Genetics Flashcards
differentiation def
specialization of (stem) cells
human genome project
1990-2003, effort to map the entire human genome > found that all humans have virtually the same genes but unique allele combinations
single-gene inheritance
traits influenced by only one pair of genes
traits that are polygenic
alcoholism (genes create addictive pull), nearsightedness, schizophrenia
factors causing genetic disorders
“advanced maternal age” (above 35), inherited disorders, spontaneous mutation, environment
- approx 60% of abortions in 1st trimester caused by chromosomal abnormalities
sex linked chromosomal disorders
red-green color blindness (pinched X) - mental disability, physical abnormalities, emotional problems
Turner syndrome (XO) - no menstrual cycle, no 2ndary sex characteristics
Klinefelter’s Syndrome (XXY) - sterile, female body characteristics
parental imprinting
same allele affects embryos differently depending on whether it comes from mom or dad
parental imprinting example
chromosome 15
dad - Prader Willi = overweight, slow moving, stubborn
mom - Angelman = underweight, hyperactive, overly happy
dominant disorders probability and examples
rare because people rarely live long enough to reproduce
ex:
Hungtington’s chorea & Marfan syndrome
recessive disorder examples
sickle cell anemia, CF, Tay-Sachs, Phenyletonurio (PKU)
why are recessive disorders passed on
sometimes because the genes are protective
ex: sickle cell anemia protects against malaria
triple/quad screen test
15-20 wks, maternal blood test for chromosomal abnormalities, low risk but cannot diagnose
ultrasound
low/no risk, helps estimate age of baby and gender, can identify physical abnormalities
chorionic villus sampling (CVS)
9/10th wk, samples hair-like material surrounding embryo
amniocentesis
16th wk, samples fetal cells from amniotic fluid
genetic counseling
diagnostic and preventative for higher risk parents that have family history etc
gene therapy
modifies a person’s genes to treat or cure disease
methods: 1. replacing/inactivating disease causing gene
- introducing a new/modified gene to help treat a disease
In Vitro Fertilization (IVF)
adding sperm to ova that have been surgically removed from woman’s ovary and then implanting fertilized egg into woman’s uterus; no evidence of disadvantage for babies; some legal restrictions
who is IVF used by
couples w/high genetic risk, gay couples, those who struggle with infertility, older women, those who want child without partner
monozygotic twins
one zygote that divides, same genotype but slight variation in pheno due to environ., change can occur right after conception due to mutations bc of separate amniotic sacs/cords
dizygotic twins
2 ova fertilized by 2 separate sperm, incidence is genetic, siblings born at the same time, older women more likely to double ovulate
methods of studying individual differences
comparing similarity to degree of relatedness
behavioral genetics
establishes the level of heritability - measure of extent to which genes determine a particular behavior or characteristic
concordance rate
% of time both members show the same characteristic, higher = greater genetic influence
heritability estimate (H^2)
estimate of the proportion (%) of variation within a population that is related to genes, higher # = higher estimate of genetic influence
problems with adoption studies
selective children, children with behavior problems, prenatal experiences unknown
equal environment assumption
assumption that MZ twins have more shared environment whereas DZ twins more non-shared; assumption that people treat MZ more similarly, evoke similar responses from others
shared vs non-shared environment
shared = similar environ/experiences
non-shared = unique experiences/activities
people = creators of environment
heritability inferences determined by….
group data, cannot be individualized, evidence of genetic influence does not imply genetic predetermination
epigenetics
study of how environmental factors affect genes and genetic expression; factors can express or silence performance of certain genes
environmental factors (epigenetics)
stress, environ, sleep, trauma, disease, diet
range of reaction
genotype specifies range within a phenotype is expressed, environ. can determine the way that a genotype will be expressed as a phenotype
passive genetic-environ interaction
environment encourages predispositions
ex: parents create home environment that matches child’s tendencies
evocative gen-env interaction
inherited tendencies evoke more positive stimulation
ex: smiling babies evoke more positive stimulation
active gen-env interaction
genetic makeups encourage “niche-picking”
ex: individual selects, seeks, or builds env. compatible with their predispositions
