1. Physiology of Cells
Cellular Processes

2. Steven Hawkins
Steven Hawkins holds a professorship at Cambridge, the same one once held by Isaac Newton and has made contributions to study of black holes and the origin of the universe.
Suffers from motor neuron disease in which his nerve cells that stimulate muscle control gradually die causing him to lose muscle control. His muscle cells are unable to open their protein channels thus preventing muscle contraction.

3. Membrane Transport Passive Transport Active Transport
Simple diffusion down concentration gradient
Facilitated Diffusion occurs through channel proteins
Active Transport
Requires energy

4. Diffusion Molecules always move from high to low concentrations
Occurs down a concentration gradient
Effective only across small distance.

6. Permeability
Plasma membrane allows only certain substance to diffuse across.
Non-polar lipid based substances, steroids, diffuse quickly through membrane

7. Solute Concentrations
Isotonic- equal amount of solutes
Hypotonic- solution has lower solute concentration
Hypertonic- solution has higher concentration of solutes

8. Osmosis Diffusion of water Occurs easily through bi-lipid layer
Aquaporins allow for quicker movement of water

9. Facilitated Diffusion
When a molecule either passes through or binds to an channel protein to cross a membrane.

10. Carrier Proteins
When substance being transported binds to protein

11. Active Transport Moves substances against concentration gradient
Sodium-Potassium pump
Digitalis, a drug given to strengthen the heart beat, exerts its effect by slowing the sodium pump, which allows more sodium and calcium to accumulate in heart muscle cells. The increased Ca2+ concentration has a positive effect on the force of cardiac cell contraction.

12. Bulk Transport Endocytosis
Phagocytosis movement of large molecules into the cell
Pinocytosis is the ingestion of extracellular fluid
Exocytosis moves large molecules out of cell
Ex: proteins, waste

14. Cell Transport

17. Diseases of Cell Membrane
Cystic Fibrosis
does not allow Cl- to pumped across the membrane
Mucus and secretions in lungs, pancreas thicken
Duchenne Muscular Dystrophy
“leaky” Ca++ channels
Type II Diabetes
Cells become less sensitive to insulin

18. Cellular Respiration
Metabolism happens in a series of separate reactions
Each step is catalzyed by a separate enzyme
Cellular respiration occurs inside the mitochondria(except glycolysis)

19. Steps of Cellular Respiration
Glycolysis
Pyruvate Oxidation
Kreb Cycle
Electron Transport Chain
Net gain of 36 ATP
Waste products CO2 & H2O

20. Redox Reactions
Oxidation= lose electrons
Reduction=gain electrons

21. NAD Nicotinamide adenine dinucleotide
Coenzyme energy carrier
NAD+(oxidized)
NADH + H+(reduced)

22. Other Coenzymes NADP (nicotinamide adenine dinucleotide phosphate)
FAD (flavin adenine dinucleotide

23. Glucose the body’s fuel
Complex carbs are broken down into glucose
Glucose is the bodies preferred source of fuel
Glucose can be used to form amino acids, which then can be incorporated into proteins.
Excess glucose can be stored by liver and skeletal muscles as glycogen.
If glycogen storage areas fill up, liver cells and fat cells can convert glucose to glycerol and fatty acids.

24. Glycolsis Glycolysis takes place in cytoplasm of cell
Creates 2 ATP(net)
2 molecules of pyruvate

25. Pyruvate Oxidation Pyruvate is oxidized to Acetyl CoA
Pyruvate + NAD+ + CoA  Acetyl CoA + NADH + H+ + CO2

26. Kreb (Citric Acid) Cycle
1 molecule of pyruvic acid produces 3 molecules of CO2,
4 molecules of NADH + H+
1 molecule of FADH2
1 molecule of GTP (guanine triphosphate, the equivalent of ATP).

27. Electron Transport Chain
The respiratory chain uses the reducing agents generated by pyruvate oxidation and the citric acid cycle.
The flow of electrons in a series of redox reactions causes the active transport of protons across the inner mitochondrial membrane, creating a proton concentration gradient.
The protons then diffuse through proton channels down the concentration and electrical gradient back into the matrix of the mitochondria, creating ATP in the process.
ATP synthesis by electron transport is called oxidative phosphorylation.

28. Electron Transport Chain

29. Electron Transport Chain
NADH + H+ passes its hydrogen atoms to the NADH-Q reductase protein complex.
The NADH-Q reductase passes the hydrogens on to ubiquinone (Q), forming QH2.
The QH2 passes electrons to cytochrome c reductase complex which in turn passes them to cytochrome c.
Next to receive them is cytochrome c oxidase complex. Then they are passed to O2.
Reduced oxygen unites with two hydrogen ions to form water.

31. Electron Transport Chain
As electrons pass through the respiratory chain, protons are pumped by active transport into the intermembrane space against their concentration gradient.
This transport results in a difference in electric charge across the membrane.
The potential energy generated is called the proton-motive force.

32. Electron Transport Chain
Chemiosmosis is the coupling of the proton-motive force and ATP synthesis.
NADH + H+ or FADH2 yield energy upon oxidation.
The energy is used to pump protons into the intermembrane space, contributing to the proton-motive force.
The potential energy from the proton-motive force is harnessed by ATP synthase to synthesize ATP from ADP.

33. Relationships between Metabolic Pathways
Catabolic interconversions:
Polysaccharides are hydrolyzed into glucose, which passes on to glycolysis.
Lipids are converted to fatty acids, which become acetate (then acetyl CoA), and glycerol, which is converted to an intermediate in glycolysis.
Proteins are hydrolyzed into amino acids, which feed into glycolysis or the citric acid cycle.

34. Relationships between Metabolic Pathways
What happens if inadequate food molecules are available?
Glycogen stores in muscle and liver are used first.
Fats are used next. But the brain can only use glucose, so it must be synthesized by gluconeogenesis which uses mostly amino acids.
Therefore, proteins must be broken down.
After fats are depleted, proteins alone provide energy.