Foundations 1 Week 2 Flashcards
A patient with hepatosplenomegaly and bone pain is determined to have deficient glucocerebrosidase enzyme. Which cell type is abnormal in this condition?
Macrophages Gaucher disease is caused by lack of glucocerebrosidase, which results in an inability to break down glucocerebroside in the lysosomes. Thus, lysosomes swell (Gaucher cells, pictured in the stem) in the organs where macrophages take up the most glucocerebroside (think: spleen, liver, bone from cell membrane).
Growth factor presence stabilizes cyclin D, which facilitates a specific post-translational modification of Rb. What modification is this, and how does it affect cell cycle progression?
Hyperphosphorylation, allows procession through G1 restriction point. Rb is normally hypophosphorylated, which allows it to bind to the E2F transcription factor complex/family, generally suppressing transcription of cell cycle genes. When it is hyperphosphorylated by cyclin dependent kinases (downstream of mitogenic signals), cell proliferation proceeds.
Cells are exposed to UV radiation, causing DNA damage. In which phase of the cell cycle are affected cells likely to remain until damaged DNA is able to be repaired? Which effector kinase mediates this halting of the cell cycle through phosphorylation of Cdc25?
G2; Chk1 In the G2 [DNA structure] checkpoint, sensors scan the chromosome for damaged DNA; if present, p53 and Chk1 are activated. Chk1 phospho-inactivates Cdc25, which normally functions as a phosphatase to activate CDK1. Recall the CDK1/cyclin B1 is the critical pairing for G2-M transition.
Which amino acid(s) is/are a precursor to both purine and pyrimidine rings?
Glutamine and aspartic acid The atoms of the purine ring are contributed by aspartic acid, glycine, glutamine, CO2, and N10-formyltetrahydrofolate; those for pyrimidines are donated by glutamine, CO2, and aspartic acid.
Which of the following amino acids are able to be synthesized in the body from carbon backbones, such as those from keto-acids? Leucine, Lysine, Glutamate, Methionine, Aspartate
Glutamate and Aspartate
How may a polymorphism in a specific gene manifest?
(1) no phenotypic effect (e.g. “silent” polymorphism – imagine swapping nucleotides to get the same amino acid or a very similar one) (2) contribute to the normal variation of a specific trait observed within the species, e.g. ApoB (3) affect disease susceptibility (which is usually multifactorially determined, e.g. type 2 diabetes) (4) directly disturb protein function and cause disease (a monogenic disorder, e.g. Duchenne muscular dystrophy)
A patient brings their 23andme report to you and asks what a polymorphism is. You say…
The occurrence of two (or more) allelic traits in a population such that the frequency of the rarer is at least 1% (i.e., the occurrence of the rarer trait can not be explained by recurrent mutation alone). Basically, a mutation (change from the standard/reference genome) that is not rarer than 1/100 individuals.
