Biochemistry Metabolism Flashcards
What are the important keys to glycolysis?
- Kinase transfers 2 ATP molecules to Glucose in order to enter the cell.
- Glucose is split into two, 3 carbon molecules, which will eventually become pyruvate.
- NADH is created from NAD +
What is substrate level phosphorylation?
Substrate-level phosphorylation reactions are characterized by the direct transfer of a phosphate group from a reactive intermediate onto an ADP or GDP molecule.
What is fermentation?
Fermentation occurs in anaerobic conditions. Glycolysis is still present. The two pyruvate molecules turn into either lactic acid or ethanol. NADH returns to NAD +. CO2 is released as a by product.
How are glycogen molecules linked?
Glycogen is a polymer of glucose molecules linked by alpha -1,4’ glycosidic bonds
What two processes help in fasting stages?
Gluconeogenesis: formation of glucose from non carbohydrate materials.
Glycogenolysis: breakdown of glycogen into glucose.
What is an MCAT tip for predicting reactions with high energy?
Look for the answer choice with ATP or NADH as these are needed for large delta g.
What requirement must a substrate have in order to participate in gluconeogenesis?
Must have a three carbon backbone.
Compare saturated and unsaturated fats in terms of energy storage.
Saturated fats have more hydrogens per carbon so they have more reducing potential. They have the ability to store more energy.
Describe beta oxidation and the steps.
BO is the process of taking fatty acids and converting them into Acetyl- COA for the Kerb’s Cycle.
- Fatty acids from adipose tissues enter the bloodstream via lipoproteins and go into the cell’s mitochondrium.
- Fatty acid is converted to acyl- coa with 1 atp.
- Goes into the matrix where it is cleaved TWO CARBONS AT A TIME to form Acetyl- COA.
- By product is NADH, FADH2.
This process works well with even numbered fatty acids.
Describe ketogenesis.
Occurs in the mitochondria of the liver. Fatty acid is converted ketone bodies for the brain to use during extreme starvation.
3 types of ketone bodies: acetone, acetoacetic acid, and beta-hydroxybutyrate.
Describe the formation of fatty acids from non lipid materials.
In the presence of insulin and excess acetyl- coa the acetyl coa can be converted into fatty acids to be stored as triglycerides.
What 3 processes occur in the “fed state”
Glycolysis, Glycogenesis, and triglyceride storage.
What 3 processes occur in the “fasting state”
beta oxidation, glycogenolysis, gluconeogenesis.
Does unsaturated fats or glucose produce more ATP per unit mass?
Unsaturated fats.
What are the two keys for metabolism?
- Brain and RBC ALWAYS require glucose
2. Glucose either comes from the liver or intestines.
Where does gluconeogenesis occur?
Liver
ATP -> ADG
Very spontaneous reaction
Describe Pyruvate Decarboxylation:
Pyruvate moves into the mitochondrial matrix via integral membrane proteins.
Pyruvate is turned into AcetylCoA, Co2, NADH, and H+.
2 pyruvate means 2 of each.
How does NADH control ETC and Kreb’s Cycle?
If there is a build up of NADH then it’ll slow down the cycle.
ETC Keys:
O2 is the final electron acceptor, it becomes h2o.
Inner membrane space becomes acidic.
Co2 is released in krebs.
Reduction of complexes as electrons move.
What are the products of PPP?
Ribose(pentose) sugar & NADPH.
Contrast Hexokinase & Glucosekinase
Hexokinase is in all cells, it has a very high affinity to glucose molecules, and therefore will have a low Km value. It is inhibited by high levels of glucose-6-phosphate.
Glucokinase is only in liver and beta cells. It has a very low affinity to glucose and therefore will have a high Km value. Induced by insulin in hepatocytes.
What is the rate limiting enzyme for glycolysis?
PFK1
Examine Phosphfructokinase 1 in glycolysis.
Rate limiting step for glycolysis for proceed. It is inhibited by large amounts of ATP & citrate which means glycolysis isn’t needed. It is activated with high levels of AMP because energy is needed.
