1. Ch. 7 – Cells

2. I. Cells
A. What is a cell? 1. Cell – the smallest unit of matter that can carry on all the processes of life

3. I. Cells
B. Who first discovered the cell? 1. Anton van Leeuwenhoek – first to observe cells 2. Robert Hooke – used the light microscope to observe cork a. First person to call the shapes inside of organisms “cells”

4. I. Cells
3. Rudolph Virchow – studied cell reproduction and discovered that all cells come from other pre- existing cells.

5. I. Cells
4. Mathias Schleiden – studied plants and discovered that all plants are made of cells 5. Theodor Schwann – studied animals and discovered that all animals are made of cells

6. I. Cells
C. What is the cell theory? 1. The cell theory was developed by theories of Hooke, Virchow, Schleiden, and Schwann. a. The cell is the basic unit of organization for organisms. b. All organisms are made of one or more cells. c. All cells come from other pre-existing cells.

7. I. Cells
2. With better microscopes, scientists observed that cells contained specialized structures. a. Organelles – cells parts that perform a specific job or function for the cell

8. I. Cells
D. Cell Diversity! 1. Your body alone contains 200 different cell types! 2. Cells Organisms can be classified by the number of cells they are made up of. a. Unicellular Organism – single celled organism Example: bacteria, yeast b. Multicellular Organism – organism made up of many cells Example: plants, animals

9. I. Cells 1. Nucleus 2. Nucleolus 3. Chromatin 4. Cell membrane
E. How are cells classified based upon the presence/absence of organelles? 1. Eukaryotic Cells – cells with a membrane-bound nucleus and organelles a. Examples: plant and animal cells
1. Nucleus
2. Nucleolus
3. Chromatin
4. Cell membrane
5. Organelles

10. I. Cells 2. DNA 3. Cell membrane 1. Ribosomes 4. Cell wall
2. Prokaryotic Cells – cells with no membrane-bound nucleus or organelles (except ribosomes) a. Examples: bacteria
2. DNA
3. Cell membrane
1. Ribosomes
4. Cell wall

11. I. Cells
Left: Colorized micrograph of a prokaryotic cell of the bacterium.
Right: Colorized micrograph of a eukaryotic cell of the green algae.

12. I. Cells 3. Review: Cell Type Nucleus? Organelles?
Uni or Multicellular?
Prokaryotic
Eukaryotic

13. Plasma (Cell) Membrane
II. Cell Boundaries
Plasma (Cell) Membrane
Function:
Surrounds cell
Allows things in and out (homeostasis)
Fact:
Selectively permeable – allows water and nutrients in and waste out
Made of phospholipids
Found in:
Prokaryotes
Eukaryotes

14. 2. Cell wall 1. Cell membrane II. Cell Boundaries Cell Wall Function:
Surrounds cell membrane to provide extra support and protection
Fact:
Made of cellulose in plants
Found in:
Prokaryotes
Eukaryotes (plants)
2. Cell wall
1. Cell membrane

15. III. Cell Control Nucleus Nucleus Nucleus Function:
Controls the organelles
Contains DNA
Fact:
“Command center” or “brain” of the cell
Most prominent structure
Found in:
Eukaryotes
Nucleus

16. III. Cell Control Chromatin Function:
Condense to form chromosomes in nucleus
Fact:
Strands of DNA that look like spaghetti
Found in:
Eukaryotes

17. III. Cell Control Nucleolus Nucleolus Nucleolus Function:
Makes ribosomes
Fact:
Found inside the nucleus
Found in:
Eukaryotes
Nucleolus

18. III. Cell Control Ribosomes Ribosomes Function: Makes proteins Fact:
Made of RNA
Can be free or attached to ER
Found in:
Eukaryotes
Prokaryotes
Ribosomes

19. III. Cell Control Nuclear Envelope/Membrane Function:
Controls what enters/exits the nucleus
Fact:
Surrounds the nucleus
Found in:
Eukaryotes

20. IV. Cell Assembly Cytoplasm Function: Suspends/holds organelles
Site of chemical reactions
Fact:
Contains clear gel-like fluid called cytosol
Found in:
Eukaryotes
Prokaryotes

21. IV. Cell Assembly Rough Endoplasmic Reticulum (ER) Function:
Produces proteins
Fact:
Helps move molecules throughout the cell
Found in:
Eukaryotes

22. IV. Cell Assembly Smooth Endoplasmic Reticulum (ER) Function:
Produces lipids (steroids)
Detoxifies poisons
Fact:
Helps move molecules throughout the cell
Found in:
Eukaryotes

23. IV. Cell Assembly Golgi Golgi Apparatus Function:
Processes, packs, and secretes proteins and lipids
Fact:
Works closely with ER
Flattened stack of membranes
Found in:
Eukaryotes
Golgi

24. IV. Cell Assembly Vacuole Vacuole Function:
Stores food, water, waste, proteins, carbs
Fact:
Helps maintain homeostasis
Found in:
Eukaryotes (plants have a LARGE
vacuole)
Vacuole

25. IV. Cell Assembly Lysosome Lysosomes Function:
Uses enzymes to digest old organelles and foreign objects (bacteria, viruses)
Fact:
“Suicide sacs”
Found in:
Eukaryotes
Lysosome

26. IV. Cell Assembly
Ever wonder how a tadpole gets rid of its tail and grows legs????
It’s lysosomes digest the cells in the tail, and these molecules are released to build different cells, like legs!

