1. Metabolism & Cellular Respiration

2. Metabolism
The sum of all the chemical reactions that occur within you as a living organism.
Anabolism – the type of reaction that uses energy to build complex organic molecules from simpler ones.
Catabolism – the type of reaction that breaks down complex organic molecules with the release of energy

3. Metabolism Anabolic Reactions Catabolic Reactions
Build complex molecules
Brea down complex molecules
Are Endergonic
Are Exergonic
Are Biosynthetic
Are Degradative
Example: Photosynthesis
Example: Cellular Respiration

4. Metabolism
Almost all metabolic reactions in organisms are catalyzed by enzymes
Many of these reactions occur in specific sequences and are called metabolic or biochemical pathways.
Metabolic pathways consist of chains and cycles of enzyme-catalyzed reactions

5. Metabolism
Activation Energy – the energy necessary to destabilize the existing chemical bonds in the substrate of an enzyme-substrate catalyzed reaction
Enzymes lower the activation energy of a chemical reaction that they catalyze
Make reactions go faster
During the process of the reaction, energy is given out as new bonds are made.
Most biological reactions are exothermic

6. Metabolism
Competitive Inhibition (CI) – a molecule, competitive inhibitor, competes directly with the usual substrate for the active site of an enzyme.
The substrate will then have fewer encounters with the active site and rate of the chemical reaction will be decreases
The competitive inhibitor must have a structure similar to the substrate to function in this way.
CI may be reversible or irreversible
Reversible may be overcome by increasing the substrate concentration

7. Metabolism Many enzymes inhibitors have been used in medicine
Ethanol has been used to act as a competitive inhibitor for antifreeze poisoning
Fomepizole, which is an inhibitor of alcohol dehydrogenase has also been used for antifreeze poisoning

8. Metabolism
Non-competitive Inhibition – an inhibitor that does not compete for the enzyme’s active site.
The inhibitor interacts with another site on the enzyme
This causes a change in the shape of the enzyme’s activity site, making it non-functional
Example is mercury binding to the sulfur group of the component amino acid of many enzymes
Changes the shape of the enzyme which causes the inhibition of this enzyme

9. End Product Inhibition
Metabolism
End Product Inhibition
Prevents the cell from wasting chemical resources and energy by making more of a substance than it needs.
Metabolic pathways can be controlled by end product inhibition
Metabolic reaction occur in an assembly line pattern
The end product the assembly line shuts down
This is done by inhibiting the action of the first enzyme

10. Inhibitor in Plasmodium
The malarial parasite (Plasmodium) has developed resistance to most anti-malarial drugs
Huge data bases are held in computers called bioinformatics
Recent study found 5,655 chemicals that might act as an enzyme inhibitor in Plasmodium
These were tested with nine Plasmodium enzymes and 6 inhibitors were found and are now being researched as anti-malarial drugs

11. The Energy in Food ATP – Adenosine Triphosphate
Cellular Respiration – A chemical process that uses oxygen to convert the chemical energy stored in foods (organic molecules) into another form of chemical energy.
Each covalent bond in a glucose, amino acid, or fatty acid represent stored chemical energy
ATP – Adenosine Triphosphate
Cells in plants and animals use ATP as their main energy supply

12. Oxidation & Reduction Oxidation Reactions Reduction Reactions
Addition of oxygen atoms to a substance
Removal of hydrogen atoms from a substance
Loss of electrons from a substance
Removal of oxygen atoms to a substance
Addition of hydrogen atoms to a substance
Additions of electrons to a substance
In respiration, the oxidation is carried out by removing pairs of H atoms, plus their electrons.
The H atoms are accepted by a carrier (NAD) therefore reduced.

