Biochemistry, Cellular Respiration

Front 1

Thermodynamics

Back 1

Study of energetics of chemical reactions, released as energy
(1) heat - movement of molecules
(2) potential energy

Front 2

Potential Energy

Back 2

Energy stored in bonds

Front 3

Heat

Back 3

Movement of molecules generating energy

Front 4

Thermodynamics
(First Law)

Back 4

"Energy of the universe is CONSTANT"
- If system decreases, universe increases

Front 5

Thermodynamics
(Second Law)

Back 5

"Disorder of the universe must INCREASE"
- Defines entropy
- Reactions occur spontaneously if the entropy increases

Front 6

Entropy

Back 6

Measurement of Disorder

ΔS

Front 7

Gibbs Free Energy
(Equation)

Back 7

ΔG = ΔH - TΔS

Where ΔH = Enthalpy
Where ΔS = Entropy

Front 8

Gibbs Free Energy
(Meaning)

Back 8

ΔG = 0 .. Equilibrium
ΔG < 0 .. Reaction occurs without net input of energy because reaction is spontaneous.. exergonic.. energy exist system
ΔG > 0 ... Reaction is non spontaneous and endergonic (energy must enter)

Front 9

Kinetics

Back 9

Study of reaction rates
NOT Thermodynamics!!!

Front 10

Activation Energy

Back 10

Energy required to produce transient intermediate product

Front 11

Catalyst

Back 11

- Lowers activation energy by stabilizing transition state
- ΔG is NOT changed
- Makes reaction more favorable by making the intermediate less thermodynamically unfavorable
- Regenerated

Front 12

Enzyme

Back 12

- Made of unique AA chain
- 3D structure folds into 4º
- Acts on substrate at "Active Site"

Front 13

Active Site

Back 13

- Stabilizes transition site, which decreases activation energy
- Where the enzyme acts

Front 14

Regulation of Enzymes
(3 Types)

Back 14

- Covalent Modification
- Protolytic Cleavage
- Allosteric Regulation

Front 15

Covalent Modification

Back 15

- Add a phosphate group to inactive or activate kinases
- Reversible

Front 16

Protolytic Cleavage

Back 16

- Synthesize enzymes in inactive forms called "zymogens"
- Activated through cleavage by proteases

Front 17

Zymogens

Back 17

Enzymes synthesized in an inactive form that require activation (cleavage)

Front 18

Allosteric Regulation

Back 18

Active site modification through molecules binding at sites other than the active site

Front 19

Feedback Inhibition

Back 19

End product shuts off enzyme early in the product formation's pathway

Front 20

Enzyme Kinetics

Back 20

Study of reaction RATES, formation of products from substrates in presence of enzymes

Front 21

Reaction Rate
(Velocity)

Back 21

- Amount of product formed in mol/s
- Depends on the amount of [S], as the cell's [E] is constant

Front 22

Saturation
(Vmax)

Back 22

Adding more [S] doesn't change the reaction, as all the active sites on the enzyme are occupied

Front 23

Enzyme Coorperativity

Back 23

- Special form of Allosteric Regulation
- Binding of a substrate increases affinity for others to bind (enzyme has more than one active site)
- Sigmoidal Curve
- Example: Hemoglobin

Front 24

Enzyme Inhibition Types (2)

Back 24

- Competitive
- Noncompetitive

Front 25

Competitive Inhibition

Back 25

- Substances that resemble substrate or transition state compete with active site binding
- Reversible, overcome by adding more [S]
- Does not affect Vmax

Front 26

Noncompetitive Inhibition

Back 26

- Bind at allosteric site
- Inhibitor not displaced by [S] increase, so DOES decrease Vmax
- Possibly changes enzyme confirmation, taking enzyme out of the ballgame

Front 27

Oxidize

Back 27

- Bind oxygen
- Remove e-
- Remove H+

Front 28

Reduce

Back 28

- Remove oxygen
- Add e-
- Add H+

Front 29

Anabolism

Back 29

Break down bonds

Front 30

Catabolism

Back 30

Build bonds

Front 31

Overall Glycolysis Reaction

Back 31

Glucose + 2ADP + 2P + 2NAD
--->
2 Pyruvate + 2ATP + 2NADH + 2H2O + 2H

(Split 6C into 3C)

Front 32

Overall Steps of Glycolysis

Back 32

G - G6P - F6P - F1,6bP - 2GP - 2,3GP - PEP - Pyruvate

Front 33

Hexokinase

Back 33

- Catalyzes first step of glycolysis (G to G6P) by phosphorylation glucose
- G6P feedback inhibits this enzyme (lots of G6P, no reason to phosphorolate glucose)

Front 34

PFK

Back 34

- Catalyzes third step (F6P - F1,6bP) by transferring a phosphate
- Extremely thermodynamically favorable (ΔG<0) from here on out
- "Committed Step"

Front 35

How does ATP regulate PFK?

Back 35

Lots of ATP means you don't need to catalyze the reaction of F6P - F1,6bP.

Front 36

Aerobic Respiration

Back 36

If we have oxygen present, pyruvate goes into the Krebs Cycle, where we regenerate NAD+

Front 37

Anaerobic Respiration

Back 37

- Without the presence of oxygen Krebs cannot happen
- Regardless we wind up with too much NADH
- Need to regenerate the electron carrier NAD to keep glycolysis running

Front 38

Main Reaction of Anaerobic Respiration

Back 38

(1) Pyruvate + NADH --> Lactate + NAD
(2)

Front 39

Pyruvate Dehydrogenase

Back 39

- Job is to turn pyruvate into Acetyl-CoA by releasing CO2
- Pyruvate + CoA-SH + NAD --> Acetyl-CoA + NADH

Front 40

Glycolysis Energetics

Back 40

Use 2ATP
Net 4ATP and 2 NADH

Front 41

Prosthetic Group

Back 41

- Nonprotein covalently bound to enzyme as part of enzyme's active structure

Front 42

Cofactor

Back 42

Organic and inorganic compounds necessary for function but never interact with enzyme

Front 43

Krebs Cycle Energetics

Back 43

6 NADH
2 FADH2
2 GTP

Front 44

Electron Transport Chain

Back 44

Furthe- Occurs in mitochondrial intermembrane space
- Purpose is to re-oxidize electron carriers that have been reduced (turn NADH back into NAD so we can keep glycolysis, Krebs running)

Front 45

ATP Synthase

Back 45

- Uses the gradient created by ETC electron carriers to synthesize ADP-->ATP
- pH higher inside matrix than IMS