8.
Is hemophilia most frequently passed onto the male or female offspring?
Male.
Genetic Mutation
Involves some sudden change in the gene structure, that was not passed on by the parents.
i.e. exposure to significant radiation may result in mutation.
All major organs completely develop in some fashion during the _____ period of pregnancy.
Embryonic.
Formation of primitive heart, sex organs, eyes and nose take shape but ears come in much later.
__% of recognized pregnancies miscarry.
__% of un-recognized pregnancies miscarry.
20%, 50%.
Main function of the Amnion:
To provide a protective cushion for the developing embryo. Protects against bumps etc.
Main purpose of the Placenta:
Provide oxygen and nutrients to the fetus, while removing CO2.
What is the third stage of pregnancy?
The Fetus, week 9-birth.
How is a developing child known to be a fetus?
Known when there are 3 things:
1) Contractions can occur & the cervix can open or dilate
2) Crowning- baby’s head appears and is pushed out of vagina.
3) Placenta/after bith is expelled.
Extra 21st chromosome causes and odds:
Down Syndrome. From either mom or dad (tirisomy 21). Odds of having baby with Down Syndrome: Age 20-24: 1 in 1400 Age 24-29: 1 in 1100 Age 25: 1 in 350 Age 40: 1 in 100 Age 45: 1 in 25
The odds of having a child with Down Syndrome _____ with maternal age, because the rate of having children decreases with age.
Increase.
Huntington’s Disease
An unusual genetic disorder because the genetic impact does not occur until a person reaches middle age.
Identical twins raised ______ score more similarly on IQ tests than fraternal twins raised ______. Therefore there is a strong genetic influence on development of such traits.
apart, together.
If GENES alone contribute to a trait, what pattern would be seen (%)?
If shared ENVIRONMENT alone what pattern would be seen?
- 00 for identical twins reared apart.
- 50 for fraternal twins raised together.
No correlation for those reared apart.
1.00 for identical and fraternal raised together
As we get older, genetic influences on intelligence _____, and environmental influences ______. However, shared environmental influences are ______ in importance.
Increase.
also increase.
Decreasing.
When 1 to both parents have schizophrenia, the odd of their children having it are greater than the average risk, in response to an environmental factor, such as an infant contracting a virus. This is an example of ______.
Gene-environment Interaction
In terms of identical twins raised apart, research shows that some of their traits are more influenced by genes than other traits. In order from highest to lowest the most influenced traits are:
- Height (most)
- Brain activity
- IQ scores
- Creativity
Depression & Genes: some genes actually ______ a person from depression, while other genes ______ a person to depression.
Protect.
Predisopose.
Active Gene-Environment Interaction
A person’s genes make it more likely he or she will seek out certain activities.
i.e. a child predisposed to be good at music actively pushes parents to get the family a piano and lessons for him.
