1. Chapter Seven
A View of the Cell

2. Cellular Organization
Tissue – group of cells functioning together.
Organ – group of tissues functioning together.
Organ System – group of organs functioning together.
Organism – group of organ systems functioning together.

3. The History of the Cell The Cell The basic unit of an organism
Discovery made possible by the invention of the microscope

4. Microscopes and Cells 1600’s.
Anton van Leeuwenhoek first described living cells as seen through a simple microscope.

5. Microscopes and Cells
Robert Hooke used the first compound microscope to view thinly sliced cork cells.
Compound scopes use a series of lenses to magnify in steps.
Hooke was the first to use the term “cell”.

6. Microscopes and Cells 1830’s.
Mathias Schleiden identified the first plant cells and concluded that all plants
made of cells.
- Thomas Schwann made the same conclusion about animal cells.

7. Cell Theory:
All organisms are made up of one or more cells.
The cell is the basic unit of organization of all organisms.
All cells come from other cells all ready in existence.

8. Two Basic Cell Types 1) Prokaryote Lacks internal compartments.
No true nucleus.
Most are single-celled (unicellular) organisms.
Examples: bacteria

9. Two Basic Cell Types 2) Eukaryote
Has several internal structures (organelles).
True nucleus.
Either unicellular or multicellular.
unicellular example: yeast
multicellular examples:
plants and animals

10. Cell size comparison most bacteria Animal cell 1-10 microns
Bacterial cell
Animal cell
most bacteria
1-10 microns
eukaryotic cells
microns
micron = micrometer = 1/1,000,000 meter
diameter of human hair = ~20 microns

11. The Parts of The Eukaryotic Cell 1) Boundaries
A) Plasma Membrane
-- Serves as a boundary between the cell and its external environment.
-- Allows materials to pass in and out of the cell.

13. 1) Boundaries B) Cell Wall
-- Surrounds the plasma membrane of the cells of plants, bacteria, and fungi.
-- Plant cell walls contain cellulose while fungi cell walls contain chitin.

14. The Parts of The Eukaryotic Cell: 2) Controls
A) Nucleus
Regulates cell function.
Surrounded by a double-layered membrane (nuclear enveloped) with large pores that allow materials to pass in and out of the nucleus.
Contains chromatin – long tangles of DNA.

15. 2) Controls B) Nucleolus
Found in the nucleus and responsible for ribosome production. Ribosomes are the sites of protein production.

17. The Parts of The Eukaryotic Cell: 3) Assembly
Cytoplasm
The jelly-like material that surrounds the organelles.

18. The Parts of The Eukaryotic Cell: 4) Transport
A) Endoplasmic reticulum
Folded membrane that acts as the cell’s delivery system.
Smooth E.R. contains enzymes for lipid synthesis.
Rough E.R. is studded with ribosomes for protein synthesis.

20. 4) Transport B) Golgi apparatus (or Golgi body)
A series of flattened sacs where newly made lipids and proteins from the E.R. are repackaged and shipped to the plasma membrane.

22. The Parts of The Eukaryotic Cell: 5) Storage
A) Vacuoles
A sac of fluid surrounded by a membrane used to store food, fluid, or waste products.

24. 5) Storage B) Lysosomes Contain a digestive enzyme.
Can fuse with vacuoles to digest food, or can digest worn cell parts.
Also known as “suicide sacs” because they can also destroy the whole cell.

26. The Parts of The Eukaryotic Cell: 6) Energy Transformers
A)Mitochondria
Produce the energy for the cell.
Also known as the “powerhouse of the cell”.
Has a highly folded
inner membrane (cristae).

27. 6) Energy Transformers B) Chloroplasts
-- Found in plant cells and some protists.
-- Transforms light energy into chemical energy which is stored in food molecules.
-- Contain chlorophyll – a green pigment that traps light energy and gives plants their green color.

29. The Parts of The Eukaryotic Cell: 7) Support
Cytoskeleton
A network of thin, fibrous materials that act as a scaffold and support the organelles.
Microtubules – hollow filaments of protein.
Microfilaments – solid filaments of protein.

30. The Parts of The Eukaryotic Cell: 8) Locomotion
1) Cilia
Short, numerous, hair-like projections from the plasma membrane.
Move with a coordinated beating action.