13. Oxidation & Reduction Remember NAD!!!!
FYI nicotinamide adenine dinucleotide

14. Phosphorylation Makes an organic molecule less stable
More likely to react
Usually ATP

15. Respiration Rapid Oxidation – rapid release of energy; wood burning
Slow Oxidation – cells break down in a step by step process (metabolism)
Cell Respiration involves the oxidation and reduction of electron carriers
Oxidative phosphorylation - the culmination of a series of energy transformations that are called cellular respiration or simply respiration
Phosphorylation of molecules makes them less stable (adding P from ATP)

16. Respiration
Glucose (from glycogen stores) typically used first as the source of energy
Glucose is acted on by a series of enzymes
These enzymes catalyze a sequence of reactions in which covalent bonds are broken (oxidized) on at a time
Each time a covalent bond is broken a small amount of energy is released.
The goal is to trap that energy in a controlled way and form ATP molecules

17. Respiration No glucose? Lipids next
Then amino acids/proteins (only in extreme cases- i.e. starvation)

18. Glycolysis Three Steps or Stages
Stage 1: Glycolysis = “Splitting Sugar”
First stage in breaking down glucose molecule
Takes PLACE outside the mitochondria in the cytoplasm
2 ATP molecules are actually used to get things started.
2 ATP’s split the glucose molecule in half. (What do you call this???)
Glucose enters the cell through the plasma membrane
An enzyme modifies the molecule slightly, then another enzyme modifies the molecule more

19. Glycolysis
A series of reactions that ultimately cleaves the 6 carbon glucose into 2 3-carbon molecules called pyruvate.
Called an investment stage because two ATP’s are used up in the process
4 ATP molecules are produced at the end
Net gain of 2 ATP
Electrons are transferred to electron carries called NAD
NADH is formed

20. Stages of Glycolysis
2 phosphate groups (from ATP) are added to glucose
Adding a phosphate group is called Phosphorylation
The hexose bisphosphate (the end product of stage 1) is split two form 2 molecules called tiose phosphate.
2 atoms of hydrogen are removed from each triose phosphate molecules. This is an oxidation. The energy released from oxidation is used to convert ADP to ATC,

21. Glycolysis Glycolysis (Payback Stage)
Remember you used 2 ATP’s to start
Gained 4 (net gain)
End Result are:
Two Pyruvic Acid Molecules
Glucose + 2ATP Pyruvic Acid molecules
+ 4ATP
Pyruvic Acid Molecules still hold most of the energy of the original glucose molecules

22. Anaerobic Respiration
All organisms start the pathway of breaking down glucose the same way
Glycolysis (small net gain of energy no O₂
Anaerobic (without oxygen)
Some derive their ATP completely without the use of oxygen and are referred to as anaerobic
AKA – Fermentation
2 types of fermentation:
Lactic Acid Fermentation (Humans / Mammals)
Alcoholic Fermentation (yeast)

23. Alcoholic Fermentation
Occurs in yeast cells
A common single – cell fungus
Uses alcoholic fermentation when oxygen is not present
Begins with glycolysis
Pyruvate converted to ethanol (2-C) and CO2 is released…both waste products for the organism
Ethanol and CO₂ are produced as waste products
Bakers’ and brewers’ yeast allows bread to rise and beer to be carbonated (most commercial beer is forcibly carbonated as well) as well as the alcohol.

25. Lactic Acid Fermentation
Normally in aerobic organisms that find themselves in a situation where oxygen is no longer available—why you breather harder when you work out
If a person’s exercise rate then exceeds his/her body’s capacity to supply oxygen some of the glucose will follow the anaerobic pathway called lactic acid fermentation
Begins with glycolysis
Pyruvate converted to lactate (3-C), no CO2 produced, no ATP produced
Lactic acid fermentation allows glycolysis to continue with small gains of ATP in addition to ATP produced thorough the aerobic pathway

26. Lactic Acid Fermentation
When O2 becomes available, lactate converted back to pyruvate and then pushed through the aerobic pathway

27. Anaerobic Respiration Lactic Acid Fermentation
DOES NOT MAKE YOU SORE
NO ATP IS MADE SO IT DOES CAUSE FATIGUE
Anaerobic respiration produces less ATP but produces ATP at a rapid rate

28. Anaerobic & Aerobic Respiration
Pyruvate produced in glycolysis can only be oxidized further with the release of more energy from it if oxygen is available
Occurs in the mitochondria
First stage is called link reaction
Enzymes in the matrix of the mitochondria then catalyze a cycle of reactions called the Kreb cycle

