6.1 human polymorphisms

polymorphism

a genetic trait contracted by a locus with more than one allele in an appreciable (>1%) level

balanced polymorphism

allele frequencies are maintained at roughly the same frequencies over time through natural selection

transitional polymorphism

allele frequencies that are in the process of change (i.e. one allele’s frequency is increasing while others are decreasing) due to natural selection

cline

the gradual geographic change in a specific genotype’s or phenotype’s expression and distribution

antigen

used to transport things in and out of the RBD and immune system to recognize own cells and distinguish between foreign cells

which blood types can “A” receive"?

“A” or “O”

what blood types can “B” receive?

“B” or “O”

what blood types can “AB” receive?

"A," "B," "AB," or "O"

which blood types can “O” receive?

“O”

which blood type is considered the universal receiver?

AB

which blood type is considered the universal donor?

O

what is the clinal distribution of “A”?

pretty much not present below North America

what is the clinal distribution of “B”?

essentially absent from the ‘new world’ and Australia; but found in highest concentration in northeast Asia (might be source)

which blood type allele is the most ancient?

O

which blood type “allele” is the next most ancient?

A

which blood type “allele” is the third most ancient?

B

which “allele” is actually made up of multiple alleles that each have different genetic mutations, but they don’t result in a different surface protein (antigen), they result in exactly the same

A

which blood type is kind of a mutated version of A?

B

which diseases are those with A blood type are more likely to suffer from?

metabolic anemia & stomach cancer

which diseases are those with O blood type are more likely to suffer from?

duodenal & stomach ulcers (that can fester into cancers)

which diseases are those with B blood type are more likely to suffer from?

forms of diarrheal infections caused by some kinds of E. Coli (O86)

why are some diseases associated with certain blood types?

they have evolved to mimic the surface protains and go under the radar

how does Rh incompatibility occur during birth?

the mothers are always Rh- whereas the infants are Rh+

why does Rh incompatibility usually not occur until the second birth?

the antibodies now can and do cross the placental border

the Rh blood system is controlled by how many separate loci (polygenic trait)?

three

what are the loci in control of the Rh blood system referred to as?

CDE

which Rh blood system locus is the most important?

D

what does the D locus of the Rh blood system do?

encodes for the absence of the structural surface protein

what do the C & E loci of the Rh blood system do?

minor modifications to the structural surface protein

what is an example of a balanced polymorphism among humans?

sickle cell anemia allele