Genes & Environment Flashcards
What are the two types of sex cells in humans? How many chromosomes do they each contain?
Sperm and ova. 23 chromosomes.
What are chromosomes?
They are threadlike structures made up of genetic material. Each cell contains 46 chromosomes, except the sperm and ova.
What are genes?
The molecules on chromosomes that transmit hereditary blueprints.
What is a genotype?
It determines the selection of genes and individual inherits; how much belongs to the mother or father.
What is a phenotype?
An organism’s observable behaviour / characteristics
What percentage of genes do dizygotic and monozygotic twins share, respectively?
50% and 100%.
What are the similarities and differences between the cystic fibrosis and PKU disorders?
Both disorders carry recessive patterns of inheritance, where only individuals with two copies of the gene can suffer from the disorder. However, PKU can be treated through diet, hence is influenced by environment more than CF.
There is a 1/4 chance of affected or unaffected if both parents are unaffected carriers, and a 1/2 chance of becoming unaffected carriers.
How is our activity level controlled?
It has a genetic component to it, where it is controlled by a large number of genes (polygenetic). This is evident in how active mice who bred together produced active offspring, whilst idle mice produced idle offspring.
What percentage of our IQ is determined by genes?
40 - 70%, where environmental contribution wanes with age.
How do our genes and environment influence our IQ?
Our genes determine the range of our IQ, whilst our environment determines where we end up on that range.
If you have an identical twin, what are your chances of developing schizophrenia, based on genetics alone?
You have a 46% chance if your twin is monozygotic, whilst a 14% chance if your twin is dizygotic.
10% if you have a sibling whom you share 50% of genes with, and 8% if you’re an adoptee who shares 50% of genes with a sibling you never grew up with.
What is the term for something that can cause serious abnormalities or even death in prenatal
development? Name an example.
Teratogens. An example is thalidomide, which was a mild tranquiliser meant to treat nausea. However, this affected limb development by preventing new blood vessel growth.
What is the period in development when specific biological / environmental events have dramatic & irreversible damage on human development?
Critical period: 18 - 60 days from conception.
For thalidomide, it is 24 - 49 days from conception.
How can alcohol consumption affect the foetus?
It restricts their oxygen supply to the brain, and interferes with their hormone: metabolism. This may result in Fetal Alcohol Syndrome (FAS).
How much alcohol needs to be consumed and when for it to be detrimental to the foetus?
If a pregnant lady drinks heavily between week 10 and its birth, it is likely to develop FAS. 10% of pregnant women drink, whilst 2% binge-drink. May affect 1 - 2% of the US population.
