1. The Structure & Function of Cells

2. Most cells are of this type (body cells, plant cells, Protists, etc.)
The Cell is the basic functional unit of ALL living things. There are 2 basic categories of cells:
1. Eukaryotic Cells= contain plasma membrane (cell membrane), organelles, nucleus, cytoplasm
Most cells are of this type (body cells, plant cells, Protists, etc.)
Evolutionarily this is a recent advancement

3. Bacteria cells are of this type
2. Prokaryotic Cells = contain plasma membrane (cell membrane) and cytoplasm but NO ORGANELLES, NO NUCLEUS
Bacteria cells are of this type
Ribosomes are the only other real internal structure
The oldest of cell types are prokaryotic
Question #1

4. Animal Cell

5. Plant Cell
Polysome
On Endoplasmic Reticulum = Rough

7. IMPORTANT PARTS OF THE CELL
Cell OR Plasma Membrane: separates the internal metabolic events from the external environment surrounding the cell
Function= control the movement of materials into and out of the cell
Structure= a double phospholipid membrane (Lipid Bilayer), Polar hydrophilic “water loving” heads pointing toward outside and inside of the cell; Nonpolar hydrophobic “water fearing” tails point toward the inside of the membrane.
Question #2

9. “Fluid Mosaic Model” of the Cell Membrane

10. 2. Integral Proteins: extend into the membrane
Fluid Mosaic Model= describes the structure of the cell membrane. PROTEINS are scattered throughout the flexible lipid bilayer. These proteins can be of 3 different types:
Question # 8
1. Peripheral Proteins: attached loosely to the inner or outer surface of the membrane
2. Integral Proteins: extend into the membrane
3. Transmembrane Proteins: an integral protein that spans across the membrane and appears at both surfaces

11. Phospholipid Bilayer with Embedded Proteins

13. Proteins in the plasma membrane provide a wide range of functions including: Question #9
Channel Proteins: provide passageways through the membrane for certain water soluble substances (i.e. polar & charged molecules)
Transport Protein: use energy to transport materials across the membrane against a concentration gradient
Recognition Proteins(Glycoproteins): used to distinguish the identity of neighboring cells
Adhesion Proteins: attach cells to neighboring cells, provide stability
Receptor Proteins: provide a binding site for hormones or other chemical triggers
Electron Transfer Proteins: transfer electrons from one molecule to another during chemical reactions

14. Features of the Plasma Membrane
It is Semi-Permeable = only small, uncharged, polar, hydrophobic molecules pass freely across the membrane
Permeable = H2O , CO2 , O2 , lipid soluble hydrocarbons
NON-Permeable = large molecules, glucose, all ions

15. Lets water flow freely, restricts the flow of glucose molecules
Water passes freely raising the water level on side 2

16. Types of Membrane Proteins

17. Features of the Plasma Membrane
Cholesterol= provide some rigidity to the fluid nature of the membrane in animal cells. Act as a “Cellular Antifreeze” to keep a cell from freezing in cold temps. or melting in warm temps.
Question #11

18. Features of the Plasma Membrane
4. Glycocalyx= carbohydrate coat covering the outer surface of the cell membrane. Used for cell to cell recognition.
Features of the Plasma Membrane

19. ORGANELLES OF THE CELL
Organelle = a structure in the cytoplasm (semi-fluid medium between nucleus and cell membrane) of the cell that serves a specific function related to the metabolism of the cell
Nucleus: contains DNA, the hereditary information of the cell.
Surrounded by a nuclear envelope
Normal DNA = Chromatin: spread out in a threadlike matrix
Chromosomes: visible when the cell begins to divide

21. The Pores in the Nuclear Envelope:
NEW SLIDE!!!!!
Nuclear Envelope = Nuclear Membrane
Provide for the movement of:
Proteins into the nucleus
mRNA out of the nucleus
Ribosome subunits out of the nucleus
Endomembrane System: Connects the nucleus to the cell membrane
Nuclear Envelope (Pores) --> Rough ER --> Golgi --> Smooth ER --> Lysosomes --> Cell Membrane
Question # 3
Question # 6

22. Nucleolus: produces rRNA & multiple copies of genes ; concentrations of DNA in the process of manufacturing the components of Ribosomes
ORGANELLES OF THE CELL
Question # 4
Synthesis & Storage of Ribosomes

23. Ribosomes: assemble amino acids into proteins in the cytoplasm
ORGANELLES OF THE CELL
Question # 14
Has large and small subunits
Cells producing secretory products have many ribosomes

24. ORGANELLES OF THE CELL
Endoplasmic Reticulum (ER): stacks of flattened sacs involved in the production of various membranes & products (#13), looks like a maze when viewed in cross-section, often connected to the nucleus
Rough ER: has ribosomes on it, specializes in protein synthesis; manufacture membranes and other secretory products (#14)
Smooth ER: NO ribosomes, specializes in the production of lipids, detoxification, storage & release of ions etc. (depends on the cell type) (#14)

26. ORGANELLES OF THE CELL
Golgi Apparatus(Complex or Body): a group of flattened sacs arranged like a stack of bowls
has a Cis and Trans face (opposite fat vs thin ends)
Function to modify and package proteins and lipids, products of Rough ER
Puts the products into Vesicles
Contents of vesicles get released outside the cell
Question # 14

