Term
| Chemistry of Food: 3 Main Classes |
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Definition
Protein (large polymers of amino acids)
Carbohydrate (sugars & their derivatives)
Fat (tricylglycerol) |
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Term
Protein
Carbohydrate
Neural Fats
Must All Be Broken Down To? |
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Definition
Amino acids
Sugar monomers (monosaccharides)
Fatty acids + monoacyglycerol |
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Term
| The enzymatic breakdown of molecules is known as |
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Definition
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Term
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Definition
| Food mastication, lubrication for swallowing, small amount of starch digested |
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Term
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Definition
Contains HCL which sterilizes, denature and partially digests protein
pH~2.0 |
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Term
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Definition
| MAJOR site of food digestion and absorption |
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Term
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Definition
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Term
| Once broken down, sugars, fatty acids and amino acids must be transported across the? |
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Definition
| Gut epithelial lining to be absorb to the body |
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Term
| Absorption of glucose into the gut |
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Definition
| Active uphill transport of glucose COUPLED to the downhill transport of Na |
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Term
| Can glucose be store as free sugar? |
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Definition
| No because the osmostic pressure in the cell would be too high causing the cell to swell/lysed. Therefore, it must be converted to GLYCOGEN. |
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Term
| Glycogen is primarily store at the ? |
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Definition
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Term
| Compare the reservation of glucose and fat |
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Definition
Glucose reserves are exhausted within 24 hrs of fasting
Fat storage is UNLIMITED and not rapidly depleted
Fat reserves are 50x that of glycogen
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Term
| Advantage of fat over glucose? |
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Definition
| Fat is more highly reduced (less oxidized) than carbohydrate. Therefore, contain > E per unit mass |
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Term
| What happens when sugar is exhausted? |
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Definition
1. The liver converts amino acids (from muscle) to glucose by gluconeogenesis
2. The liver converts fatty acids to ketone bodies (satisfy ~50% of brain E) |
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Term
| After eating a meal, blood glucose? |
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Definition
| Increases to ~10 mM but will reset after 2 hrs back to ~2-5 mM |
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Term
| Glucose Uptake Differences Between Liver, Brain, RBC and Muscle, Adipose Tissue |
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Definition
The liver, brain and RBC is NOT insulin dependent
The muscle, adipose tissue IS insulin dependent |
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Term
| Describe how muscle, adipose tissue is insulin dependent. |
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Definition
| Insulin binds to cell surface receptors -> increases the # of glucose transporters on cell surfaces -> increases glucose uptake |
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Term
| Can glucose simply be added to the glycogen chain? |
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Definition
| No because that is thermodynamically UNFAVORABLE |
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Term
| How is glucose modified to be incorporated into glycogen? |
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Definition
| Using the two enzymes, hexokinase and glucokinase, glucose is converted to glucose-6-phosphate. Since glucose is phosphorylated, it is so HIGHLY-charged that it is unable to diffuse out of the cell. |
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Term
| Where is hexokinase and glucokinase found? |
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Definition
Hexokinase (brain)
Glucokinase (liver)
G= -16.7 kjmol^-1 |
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Term
| What does phosphoglucomutase do? |
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Definition
| This enzyme converts glucose-6-phosphate to glucose-1-phosphate with -7.3kJmol^-1 of G |
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Term
| What does UDP-glucose pyrophosphorylase do? |
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Definition
| This enzyme injects energy into the system and generates an activated glucosyl group -UDP-glucose. Adding a glycosyl group to glycogen makes the reaction energetically FAVORABLE. |
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Term
| Glycogen breakdown occurs at its |
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Definition
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Term
| Why does liver have glucokinase and hexokinase? |
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Definition
When glucose levels are LOW, glucokinase activity in liver is LOW.
