1. Chapter 6 Cellular Respiration
Cellular metabolism involves the breaking down & building up of molecules.
Catabolism= breaking down molecules
Ex. Breaking down the foods we eat (digestion)
Anabolism= the building up of molecules
Ex. Glucose making glycogen, amino acids bonding together to
form protein
Cellular respiration is the breaking down of glucose in the presence of oxygen to make ATP (energy).

2. Chapter 6 Metabolism: Energy & Enzymes
Energy is the ability to do work
Carry out metabolic activities
Growth
Development
Locomotion
Reproduction
Most organisms get their energy from photosynthesizers
Algae
Plants
Some bacteria

3. Forms of Energy 2 forms of energy: Kinetic: energy of motion
Potential: stored energy
The food we eat contains chemical energy in chemical bonds of organic molecules.
Solar energy-> chemical energy-> mechanical energy-> heat

4. Two Laws of Thermodynamics
1st Law of Thermodynamics (Law of Conservation of energy): Energy cannot be created or destroyed, but it can be changed from one form to another.
2nd Law of Thermodynamics: Energy cannot be changed from one form to another without a loss of usable energy.
Heat is NOT a form of usable energy (it is waste energy)!
Energy transformations make the universe less organized & more disorganized (chaos).

5. Metabolism: sum of all the chemical reactions occurring in the cell
Reactants: substances that participate in reaction
Products: substances that form as a result of reaction
Can you name the products & reactants in the
chemical equation for cellular respiration?
C6H12O6 + 6O2  6CO2 + H2O + ATP
Glucose + oxygen  carbon dioxide + water + energy

6. ATP: Energy for Cells ATP is an energy molecule made up of 3 parts:
Base adenine
Sugar
Three phosphate groups
ATP supplies the energy need to do:
Chemical work: making macromolecules that make up cell
Transport work: moving substances across cell membrane
Mechanical work: allowing muscles to contract, cilia & flagella to beat, chromosomes to move, etc.
When a phosphate group is removed from ATP, energy is released.
ATP  ADP + P + energy

7. Enzymes:. proteins that speed up the rate
Enzymes: proteins that speed up the rate of chemical reactions without being used up in the reaction
Energy of activation:
the energy that must be added to molecules to cause them to react H
Enzymes lower activation energy required for reactants to react by bringing the reactants in close physical proximity to each other.

8. How Enzymes Function
Enzymes work by forming enzyme-substrate complexes
S + E  ES  E + P
Enzymes have active sites where the substrates fit
Induced-fit model: enzymes slightly changes shape to help reaction take place

9. Factors Affecting Enzymatic Speed
Substrate concentration
Enzyme activity increases as substrate concentration increases
Due to more collisions between substrate & enzyme
Temperature
As temperature increases, enzymatic activity increases
High temperatures can denature enzymes & make them useless (changes shape) pH
Extreme pH denatures enzyme

10. Enzyme Cofactors
Inorganic or organic (non-protein) helpers that aid enzymes in functioning properly
Cofactors are inorganic ions (metals) like copper, zinc, or iron
Coenzymes are organic non-protein molecules
Vitamins required to make coenzymes in our body

11. Oxidation-Reduction Reactions
Oxidation is the loss of electrons
Reduction is the gain of electrons
Na + Cl  NaCl
Can apply to covalent reactions in cell
Oxidation is loss of hydrogen atom (e- + H+)
Reduction is the gain of hydrogen atoms

12. Cellular respiration
Cellular respiration: breaking down food (primarily glucose) to release usable energy (ATP)
4 step process
Glycolysis: takes place in the cytoplasm, anaerobic, releases a two ATP by breaking down glucose into two molecules of pyruvate (a C3 molecule).
Pyruvate to acetyl-CoA: takes place in outer compartment of mitochondria; pyruvate is converted to a C2 acetyl group attached to coenzyme A (CoA) and CO2 is given off.
TCA (Citric Acid, Krebs) cycle: takes place in the matrix of the mitochondria, aerobic, releases two ATP molecules per glucose molecule.
Electron transport and chemiosmosis: takes place in the cristae of the mitochondria, aerobic, releases A LOT of ATP (36-38 ATP molecules).

13. NAD+ and FAD Two coenzymes involved in oxidation-reduction reactions
They each can hold only two electrons and two hydrogen nuclei
Carry electrons to the electron transport chain in the cristae of the mitochondria, where they drop them off.

14. Summary of Glycolysis
1. Anaerobic process that breaks down one 6 carbon molecule of glucose into two 3 carbon pyruvates.
2. As glucose is broken down, some of its hydrogen atoms are transferred to electron acceptor NAD+ forming 2 NADH molecules.
3. Glycolysis takes 2 ATP molecules to break apart the bonds of glucose and makes 4 ATP molecules.
The net gain of ATP is two.
Pyruvate and NADH will be transported to mitochondria for more reactions.

15. Pyruvate to Acetyl CoA
Each pyruvate reacts with a Coenzyme-A molecule, releasing one molecule of CO2, and producing one NADH + H+ and one acetyl-CoA molecule (two for each glucose molecule we started with).
The acetyl-CoA will enter the TCA cycle in matrix.
The CO2 is released as a waste product.
No ATP is produced in this step, but the NADH + H+ will enter electron transport chain to release ATP later.

16. The Citric Acid Cycle TCA (Tricarboxylic acid, citric acid,
Krebs) cycle
Through a complex series of biochemical
reactions, the 2-C acetyl group from
the acetyl-CoA first binds to another
molecule, then is broken down. The
CoA is released to go back to the
outer compartment.
This entire process consumes water
(to get oxygen, making the process
aerobic), and releases 6 NADH + H+
& 2 FADH2 molecules, 4 CO2 molecules
per glucose molecule that we started
with, and produces 2 ATP per glucose molecule that we started with.

17. The Electron Transport Chain & Chemiosmosis
The electron transport chain is a series of cytochrome molecules located in the cristae
NADH & FADH2 give up their electrons & the H+ (hydrogen ions) are released into the matrix
The energy released by the electrons as they move down the chain is used to pump the hydrogen ions into the intermembrane space
Hydrogen ions build up there forming a concentration gradient

18. The Electron Transport Chain & Chemiosmosis
Hydrogen ions then pass through ATP synthase (an enzyme) back into the matrix by simple diffusion
Hydrogen ions flowing through ATP synthase cause synthesis of ATP from ADP + P by chemiosmosis
The final electron acceptor at end of electron chain is oxygen
Water is formed when oxygen and the electrons from the electron transport chain rejoin its hydrogen protons forming water

19. Fermentation
Anaerobic process of glucose breakdown forming lactic acid or ethanol
Inefficient source of energy
One molecule of glucose only forms 2 ATP molecules
Unicellular organisms use alcoholic fermentation to gain energy
Muscle cells can switch to lactic acid fermentation when not enough oxygen is available