27. Lysosomes: Acidic pH; vesicles that contain hydrolytic digestive enzymes to digest macromolecules . NOT FOUND IN PLANT CELLS
ORGANELLES OF THE CELL

28. ORGANELLES OF THE CELL Peroxisomes: breakdown various substances
O2 + H2  H2O2
Common in liver and kidney cells
ORGANELLES OF THE CELL

29. ORGANELLES OF THE CELL Mitochondria: carry out cellular respiration
Energy in the form of ATP is obtained from carbohydrates
ORGANELLES OF THE CELL
Double membrane sac with Cristae (folding inner membraene)

30. Chloroplasts: carry out photosynthesis in plants; this is where plants incorporate energy from the sun to make carbohydrates
ORGANELLES OF THE CELL
Thylakoids (Grana): System of flattened sacs inside chloroplast

31. ORGANELLES OF THE CELL MAINTAIN CELL SHAPE & Anchors Organelles
Cytoskeleton: internal structure of the cytoplasm
MAINTAIN CELL SHAPE & Anchors Organelles
Microtubules = provide support and motility, made of protein tubulin (spindle fibers during cell division; cilia & flagella) (#10)
Intermediate Filaments = support, maintain cell shape
Microfilaments = made of protein actin, involved in cell motility

32. Internal Anatomy of a cell

33. ORGANELLES OF THE CELL
Flagella and Cilia: protrude from the cell membrane, used for movement
Flagella = long and few
Cilia = short and many
Both arranged in “9+2” arrangement

34. Centrioles and Basal Bodies: Microtubule organizing centers
ORGANELLES OF THE CELL

35. Cell Wall: found only in plants; outside of plasma membrane, provides support, made of Cellulose
ORGANELLES OF THE CELL

37. ORGANELLES OF THE CELL
Vacuoles and Vesicles: fluid filled, single membrane bound bodies
Transport Vesicles= move materials between organelles
Food Vacuoles= temporary food storage
Storage Vacuoles= store starch, pigments, and toxins
Central Vacuole= fill up most of the interior in plant cells, maintain rigidity of the cell (Plant)
Contractile Vacuoles= collect and pump excess water out of a cell (Plant or Animal)

39. ORGANELLES OF THE CELL
Cell Junctions: serve to anchor cells to one another
Desmosomes= act as “spot welds” to hold adjacent animal cells together in high stress tissues (skin, heart muscle)
Tight Junctions= “stitched seams” between animal cells, prevent movement of material between the cells (cells lining the digestive tract).
Gap Junctions= narrow tunnels between animal cells, allow passage of small ions and molecules, communication through electrical impulses
Plasmodesmata= narrow channels between plant cell

40. Types of Cell Junctions
Desmosome
Tight Junction
Gap J unction

41. Plants = cell walls, large vacuole, chloroplasts
Animal = lysosomes, centrioles
Plant vs. Animal Cells
Animal Cell
Plant Cell

42. Prokaryotes vs. Eukaryotes
Prokaryotes: No nucleus, No Organelles, Single stranded “naked” DNA, Only Bacteria
Eukaryotes: Have a nucleus, Lots of Organelles, DNA in chromosomes, All other cells

43. The Movement of Substances
The cell membrane and the membrane of other organelles are Semi-permeable = only certain substances can cross the membrane
Selective Permeability= allowing only specific substances to pass
Water = solvent; dissolved particles = solute
Movement of substances may be from higher to lower concentrations (down or with the concentration gradient) or the reverse (up or against the gradient)
The movement of substances may be active or passive

44. Selective Permeability

45. Solute concentrations may be compared:
Hypertonic= higher concentration of solutes
Hypotonic= lower concentration of solutes
Isotonic= equal concentration of solutes
………relative to another region.

50. Other Types of Movement
Bulk Flow= collective movement of substances in the same direction in response to some force or pressure (blood moving through a vessel)

51. Passive vs. Active Transport
Passive Transport= Movement of molecules down a concentration gradient (high  low)
Does not require the cell to expend any energy!
1. Diffusion: due to the random nature of molecules in motion (dye in a beaker of water)
Rates of diffusion are determined by:
Concentration gradient
Shape and size of the molecules
Temperature (higher temp. = faster diffusion time)
Liquid vs. gas (slower in liquids)

53. Passive Transport
2. Osmosis: the diffusion of water molecules across a semi-permeable membrane
Osmotic Pressure = force water exerts against the inside of a cell
Turgor Pressure = pressure water exerts against the inside of a plant cell, used for structural support

55. Passive Transport
3. Dialysis: diffusion of solutes across a semi-permeable membrane
4. Plasmolysis: movement of water out of a cell, results in the collapse of the cell
5. Facilitated Diffusion: use channel proteins embedded in the membrane to transport solutes

57. Active Transport
Active Transport= requires the cell to expend energy to move substances against the concentration gradient (low high)
Usually utilizes transport proteins to move: small ions (Na+, K+, Cl-, H+), amino acids, simple sugars

58. Active Transport
Exocytosis: Large particles are released from the cell by vesicles forming and fusing with the cell membrane
Endocytosis: Large particles enter the cell by vesicles forming and fusing with the cell membrane
Phagocytosis = cell eating (white blood cells attacking bacteria)
Pinocytosis = cell drinking
Receptor Mediated Endocytosis = special receptors attract certain molecules (cholesterol transport in the blood, hormones)