2.1 Flashcards
gamete
reproductive cell
zygote
sperm + egg
genes
the basic unit of genetic information
dna
substance that makes up genes
determines nature n function of every cell in body
chromosome
rod shaped portions of dna
organized into 23 pairs
how many chromosomes are in a human somatic cell?
46
monozygotic twins
twins that came from a single fertilized cell
they r genetically identical
dizygotic twins
twins that came from two separate sperm + eggs
genetically diff.
which pair of chromosomes determines the sex of the child?
the 23rd
what is the 23rd chromosome pair in males n females?
males: XY
females: XX
dominant trait
the trait that is expressed when there r 2 competing traits
recessive trait
the trait that is not expressed when two competing traits r present
genotype
the genetic makeup of an organism
phenotype
the observable trait
homozygous
having two of the same allele
the allele of a gene you get from your mom matches the allele of the same gene you get from your dad
heterozygous
having two different alleles
the allele of a gene you get from your mom doesn’t match the allele of the same gene you get from your dad
PKU
recessive genetic disease that makes children unable to use an amino acid in milk, and lets it build up to toxic levels
polygenic inheritance
when a combo of multiple genes r responsible for production of a particular trait
x linked genes
recessive genes that r on the x chromosome
are men or women more susceptible to x-linked disorders? why?
men
they only have one x chromosome, so if they get an x chromosome with the recessive gene, they don’t have another X chromosome with the possibility of having the dominant gene to cancel it out, like women do
red-green colour blindness is an x linked disorder. are more men or more women red green colourblind?
men
T/F 50% of the gene sequences is shared by all humans
false
99.9% of the gene sequence
behavorial genetics
studying the effects of heredity on behavior
down’s syndrome
disorder produced by presence of an extra chromosome on the twenty first pair
mongolism
the extra chromosome in the 21st pair of someone with down syndrome
Most frequent cause of intellecual impairment
Downs syndrome
T/F the risk of downs syndrome is much higher in younger mothers and much lower in older mothers
False
It’s much higher in both young and old mothers
Fragile X syndrome
Occurs when a particular gene is damaged on x chromosome, causes mild-moderate mental retardation
Sickle cell anemia
Blood disorder that caused misshapen blood cells
T/F 1 in 10 people of african descent have sickle cell anemia
False
1 in 10 carry the gene for sickle cell anemia
Symptoms of sickle cell anemia
Stunted growth
Swollen stomach
Yellowish eyes
Tay sachs disease
Disorder. Causes blindness and muscle degeneration before death
What is the treatment for tay sachs disease
There is no treatment
Klinefelter’s syndrome
A disorder caused by an extra X chromosome on a male
What is the genotype of someone with Klinefelter’s syndrome?
XXY
Symptoms of Klinefelter’s syndrome
Underdeveloped genitals
Extreme height
Enlarged breasts
Children with sickle cell anemia die more in north america than in africa, why?
Carrying sickle cell disease raises immunity to malaria, which is common in west africa, giving them a genetic advantage
Genetic counselling
Focuses on helping people deal with issues relating to inherited disorders
What techniques can be used in prenatal testing?
First trimester screen
Ultrasound sonography
Chorionic villus sampling
Amniocentesis
First trimester screen
The earliest test you can do, 11-13th week
Combines blood test and ultrasound sonography
Identify chromosomal abnormalities and disorders like heart problems
Ultrasound sonography
High frequency sound waves go through the womb and make an image
This way we can see size and shape of bbay
Chorionic villus sampling
Can be used if ultrasound and blood tests identify a problem
Insert thin needle in fetus and get hair like- samples
What is the risk of Chorionic villus sampling?
1 in 100 to 1 in 200 has a risk of miscarriage
Amniocentesis. What happens, when it happens, what it does
Small needle inserted in amniotic fluid and draws out fetal cell samples
Carried out 15-20 weeks into pregnancy
Can identify genetic defects with almost 100% accuracy
T/F genetic counsellors, after going through the procedures, will give recommendations to the parents on how to deal with the issue
False
They will merely tell the parents their options
What is the newest role of genetic counsellors
To screen people, not their children, for susceptibility to genetic disorders
Why is genetic testing a difficult ethical issue?
It can cause emotional issues if you get a positive result, since now you know you have the gene for a disease
Temperament
Patterns of arousal and emotionality that represent consistent and enduring characteristics in people
Multifactorial transmission
The determination of traits by a combo of both genetic and environmental factors
Why do some children who genetically have a heightened reactivity to stimuli end up shy and some end up outgoing?
The environment they’re raised in makes the difference
T/F environment can always affect phenotype
False
For ex: when mothers were malnourished while pregnant during WWII, it had no effect on the babys intelligence or physical health
What happens in nonhuman animal studies
We can observe genetically similar animals in different environments, to see effect of environment
We can observe genetically dissimilar animals in similar environments, to see effect of heredity
Cons to nonhuman animal studies
We can’t know how it applies to humans
We’re limited cuz no single animal models behavior just like a human
Twin studies
Looking at twins that were adopted at birth and raised in different environments
What factors can affect the results of twin studies?
Adoption agencies try to match babies with adoptive parents similar to their biological ones, so the environments are similar anyways
T/F the closer genetic link between individuals, the greater the correspondence of their IQ scores
True
T/F personality in determined by genetics
~
Personality is partly determined by genetics, but environment has a role too
T/F the risk for schizophrenia is determined entirely by genetics
False
Genetics play a large role, but environment has a role
T/F alcoholism has a genetic component
True
What are the three ways a child’s genes can influence their environment
Passive
Evocative
Active
Passive genotype-environment
The parent, who is directed by their genes, chooses the environment for their child, who shares their genes
Evocative genotype-environment
The child’s traits cause an influence on the environment
Active genotype-environment
A child who is genetically predisposed to certain traits may choose environments where that trait is beneficial
What type of genotype-environment relationship is the following:
A child who is genetically predisposed to be sensitive to stimulus and cries a lot, this causes the parents to be more attentive to the baby and it’s demands
Evocative
What type of genotype-environment relationship is the following:
A child who is genetically well coordinated plays with a ball a lot in the house. The parents see this and decide to give her sports equipment
Evocative
What type of genotype-environment relationship is the following:
An active child gravitates towards joining the sports team whilst a reserved child decides to stay home and read
Active
What type of genotype-environment relationship is the following:
A sports-oriented parent has genes that promote good physical condition, and provides many opportunities to play sports
Passive