HIGH affinity of hexokinase for glucose at LOW glucose conc. ensures the brain scavengers what glucose is available under starvation. |
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Term
| Name the 3 major steps of food->energy |
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Definition
Glycolysis
Kreb Cycle
Electron Transport Chain |
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Term
| Where does glycolysis occur? |
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Definition
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Term
| What happens in glycolysis? |
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Definition
| Glucose is split into 2 molecules of pyruvate with a net production of 2 ATP molecules, 2 NADH. |
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Term
| Why are NAD+ and NADH important? |
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Definition
These enzymes are the most important carriers of transferable e- in catabolic rxn.
Play roles in redox rxn by assisting the transfer of e- to and from metabolites |
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Term
| If a reaction has a NEGATIVE G, then? |
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Definition
| The reaction is irreversible because it is negative and favored. |
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Term
| Where does the TCA (Kreb Cycle) occur? |
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Definition
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Term
| What must happen before pyruvate enters the Kreb Cycle? |
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Definition
| Pyruvate must be converted to acetyl CoA by oxidative decarboxylation of pyruvate with release of O2. |
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Term
| What product is release from the conversion of pyruvate -> acetyl CoA and how much energy did it take? |
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Definition
1 NADH and 1 CO2
G= -33.5 |
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Term
| What is the purpose of the TCA Cycle? |
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Definition
| Acetyl CoA oxidation to CO2 results in a release of HIGH-ENERGY ELECTRONS, which is initially held by NADH and FADH2 |
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Term
| By the time it reaches the electron transport chain, how many per molecule of oxidized glucose are there? |
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Definition
4 ATP (2 net from glycolysis and 2 from TCA cycle)
10 NADH (2 from glycolysis, 2 from pyruvate dehydrogenase, 6 from TCA cycle)
2 FADH (from 2 TCA Cycle) |
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Term
| Where does the electron transport chain occur? |
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Definition
| The inner mitochondrial membrane |
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Term
| What does NADH and FADH2 serve as? |
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Definition
| These reduced coenzyme serves as a source of electrons to drive the electron transport chain |
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Term
| How does the electron transport chain work? |
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Definition
| Series of electron carriers- electrons flow from a carrier of HIGH reducing potential to one of LOWER reducing potential. |
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Term
| What are the two main mobile electron carriers in electron transport chain? |
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Definition
| Ubiquinone (Q) and cyctochrome C |
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Term
| What is unique about ubiquinone (Q)? |
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Definition
| An electron carrier that is not associated with a membrane bound protein complex |
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Term
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Definition
| Carriers e- from NADH to ubiquinone |
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Term
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Definition
| Carries e- from succinate via FADH2 to ubiquinone |
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Term
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Definition
| Uses UbiquinoneH2 to reduce cytochrome C |
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Term
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Definition
| Transfers e- from cytochrome C to oxygen |
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Term
| What is the function of the ATP synthase complex? |
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Definition
1. Inflow of H+ down an electrochemical gradient through the proton conducting channel.
2. Electrochemical energy converted to mechanical energy- rotation of stalk
3. Rotation of stalk is linked to the rotation of ATP synthase catalytic subunits which drives ADP+Pi to ATP |
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Term
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Definition
| Shell of phospholipids, protein and cholesterol with a core of TAG and cholesterol esters. |
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Term
| 3 Steps required to feed fatty acid metabolites into the TCA Cycle? |
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Definition
1. Fatty acid activation: fatty acid converted to acyl-CoA
2. Production of acetyl CoA through the fatty acid oxidation cycle: acyl-CoA broken down by removing 2 C at a time
** Acetyl CoA then enters the TCA cycle as it normally would. |
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Term
| How is fatty acid activated? |
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Definition
Fatty acids in the cytoplasm are converted to thioesters of coenzyme A
This requires ATP and acyl-CoA synthase |
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Term
| How many molecules does the conversion of fatty acyl-CoA to acetyl-CoA produced? |
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Definition
1 acetyl-CoA
1 NADH
1 FADH2 |
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