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CellsThe Building Blocks of Life
The cell is the smallest unit capable of
performing life functions.
Cell Trivia
• The average human being is composed of around 100 Trillion individual cells!!!
• It would take as many as 50 cells to cover the area of a dot on the letter “i”
History of Cells1665- English Scientist, Robert Hooke, discovered cells
while looking at a thin slice of cork (bark of tree)– He described the cells as tiny boxes or a honeycomb– He thought that cells only existed in plants and fungi
1673- Anton von Leuwenhoek, invented the microscope and observed pond scum and discovered single celled organisms
•He called them “animalcules”He called them “animalcules”•He also observed blood cells from fish, birds, frogs, dogs, He also observed blood cells from fish, birds, frogs, dogs, and humansand humans•Therefore, it was known that cells are found in animals as Therefore, it was known that cells are found in animals as well as plantswell as plants
More history…
• 1838- German Botanist, Matthias Schleiden, concluded that all plant parts are made of cells
• 1839- German physiologist, Theodor Schwann, who was a close friend of Schleiden, stated that all animal tissues are composed of cells.
3. All cells come from pre-existing cells through cell division.
Francesco Redi did first experiments to disprove spontaneous generation – Life comes from life - biogenesis
Compound Light Microscope• Use in class• Compound –
Eyepiece (10x) times objective lens
10x X 4x=40x10x X 10x=100x10x X 40x = 400x
Number of Cells in an organism
•Unicellular – composed of one cell
• Multicellular- composed of many cells that organize
1. Prokaryotes- ONLY bacteria, one celled, lack a nucleus or membrane-bound organelles
Two basic cell types
2. Eukaryotes- (Like U-you) all other living things (plants, animals & fungi), have a nucleus and membrane-bound organelles.
May be unicellular or multicellular
Plasma (Cell) Membrane
Boundary between the internal and
external environment of
the cell.
Controls what goes in & out of
cell
Cell WallInflexible structure composed
of cellulose, found only in PLANTS and bacteria.
Supports and protects the cell.
Endoplasmic Reticulum(E.R.)
Makes lipids (fats) delivery system - manufactures and transports.
Smooth and rough
RibosomesMake proteins Each cell contains
thousandsFound on ribosomes and
floating throughout the cell
.
“Mighty” Mitochondria
“Powerhouse”, makes energy for cell. Site of cellular respiration
(converts food into usable energy)
ChloroplastsFound only in plants - makes
food
Changes the sun’s energy into chemical energy (photosynthesis).Contains chlorophyll (gives plants green color)