1. Cells: The Basic Units of Life

2. Robert Hooke was the first person to describe cells
Anton van Leeuwenhoek was the first person to make a microscope.
Cell Theory
1. All organisms are made of one or more cells.
2. The cell is the basic unit of all living things.
3. All cells come from existing cells.

3. PARTS OF THE CELL:
Cell Membrane – protective layer that covers the cell’s surface and acts as a barrier
Organelle – structures that perform specific functions within the cell
DNA – deoxyribonucleic acid, genetic material that carries information needed to make new cells and new organisms
Nucleus – encloses DNA

4. TWO KINDS OF CELLS:
Two basic cell types:
Prokaryotes – do not have a nucleus and do not have membrane-bound organelles
(ex. eubacteria and archaebacteria)
Eukaryotes – do have a nucleus and have membrane-bound organelles
(ex. animals, plants, and fungi)

5. PROKARYOTES: EUBACTERIA AND ARCHAEBACTERIA:
Prokaryotes are single celled organisms that have no nucleus, circular DNA, and no membrane-bound organelles.
The most common prokaryote is eubacteria = bacteria.
Bacteria
world’s smallest cells
live in places no other organisms could live
Archaebacteria = archae
are heat-loving, salt-loving, and methane-making

6. EUKARYOTIC CELLS:
Eukaryotic cells are microscopic but are 10 times larger than most bacterial cells.
Eukaryotes are the largest cells.
All living things that are not bacterial are eukaryotes.
Eukaryotes are multi-cellular with linear DNA, a nucleus, and membrane-bound organelles.
multi-cellular = “many cells”

7. Prokaryotes Eukaryotes
Number of Cells
DNA
Nucleus
Organelles
single celled
multicellular
circular
linear
nucleus present
no nucleus
no membrane-bound organelles present
membrane-bound organelles present

8. Cell Wall
the rigid structure that gives support and protection to the plant cell
outermost structure of a plant cell
found only in plants, algae, and fungi
plants and algae cell wall made of cellulose
fungi cell wall made of chitin
helps the plant stand up right

9. protective barrier that encloses animal cells
Cell Membrane
protective barrier that encloses animal cells
outermost structure of an animal
contains proteins, lipids, and phospholipids
main functions:
1) encloses cells and separates and protects the cell’s contents from the cell’s outside environment
2) controls movement of materials (food and water) into and out of the cell
Security Guard or
Border Patrol

10. Cytoskeleton
a web of protein that give support and structure to the cell
keeps the cell membrane from collapsing
give the cell shape

11. Nucleus (control center)
large dark structure in the cell
contain the cell’s DNA
directs all activities in the cell
contains two membranes
contains nucleolus which stores materials that will be used to make ribosomes

12. Ribosomes
structures where proteins are made
the smallest of the organelles
more ribosomes in a cell than any other organelle
not covered by a membrane
all cells have ribosomes

13. Endoplasmic Reticulum (ER)
system of folded membranes in which proteins, lipids and other materials are made
transport materials inside the cell
internal delivery system of cell
rough ER (cover with ribosomes) makes proteins
smooth ER (lacks ribosomes) makes lipids and breaks down toxic material that could damage the cell

14. Mitochondria
the place where sugar is broken down to produce energy
covered by two membranes
the powerhouse of the cell
stores ATP = energy
has its own DNA

15. Chloroplasts (plants and algae only)
place where photosynthesis takes place
photosynthesis is the process where plants and algae use sunlight, carbon dioxide, and water to make sugar and oxygen
has two membranes
is green in color

16. Golgi Complex/Body
packages and distributes proteins
received proteins from ER
final product is enclosed in a piece of the Golgi complex’s membrane
membrane is pinched off to form a bubble (vesicle)
Vesicle
is a small sac that surrounds material to be moved into or out of a cell
all eukaryotic cells have vesicles

17. Lysosomes
contain digestive enzymes and responsible for digestion inside a cell
destroy worn-out organelles
get rid of waste materials (clean up department)
protect the cells from invaders

18. Vacuoles
large vesicles
in plant and fungal cells, act like lysosomes (store digestive enzymes and aid in digestion)
in some plant cells, stores water and other liquids (cell’s watering system)