31. 8) Locomotion B) Flagella
Longer, less numerous projections from the plasma membrane.
Move with a whiplike action.

32. The Parts of The Eukaryotic Cell: 9) Cell Division
Centrioles
made of protein.
play a role in the splitting of the cell into two cells.
found in animal and fungi cells.

34. Composite Animal Cell Flagella nucleolus Nucleus Chromosomes
Ribosomes
Endoplasic
reticulum
Microtuble
Mitochondrion
Picture adapted from Access Excellence’ rescource center:
Golgi apparatus
Centrioles
Cillia
Composite Animal Cell

35. Teachers: you may want to print out this diagram, photocopy it for each
student and have them fill in the blanks as you go through this presentation.
Composite Animal Cell

36. Types of cells animal cells plant cells bacteria cells Prokaryote
- no organelles
Eukaryotes
- organelles
animal cells
plant cells

37. Movement Across the Membrane
Establishes Homeostasis
Occurs through channel proteins
Can be active or passive
Passive does not require energy
Active does require energy

38. Passive Transport-Diffusion
Particles in a solution move constantly
Particles tend to move from an area of high concentration to low concentration
When concentration is equal everywhere, it has reached equilibrium
Substances diffuse across membranes without requiring the cell to use energy (passive transport)

39. Diffusion
Diffusion-
movement from HIGH concentration LOW concentration

40. Passive Transport-Osmosis
If a substance can diffuse across a membrane, the membrane is said to be permeable to it and impermeable if it can't diffuse across it
Water diffuses easily
Osmosis is the diffusion of water across a selectively permeable membrane from an area of high concentration to low concentration

41. Osmosis hypotonic hypertonic
The direction of osmosis is determined by comparing total solute concentrations
HYPERTONIC-more solute, less water
ISOTONIC- equal solute, equal water
HYPOTONIC- less solute, more water
hypotonic
hypertonic

42. Managing water balance
Cell survival depends on balancing water uptake & loss
freshwater
balanced
saltwater

43. Diffusion through phospholipid bilayer
What molecules can get through directly?
fats & other lipids
What molecules can NOT get through directly?
polar molecules
H2O
ions (charged)
salts, ammonia
large molecules
starches, proteins
lipid
inside cell
outside cell
salt
NH3
sugar aa
H2O
Semipermeable

44. Passive Transport-Facilitated Diffusion
Cell membranes have protein channels that act like carriers, making it easier for certain molecules to cross. They "facilitate" the diffusion of molecules.
There are hundreds of different channels that only allow certain molecules to come through.
It will only occur if there is a higher concentration on one side of the membrane. It doesn't require energy. It's passive transport.
Channel protien

45. Active Transport
Cells may need to move molecules against concentration gradient
conformational shape change transports solute from one side of membrane to other
protein “pump”
“costs” energy = ATP
conformational change
LOW
HIGH
Some transport proteins do not provide channels but appear to actually translocate the solute-binding site and solute across the membrane as the protein changes shape. These shape changes could be triggered by the binding and release of the transported molecule. This is model for active transport.
ATP
“The Doorman”

46. How about large molecules?
Moving large molecules into & out of cell
through vesicles & vacuoles
endocytosis
phagocytosis = “cellular eating”
pinocytosis = “cellular drinking”
exocytosis
exocytosis

47. Endocytosis phagocytosis pinocytosis receptor-mediated endocytosis
fuse with lysosome for digestion
phagocytosis
non-specific process
pinocytosis
triggered by molecular signal
receptor-mediated endocytosis

48. Getting through cell membrane
Passive Transport
Simple diffusion
diffusion of nonpolar, hydrophobic molecules
lipids
HIGH  LOW concentration gradient
Facilitated transport
diffusion of polar, hydrophilic molecules
through a protein channel
Active transport
diffusion against concentration gradient
LOW  HIGH
uses a protein pump
requires ATP
ATP

49. Cell Membrane
Cell membrane establishes homeostasis for the cell by controlling what passes in and out of the cell.
HOW?
PHOSPHOLIPID BILAYER creates a barrier
Protein channels that allow polar substances through
Glyco-proteins are name tags

50. Phospholipid Bilayer
Glycoprotein
Integral Proteins
Peripheral Proteins