1. Chapter 8 Cell Structure

2. Cell Theory
Schleiden, Schwann, and Virchow were the three scientists whose work led to the formation of the cell theory:
All living things are made of one or more cells.
Cells are the basic units of structure and function in organisms.
All cells arise from existing cells.

3. Cell Size Small cells function more efficiently than large cells.
Substances do not need to travel as far to reach the center of a smaller cell.

4. Common Features of All Cells
Structure
Function
Cell Membrane
Outer boundary; regulates what enters & exits a cell
Cytoplasm (cytosol)
Cell’s interior
Cytoskeleton
Web of protein fibers that hold the cell together & keep the membrane from collapsing
Ribosomes
Cellular structures on which proteins are made
DNA
Provides the instructions for making proteins

6. Two Major Types of Cells: Prokaryotes & Eukaryotes
Smallest, most simple cell;
early prokaryotes lived at least 3.5 billion years ago
No nucleus & no membrane-bound organelles
Example = Bacteria
DNA – single, circular molecule located in the center of the cell
Flagella – In prokaryotes
S: long thread-like structures
F: movement

7. Two Major Types of Cells: Prokaryotes vs. Eukaryotes
Early eukaryotes evolved 2.5 billion years ago
Cells that have a nucleus & organelles
Organelles – internal structures that carry out specific functions
Vesicles – in eukaryotes
S: envelopes; pods
F: move substances around the cell (vehicle)
Cilia – in eukaryotes
S: short, hair-like structures
F: movement

8. Cell Membrane Located in prokaryotic and eukaryotic cells
S: Phospholipid bilayer: double layer of phospholipids
F: Protection; barrier between cell & its environment; maintain homeostasis
Selective Permeability – determines what enters or leaves the cell.

9. Cell Membrane
Proteins are embedded in the cell membrane. Marker Proteins – advertise cell type; protein with a carbohydrate attached Receptor Protein – recognizes & binds to substances outside of the cell Transport Proteins – helps substances move across the cell membrane (like a gate)
Marker protein

10. Cell Organelles Nucleus (Control Center) Nuclear Envelope/Membrane
Eukaryotic (Plant and Animal)
S: large mass in the middle of the cell
F: stores the cell’s DNA
Nuclear Envelope/Membrane
S: surrounds the nucleus; envelope
F: controls movement in/out of the nucleus through nuclear pores
Nucleolus
S: area inside the nucleus
F: assembles ribosomes

11. Cell Organelles Ribosomes Endoplasmic Reticulum (E.R.)
Prokaryotic & Eukaryotic
S: can be “free” (floating in cytoplasm) or attached to ER
F: make proteins
Endoplasmic Reticulum (E.R.)
Eukaryotic
Rough ER
S: network of tubes; ribosomes sprinkled on surface
F: Move proteins made by attached ribosomes into the ERinto vesicles)
Smooth E.R.
S: smooth surface; network of tubes with no ribosomes attached
F: makes lipids & breaks down toxins

12. Cell Organelles Golgi Apparatus –Packaging & Distribution (UPS)
Eukaryotic
S: flattened sacs; look like a stack of pancakes
F: Modifies & Re-packages proteins into new vesicles & sends them to the cell membrane to be released outside of the cell

13. Cell Organelles Mitochondria--Powerhouse Eukaryotic
S: Double membrane organelle; complex matrix inside
F: Convert energy from food to make energy called ATP- called cellular respiration
Muscle cells (require lots of energy) may contain hundreds or thousands of mitochondria

14. Cell Organelles Lysosomes – Garbage Disposal S: small round pods
F: contain digestive enzymes; break down old cell parts and food

15. Structures of Plant Cells
Plant cells are also eukaryotic cells; they have 3 additional structures that are NOT found in animal cells
Cell wall –
S: thick wall that surrounds the cell membrane; make of cellulose
F: helps support the shape of a plant cell, protects the cell from damage, & connects it with neighboring cells
Chloroplasts –
S: Green pods containing stacks of thylakoids
F: use sunlight to make carbohydrates from carbon dioxide (CO2) and water (H2O)
Central Vacuole –
S: large, membrane-bound sac that takes up most of the cell’s space
F: stores water, nutrients, ions, and wastes

16. Cytoplasm and Microtubules
Location: prokaryotic and eukaryotic
Structure: thick, jelly-like substance
Function: interior of cell; organelles float around in it
Microtubules
Location: eukaryotic cells
Structure: “rails” like train tracks that go around the cell
Function: support, highway system for the cell

17. Microscopes: Compound Light Microscope
Body Tube
Revolving Nose Piece
Objective Lens
Stage Clips
Diaphragm
Light Source
Ocular Lens/Eye Piece (10X)
Arm
Stage
Course Adjustment Knob
Fine Adjustment Knob
Base

18. Determining Total Magnification:
Microscopes
Magnification – the quality of making an image appear larger than its actual size
Resolution – a measure of the clarity of an image (how clear or fuzzy the image looks)
Determining Total Magnification:
Formula:
Ocular Lens x Objective Lens =
Example: 10 x 4 = 40X (Scanning Power)
What would be the total magnification if you used the high power objective lens?
10 x 40 = 400X

19. Cell Size Small cells have a large surface area-to-volume ratio
Which means…not much volume (inside) and substances do not have to travel as far to enter or leave a cell!!