True or False?
An IDP can be a peptide or a glycopeptide.
True.
How many monomers long is a typical IDP?
5-8 amino acids or sugars long.
What term describes a group of epitopes whose inheritance is controlled by the same gene or group of genes?
An epitope system. For example, the blood-type ABO system.
About how many epitope systems exist in the human genome?
Around 23, controlling about 100 epitopes.
What is the significance of having endogenous epitopes on our cell surfaces or molecules?
It is how the body recognizes a target as "self" or "foreign."
When does the body learn self recognition? Where does it occur in the body?
During weeks 8-9 during fetal development, in the Thymus gland. If an epitope is not present in the body at that time, it will be seen as foreign.
True or False?
Endogenous epitopes are genetically based.
True.
A locus on a chromosome that codes for a peptide is known as a _________, while different expressions of it are known as _________.
1.) Gene
2.) Alleles (ex. eye color)
How many genes control the ABO epitope system? What are they?
1.) 2 different genes
2.) The "O" gene and the "AB" gene.
What alleles exist for the "O" gene?
"O" allele and the "amorph" allele.
What term describes an allele or gene with no detectable, analyzable, or observable effect?
An amorph allele/gene.
True or False?
Given their nature, the human genome contains only a small number of amorph alleles/genes.
False.
What alleles exist for the "AB" gene?
The "A" allele, "B" allele, and the "amorph" allele.
One or two copies of the "O" allele at the "O" gene code for what enzyme?
Fucosyl Transferase.
What is the function of Fucosyl transferase?
It transfers a 5-carbon sugar (fucose)
What is the ABO epitope's lipid anchor on an erythrocyte's membrane?
Ceramide.
True or False?
The 5-carbon sugar fucose can be found on the ABO epitope-precursor.
False.
By definition, the precursor is the structure without fucose. Once the "O" allele of the "O" gene codes for fucosyl transferase and the sugar is added, it exists as one of the epitopes A, B, or O.
Between the "O" gene and the "AB" gene, which functions first?
The "O" gene first codes for fucosyl transferase. Once fucose is added, the inherited alleles of the "AB" gene determine which epitope is expressed.
About how many of the ABO epitopes are present on the surface of an RBC?
Around 1,000.
True or False?
ABO epitope-precursors are innert.
True.
About ________ % of the world's population has at least one copy of the "O" gene, while ________ % do not, and are known as ________________.
1.) 98%
2.) 2%
3.) Bombay individuals
Why is the addition of fucose necessary for the expression of an ABO epitope?
Galactose is the last sugar of the precursor sequence. It's C-3 position is not available for binding. However, when fucose is attached at C-2, a conformational change opens the C-3 position for binding.
If an individual has at least one "O" allele at the "O" gene, but is amorph/amorph at the "AB" gene, they are classified as having type ________ blood and comprise _________ % of the population.
1.) Type "O" blood
2.) 45 %
If an individual is B/amorph or B/B at the "AB" gene, they are classified as having type ________ blood and comprise _________ % of the population.
1.) Type "B" blood
2.) 10 %
If an individual is A/amorph or A/A at the "AB" gene, they are classified as having type ________ blood and comprise _________ % of the population.
1.) Type "A" blood
2.) 40 %
True or False?
The "A" epitope has an extra amino group and acetyl radical as compared to the "B" epitope - molecularly a huge difference.
True.
True or False?
Nature is so efficient that of 1,000 ABO epitope-precursors, all 1,000 will express the "A" epitope in an "A" blood-type invidividual.
False.
Nature is not 100%.
Describe an RBC of an individual with one "A" allele and one "B" allele at the "AB" gene.
On a single given RBC, about 1/2 of its epitope structures will be the "A" type, and 1/2 will be the "B" type (with a few unconverted "O").
True or False?
Natural antibodies to the blood types other than the one you were born with show up very shortly after birth.
True.
Explain how a young baby has antibodies against blood types it has never been exposed to.
Young babies are exposed to bacteria almost immediately after birth (or perhaps before). Streptococcal bacteria have epitopes identical to type "A". E. coli have epitopes identical to type "B".
If Strep. and E. coli have surface epitopes identical to those on our RBC's, why does our immune system recognize them as foreign?
These bacteria may have at least 20-30 other epitopes that can be used for immune recognition.
