1. Cell Structure
Chapter 3

2. Looking at Cells 1st microscope invented in the 1600s
Robert Hooke (Cork Cells)
Scientists use the Metric System or International Systems of Measurements
SI units are based on powers of 10
μ = micro μm = micrometer

3. Characteristics of Microscopes
Light Microscope
Light passes through one or more lenses to produce an enlarged image
Electron Microscope
Forms an image of a specimens using a beam of electrons rather than light

4. Characteristics of Microscopes
MAGNIFICATION – is the quality of making an image appear larger than its actual size
RESOLUTION – is the measure of the clarity of an image

5. Types of Microscopes Compound Light Microscopes
2 lenses
Objective Lens (40 X)
Ocular Lens (10 x)
Magnification up to 2000 X
View images from 0.5 μm to 0.5 cm
Used to view images such as living cells
Lower magnification than electron microscopes

6. Types of Microscopes Electron Microscope Magnification up to 200,000 X
Object & electron beam are placed in a vacuum chamber
Object is stained with metal ions
Electron beam is absorbed by the ions
Electrons produce a fluorescent image called the TEM

7. Types of Microscopes Scanning Electron Microscope
Electrons bounce off the specimen
Creating a 3-D image
Scanning Tunneling Microscope
Uses needle-like probe to measure differences in voltage caused by electrons that leak from the surface
3-D images
Living organisms can be viewed with this scope

8. Section 1 Review 1. How many cm are in a m?
2. What is the difference between resolution and magnification?
3. What measurement system do scientists use?
4. Why can living cells not be viewed under an electron microscope?
5. The English scientist Robert Hooke used a crude microscope to examine these….

9. Section 2: Cell Features
Schleiden, Schwann, Virchow
CELL THEORY
1) All living things are made of one or more cells
2) Cells are the basic units of structure and function in organisms
3) All cells arise from existing cells

10. Cell Size Small cells are more efficient than large cells
All substances that enter or leave a cells have to cross the cell’s surface
Surface area- to- Volume
LOW – substances can not enter or leave
Small cells have a higher surface area- to – volume ratio
Shorter distance to travel

11. Common Features of Cells
CELL MEMBRANE – encloses the cell
Regulates what enters & leaves the cell
CYTOPLASM – cell’s interior
CYTOSKELETON – fibers suspended in the cytoplasm
RIBOSOMES – cellular structures on which proteins are made
DNA – instructions for the cell

12. Prokaryotes The smallest and simplest cells
Are single-celled organisms
Lack a NUCLEUS
Examples: Bacteria
Reproduce Rapidly
Do not need oxygen to survive
Some can make their own food

13. Characteristics of Prokaryotes
CYTOPLASM – semi-solid material that surrounds everything inside the cell
DNA, Ribosomes & enzymes
CELL WALL – surrounds the cell membrane
Function: Provides support & structure
Found in plants, fungi & some bacteria
Made of polysaccharides

14. Characteristics of Prokaryotes
Capsule – surrounds the cell
Cling to lots of things
Flagella – long, threadlike structures that extend from the cell surface
Function: helps the cell move

15. Eukaryotic Cells Have a Nucleus NUCLEUS – houses the DNA
Organelles - internal compartments
Carry out specific activities in the cell
Vesicles – move proteins & other molecules from cell to cell
CILLIA – short hair-like projections
Functions: Movement & transport of materials across the cell membrane

16. Eukaryotic Cells CYTOSOL – fluid material that makes up the cytoplasm
CYTOSKELETON
Made of protein fibers
Function: Holds the cell together
All connected to one another
3 kinds of fibers – Actin Fibers, Microtubules & Intermediate Fibers

17. Cytoskeleton Actin Fibers – determine the shape
Microtubules – act as a highway system
Transport info from the nucleus to the rest of the cell
Intermediate Fibers – are an anchor for ribosomes & enzymes

18. The Cell Membrane Selective Permeability
Only let certain things enter or exit
Phospholipid = 1 lipid + 2 fatty acids
Head  Polar
Phosphate Group
Attracted to water
2 Tails  NonPolar
Repel water

19. The Cell Membrane LIPID BILAYER – double layer of phospholipids
Marker Proteins “Name Tags”
Direct cells to the proper location
Receptor Proteins “Antenna”
Receive and transmit info
Transport Proteins “Locked Door”
Allow only certain ions and molecules to cross the cell membrane
Enzymes – assist in biochemical reactions

20. Section 2 Review
1. Describe the importance of surface-area-to volume ratio of a cell.
2. How are Prokaryotic & Eukaryotic Cells similar? Different?
3. Describe the function of 2 cell membrane proteins.
4. What does the cell theory state?
5. What does the term “selectively permeable” mean in regards to a cell membrane?

21. Section 3: Cell Organelles
Cell functions are controlled by the NUCLEUS
Surrounded by the NUCLEAR ENVELOPE
Made up of 2 lipid bilayers
NUCLEAR PORES
Ribosomal RNA pass through the pores into the cytoplasm
Ribosomes are partially assembled in the NUCLEOLUS

22. The Nucleus DNA stored inside the nucleus
Eukaryotic DNA is wound around proteins
CHORMOSOMES – DNA strands
Humans = 46
Garden Peas = 14

23. Ribosomes & the ER RIBOSOMES make protein & RNA ENDOPLASMIC RETICULUM
Mobile in the cytoplasm
Stationary on the Rough ER
ENDOPLASMIC RETICULUM
Move proteins & other substances throughout the cell
Has a membrane that is made up of a lipid bilayer

24. Ribosomes & the ER
VESICLE – is a small membrane bound sac that transports substances inside the cell
Separates proteins made on the Rough ER from proteins made in the cytoplasm
SMOOTH ENDOPLASMIC RETICULUM
Lacks ribosomes
Function: Makes lipids & breaks down toxic substances

25. Packaging & Distribution of Proteins
GOLGI APPARATUS
Is a set of flattened, membrane-bound sacs that package & distribute
Proteins are modified in the GA & enter new vesicles
Vesicles take the proteins outside the cell OR
Vesicles remain in the cell & become LYSOMES
Contain digestive enzymes

26. Mitochondria Function: Harvest energy to make ATP
Muscle cells can have 100s – 1000s
2 Membranes (Inner & Outer)
Here chemical reactions produce ATP
Also has DNA
Circular – similar to prokaryotic DNA

27. Structures of Plant Cells
3 Organelles NOT found in Animal Cells
1) CELL WALL
Adds additional support, give shape, protects from damage & connects with adjacent cells
2) Chloroplasts
Use light to make carbohydrates from carbon dioxide and water
Surrounded by 2 layered membrane & contains DNA

28. Structures of Plant Cells
3) Central Vacuole
Takes up most of volume
Contains
Water
Ions
Nutrients
Waste
When full it makes the cell rigid
Allows the plant to stand upright

29. Section 3: Review
1. Describe the role of the nucleus in cell activities.
2. Sequence the course of newly made proteins from the rough ER to the outside of the cell.
3. Name 2 organelles a plant has that an animal cells does not.
4. The mitochondria has the nickname “The Powerhouse”. Why is this a good nickname?