1. Cell Structure & Function
Chapter 7

2. The Discovery of the Cell
Without a tool to make them visible cells were until the invention of the microscope
Robert Hooke used an early microscope to look at cork cells.
About the same time Anton van Leeuwenhoek observed tiny organisms in pond water.

3. Early Discoveries
Matthias Schleiden a German botanist concluded that all plants are made of cells.
Theodor Schwann a German biologist stated that all animals are made of cells.
Rudolf Virchow a German physician concluded that new cells can only be produced by division of existing cells

4. Cell Theory All living things are made up of cells.
Cells are the basic units of structure and function in all living things.
New cells are produced from existing cells through cell division.

5. How do microscopes work?
Most use lenses to magnify the image of an object by focusing light or electrons.
Types of microscopes:
Light microscopes – images 1 millionth of m
Electron microscopes – images 1billionth of m
TEM – transmission – thin samples, can see cell structures & molecules
SEM – scanning – 3-D surface images

6. Light Microscope image

7. SEM Images

8. TEM Images

9. Examples of Cells Amoeba Proteus Plant Stem Bacteria Red Blood Cell
Nerve Cell

10. As you can see cells come in many sizes and shapes

11. All cells have some similarities:
At some point they contain DNA
All cells are surrounded by a thin flexible barrier called a cell membrane or plasma membrane.
But they also have differences and so are seperated into 2 broad groups:
Eukaryotes and Prokaryotes

12. Prokaryotic Do not have structures surrounded by membranes
Do not separate DNA within a nucleus
One-celled organisms, Bacteria

14. Eukaryotic Plant Animal
Contain organelles, specialized structures that perform specific functions; surrounded by membranes
Nucleus separates DNA from the rest of the cell
Most living organisms, great variety
Plant
Animal

15. What do these cells have
In common?

16. “Typical” Animal Cell

17. “Typical” Plant Cell

18. Cell Parts
Organelles

19. Inside the Cell Two major parts

20. Cytoplasm Gel-like mixture also called cytosol
Portion outside the nucleus
Surrounded by cell membrane
Contains organelles of eukaryotes – specialized structures that perform specific tasks

21. Nucleus Directs cell activities
Separated from cytoplasm by nuclear membrane
Contains genetic material – DNA – which contains coded information to make proteins
Prokaryote cells lack a nucleus but they do contain DNA

22. Nuclear Membrane Surrounds nucleus Made of two layers
Openings called nuclear pores allow material to enter and leave nucleus
Also called the nuclear envelope

23. Chromosomes In nucleus Made of DNA
Contain instructions for traits & characteristics
Usually in the form of long thin threads called chromatin

24. Nucleolus Small dense region inside nucleus
Involved in the assembly of organelles called ribosomes

25. Vacuoles
Membrane-bound sacs for storage of water, salts, proteins, and carbohydrates
Plants usually have a large vacuole that helps maintain shape
Paramecium – contractile vacuole

26. Lysosome Small organelles filled with enzymes to digest waste
Transports digested material to cell membrane for removal
Also breaks down old organelles no longer needed

27. Cytoskeleton Helps maintain cell shape and also in movement.
Internal network of protein fibers:
Microfilaments
Microtubules

28. Ribosomes Each cell contains thousands
Make proteins using instructions from DNA

29. Endoplasmic Reticulum
Internal membrane system where compounds are assembled and transported
Smooth ER: lacks ribosomes; makes lipids
Rough ER(pictured): ribosomes embedded in surface; modify proteins made by ribosomes

30. Golgi Apparatus
Modifies, sorts, and packages proteins and other materials from the ER for storage in the cell or released outside the cell.
Bundles proteins in tiny vesicles.

31. Mitochondria
Convert chemical energy stored in food (glucose) into compounds that are able to be used by cells –ATP
In humans most all of our mitochondria come from the cytoplasm of the egg cell – so you got yours from your mother.
They also contain their own DNA!

32. Chloroplast
Capture energy from sunlight and convert it into food – sugars – that contain chemical energy in a process called photosynthesis.
Surrounded by two membranes
Contain pigment called chlorophyll

33. Surrounding the Cell

34. Cell Membrane
Outer membrane of cell that controls movement in and out of the cell
Double layer
Also known as the plasma membrane

35. Cell Wall Most commonly found in plant cells & bacteria
Supports & protects cells