I. Cell Theory
A. Discovery of the cell
1. Seventeenth Century
a) required the microscope
2. Leeuwenhoek
a) developed the microscope
b) first to describe microscopic organisms
3. Robert Hooke
a) studied cork chambers and called them "cells'
4. Schleiden, Schwann, and Virchow came up with the "cell theory"
a) Cells are basic units of life
b) All organisms are made of one or more cells
c) All cells come from other cells
II. Parts of the Cell
A. The cell membrane
1. Surrounds the cell
2. Made of lipids and proteins
a) Lipids are phospholipids which form two layers called a bilayer.
b) Phospholipids and proteins form a surface called a fluid mosaic model.
3. Controls what enters and leaves the cell
B. The nucleus
1. Controls the cell
2. Most visible structure in the cell
3. Surface looks like dimples on golf ball that are pores that allow movement of proteins and chemical messengers
4. Contains DNA
a) hereditary material called chromatin which form chromosomes during cell division
b) Chromosomes contain coded "blueprints" that control all cellular activity
5. Contains at least one nucleolus
a) makes ribosomes that make proteins
b) looks like dark spot
6. Prokaryotes are organisms whose cells do not contain a nucleus a) ex. bacteria
7. Eukaryotes are organisms whose cells do contain a nucleus, a) ex. plants and animals
C. Cytoplasm
1. Everything between the nucleus and the cell membrane
2. Cytosol is the jellylike material that is made mostly of water along with organic compounds
3. Organelles are structures that work like miniature organs carrying out specific functions.
III. Organelles
• Enable the cell to perform the functions of living things
A. Ribosomes
1. Make Proteins
2. Look like black dots
3. Some are free in the cytoplasm and others attached to the (rough) endoplasmic reticulum
B. Endoplasmic Reticulum
1. Transportation and detoxification system
a) look like tunnels
b) connects the nuclear membrane with the cell membrane
c) transports materials through the cell
2. Rough ER
a) has ribosomes, processes proteins
3. Smooth ER
a) no ribosomes, processes lipids and carbohydrates
C. Golgi Apparatus
1. Look like a stack of pancakes
2. Packaging and secreting cell products
D. Mitochondria
1. "Powerhouse" of the cell
2. Releases energy from food (glucose) and stores it in ATP a) process called cellular respiration
E. Lysosomes
1. Contain enzymes that break down waste materials and package them for removal from the cell.
2. Form from the Golgi apparatus

IV Cell Diversity
A. Plant Cells
1. Cell Walls (in plants and fungi)
a) located outside the cell membrane
b) made of polysaccharide cellulose
c) provides stiffness and structure
2. Chloroplasts (only in plants
a) a type of plastid
b) converts sunlight, CO2, and water into sugar (glucose)
c) green color comes from the chlorophyll which absorbs the energy from sunlight
3. Vacuole (large in plants)
a) Storage
(1) water, proteins, ions, waste, and other products
(2) some may contain poison to protect the plant
b) Contractile vacuole found in some simple organisms to adjust water content
B. Cell Shape
1. Depends on function
a) Nerve - long and thread like
b) Blood - round discs
c) Plant cells - rigid because of cell walls
d) Animal cells - internal framework called cytoskeleton made of microtubulesand microfilaments
2. Microtubules
a) Hollow tubes
b) Maintain cell shape
c) Tracks for organelles to move
d) May form cilia and flagella (for movement)
(1) ex. Paramecium with cilia
(2) ex. Euglena with flagella
3. Microfilaments
a) Not hollow
b) Can contract to cause movement
(1) ex. muscle cells
(2) ex. scabs getting smaller
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