Block B Flashcards
Which one of the following amino acids is not hydrophillic:
-Leucine
-Threonine
-Asparagine
-Cysteine
-Serine
Leucine
Which one of the following amino acids is not hydrophobic:
-Proline
-Valine
-Isoleucine
-Cysteine
-Alanine
Cysteine
What happens to the parameters Km and Vmax with increasing concentrations of a non-competitive, reversable inhibitor
Km unchanged, Vmax decreases
TRUE/FALSE: Enzyme-catalysed reactions are irreversible
False
TRUE/FALSE: Enzymes make reactions happen faster by lowering the activation energy
True
What is the difference between galactose and glucose
The position of the -OH group at C4
How do disulfide bonds form
form by the oxidation of 2 cysteines
In an alpha helix structure, how are the R groups laid out.
the R groups are sticking out from the axis of the helix
In a B strand structure, how are the R groups laid out.
the R groups alternate between above and below the strand
What is the result of the lack of post-translational modifications, give an example (2 marks)
could result in pathological conditions, e.g lack of carboxylation of clotting proteins results in hemorrhaging
Define catalyst (4 marks)
lowers the activation energy, accelerates chemical reactions, increses rate of reaction and is not consumed.
Describe the stages of an enzyme-catalysed reaction. (3 marks)
-substrate enters active site and is held there by weak interactions
-substrates are converted to products
-products are released and active site is available for new substrates
Describe the process of cholestreol synthesis. (3 marks)
-synthesis of isopentyl pyrophosphate via mevalonate
-6 molecules of isopentyl pyrophosphate to form squalene
-squalene is cyclised to lanosterol which is then processed into cholesterol
Whats the main site of cholesterol synthesis
Liver
What enzyme is used to control cholesterol biosynthesis.
HMG-CoA reductase
