Cellular metabolism Flashcards
Fermentation, glycolysis, TCA cycle, ETC, Oxidative phosphorylation
Describe Alcohol Fermentation
pyruvate looses Co2 by pyruvate decarboxylase
Alcohol dehydrogenase turns NADH to NAD+ to form Ethanol
Describe Lactate fermentation
Pyruvate is consumed, Lactate is produced, and NADH is oxidized to form NAD+. Catalyzed by lactate dehydrogenase.
What is the difference between catabolic and anabolic reactions?
Catabolic - breaking down large molecules
Anabolic - synthesis of large molecules
What is Product inhibition?
general name given to a type of inhibition where the product of an enzyme binds to enzyme and inhibits its activity.
Product usually resembles the substrate, and this type of regulation is usually competitive.
An example would be step 10 of glycolysis where ATP is produced, but also involved in the rxn.
What is Glycolysis and where does it occur?
A metabolic pathway that splits a glucose into 2 pyruvate, and creates ATP, with or without the presence of oxygen. Glycolysis occurs in the cytoplasm of cells.
total products (with one glucose) - 2 Pyruvate, 2 ATP, 2 NADH molecules
What are the 3 stages of cellular respiration?
Glycolysis - breaks down one glucose into 2 pyruvate.
TCA cycle - completes the breakdown of glucose.
Oxidative Phosphorylation - most of ATP synthesis
what are 4 of the most important reactions in Glycolysis, and the enzymes that catalyze them?
1) Glucose -> Glucose 6-Phosphate (Hexokinase)
3) Fructose 6-phosphate -> Fructose 1, 6-biphosphate (PFK)
6) 1,3-biphosphoglycerate -> Glyceraldehyde 3-Phosphate (Glyceraldehyde 3-Phosphate Dehydrogenase)
10) Phosphoenol Pyruvate -> Pyruvate (Pyruvate Kinase)
What is feedback Inhibition?
when a compound in a metabolic pathway feeds back and inhibits an enzyme catalyzing an earlier step in that pathway; usually non-competitive. An example is alanine in step 10 of glycolysis.
What is Feedforward inhibition?
when an intermediate in a metabolic pathway feeds forward and speeds up the activity of enzyme catalyzing a later step in that pathway. An example would be Fructose 1, 6-biphosphate in step 10 of Glycolysis.
Which molecule in glycolysis represents a commitment step?
Phosphofructosekinase (PFK), the most regulated enzyme in glycolysis.
What is Substrate Inhibition?
when high concentration of substrate inhibits the reaction which would produce more of it
(Not common; another example is pyruvate inhibiting LDH)
Dehydrogenase enzymes catalyze what type of reactions?
Oxidation-reduction reactions.
Step 6 of glycolysis shows this with NAD+ and NADH.
NAD+ = oxidized form
NADH = Reduced form
During step 6 of glycolysis, how is GAPDH regulated?
-Insulin & hypoxia activate a cell signaling cascade that ultimately turns on a protein kinase called Akt, and one of Akt’s targets is GAPDH
-Insulin & hypoxia also upregulate expression of the GAPDH gene, so that the absolute amount of GAPDH increases in the cell
Describe the big picture pathway of cellular metabolism
Glucose enters cell –> Glycolysis (in cytoplasm)–> Pyruvate–> Fermentation–> Lactate
OR
Pyruvate–> TCA cycle (mitochondria) –>ATP
What is Pyruvate oxidation and what process does it lead into?
Pyruvate combines with CoA to produce Acetyl CoA, and Co2. Coupled with the reduction of NAD+ to NADH. This process is catalyzed by Pyruvate dehydrogenase, and is a redox reaction. Feeds into the TCA Cycle
What is Oxidative Phosphorylation?
Coupled process of the Electron transport chain into ATP Synthase
Explain the ETC when NADH is the electron donor
Complex I–>CoQ–>Complex III–>Cytc –>Complex IV –> 1/2 O2 + 2H = H2O
Explain the ETC when FADH is the electron donor
Complex II–>CoQ–>Complex III–>Cytc–>Complex IV–> 1/2 O2 + 2H = H2O
If one glucose enters glycolysis and the TCA cycle, what are the products?
Glycolysis–>Pyruvate oxidation–>TCA
1 glucose yields, 2 ATP, 2 GTP, 2 FADH2, and 10 NADH
What is the Electron transport Chain?
made up of 4 large complexes, and two smaller mobile electron carriers (CoQ, Cytochrome C).
Additionally, feeds into the F0 F1 ATP Synthase
Describe the functions of the F0 and F1 subunits.
the F0 subunit moves protons down their ECG, across the IMM. the unit turns and
The F1 subunit synthesizes ATP