29. Link Reaction
Pyruvate from glycolysis is absorbed by the mitochondria.
Enzymes in the matrix of the mitochondria remove hydrogen and carbon dioxide from pyruvate
The hydrogen is accepted by NAD
Removal of hydrogen is oxidation
Removal of carbon dioxide is decarboxylation.
Oxidative Decarboxylation
The product of oxidative decarboxylation of pyruvate is an acetyl group, which is attached to coenzyme A to acetyl coenzyme A

30. Link Reaction

31. Aerobic Cell Respiration
Aerobic Process – means it requires oxygen
Cells that have mitochondria use aerobic pathway
Cells Exchange:
Oxygen into the cell
Carbon Dioxide out of the cell
Body: In your lungs – Blood Exchange:
Oxygen (in)
Carbon Dioxide (out)

32. Aerobic Cell Respiration
Reviewing the Mitochondria
Found in almost all Eukaryotic Cells
The Mitochondria structure is key to its role in cellular respiration
An example of form and
function

33. Aerobic Cell Respiration
Stage 2: The Kreb Cycle
Named after biologist Hans Krebs
Blame this guy

34. Aerobic Cell Respiration
The Kreb Cycle
Finishes the breakdown of Pyruvic Acid molecules to CO₂ - releasing more energy.
Pyruvate loses a C as CO2, converted acetyl compound
Said to be decarboxylated and oxidized
Acetyl compound is attached to coenzyme A to form Acetyl Coenzyme A
Enzymes are dissolved in the Matrix inside the Matrix
Called the Fluid Matrix

35. Aerobic Cell Respiration
The Kreb Cycle
Acetyl Co A joins a 4 Carbon Acceptor molecule
It is oxidized (removal of H)and coupled to the reduction of hydrogen carriers releasing CO₂ (Decarboxylation)
Produces 2 CO₂ + 1 ATP per Acetyl CoA
NADH and FADH₂ (another electron carrier) trap most of the energy and carry it to the cristae.
At the end you are left with a 4 carbon acceptor molecule
So the cycle can continue

36. Aerobic Cell Respiration
Substrate – level phosphorylation – ATP produced

37. Aerobic Cell Respiration
The Kreb Cycle
Results:
Glycolysis produces 2 Pyruvic Acid molecules from 1 glucose molecule
Each Pyruvic Acid molecule makes 1 Acetyl CoA
Cycle turns 2 TIMES
Producing: 4 CO₂ + 2ATP’s

38. Aerobic Cell Respiration
Electron Transport Chain & Chemiosmosis
Occurs on the inner mitochondrial membrane and on the membranes of the cristae.
First: (carrier molecules) NADH transfers electrons from the original glucose molecule to an electron transport chain.
Remember: eˉ move to carriers that attract them more strongly
This is why they move from carrier to carrier
One carrier attracts them more than the one carrying; moving the eˉ to the inner mitochondria
Some electron carriers act as proton pumps and use this energy to pump protons (H⁺) against the concentration gradient
FAD comes in a little later (only 2 stages)

39. Aerobic Cell Respiration

40. Aerobic Cell Respiration
Finally being pulled by oxygen at the end of the chain.
2 H⁺ combines with oxygen forming H₂O
The transfer of electrons between carriers in the electron transport chain in the membrane of the cristae is coupled to proton pumping
Chemiosmosis involves the movement of proton (hydrogen ions) to provide energy so that phosphorylation can occur
Protons diffuse through ATP synthase to generate ATP
O₂ is needed to bind with free protons to maintain H gradient forming water. Terminal e⁻ acceptor

41. Aerobic Cell Respiration Electron Transport Chain & ATP Synthase Action
Chemiosmosis – the generation of ATP using energy released by the movement of hydrogen ions across the membrane

42. Aerobic Cell Respiration Electron Transport Chain & ATP Synthase Action
ATP Synthase – Protein structures inside the mitochondria that receives the H⁺ uses that flow to convert ADP into ATP.
Can make up to 34 ATP’s

43. Electron Transport Chain 34 ATP
The Final Count
Glycolysis 2 ATP
Kreb Cycle 2 ATP
Electron Transport Chain 34 ATP
Maximum ATP for 1 Glucose Molecule = 38
Notice most ATP is made after Glycolysis and Kreb Cycle – which are anaerobic (without O₂)

44. Cellular Respiration Chemical Formula:
Each glucose molecule yields 38 ATP molecules

45. Aerobic respiration