1. Understanding Homeostasis at the Cellular Level
CELL THEORY AND STRUCTURE

2. What are the 3 parts of the Cell Theory?
All living things are made of cells
Cells are the basic unit of structure and function in an organism (basic unit of life)
Cells come from the reproduction of existing cells (cell division)

3. History of Cells & the Cell Theory
In 1665,Hooke is responsible for naming cells
In 1673, Leeuwenhoek was first to view living organisms in pond water
In 1838, Schleiden concluded that all plants were made of cells
In 1839, Schwann concluded that all animals were made of cells
In 1855, Virchow observed, under the microscope, cells dividing and reasoned that all cells come from other pre-existing cells by cell division

4. Remember Endosymbiotic Theory
In 1970,Lynn Margulis, provided evidence that some organelles within cells were at one time free living cells themselves – this is called Endosymbiotic Theory
Chloroplasts and mitochondria were the organelles she pointed to as evidence of this theory
Chloroplast and Mitochondria have their own DNA which is different from the DNA of the cell

5. Number of Cells Unicellular – composed of one cell Ex: bacteria, yeast
Multicellular - composed of many cells that may organize
Ex: butterfly, flower

6. Prokaryotes Have a nucleoid region contains the DNA (no nucleus)
Have a cell membrane & cell wall
Contain ribosomes to make proteins in their cytoplasm

7. Eukaryotic Cell Contain 3 basic cell structures:
Nucleus (containing DNA)
Cell Membrane
Cytoplasm with organelles
Organelles have specific functions

8. Two Main Types of Eukaryotic Cells
Plant Cell
Animal Cell

9. Lysosome Contain digestive enzymes
Use Active Transport to trap and break down food an worn out cell parts

10. Nucleolus
Inside nucleus
Produces the ribosomes that make proteins

11. Smooth & Rough Endoplasmic Reticulum
Smooth ER - lacks ribosomes & detoxifies poisons and synthesizes lipids
Rough ER - has ribosomes on its surface & makes proteins to EXPORT

12. Mitochondria
Site of Cellular respiration – the capturing of energy from food
Breaks down glucose to produce energy ATP

13. Plant Cell Organelles Chloroplast
Process called photosynthesis occurs here

14. Plant Cell
Cell wall
Made of cellulose
Found in plant cells

15. Plant Cell Organelles
Vacuole
Have a large central vacuole

16. Animal Cell Organelles
Glycogen is stored in the cytoplasm of animal cells for food energy
glycogen granule

17. Animal Cell Organelles
Near the nucleus in an animal cell
Help cell divide

18. Differences between plant cells and animal cells
Relatively small in size
Relatively large in size
Irregular shape
Regular shape
No cell wall
Cell wall present

19. Differences between Plant Cells and Animal Cells
Vacuole small or absent
Large central vacuole
Glycogen as food storage
Starch as food storage
Nucleus at the center
Nucleus near cell wall

20. The Cell Membrane

21. Cell or Plasma Membrane
Composed of double layer of phospholipids and proteins
Controls what enters or leaves the cell
Surrounds outside of ALL cells
Outside
of cell
Inside
(cytoplasm)
Cell
membrane
Proteins
Protein
channel
Lipid bilayer
Carbohydrate
chains

22. Semipermeable Membrane
The cell membranes of all cells are selectively permeable
This means that some materials can pass easily through the membrane
Examples: H20, CO2 and O2
This also means that some materials cannot pass easily through the membrane
Examples: glucose and salts

23. Cell Membrane Proteins
Proteins help move large molecules or aid in cell recognition
Peripheral proteins are attached on the surface (inner or outer)
Integral proteins are embedded completely through the membrane

24. Other Functions of Plasma Membrane
Provide a binding site for enzymes
Interlocking surfaces bind cells together (junctions)
Contains the cytoplasm (fluid in cell)

25. Phospholipids Phospholipid bilayer makes up the cell membrane
Contains a polar head (attracts H2O) and 2 non-polar fatty acid tails (repels H2O)
How is a phospholipid different from a triglyceride?

26. Fluid-Mosaic Model of the Cell
Fluid: individual phospholipids and proteins can move side-to-side within the layer, like a liquid.
Mosaic: the pattern produced by the scattered proteins on the surface of the cell when the membrane is viewed from above.

