1. Prokaryotes Part I

2. Introduction to Cells
Compound Light Microscope: Allows light to pass through a specimen and magnifies the image with lenses
Ch. 7

4. Electron microscopes: Use beams of electrons to produce images.
Scanning EM: Produces three-dimensional images
Transmission EM: Produces images that look almost like light microscope images (but much more magnified)

6. Anton van Leeuwenhoek
First to create glass of a high enough quality to be useful in microscopes.
First person to observe single celled organisms (which he called animalcules - “little animals”)
Observed bacteria, spermatozoa, muscle

7. Robert Hooke Used a crude compound microscope
First to see and identify cork cells.
Coined the term “cells.”

8. The Cell Theory All living things are made of cells
Cells are the basic structural and functional unit of life
New cells arise from pre-existing cells

9. Amoeba
Sea Urchin Embryo
Corn Leaf Cell

10. Why are cells so small? Cells are small for two possible reasons:
Increase surface area
Cells need nutrients
Cells need to get rid of waste materials
These nutrients/wastes must move out of the cell – if the cell were large it would have to move large distances to exit the cell
Permit specialization
Having a large number of cells allows there to be different types of cells doing different things

11. Cell Types
Cells are classified based on internal structures (or lack thereof)
Eukaryotic (eu-: true; -kary-:nucleus):
Animals
Plants
Fungi
Protists
Prokaryotic (pro-: before; -kary-: nucleus):
Bacteria

12. Animal Eukaryotic Cells
Very complicated cells
Contain little membrane-bound structures that have specific functions (organelles: “little organs”)
Nucleus is well defined – contains DNA
Nucleus was discovered by Robert Brown
Organelles are suspended in a jelly-like substance called the cytoplasm
Everything is held inside of the cell by a membrane called a cell membrane

13. Animal Cell

14. Plant Eukaryotic Cells
Almost identical to animal cells except they have three more organelles than animals cells
Cell wall: allows plants to stand upright
Chloroplast: where photosynthesis takes place
Large Central Vacuole: storage compartment

15. Plant Cell

16. Bacterial Prokaryotic Cells
Simplest cells
The first forms of life were probably bacterial cells (or something like it)
Lack membrane-bound organelles
Contain cytoplasm (cell jelly)
All prokaryotes are unicellular

17. Characteristics of Prokaryotes con't
Do not possess a distinct nucleus
Nucleoid: Ill-defined region of the cell where the DNA is usually located.
DNA Loop: DNA is a long single fiber that contains almost all of the genetic material of the cell.
Plasmid: Small circular loop of DNA that contains the rest of the genetic material
Can be transferred between bacterial cells
Can contain genes for antibiotic resistance

18. Characteristics con't Have ribosomes floating freely in the cytoplasm
The ribosome is where proteins are made
Certain antibiotics (tetracycline and streptomycin) prevent prokaryotic ribosomes from working
Most prokaryotes have a cell wall
Some can develop a capsule
Many prokaryotes have a flagellum (or multiple flagella, plural) for movement

20. Cell Wall
Functions:
Give the cell shape
Protects the cell from hostile environmental conditions
Made up of peptidoglycans (mesh of sugars and proteins)
Two types
Gram-positive cell wall
Gram-negative cell wall
Penicillin and Lysozyme

21. Capsule Jelly-like coating that surrounds the cell wall
Composed of carbohydrates
More common in gram-negative bacteria
Four functions:
Prevent dessication (drying out)
Help bacterial cells stick to each other or to other surfaces (e.g., tissues of other organisms)
Protect bacteria from antibiotics
Prevent bacteria from being phagocytized.

22. Capsule con't
Capsule
Bacterial Cell

23. Flagellum Provides movement
Proteins that stick out through holes in the cell membrane
Spin like propellers