1. Chapter 7: Cell Structure and Function
Section 7-1: Life is Cellular
Harvard - Inner Life of the Cell

2. The observations and conclusions of many scientists helped to develop the current understanding of the cell
Put it in perspective:
1605 – English settlers found the colony at Jamestown, Virginia

3. The Cell Theory
Robert Hooke (1665)
English physicist used primitive compound microscope to look at plant tissue (cork).
He called the chambers “cells” because they reminded him of the small rooms in a monastery

4. The Cell Theory Rudolph Virchow (1855)
Proposes that all cells come from existing cells
Where did the first cell come from?

5. THE CELL THEORY All living things are composed of cells.
Cells are the basic unit of structure and function in living things.
New cells are produced from existing cells.

6. How small are cells? How much is a micrometer?
1 micrometer (µm) = 1/1,000,000 m
Typical cell size = 5 to 50 µm in diameter
In a dice that is 1 cm3
We could fit 1,000,000 cells
Cells Alive

7. How small are cells?

8. Two categories of cells
1. Prokaryotic Cells
pro = before; karyon = nucleus or kernel
contain cell membranes and cytoplasm but no nucleus
DNA is scattered through cytoplasm
examples: bacteria

9. Two categories of cells
2. Eukaryotic Cells
eu = true; karyon = nucleus or kernel
contain a nucleus that holds DNA and membrane bound organelles that have specific functions
examples: all plants, animals, some fungi, some microorganisms

10. Two categories of cells
Prokaryotic
Eukaryotic
-No Nucleus
-Nucleus
-Cell wall (plants and bacteria)
-Complex
-Less complex
-Membrane bound organelles
-Smaller Ribosomes less complex
-Cell membrane
-DNA
- Ribosomes larger and complex
-Cytoplasm
-DNA is circular
-Ribosomes
-DNA is linear

11. Animal Cell - Eukaryotic
Prokaryotic
Plant Cell - Eukaryotic
Animal Cell - Eukaryotic

12. 7-2 Cell Structures
Organelle – a specialized structure that performs a specific function inside a cell
Cytoplasm
Found – between the nucleus and cell membrane
Structure – a clear jelly-like fluid
Function – supports the organelles

13. The Nucleus Nuclear Envelope Found: around the outside of the nucleus
Structure: two thin membranes with thousands of pores
Function: allows materials to move in and out of the nucleus.

14. The Nucleus
Chromatin
Found: between the nucleolus and the nuclear membrane
Structure: DNA bound to proteins
Function: contain genetic information

15. The Nucleus Nucleolus Found: In center of the nucleus
Structure: a small, dense, round sphere
Function: Produces the ribosomes.

16. The Nucleus Found: In the cytoplasm of the cell
Structure: a sphere covered by a porous membrane
Function: Contains the cell’s DNA and all instruction for making protein and directing cell activities.
Nucleolus
Chromatin
Nucleus
Nuclear Envelope

17. Cytoskeleton Found: Throughout the cell
Structure: A network of protein filaments
Microtubules (25 nm)
Microfilaments (7nm)
Function: Helps support the cell & maintain shape
Involved in several types of movement

18. Cytoskeleton Microfilaments (7nm) Microtubules (25 nm)
Thread like structures made of protein (actin)
Support the cell
Responsible for cytoplasm streaming – the movement of cytoplasm within a cell (amoeba crawls)
Microtubules (25 nm)
Tube-like structure made of proteins (tubulins)
Important in cell division
Used to build cilia and flagella

19. Vacuoles Found: In the cytoplasm Structure: Saclike
Very large in plant cells
Smaller in animal cells
Function: Storage (water proteins, carbs, salts)

20. Vesicles Found: In the cytoplasm Structure: membrane bounded sac
Function: transports and/or stores cellular products

21. Lysosomes “The Cells Clean-up Crew” Found: In the cytoplasm
Structure: Small enzyme filled organelles
Function: Breakdown large organic molecules, and old nonfunctioning organelles

22. Ribosomes Found: In the cytoplasm
Structure: Small and grain-like, made of large and small subunits
Function: produce proteins from directions given by DNA

23. Endoplasmic Reticulum
Found: just outside the nucleus
Structure: a maze of membranes
Rough ER: (ribosomes imbedded in membrane) produces and transports proteins.
Smooth ER: (no ribosomes) produces lipids and detoxifies drugs.

24. Golgi Apparatus Found: In the cytoplasm
Structure: A stack of membranes
Function: to modify, sort and package materials from the ER for storage or to be transported outside the cell.

25. Chloroplast Found: In the cytoplasm of plant cells
Structure: Stack of membranes that contain photosynthetic pigments (chlorophyll)
Function: Use energy from the sun to make food (photosynthesis)

26. Mitochondria “Powerhouse of the Cell”
Found: In the cytoplasm
Structure: Rod-shaped with a folded double membrane
Function: Provide the cell with energy.

27. Cell Wall Found: Located outside the cell membrane
Structure: Fibers of carbohydrate, cellulose in plant cells
Function: Provide support and protection for the cell

28. Cell Membrane Found: Located around the perimeter of the cell
Structure: Made of a phospholipid bilayer
Function: Regulates what leaves and enters the cell and provides protection and support

29. Centrioles Found: Within the cytoplasm only in animal cells
Structure: Made of a microtubules (tubulin)
Function: Help organize the cell during cell division.
Centrioles - Miosis