Heredity Flashcards
Discrete Traits
Trait which is controlled by alleles at only one genetic locus They are also called Mendelian Traits
Polygenic traits
Polygenic traits are continuous traits governed by alleles at more than one genetic locus. ex)Skin color is a common example of a polygenic trait it is governed by 6 loci and at least 12 alleles.
Continuous traits
Continuous traits show gradations, there is a series of measurable intermediate forms between two extremes.
Achondroplasia dwarfism
- occurs as a sporadic mutation in approximately 85% of cases
- may be inherited in an autosomal dominant genetic disorder that is a common cause of dwarfism
- If both parents of a child have Achondroplasia, and both parents pass on the mutant gene, then it is very unlikely that the homozygous child will live past a few months of its life.
Fibroblast growth factor receptor 3
is a protein that in humans is encoded by the FGFR3 gene - negative regulatory effect on bone growth
- Single nucleotide mutation,
higher prevalence with older
males (> 35) during
spermatogenesis
PKU
- A birth defect that causes an amino acid called phenylalanine to build up in the body.
- Phenylalanine plays a role in the body’s production of melanin, the pigment responsible for skin and hair color.
- Therefore, infants with the condition often have lighter skin, hair, and eyes than brothers or sisters without the disease
Where is PKU most common in the world?
PKU is most common in Ireland and western Scotland,
What is the PAH gene?
- The PAH gene provides instructions for making an enzyme called phenylalanine hydroxylase.
- This enzyme is responsible for the first step in processing phenylalanine, which is a building block of proteins (an amino acid) obtained through the diet.
- Phenylalanine is found in all proteins and in some artificial sweeteners.
Carrying Tay-Sachs can protect again what?
- tuberculosis (TB).
- Often, healthy relatives of children with Tay-Sachs disease did not contact TB, even when repeatedly exposed.
What is Cholera?
Cholera opens chloride channels, letting chloride and water leave cells.
What does the CFTR protein do?
CFTR protein does the opposite of cholera, closing chloride channels and trapping salt and water in cells, which dries out mucus and other secretions.
- A person with CF cannot contract cholera, because the toxin cannot open the chloride channels in the small intestine.
What is Coloration?
Coloration produced by melanin, produced by melanocytes
What is Eumelanin?
is found in hair, areola, and skin, and colors hair grey, black, yellow, and brown. In humans, it is more abundant in people with dark skin
What is Pheomelanin?
imparts a pink to red hue and, thus is found in particularly large quantities in red hair. Pheomelanin also may become carcinogenic when exposed to the ultraviolet rays of the sun.
What are Melanosomes?
Melanosomes are vesicles or packages of the chemical inside a plasma membrane. The melanin is in organelles called “melanosomes”, which are organized as a cap protecting the nucleus of the keratinocyte- predominant cell type in the epidermis as protective barrier.
