1. Structure of a Generalized Cell

2. The Cell The cell is the basic structural and functional unit of life.
The cells structural anatomy will determine its overall function.
All cells contains organelles which are the equivalent to organs of an organism.
They provide a specific function within the cell.
produces different types of proteins (enzymes)
That carry out overall cell activity.
There are many different types of cells that contain different proportions on organelles and enzymes.
This will dictate the cells overall specific function.
It is necessary to understand how the individual cell functions if you want to understand:
Function of the whole organism
Disease: start at a cellular level.
i.e. cancer

3. Variations in cells types

4. Fluid Mosaic Model of the Cell Membrane
Phospholipids bilayer with imbedded, dispersed proteins
Cholesterol provides stability to the membrane.
You can make these from essential fatty acids.
glycolipids: are lipids with bound carbohydrate
Glycocalyx is a glycoprotein important for cell recognition.

5. Plasma Membrane
Plays a dynamic role in cellular activity by controlling the movement of chemicals into/out of the cell
The cell membrane can control the passage of various substances including
ions
monosaccharides
amino acids
nucleotides
water

6. Phospholipids in a Bilayer
polar heads
non-polar tails
The polar heads: of each layer face outward towards the water molecules both in and out of the cell.
The non-polar tails face inward toward each other creating a barrier against the movement of polar substances into or out of the cell
Many organelles of the cell have one or more phospholipid bilayers .
endoplasmic reticulum
mitochondria
nucleus
Golgi complex
lysosomes

7. Integral or Transmembrane Proteins
Completely pass through the bilayer

8. Peripheral Proteins Do not penetrate through the membrane.
They associated with integral membrane proteins.

9. Mitochondria: Is known as the powerhouse of the cell.
In the presence of oxygen it can convert organic macromolecules into energy for the cell. (ATP) 18

10. Endoplasmic Reticulum (ER)
Interconnected network tubes within cytoplasm.
Rough ER Smooth ER

11. Rough ER External surface is studded with ribosomes.
Roles in the synthesizing both integral proteins, antibodies and phospholipids.
proteins synthesized in the ribosomes are taken inside (cisterna) the ER where they are modified into functional proteins.
( formation of H-bonds to create it’s 3 dimensional structure)
The proteins that are synthesized in the rough ER are shuttled to the Golgi apparatus for further modification.

12. Site for protein synthesis:
Ribosomes
Site for protein synthesis:
The assembly of amino acids to form proteins .i.e. enzyme, membrane-bound protein and muscles.
Free ribosomes in the cytoplasm
synthesize proteins that remain inside the cell
Membrane-bound ribosomes
can synthesize proteins such as integral proteins or proteins that get exported out of the cell.

13. Ribosome RER

14. Chaperones Proteins
Drags new protein from ribosome into cisterna of ER where they function to:
assist in proper folding of amino acids into proper 2nd and tertiary molecular structure
This is a result of the formation of disulfide bridges and H-bonds
remove some amino acids and adding carbohydrates when necessary.
Escort protein to Golgi Apparatus

15. Golgi Apparatus

16. Golgi Apparatus
Stacked and flattened membranous sacs that functions in modifying, concentrating and packaging proteins.
Create secretary vesicles contain modified proteins that leave the Golgi and export them through the cell membrane
This functions as the UPS of the cell.
Produces glycoproteins and proteoglycans
Lysosomes and peroxiosomes

17. Lysosomes
Vesicles containing digestive enzymes which hydrolyze macromolecules (intracellular digestion.)
Lysosomes function to:
hydrolyze ingested bacteria and viruses and toxins.
Recycle organic molecules such as amino acids, monosaccharides, fatty acids and nucleotides to make new macromolecules
Degrade nonfunctional organelles
Breakdown glycogen and release thyroid hormone
Breakdown bone to release Ca2+

18. Peroxisomes
Detoxify harmful or toxic substances such as alcohol and other drugs.
Abundant in the liver and kidneys
Neutralize dangerous free radicals
Free radicals – highly reactive chemicals with unpaired electrons (i.e., O2–)
H2O H2O +O2
Catalase:
converts hydrogen peroxide to water and oxygen.

