Chapter 9 - Genes in Population Flashcards
how many oocytes are ovulated over a women’s lifetime? How does this compare to the number at birth and the number at puberty?
There are 500 over the course of a lady’s lifetime. 1 million at birth and 500k at puberty.
What is Klinefelter’s syndrome?
This is when a male is born with two X chromosomes. This is caused by non-disjunction in the male sperm or the female egg. The male is XXY.
What is Trisomy X syndrome?
This is when a women is born with three X chromosomes. This can be caused by either non-disjunction in the male sperm or in the female egg.
What is Jacob’s syndrome?
When a male is born XYY. This happens when non-disjunction of the Y chromosome occurs in the male zygote.
What is turner’s syndrome?
When a female is born with just one X chromosome, due to either the female egg or the male sperm not containing an X chromosome.
Can a man be born with just a Y chromosome? If so what is that called?
No, the X chromosome contains too many important genes that the embryo would not develop.
What are the two important equations of the Hardy Weinberg model?
p+q=1 and p2+q2=1
What does the Hardy Weinberg model assume?
No selection, a large population, no migration or mutation, and random mating.
Why does eugenics not work?
Because every single person is carrier of many serious genetic disorders. For example, cystic fibrosis is carried by approximately 1/50 people, and other diseases are similar.
Why is cystic fibrosis more popular in Europe, especially Ireland?
Because carrying cystic fibrosis is thought to increase resistance to diseases such as typhoid and cholera, making people who carried the disease live longer and more likely to reproduce and pass on their genes.
The cystic fibrosis allele would help against cholera because it reduces fluid loss.
What is the heterozygote advantage? What are some examples?
Beings who are heterozygous for many traits tend to have better health, as they have greater genetic variety. This increases health as many alleles offer resistance to certain conditions.
An example is the Manx cat, where MM is lethal, mm is normal, but Mm are born without tails, and are loved by humans.
Another example is sickle cell anemia providing resistance to malaria, or purebread dogs being more unhealthy than bastards.
What is sickle cell anemia? How does carrying it offer resistance to malaria?
Sickle cell anemia: deformation of haemoglobin causing red blood cells to coil up, especially in low oxygen.
This disease often prevents the blood from reaching certain parts of the body or certain organs, as the larger red blood cells clog up pathways.
Malaria causes the plasmodium parasite (protist) to eat the oxygen in red blood cells. When the oxygen is lowered in someone carrying the disease, the red blood cells will coil up and starve the protist, killing the malaria virus.
What is a population? What are 3 ways of describing a population?
A population is a group of individuals from the same species that live together in the same place and time.
Descriptors:
Range: where they live
Dispersion: how the population is distributed (random, uniform, clumped)
Density: number of individuals per unit area.
What is a species:
A group of actually or potentially interbreeding natural populations which are reproductively isolated from other such group.
What are abiotic factors affecting populations?
Abiotic factors are non-living factors of the environment which affect a population.
Examples are temperature, water, sunlight, soil, nutrients and heterogeneity.
