1. Chapter Four
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
Animations

4. 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”.

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

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. Types of Microscopes Used Today:
Light Microscope:
uses a beam of light to produce image; LIVING tissue/organisms
Compound Light microscope: multiple lenses (scanning, low, high power)
Electron Microscope: uses an electron beam to produce image; more powerful than light; for NON-LIVING things
Scanning (SEM): external surface of cells
Transmission (TEM): internal structures of cells

8. Electron microscopes

9. Microscope Images Light microscope Scanning e- microscope
Transmission e- microscope
Scanning e- microscope

10. Cell Theory:
All organisms are made up of one or more cells.
The cell is the basic unit of all organisms.
All cells come from other pre-existing cells.

11. Two Basic Cell Types 1) Prokaryotes Lacks internal compartments.
No true nucleus.
Most are single-celled (unicellular) organisms.
Have circular DNA and ribosomes
Have cell wall
Examples: bacteria

12. A general prokaryotic cell

14. Two Basic Cell Types 2) Eukaryote
Includes plant, animal, fungi and protists
Has several internal structures (organelles).
True nucleus: DNA is encapsulated
Either unicellular or multicellular.
unicellular example: yeast
multicellular examples: plants and animals

15. Eukaryotic Cell

16. Cell Organelles
Internal structures of a cell that help it maintain functioning and homeostasis

17. All cells have cell boundaries
Plasma Membrane
(cell membrane)
Serves as a boundary between the cell and its external environment.
Regulates the materials that pass in and out of the cell.
Made up of 2 layers of phospholipids with proteins (phospholipid bilayer)
FOUND IN ALL CELLS!
All cells have cell boundaries

18. All cells have cell boundaries
Cell Wall
Only found in certain cells - plants, bacteria, and fungi.
Extra layer of support surrounding the plasma membrane
Plant cell walls contain cellulose while fungi cell walls contain chitin.
All cells have cell boundaries

19. Cell Organelles Cytoplasm (Both Eukaryotic & Prokaryotic Cells)
The jelly-like material that surrounds the organelles.
Fluid space between organelles that help with movement of materials in the cell.

20. Cell Organelles Nucleus (Eukaryotic Cells only!)
Regulates all of the cell’s functions.
Surrounded by a double-layered membrane (nuclear envelope) with large pores (nuclear pores) that allow only certain materials to pass in and out of the nucleus.
Contains chromatin – long tangles of DNA wrapped around protein
Nucleolus Found in the nucleus and responsible for ribosome production.

21. (Eukaryotic Cells only!)
Cell Organelles
(Eukaryotic Cells only!)
Endoplasmic reticulum
Folded membrane that acts as the cell’s delivery system of materials made in the cell.
Smooth E.R. contains enzymes for lipid synthesis.
Rough E.R. is surrounded with ribosomes for protein synthesis.

22. (Eukaryotic AND Prokaryotic Cells)
Cell Organelles
(Eukaryotic AND Prokaryotic Cells)
Ribosomes
Float around the cell but are mostly attached to the Rough E.R. (give the rough ER it’s “rough” or bumpy appearance)
Center for making proteins – for enzymes, structural support, antibodies, etc.

23. (Eukaryotic Cells only!)
Cell Organelles
(Eukaryotic Cells only!)
Golgi bodies (or Golgi apparatus)
A series of flattened sacs where newly made lipids and proteins from the E.R. are repackaged and shipped to the plasma membrane for export out cell or to parts inside the cell where they are needed.

24. (Eukaryotic Cells only!)
Cell Organelles
(Eukaryotic Cells only!)
Vacuoles
A sac of fluid surrounded by a membrane used to store food, fluid, or waste products.
Plants- one large, central vacuole that help maintain cell shape and smaller vacuoles around rest of the cell.
Animals- small vacuoles throughout the cell

25. (Eukaryotic Cells only!)
Cell Organelles
(Eukaryotic Cells only!)
Lysosomes
Bubbles containing digestive enzymes
Can fuse with vacuoles to digest food, or can digest worn cell parts, or microorganisms invading the cell.
Also known as “suicide sacs” because they can also destroy the whole cell.

26. (Eukaryotic Cells only!)
Cell Organelles
(Eukaryotic Cells only!)
Mitochondria
Produce the energy for the cell in the form of ATP.
Also known as the “powerhouse of the cell”.
Has a highly folded inner membrane (cristae).

27. (Eukaryotic Cells only!)
Cell Organelles
(Eukaryotic Cells only!)
Chloroplasts
Found in plant cells and some protists.
Transforms light energy into chemical energy which is stored in food molecules; where photosynthesis takes place.
Contain chlorophyll – a green pigment that traps light energy and gives plants their green color.

28. (Eukaryotic Cells only!)
Cell Organelles
(Eukaryotic Cells only!)
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.
animation

29. (Eukaryotic Cells only!)
Cell Organelles
(Eukaryotic Cells only!)
Centrioles
made of protein.
play a role in splitting the cell into two cells during mitosis (cell division process)
found in animal and fungi cells.

30. Cell Structures of Locomotion
(Eukaryotic and Prokaryotic Cells)
Cilia
Short, numerous, hair-like projections from the plasma membrane.
Move with a coordinated beating action.
Flagella
Longer, less numerous projections from the plasma membrane.
Move with a whiplike action.

31. Flagella nucleolus Nucleus Chromosomes Endoplasmic reticulum
Ribosomes
Endoplasmic
reticulum
Microtubule
Mitochondrion
Picture adapted from Access Excellence’ rescource center:
Golgi apparatus
Centrioles
Cilia

32. Why are cells so small?
a. Efficiency:  smaller cells have larger surface area , smaller volume
b. Specialization: Having numerous small cells permits specialization
*The bigger the difference between surface area : volume ratio, the more efficient the cell. (Ex. 6:1 is better than 2:1)

33. Cube Surface area = L X W x 6 sides
As an object increases in size, its volume increases, while surface area increases as well.
Cube Surface area = L X W x 6 sides
Volume = L X W X H
As these cubes illustrate, the surface area to volume ratio of a small object is larger than that of a large object of similar shape
This ratio limits how large cells can be

34. Review Questions
Which of these is not a type of cell? a) bacterium; b) amoeba; c) sperm; d) virus
A prokaryotic cell would NOT have which of these structures? a) ribosome; b) nucleus; c) cell membrane; d) cell wall
Ribosomes are cellular structures involved in ____. a) photosynthesis; b) chemosynthesis; c) protein synthesis; d) carbohydrate synthesis
The earliest microscopes used to image the specimens. a) high energy electron beams; b) interatomic forces; c) low energy electron beams; d) light
Plant cells have ___ and ___, which are not present in animal cells. a) mitochondria, chloroplasts; b) cell membranes, cell walls; c) chloroplasts, nucleus; d) chloroplasts, cell wall
The ___ is the membrane enclosed structure in eukaryotic cells that contains the DNA of the cell. a) mitochondrion; b) chloroplast; c) nucleolus; d) nucleus
The mitochondrion functions in ____. a) lipid storage; b) protein synthesis; c) photosynthesis; d) DNA replication; e) ATP synthesis
Which of these cellular organelles have their own DNA? a) chloroplast; b) nucleus; c) mitochondrion; d) all of these
Answers 1.D 2.c 3.b 4.c 5.d 6.d 7.d 8.e 9.d