19. Organelles of Protein Production and Excretion

20. Smooth ER
Smooth ER
Storage reserve for calcium (Ca2+) required for the functioning of the muscular contractions and transmission of nerve impulses.
Produce enzymes which:
Synthesize lipoproteins and metabolize lipids
Production of steroids based hormones such as testosterone.
Detoxify drugs and toxins such as alcohol and convert them to a less toxic water soluble form which can be excreted by the kidneys.
Long term use of drugs increase SER development resulting in more efficient drug detoxifying and greater drug tolerance

21. Cytoskeleton The “skeleton” of the cell
Dynamic, elaborate series of rods running through the cytosol
Consists of microtubules, microfilaments, and intermediate filaments

22. Nucleus

23. Largest organelle: functions as the control center of the cell.
Nucleus
Largest organelle: functions as the control center of the cell.
Contains (DNA) which provides instructions for the synthesis of all proteins.
DNA determines what proteins are synthesized
The proteins produced determine cellular function.
Some cells such as the RBC are anuclear
(no nuclei)
The liver and muscle cells are multinucleate
(More than one nucleus)

24. Nuclear Envelope/ Nucleoli
Nuclear Envelope :double membrane (phospholipid bilayer) structure containing many nuclear pores (allow passage in and out of the nucleus):
Raw material for the production of DNA and RNA
Enzymes that are made in the cytoplasm but function in the nucleus.
Nucleoli : Dark-staining spherical bodies within the nucleus contain the RNA that produces rRNA
code for the production of ribosome subunits.
These subunits can leave the nucleus through nuclear pores and join to form functional ribosomes.

25. Membrane Transport Movement of molecules through a membrane.
Passive transport: No ATP required!
Filtration
Simple diffusion
Facilitated diffusion
Osmosis
Active transport: Requires the break down of ATP!
Primary
Secondary
Exocytosis
Endocytosis

26. Passive Transport
Substances diffuses across the cell membrane from a high concentration to a low.
Like a ball rolling down a hill.
There is no energy expenditure! (ATP)
Various substances may accomplish this by different mechanisms:
nonpolar molecules such as lipids diffuse through the phospholipid bilayer unimpeded by a process called simple diffusion.
Some smaller polar molecules such as electrolytes and use integral membrane proteins. (channels)
Larger molecules such as sugar and amino acids require help (facilitation) of to cross the bilayer in a process called facilitated diffusion.

27. Diffusion
Molecules that are closer to each other collide and ricochet off each other. This results in a natural tendency to scatter.
A substance will always move down its gradient unless energy is put into the system.

28. Facilitated Diffusion
Required for larger substances such as glucose, amino acids, and some ions.
Travel down their concentration gradient binding to a
specific carrier protein. The carrier protein changes configuration and releases to substance into the cell.

29. Summery of Diffusion
Simple diffusion – nonpolar and lipid-soluble substances
Non polar molecules diffuse directly through the lipid bilayer
Polar molecules diffuse through channel proteins

30. Factors Affecting the Rate of Diffusion
Concentration (gradient)
The greater the difference in the concentrations of a substance, the greater the rate of diffusion.
Temperature
As temperature increases, the rate of diffusion increases.
Size of the substance
As the size of substances increase, the rate of diffusion decreases.

31. the more water will move toward the area of higher concentration.
Osmosis
The diffusion of water (solvent) across a selectively permeable membrane through water channels (aquaporins)
Water has a natural tendency to diffuse toward the area with the greatest amount of solutes
(dissolved substances in the water)
Think of making orange juice from concentrate. The concentrated orange juice is are the solutes. You must add the solvent (water) to it.
Osmotic pressure
the greater the difference in concentration of solutes the greater the osmotic pressure.
the more water will move toward the area of higher concentration.

