1. Cell Theory, Microscopes and Prokaryotes/Eukaryotes

2. Microscopes

3. What are the two main types of microscopes?
Compound Light Microscope: Allows light to pass through a specimen and magnifies the image with lenses
Ch. 7

5. What are the two types of EMs?
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)

7. The Discovery of the Cell LIFE IS CELLULAR!!
Who was Robert Hooke?
In 1665, Robert Hooke used an early compound microscope to look at a thin slice of cork, a plant material.
Cork looked like thousands of tiny, empty chambers.
Hooke called these chambers “cells.”
(THINK PRISON CELLS)
Cells are the basic units of life.
Digestive enzyme from a pitcher plant that could be used as an antibacterial agent.
Picture:
Hooke’s Drawing of Cork Cells
Introduction To Cell – Life is Cellular

8. Who was Anton van Leeuwenhoek?
Anton van Leeuwenhoek used a microscope to observe tiny living organisms (microorganisms) in pond water- called them animalcules “little animals”
First to create glass of a high enough quality to be useful in microscopes.

9. The Discovery of the Cell
The Cell Theory In 1838, Matthias Schleiden concluded that all plants were made of cells. In 1839, Theodor Schwann stated that all animals were made of cells.

10. The Discovery of the Cell
In 1855, Rudolph Virchow concluded that new cells were created only from division of existing cells.
These discoveries led to the cell theory!

11. The Discovery of the Cell
What does the cell theory state?
All living things are composed of one or more cells. (you, me, plants, bugs, fish, Spiderman, Colonel Sanders, Jimmy Neutron, Bacteria, Yeast, Jackie Chan)
Cells are the basic units of structure and function in living things. (what keeps us upright and helps us live, basically small workers responsible for how we function!)
New cells are produced from existing cells. (they can’t just appear out of thin air…cells make new cells by dividing!)
Cell Theory

12. 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
How are Cells Classified?
Cells are classified based on internal structures (or lack of them)

13. What is ENDOSYMBIOTIC THEORY?
In 1970, American biologist, Lynn Margulis, provided evidence that some organelles within cells were at one time free living cells themselves
Supporting evidence included organelles with their own DNA
Chloroplast and Mitochondria
Endosymbiotic Theory - video

14. What are the two types of cells? Prokaryotes and Eukaryotes
What are the characteristics of prokaryotes and eukaryotes?
Eukaryotes are cells that contain nuclei.
Prokaryotes are cells that do not contain nuclei.

15. PROKARYOTES AND EUKARYOTES
Both Have:
Cytoplasm
Ribosomes
Plasma Membrane
With Plants: Cell Wall
With (some) Animals: Flagella
Prokaryotes do not have a nucleus!
Eukaryotes are more complex
Eukaryotes are larger

16. Why are cells named that way?
From Greek words…
EU means TRUE. (YOU HAVE)
PRO means BEFORE. (NO)
KARYON means NUCLEUS.
Eukaryote = TRUE NUCLEUS;
Prokaryote = BEFORE NUCLEUS.
All cells have DNA, in eukaryotes it is stored in the nucleus.
Prokaryotes don’t have a nucleus, and it floats around in the cytoplasm in an area called the nucleoid.
Only eukaryotes have membrane-bound organelles.
Video-Comparing Prokaryote and Eukaryote Cells

17. Test Yourself! Statement Prokaryotic Eukaryotic 1. Have a nucleus
2. Have membrane-bound organelles
3. Contain genetic material (DNA)
4. Can be single or multi-celled
5. Can only be single-celled.
6. Have a plasma membrane and cytoplasm

18. Prokaryote Has no nucleus. Just a mass of circular shaped DNA
No organelles except ribosomes & cytoplasm
Always unicellular
Example : bacteria

19. Eukaryote Cells Contain a nucleus. Unicellular or Multicellular-
Have organelles, which are
surrounded by membranes.
Example: plant cells, animal cells,
fungi, protist

20. 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

21. Animal Cell

22. 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

23. Plant Cell

24. 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

25. 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

26. 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

27. Prokaryote: Bacteria

28. 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

29. 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.

30. Capsule con't
Capsule
Bacterial Cell

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