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66 Cards in this Set
- Front
- Back
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What is potential energy?
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energy by virtue of position
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What is chemical energy?
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the energy that can be released in a reaction by breaking and forming bonds
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What is mechanical energy?
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the sum of potential and kinetic energy
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Energy transduction
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- Heat is related to the internal kinetic energy of a mass
- not a form of energy itself - since it is a change in energy, it is more like a form of work |
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Chemically, energy is:
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- used for mechanical work
- converted to heat - stored as chemical potential energy |
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Thermodynamics
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the change in energy of a system undergoing a change of some sort
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Equation for Energy Change
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change in E=q+w
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At constant pressure q is called the change in ________?
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enthalpy?
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T/F Heat and work are not completely equivalent.
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True
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T/F It is possible to convert heat completely to work
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False. It is impossible to convert heat completely to work.
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What are the conditions of energy and work at equilibrium?
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No work is being done; no net energy transfer, net energ change is zero
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The change in free energy is the...
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net work done on a system in a reversible process at constant temp and pressure
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What is free energy in relation to heat and work?
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amount of reaction heat that can be converted into new work
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What is enthalpy in relation to heat and work?
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reaction heat at constant pressure; total heat
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What is TdeltaS in relation to heat and work?
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heat change when process carried out reversibly; heat unavailable for work; energy lost to entropy
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How do you calculate overall equilibrium constant?
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Keqtot=Keq1 x Keq2 x Keq3
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At what quantitative point is a reaction irreversible?
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G<-23kJ/mol
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What conditions must be met for a reaction to proceed spontaneously?
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Ke1>>>1 then deltaG<<<0
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What occurs in teh first part of glucose oxidation and what is it called?
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Glucose is brokendown into a 3 carbon pyruvate; glycolysis
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How is glucosed stored for later enrgy use?
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polymerization
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Maximum rate for formation of P when concentration of....
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Substrate is highest
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Pre steady state
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during initial (very early) period, concentration of ES is building up (usually too short to measure)
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Steady state kinetics
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After initial pre-steady state concentration of ES and any other intermediates reaches point where concentrations are approximately constant
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Which step is the rate limiting step in the formation of products?
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The second rate limiting step. The rate of the forward limiting reaction is proportional to the concentration of its reactant ES.
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The Michaelis-Menten equation
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Vo=(Vmax[S])/(Km + [S])
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When glucose is oxidized what is the process it undergoes when oxidized and what is it oxidized to?
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Glycolysi, pyruvate
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Under anaerobic conditions pyruvate yields ________?
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2 Lactate
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Under aerobic conditions pyruvate, produced through glycolysis from glucose produces what?
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2 CO2, 2 Acetyl CoA, which yields 4CO2 + 4H2O
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The oxygen supply in cancerous tissue is affected how?
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- Poor Vascularization
- Anaerobic environment - Glycolysis in solid tumors can be 200x normal glycolysis rate |
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Under anaerobic (tumor) conditions what is the fate of pyruvate? What are the effects?
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- Pyruvate reduces to lactate
- Makes tumor acidic (H+ produced in glycolysis) - Favors proteolytic breakdown of extracellular matrix (metastasis) |
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In nuclear medicine FDG helps diagnose what?
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Cancer
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How does FDG indicate that there is cancer tissue present?
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Indicates energy utilization or metabolic activity of tissue based on glucose uptake
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What are the limitations of FDG?
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- Brain imaging is complicated by high normal uptake of glucose
- Prostate and other other slow growing tumors may not be FDG avid - FDG measures metabolism but not proliferation of tumor cells |
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What is the causative organism of caries?
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Streptococcus mutans
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Why is streptococcus mutans cause caries?
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- A facultative anaerobe
- Produces lactace and acetate - Glycolysis produces protons (acidic) |
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What is the most abundant sugar in milk?
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Lactose
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What happens to lactose in the body?