32. Osmosis Diffusion of water through a semi-permeable membrane
from area of more water to area of less water
from low to high concentration of solute.
Aquaporins = channel proteins specialized for osmosis

33. Osmotic Pressure The water shifts to the left by osmosis.
Where there is a higher concentration of solutes.
Osmosis will stop due to filtration of water back across membrane due to hydrostatic pressure
The pressure of gravity on the left side.

34. Tonicity
Tonicity - ability of a solution to affect fluid volume and pressure within a cell.
depends on concentration and permeability of solute
Hypotonic solution (dilute outside the cell)
low concentration of solutes (high water concentration)
cells absorb water, swell and may burst (lyse)
Hypertonic solution (concentrated outside cell)
has high concentration of solutes (low water concentration)
cells lose water + shrivel (crenate)
Isotonic solution = (Equal concentrations both in and out of the cell.)
Cell will be at an osmotic equilibrium with solution
Water will always move to where it is more concentrated with solutes.

35. Tonicity of Red Blood Cells
Hypotonic Isotonic Hypertonic
(Swell) (No change) (Crenate/Shrink)

36. Clinical Application
You are a nurse working in the hospital and your patient’s doctor orders an IV because their blood work suggested they were dehydrated. What would you give the patient.
Distilled water
Normal saline .9%NACL
2% NACL saline
All of the above
None of the above

37. Clinical Application
You are a cyclist finishing a 2 hour ride on a hot summer day. What would be the drink of choice to replace your fluid loss.
Water
Gatorade
Protein shake
Orange juice
Corona

38. Filtration
Uses hydrostatic pressure (fire hose) Pressure gradient pushes solute-containing fluid from a higher-pressure area to a lower-pressure area.
The movement of water, nutrients and gases through capillary walls to supply the cells with nutrients. The pressure also allows the kidneys to filter the blood. (filtrate)

39. Types of Active Transport
Primary active transport – hydrolysis of ATP provides the energy to move solutes against their concentration gradient.
Secondary active transport – use of an exchange pump (such as the Na+-K+ pump) indirectly to drive the transport of other solutes
Exocytosis-Transport of substances out of the cell enclosed with in a membranous vesicle. The secretion of neurotransmitters, hormones, mucus and cellular waste.
Endocytosis - Substances are moved into the cell by engulfing them in a vesicle

40. Primary Active Transport
Process that hydrolyzes the high energy bond in a molecule of ATP (releasing energy)
Breaking the high energy bonds converts chemical energy within the bond to mechanical energy.
A substance can be forced from a region of lesser to greater concentration :
High Energy Bonds / lower energy bonds

41. Examples of Primary Active Transport
Na+,K+ Pump
located in the plasma membrane
actively pumps:
3 Na+ from the ICF →ECF
2 K+ from the ECF →ICF
maintains a Na+,K+ gradient across the cell membrane

42. Sodium-Potassium Pump
Extracellular fluid 6
K+ is released and Na+ sites are ready to bind Na+ again; the cycle repeats. 1
Binding of cytoplasmic Na+ to the pump protein stimulates phosphorylation by ATP.
Cytoplasm 2
Phosphorylation causes the protein to change its shape.
Concentration gradients of K+ and Na+ 5
Loss of phosphate restores the original conformation of the pump protein. 3
The shape change expels Na+ to the outside, and extracellular K+ binds. 4
K+ binding triggers release of the phosphate group.
Figure 3.10

43. Na+, Glucose Cotransporter

44. Example of Secondary Active Transport
Na+, glucose cotransporter
cotransports: Moves in the same direction as Na+
Na+ moves down its concentration gradient into the cell as a result of the gradient created by the Na+,K+-ATPase located at the basal (bottom) surface of cells.
SGLT(Na+ glucose transport protein): At the apical surface glucose is taken into the cell with Na+ down their concentration gradient by facilitated diffusion.
SGLT are important for reabsorbing glucose in kidney

45. Exocytosis

46. Types of Endocytosis Phagocytosis (cell eating)
endocytosis of few very large substances (bacteria, viruses, cell fragments)
vesicles containing cells fuse with lysosomes which digest the cells
Pinocytosis (cell drinking)
endocytosis of extracellular fluid

47. Phagocytosis