Molecules, Genes and Disease Flashcards
What is the function of the mitochondria?
ATP synthesis
What are the functions of the plasma membrane?
Transport of ions and small molecules
Cell morphology and movement
What are the functions of the cytoplasm?
Metabolism of carbohydrates, amino acids and nucleotides
Fatty acid synthesis
What are the functions of the nucleus?
DNA synthesis and repair
RNA synthesis and processing
Ribosome assembly
What are the functions of the Golgi?
Export of proteins
Detox reactions
What is pK
How readily an acid will dissociate, and therefore how strong it is
How can amino acids be classified?
Aliphatic or aromatic
polar, uncharged, non polar, negatively charged or positively charged
What is the isoelectric point?
The pH at which a molecule has no overall charge
Why does haemoglobin have a sigmoidal affinity curve for oxygen?
Because it can exist in a tense or relaxed state. When one oxygen molecule brings it changes from the low affinity T state to the high affinity R state. This makes it more sensitive to slight changes in partial pressure.
What are the functions of the smooth and rough ER?
Protein synthesis and transport
Membrane synthesis
Lipid and steroid synthesis
Detox reactions
Describe the Bohr effect
Presence of protons and carbon dioxide in the blood make it more acidic, reducing the O2 affinity of haemoglobin, causing increased oxygen deposition in the more metabolically active tissues.
What affect does BPG have on haemoglobin and what does BPG stand for?
Reduces O2 affinity, shifts association curve to the right, promotes oxygen deposition in the tissue.
2’3-bisphosphoglycerate
What affect does CO have on haemoglobin?
Binds irreversibly, reducing the amount of haemoglobin available for oxygen transport.
What is the mutation and a.a. Change in sickle cell anaemia?
A to T point mutation
Glutamic acid to valine substitution
What is the consequence of the sickle cell mutation?
Valine is hydrophobic, so creates a hydrophobic ‘sticky’ region in the beta chain, when in T state the haemoglobin polymerises causing RBCs to adopt a sickle shape. Can occlude small vessels.
What factors promote sickle cell crisis?
Anything that reduces O2 concentration e.g. Smoking, obesity.
What are the complications of sickle cell anaemia?
Haemolytic anaemia
Jaundiced due to excess bilirubin due to increased RBC turnover
What are the two types of thalassemia, and why are they different?
Alpha - due to decreased or absent alpha haemoglobin chains, appears before birth.
Beta - due to decreased or absent beta haemoglobin chains, appears after birth because fetal haemoglobin contains alpha and theta chains.
Define Vmax
Maximal rate when all enzyme sites are saturated with substrate
Define Km
Substrate concentration that gives half the maximal rate of reaction
What do the intercepts on the lineweaver-burk plot show?
X axis - negative reciprocal of Km
Y axis - reciprocal of Vmax
What kind of inhibitors bind covalently and destroy enzyme function?
Irreversible
What are the two types of reversible inhibitors?
Competitive -bind to active site, affect kM not Vmax. Can be overcome by increasing substrate concentration.
Non competitive - bind away from active site, affect Vmax not Km. can’t be overcome by increasing substrate concentration.
What is allosteric control?
Multi subunit enzymes which have multiple binding sites, either for the binding of inhibitors or activators, or for one substrate to bind to, promoting the binding of a second substrate.