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- Poorly absorbed
- Small intestine secretes lactase which breaks down to galactose and glucose so it can be more easily absorbed - Liver gonverts galactose ot glucose and released into blood |
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What happens to unabsorbed lactose?
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continues to colon and is an energy source for bacteria in relatively anaerobic environment
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How does a person who is lactose intolerant get diarrhea after consuming lactose?
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Lactose and fermentation products increase osmotic pressure in colon, preventing water absorption
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What are the three types of lactose intolerance?
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Primary, secondary, and congenital
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What are the characteristics of primary lactose intolerance?
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- Due to genetically controlled decline in intectinal lactase
- permanent |
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What are the characteristics of secondary lactose intolerance?
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- due to damage to intestine wall
- temporary |
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What are the characteristics of congenital lactose intolerance?
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- genetic lack of lactase
- rare |
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How is lactose intolerance diagnosed?
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- lactose tolerance test (old method)
- hydrogen breath test - stool acidity test |
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What is the overall reaction in glycolysis?
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Glucose + 2NAD+ + 2ADP + 2Pi -> 2 pyruvate + 2NADH + 2H+ + 2ATP + 2H2O
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Where does glycolysis occur in a cell?
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In the cytosol of almost all cells
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What is key about hte 1st phase of glycolysis?
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invest energy (ATP) to break bonds and create two high energy 3 carbon compounds
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What is key about hte 2nd phase of glycolysis?
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- Oxidize these two compounds to pyruvate
- NAD+ gets reduced - Couple energy released to ATP synthesis |
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What is key about the energy released and used up in glycolysis?
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Release more nergy in the second phase than used up in the first phase
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The first phase of glycolysis is the investment part of the reaction. Why?
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- Uses 2 ATP
- Endergonic reactions - 6C -> 2x 3C - Glucokinase in liver not hexokinase - Step 4 (aldolase) is the LYSIS step |
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What are the products of the first phase of glycolysis and are does it come to those products?
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- Dihydroxyacetone phosphate is ISOMERIZED to glyceraldehyde-3-phosphate
- Glucose molecules go into payoff phase as 2 x glyceraldehyde-3-phosphate |
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What is involved in the second (payoff) phase of glycolysis?
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- 2 x ATP invested so far
- Phosphorylation by INORGANIC phosphate (NOT ATP) - 2 x NADPH+ - Overall payout=2 x ATP - Total ATP created=4ATP |
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What does hexokinase/glucokinase do?
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- catalyze phosphorylation of Glucose to G6P
- Glucokinase is in the liver |
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How does glucose enter a cell?
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Concentration driven facilitated diffusion through a transporter in membrane
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Hexokinase I
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- Main enzyme in brain and RBC
- Lots in muscle |
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Hexokinase II
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- Main enzyme in muscle
- Fastest rate of reaction |
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Hexokinase IV (Glucokinase)
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- Acts as glucose sensor; reaction rate geared to blood glucose level
- Low blood glucose, enzyme in liver has low activity - High glucose; fully active to capture glucose in hepatocytes |
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What are precursors to pyruvate?
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Oxaloacetate
Alanine |
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How do we regenerate NAD+?
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- Anaerobic: reduce pyruvate to lactate
- Aerboic: send pyruvate to TCA cycle and oxidative phosphorylation |
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How can you get ethanol from pyruvate?
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Yeast reduces pyruvate to ethanol
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When do we see anaerobic conditions in mammals?
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- Skeletal muscle duringexertion
- NEVER in the brain or heart |
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What do red blood cells rely on for energy?
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Glycolysis and produce lactate
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What is a facultative anaerobe?
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- Can grow in presence/lack of oxygen
- Not affected by oxygen levels |
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Obligate aerobe
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Needs oxygen to survive
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Obligate anaerobes
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Oxygen is poisonous to these bacteria
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Cori Cycle
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-Under highexercise conditions muscles convert glucose to lactate via glycolysis
- Lactate enters blood stream - Liver uses lactate and ATP to synthesize glucose via gluconeogenesis during recovery |