27. Solubility of the Membrane
Materials that are soluble in lipids can pass through the cell membrane easily
Ex: Oxygen, carbon dioxide, and water

28. Cell Transport Mechanisms
Passive Transport
Active Transport
Does not require cellular energy
Types:
Simple Diffusion
Osmosis
Facilitated Diffusion
Does require cellular energy
Types:
Membrane Pumps
Endocytosis
Exocytosis

29. Passive Transport

30. Simple Diffusion
Movement of materials from a region of high concentration to a region of low concentration
Materials are moving down/with their concentration gradient
Example:
Oxygen diffusing
into a cell and carbon dioxide
diffusing out using kinetic
energy

31. Simple Diffusion

32. Osmosis
Osmosis is the passive transport (diffusion) of water across a membrane
Moves from a region of HIGH water potential (low solute) to a region of LOW water potential (high solute)

33. Osmosis
The purpose of osmosis is to balance out the concentration of materials between the environment inside of the cell and the environment outside the cell
Water moves because the other materials cannot
This allows the cell to be in equilibrium - balance

34. Types of Solutions a Cell May be Found In
Solution - a liquid mixture in which the minor component (the solute) is uniformly distributed within the major component (the solvent).
Examples – salt water or glucose solutions; solutes are salt or glucose, solvent is water
Types of solutions:
Isotonic
Hypotonic
Hypertonic

35. Isotonic Solution ENVIRONMENT CELL
10% NaCL 90% H2O
ENVIRONMENT
CELL
10% NaCL
90% H2O
Q: What is the direction of water movement in an isotonic solution?
A: No net movement (water molecules moving equally back and forth)

36. Hypotonic Solution ENVIRONMENT CELL
10% NaCL 90% H2O
CELL
20% NaCL
80% H2O
Q: What is the direction of water movement in a hypotonic solution?
A: Water moves into the cell

37. Hypertonic Solution ENVIRONMENT CELL
15% NaCL 85% H2O
CELL
5% NaCL
95% H2O
Q: What is the direction of water movement in a hypertonic solution?
A: Water moves out of the cell.

38. Hypertonic or Hypotonic?
Hypotonic solution will result in cytolysis – cell bursts from build up of water inside cell
Hypertonic solution will result in plasmolysis – cell membrane pulls away from the cell wall in plant, fungal or bacterial cells
Plant cells prefer a hypotonic environment
Animal cells prefer an isotonic environment

39. Label the pictures: hypotonic, hypertonic, isotonic

40. Facilitated Diffusion
Uses transport proteins to move materials from high to low concentration
Examples: Glucose or amino acids moving from blood stream into a cell.

41. Active Transport

42. Proteins and Cell Membrane Function
Types of Membrane Proteins:
Structural
Cell recognition
Communication
Transport:
Channel proteins are embedded in the cell membrane & have a pore for materials to cross
Carrier proteins can change shape to move material from one side of the membrane to the other

43. materials to pass across
Channel Proteins
Channel proteins act
as bridges to allow
materials to pass across
the membrane

44. Carrier Proteins
Some Carrier proteins do not extend through the membrane.
They bond and drag molecules through the lipid bilayer

45. Protein Pumps
Cells need a steady supply of sodium (Na+), potassium (K+), calcium (Ca2+) and hydrogen (H+) in order to function correctly
Protein pumps that span the cell membrane are powered by ATP and supply these materials to the cell on demand
This requires a steady supply of ATP
Materials are moving from and area of low concentration to an area of high concentration
They are moving up/against their concentration gradient

46. 3 Na+ pumped out for every 2 K+ pumped in
Sodium Potassium Pump
3 Na+ pumped out for every 2 K+ pumped in

47. Types of Active Transport using Vesicles
Q: What is a vesicle?
A: A small bubble within a cell surrounded in its own lipid bilayer.
Q: What is the function of a vesicle?
A: Vesicles are involved in:
Metabolism
Transport of materials
Enzyme storage
Types of active transport using vesicles:
Exocytosis
Endocytosis

48. Exocytosis -using a vesicle to move big stuff out of the cell

49. Exocytosis How it works:
Vesicle is formed around some sort of material made by the cell (like proteins or hormones)
Vesicle is released and travels toward cell membrane
Vesicle fuses with cell membrane
Vesicle expels materials to the outside of the cell membrane

50. Endocytosis
Large amount of materials move into the cell by one of two forms of endocytosis:
Pinocytosis -
Materials dissolve in water to be brought into cell
Called “Cell Drinking”
Phagocytosis - Used to engulf large particles such as food, bacteria, etc. into vesicles.
Called “Cell Eating”
White blood cells eat foreign substances in your body this way

51. Endocytosis
Pinocytosis