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MediBiochem
Glycolysis
| Question | Answer |
|---|---|
| Which nutrients provide us with energy? | Carbohydrates, proteins, and fats |
| what are the initial breakdown products? | Carbohydrates break down to monsaccharides Triglycerides break down to fatty acids Proteins breakdown to amino acids |
| Aerobic Cellular Respiration | Stage 1: Acetyl CoA production separate metabolic pathways coverage acetyl CoA=2carbon unit, "activated acetate" |
| Aerobic Cellular Respiration | Stage 2: Acetyl CoA oxidation citric acid cycle removes electrons and produces NADH and FADH2 |
| Aerobic Cellular Respiration | Stage 3: electron transfer and oxidative phosphorylation: electrons are transferred from NADH and FADH2, ultimately to O2. 90% of cellular ATP production. |
| USDA Recommended caloric distribution | 50% Carbs 30% Fats 20% Proteins |
| Why do we need carbohydrates? | 1. Glucose is the preferred energy source for brain D.R. is 160g 120g for brain 2. Glucose is quick energy source in other tissues 3. Glucose is required for nucleotide synthesis (ribose 5-P) |
| Why do we need carbohydrates? card 2 | 4. Glucose is required to synthesize structural polymers (extracellular matrix) 5. Glucose is conveniently stored as glycogen for later use |
| How does glucose enter the bloodstream? | 1. Ingest food containing glucose, disaccharides, or polysaccharides 2. Breakdown polysaccharides w/ amylase secreted from salivary glands and pancreas starch breaks down to glucose glycogen breaks down to glucose |
| How does glucose enter the bloodstream? card 2 | 3. Breakdown disaccharides with membrane-bound enzymes in intestinal epithelium maltose breaks down to glucose + glucose sucrose breaks down to glucose + fructose lactose breaks down to glucose + galactose |
| How does glucose enter the bloodstream? card 3 | 4. Transport glucose from intestinal lumen epithelial cells (Na+-glucose symporter secondary active transport) 5. Transport glucose into blood stream by way of the liver (GLUT2 facilitated transport) |
| When serum glucose levels are average (4-8 mM) | Basal glucose uptake into nearly all mammalian cells thru GLUT1 and 3 Kt = 1mM (low number indicates high affinity) |
| When serum glucose levels are high | -Import into liver thru GLUT2 (Kt=20mM) liver synthesizes glycogen for storage -Import into pancreas thru GLUT2 pancreas secretes insulin into bloodstream -Insulin increases # of GLUT4 transporters (Kt=5mM) in muscle and adipose tissue |
| when serum glucose levels are high card 2 | -Import into muscle tissue (glucose to glycogen) and adipose tissue (glucose and fat) |
| When serum glucose levels are low card 3 | -Pancreas secretes glucagon into bloodstream this triggers liver to breakdown stored glycogen -Export glucose from liver thru GLUT2 |
| Glycolysis | Metabolic pathway required to breakdown glucose Process essentially universal; all living organisms and all kinds of cells |
| Breakdown of Glucose | Yields two pyruvate molecules |
| Glycolysis Enzymes | Located in Cytoplasm (10 steps) |
| Label a specific glucose carbon with C14 where does it end up? | glucose carbon 1 glucose carbon 5 |
| Why so many reactions? | Glycolysis is a central pathway Most intermediates serve as branch points to other metabolic pathways |
| Why all the phosphorylation? | Keeps the intracellular [glucose] low this leads to more glucose import Phosphorylated sugars can't use the GLUT transporters they are trapped in the cell Some of the intermediates will eventually tranfer P back to ADP to make ATP |
| Pyruvate in Aerobic Conditions | pyruvate enters mitochondria this produces Acetyl coA citric acid cycle electron transport chain oxidative phosphorylation lots of ATP produced! "aerobic cellular respiration" |
| Pyruvate in Anaerobic conditions | fermentation in yeast this yields ethanol (beer, wine) in microorganisms this yields lactic acid (yogurt) in aggressive tumors that outgrow their capillaries this yields lactic acid |
| Pyruvate in Anaerobic conditions card 2 | in muscles during intense activity this leads to hypoxia this leads to lactic acid then <pH, then cramps and muscle fatigue(until lactic acid delivered to liver, reconverted to glucose: Cori cycle) |
| Regardless of Conditions | fermentation in erythrocytes this produces lactic acid (no mitochondria to do citric acid cycle) |
| Fermentation | regenerates NAD+ for continued glycolysis |
Created by:
anthony_lavell
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