27. V. Energy Transformers Chloroplast Chloroplast Function:
Capture light (solar energy) and
convert it to chemical energy
during photosynthesis
Fact:
Glucose is the sugar made
Found in:
Eukaryotes (plants)
Chloroplast

28. V. Energy Transformers Mitochondria Mitochondria Function:
Breaks down food into ATP energy during cellular respiration
Fact:
“Powerhouse” of the cell
Found in:
Eukaryotes
Mitochondria

29. VI. Support & Locomotion
Cytoskeleton
Function:
Maintains the shape & supports the cell
Fact:
Made of microfilaments & microtubules
Found throughout the cytoplasm
Found in:
Eukaryotes
Prokaryotes

30. VI. Support & Locomotion
Cilia
Function:
Movement of cells or fluids
Fact:
Short hair-like fibers
Found in:
Eukaryotes
Prokaryotes

31. VI. Support & Locomotion
Cilia
Flagella
Function:
Movement of cells
Fact:
Long hair-like fibers
Found in:
Eukaryotes
Prokaryotes
Flagella

32. VII. Levels of Organization
A. Organization: Organelles  Cells  Tissues  Organs  Organ systems  Organisms

33. VIII. THE CELL MEMBRANE
A. A cell’s survival depends on the cell’s ability to maintain the necessary conditions inside itself.
1. Maintaining these constant internal conditions is called homeostasis.

34. VIII. THE CELL MEMBRANE
B. Cell Membrane – flexible boundary between the cell and its outside environment
1. Allows water and nutrients to enter the cell and wastes to leave the cell.
Water
Cell Membrane

35. VIII. THE CELL MEMBRANE
2. Selectively Permeable – allowing some materials to pass while keeping others out
a. Example: A spaghetti strainer allows water, but not spaghetti to pass through

36. VIII. THE CELL MEMBRANE
C. What is the cell membrane made up of? 1. Phospholipids – diglyceride with a phosphate group attached

37. VIII. THE CELL MEMBRANE
a. Phospholipid Bilayer – the cell membrane is TWO layers thick

38. VIII. THE CELL MEMBRANE
b. Phospholipids have a polar “head” and non polar “tail”.
- Polar “heads” are attracted to water, sugars, and proteins.

39. VIII. THE CELL MEMBRANE
- Non-polar “tails” repel water, sugars, and proteins.
- Resulting in a selectively permeable membrane.

40. VIII. THE CELL MEMBRANE
2. Proteins are embedded in the cell membrane to recognize substances that can enter and exit the cell.

41. VIII. THE CELL MEMBRANE
3. Cholesterol stabilizes the membrane by preventing lipids from sticking together.

42. VIII. THE CELL MEMBRANE
D. Fluid Mosaic Model - describes how phospholipids can move around like a fluid and the proteins make a pattern

43. VIIII. Cell Transport
A. What types of materials need to cross the cells membrane? Water, nutrients, oxygen, waste B. In cells, particles always move to reach equal concentrations. 1. Concentration Gradient – unequal distribution of particles

44. VIIII. Cell Transport
C. Types of Transport 1. Passive Transport – movement of any substance across a membrane WITHOUT the use of chemical energy. a. Occurs from high to low concentration, with the concentration gradient.

45. VIIII. Cell Transport
b. Types of Passive Transport - Diffusion – movement of molecules across a selectively permeable membrane; occurs from high to low concentration, with the concentration gradient.

46. VIIII. Cell Transport
- Example: Oxygen diffuses into the bloodstream because of a high pressure in the lungs.

47. VIIII. Cell Transport
- Osmosis – movement of water across a selectively permeable membrane; occurs from high to low concentration, with the concentration gradient.

48. VIIII. Cell Transport
c. How are larger and strongly charged molecules, such as glucose, able to pass through the cell membrane more quickly than they should? - Facilitated diffusion – passive transport of large particles across a membrane with the help of proteins; occurs from a high to low concentration, with the concentration gradient - Example: Sugars, Amino Acids
Glucose
molecules
Low
Concentration
Cell
Membrane
High
Protein
channel

49. VIIII. Cell Transport

50. VIIII. Cell Transport
2. Types of Solution – How does the water “know” which way to move? a. Hypertonic Solution – (high solute concentration) more water on the inside of the cell than the outside of the cell. - Water moves OUT of the cell. - Size of the cell = shrinks (plasmolysis)
Cell
Over
time
H2O + NaCl Solution

51. VIIII. Cell Transport
b. Hypotonic Solution – (low solute concentration) more water on the outside of the cell than the inside of the cell. - Water moves INTO the cell. - Size of the cell = swells - Cytolysis = animal cells burst - Turgor Pressure = water pushes against cell wall in plants
Cell
Over
time
H2O + NaCl Solution

52. VIIII. Cell Transport - Water moves in and out of cell equally.
c. Isotonic Solution – equal concentration of water and solute inside and outside the cell
- Water moves in and out of cell equally.
- Size of cell = stays the same
Cell
Over
time
H2O + NaCl Solution

53. VIIII. Cell Transport Criteria Inside Cell Outside Cell
Where is there more solvent (water)?
hypertonic
hypotonic
Where is there more solute (salts, dissolved substances)?

54. Cell Transport

55. VIIII. Cell Transport
3. Diffusion is a powerful process, however, sometimes cells need to move materials in the opposite direction. a. Active Transport – proteins are used to move ions or molecules against the concentration gradient, using ATP energy. - Occurs from areas of low to high concentrations. - Examples: minerals, nutrients

56. VIIII. Cell Transport
4. Types of Active Transport a. Endocytosis – process when a cell surrounds and takes in materials from the environment - Example: White blood cell engulfing a bacterium.

57. VIIII. Cell Transport
- Two types of Endocytosis - Pinocytosis – movement of liquids into a cell - Phagocytosis – movement of solids in a cell

58. VIIII. Cell Transport
b. Exocytosis – the explusion (exit) or secretion of material out a cell - Example: Cell getting rid of waste.

59. VIIII. Cell Transport
c. Although endocytosis and exocytosis are different, the two processes often work TOGETHER.