1. Chapter 7
Cell structures

2. 7.1 Microscopes Compound light microscopes Electron Microscopes
Use a series of lenses to magnify objects
Can magnify up to 1500 times
Uses a beam of light
Electron Microscopes
Uses a beam of electrons to magnify objects
Can magnify up to 500,000 times
Specimens must be examined in a vacuum
Two types:
Scanning electron microscope scans the surface of cells to view the 3 dimensional shape
Transmission electron microscopes allow scientists to study structures in a cell

3. 7.1 Cell Theory
With the invention of microscopes, scientists were able to conduct more in-depth investigations and created the cell theory, which has 3 basic ideas:
All organisms are composed of one or more cells
The cell is the basic unit of structure and organization of organisms
All cells come from cells that already existed

4. 7.1 Types of cells There are 2 basic types of cells
Prokaryotes
Do not have membrane bound organelles
Include most single celled organisms
Eukaryotes
Have membrane bound organelles
Includes most multi celled organisms
Have a nucleus, which manages and controls cellular functions
Organelles each have a specific function within the cell

5. 7.1 Prokaryotic cells Prokaryotic cells have the following structures:
Cell wall
Plasma membrane*
Ribosomes*
DNA*
Cytoplasm

6. 7.1 Eukaryotic Cells
Eukaryotic Cells contain the following structures:
Plasma membrane
Cytoplasm
Chromosomes
Nucleus containing
Nucleolus
Organelles

7. 7.2 Plasma Membrane
The plasma membrane is the flexible boundary between the cell and its environment
It allows nutrients to enter and exit the cells
It allows waste to exit the cell
It is described as being selectively permeable, because it lets some things through but not others
It can also change what it allows to pass through at different times

8. 7.2 Plasma Membrane Structure
The plasma membrane is made of a phospholipid bilayer, which is composed of 2 layers of phospholipids back to back
Phospholipids are composed of a glycerol backbone, 2 fatty acids chains and a phosphate group
The fatty acid tails are non-polar
These are on the inside of the bilayer
The phosphate head is polar
This is on the outside of the bilayer

9. 7.2 Fluid Mosaic Model
The model of the plasma membrane is called the fluid mosaic model
Fluid because the phospholipids move within the membrane (similar to water waves moving in a lake)
Mosaic because proteins create a pattern on the surface of the bilayer

10. 7.2 Other components Cholesterol Transport proteins
Stabilizes the phospholipids by preventing their fatty acid tails from sticking together
Cholesterol can be harmful in large quantities, but some is necessary for this purpose
Transport proteins
Regulate which substances enter and leave the cells

11. 7.3 Cell Structures
Eukaryotic Cells are divided into 2 categories: plant cells and animal cells
Animal cell structures include a plasma membrane, ribosomes, a cytoskeleton, an endoplasmic reticulum, a golgi apparatus, lysosomes (some cells), mitochondrion, a nucleus, a nucleolus, and vacuoles (some animal cells)
Plant cells include these items plus a cell wall and chloroplasts

12. 7.3 Cell Parts & Functions
Plasma membrane- flexible cell boundary that is selectively permeable
Cell wall- rigid cell boundary outside the plasma membrane that provides additional structural support
Nucleus- controls organelle activity and includes directions to make proteins in the DNA, which is in a stringy form called chromatin
Nucleolus- inside the nucleus-makes ribosomes

13. 7.3 Cell Parts & Functions
Ribosomes- where cells produce proteins according to the directions in DNA
Cytoplasm-clear gelatinous fluid inside a cell-suspends organelles
Endoplasmic reticulum (ER)- site of cellular chemical reactions
Rough ER has ribosomes
Smooth ER does not have ribosomes

14. 7.3 Cell Parts & Functions
Golgi Apparatus- modifies proteins by sorting and packaging them and sending them to the correct location
Vacuoles- temporary storage of materials (food, enzymes, waste)
Lysosomes- contain digestive enzymes that digest extra or worn out organelles, food, and viruses/bacteria
They can fuse with vacuoles to empty their contents

15. 7.3 Cell Parts & Functions
Chloroplasts- trap light energy and convert it to chemical energy; contain chlorophyll a green pigment that traps light energy
Mitochondria- transform energy for the cell
Cytoskeleton- a network of rods (microtubules) and filaments (microflaments) inside the plasma membrane that provide structure and maintain the shape of the cell

16. 7.3 Cell Parts & Function Centrioles- play a role in cell division
Cilia- short numerous projections that look like hairs that allow the cell to move
Flagella-long projections (1 or 2 per cell) that allow the cell to move
Nuclear membrane- separates the cytoplasm from the nucleus

17. 7.3 Animal Cell lysosome Plasma membrane Golgi Apparatus centriole
nucleolus
mitochondria
Endoplasmic reticulum
vacuole
nucleus
ribosomes
cytoplasm
Nuclear membrane

18. 7.3 Plant Cell Nuclear membrane Cell wall mitochondria cytoplasm
nucleus
nucleolus
ribosomes
Endoplasmic reticulum
Golgi apparatus
Plasma membrane
Vacuole
cytoskeleton
chloroplast