Tutorials Flashcards
Why are Pro-drugs useful?
They can be taken orally, when some drugs can only be taken through IV
What is Acyclovir an analogue of?
Deoxyguanosine
Why does acyclovir only affect Viral DNA?
Viral Thymidine Kinase is required to phosphorylate it to produce acyclo-GMP before host cells can produce Acyclo-GTP
How does resistance to Acyclovir emerge?
Downregulation/mutation of thymidine kinase
What reaction does creatine kinase catalyse?
Creatine Phosphate + ADP
to
Creatine + ATP
What isoforms of creatine kinase are found where?
Mycardium: MB
Brain: BB
Muscle: MM
When in creatine kinase found in the blood?
Traumatic tissue/muscle damage leads to increased permeability allowing CK to leak into blood.
What causes plasma membrane of myocardial cell to become leaky?
In myocardial infarction, cells starved of oxygen and glucose cannot respire to produce ATP, and so die. When ATP reserves are exhausted, active transport proteins stop working, allowing an efflux to occur due to large concentration gradients
How are levels of CK determined given that CK is hard to detect?
Coupled Assay.
PCr + ADP → Cr + ATP
ATP + D-glucose →(hexokinase) ADP + glucose-6-phosphate
glucose-6-phosphate + NADP+ →(G6P dehydrogenase) 6-phosphoglycerate + NADPH + H+
NADPH detectable; used to calculate initial CK conc.
How would you seperate different isoforms of CK?
Electrophoresis, as each has a different charge.
What is a better indicator of myocardial damage than CK?
Troponin I
What mutation causes Osteogenesis imperfecta?
Point mutation in T1 collagen gene, leading to substitution of glycine with cysteine, causing a loss of the triple helix.
Why might only some of the alpha1(I) chains be affected in OI?
Patient heterozygous for mutation, and as there are 2 alpha1(I) chains in each helix, some will be normal, some have one mutant, or some have two.
What are the implications of faulty alpha1(I) chains in OI?
Cysteine causes kinks in normally straight chain, so collagen won’t have usual straight fibres that strengthen bone. Also may form inappropriate disulphide bridges w/ other chains.
Why does faulty collagen cause brittle bones?
Defects in the scaffold lead to faulty mineralisation and subsequent weakness of bones.
