Human Variation Flashcards
(32 cards)
What is micro evolution
Changes in gene frequencies influencing human genetic and phenotypic variation
What are the factors of variation?
Mutation
Gene flow
Random genetic drift
Natural selection
What is natural selection
Change in allele frequency relative to specific environmental factors
What is directional selection?
Shift in the average value for a continuous trait
What is Bergman’s rule?
Warmer areas have more slender body’s and cooler areas have more robust bodies
What is Allen’s rule?
Warmer areas= protruding body parts(limbs longer) cooler = shorter
What is a complex trait
Genetic potential in concert with environmental influences
What is normalizing selection
Selection for the mean (against the tail in a graph)
What is balancing selection
When the heterozygote (Aa) has a greater fitness relative to either homozygous dominant and recessive
What is the typical time of a round trip for a red blood cell?
30-45 seconds
Where are red blood cells created
Stem cells in bone marrow
What’s the typical life expectancy of red blood cells? What about with sickle cell?
120 days
Sickle cell 2-3 weeks
What is sickle cell disease?
More likely that the cell will sickle infers stress, which would block blood flow and cause organ and tissue damage
What is a reflective spectrophotometer?
Provides a quantitative measure of skin pigmentation and can evaluate genetic and environmental effect
What is a complex trait?
Multiple genes and environmental factors
Define tanning
The result of exposure to sunlight (uv radiation)
What are age spots?
Uneven pigmentation due to damage melanocytes
What are the 3 hypotheses in skin pigmentation?
- Skin cancer
- cold injury
- vitamin d hypothesis
Why is vitamin d important?
Helps with the absorption of dietary calcium
What does darker pigmentation provide?
- malignant melanoma
- skin gland from uv damage (thermoregulation)
Why was lighter skin pigmentation selected for in more temperate locations?
- low uv rays challenge vitamin D synthesis
- darker skin can require 6 times as long to make same amount of vitamin D as lighter skin
What happens when the body is deficient in vitamin D
-can impair calcium absorption leading to rickets or osteomalacia
What cultural factors can limit vitamin D exposure?
- clothing
- industrial revolution
- sunscreen
- vitamin D is added to milk and juice
What percentage of women and children have vitamin D deficiency in northern Manitoba?
76% of women
43% of children
