1. Cell Structure and Function
Chapter 7
Biology
Miller • Levine

2. The Scientists… Robert Hooke (1665) Anton van Leeuwenhoek (1674)
Viewed cork under a microscope
Called the chambers he saw “cells”
Anton van Leeuwenhoek (1674)
First to see living organisms in a drop of water

3. The Scientists… Matthias Schleiden (1838) Theodor Schwann (1839)
All plants are made of cells
Theodor Schwann (1839)
All animals are made of cells
Rudolf Virchow (1855)
All cells come from preexisting cells

4. The Cell Theory All living things are composed of cells
Cells are the basic units of structure and function in living things
New cells are produced from existing cells

5. Unicellular vs. Multicellular
Unicellular – single-celled organism
Multicellular – many-celled organism
Cell specialization – cells are specialized to perform certain functions
Cells → Tissues → Organs → Organ systems → Organism

6. Prokaryotes vs. Eukaryotes
Have a cell membrane & cytoplasm, but do not have a nucleus
Ex. Bacteria such as E.coli
Eukaryotes
Have a nucleus, cell membrane, cytoplasm & organelles
Ex. Plants, Animals, Fungi

7. Prokaryotes vs. Eukaryotes

8. Basic Cell Structures
Cell membrane – thin, flexible barrier around the cell; protects the cell
Present in all cells
Cytoplasm – material inside the cell membrane (not including the nucleus)
Prokaryotes & Eukaryotes

9. Cell Wall
Found in many organisms, including plants, algae, fungi and nearly all prokaryotes
Not found in animal cells
Lies outside the cell membrane
Main function is to provide support & protection for the cell

10. Nucleus
Almost all eukaryotic cells, including plants and animals have a nucleus
Prokaryotes do not have a nucleus
Controls most cell process and contains the DNA

11. Nucleolus and Nuclear Envelope
Inside the nucleus
Where ribosomes are made
Nuclear Envelope:
Double-membrane layer around the nucleus
Allows material to move into and out of the nucleus

12. Nucleus

13. Cytoskeleton Found in all eukaryotic cells Not found in prokaryotes
A network of protein filaments that helps the cell maintain its shape
It also is involved in cell movement

14. Ribosomes Found in all cells Main function is to make proteins
Can be found floating in the cytosol or attached to endoplasmic reticulum

15. Endoplasmic Reticulum (ER)
Found only in eukaryotic cells
Where components of the cell membrane are assembled
Two kinds: Smooth ER & Rough ER
Smooth ER: no ribosomes; makes lipids
Rough ER: has ribosomes; involved in making proteins

16. Endoplasmic Reticulum

17. Golgi Apparatus Found only in eukaryotic cells
Enzymes attach carbohydrates & lipids to proteins
Send proteins to their final destination

18. Lysosomes Found in animal cells only
Break down lipids, carbohydrates & proteins from food into particles that can be used by the cell
Also break down “dead” organelles

19. Vacuoles Not found in prokaryotes
Animal cells have small or no vacuoles
Plant cells have a large central vacuole
Store materials such as water, salts, proteins & carbohydrates

20. Chloroplasts Found in all plant cells
Some prokaryotes have them, but most do not
Use the energy from sunlight to make energy-rich food molecules during photosynthesis

21. Chloroplasts

22. Mitochondria Found in eukaryotic cells only
Release energy from stored food molecules

23. Cell Membrane
Regulates what enters and leaves the cell (selectively permeable)
Provides protection and support
Lipid bilayer – two layers of lipids
Proteins run through the layers
Carbohydrates are attached to some of the proteins
Fluid Mosaic Model

24. Cell Membrane

25. Diffusion
Molecules move from an area of high concentration to an area of low concentration
Movement continues until equilibrium is reached
Many substances move across the membrane by diffusion
Does not require energy (passive transport)

26. Diffusion

27. Osmosis The diffusion of water No energy is required
Isotonic – equal concentration
Nothing happens
Hypertonic – higher concentration
Water moves out of the cell
Hypotonic – lower concentration
Water moves into the cell
No energy is required

28. Effects of Osmosis on Cells

29. Osmotic Pressure In pure water, an animal cell would burst
Plant cells are protected by their cell wall
Some freshwater organism have special structures like contractile vacuoles to get rid of extra water

30. Facilitated Diffusion
Some molecules cannot cross the membrane without help
Some of the proteins in the membrane form protein channels
Materials still move from higher to lower concentrations
No energy is required

31. Facilitated Diffusion

32. Active Transport
Materials move from lower concentration to higher concentration
Requires an input of energy
Works kind of like a pump

33. Transport of Large Amounts
Endocytosis – movement into the cell
Phagocytosis – “cell eating” – solid particles
Pinocytosis – “cell drinking” – particles dissolved in water
Exocytosis – movement out of the cell

34. Phagocytosis

35. Pinocytosis