CELL THEORY
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Cell theory is revision from year 8 and 10
Read 2.1 Heinemann-history of cell theory
Points to note: remember
◦ Van Leeuwenhoek, Robert hook, cork, little boxes,
microscopes etc
◦ Write out the cell theory below after your own reading
and notes:
Cells are the basic functional and structural unit of living
organisms
All organisms are made up of cells and the products of
cells
All cells come from preexisting cells
The cell is the smallest living organizational unit
All cells are basically the same chemical composition
All energy flow (metabolism & biochemistry) of life
occurs within cells
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Cell Membrane:
Holds cell together
Controls what passes in and out of the cell
Referred to as selectively permeable- won’t
let all molecules through depending on size
and etc.
Nucleus:
Control centre of the cell
Controls all processes the cell does
Contains threadlike bodies- chromatin
granules important in cell division
During division chromatin appears as
chromosomes
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All the contents of a cell within the
plasma/cell membrane.
The semifluid medium between the nucleus
and the plasma membrane is called cytosol.
(cytoplasm)
Controlled by the nucleus
Various functions occur here
Functions are controlled by different
organelles
Lots of chemical reactions occur in the
cytoplasm – This is called metabolism
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Mitochondria:
Through the process of cellular respiration it
produces energy
Small Granules:
Glycogen in animals
Starch in plants.
Plastids:
These are small bodies in a cell which contain a
chemical substance
Eg: Chloroplast is a plastid that contains the
chemical chlorophyll
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It is a transport system for the cell but it also
makes lipids
Processes carbohydrates
Detoxifies substances such as poisons and
alcohol
◦ Can be rough – contains ribosomes (Rough
Endoplasmic Reticulum) RER
◦ It can be smooth – No ribosomes (Smooth
Endoplasmic Reticulum) SER
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Carries proteins from the nucleus to a Golgi
Complex
Ribosomes
THESE ARE SMALL ORGANELLES RESPONSIBLE FOR THE
MANUFACTURE OF PROTEINS IN THE CELL.
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The function of the Golgi Body is to sort,
chemically alter, and package important
molecules
Plants also have cell membranes, ribosomes,
mitochondria and endoplasmic reticulum.
Only Plant Cells
Chloroplast:
 Membrane bound organelle, it is the site of
photosynthesis and ATP production in
autotrophic plant cells
Cell Wall:
 Cellulose layer that surrounds the plasma
membrane of plant cells.
 Because it is very porous the cell wall permeable
to molecules and ions that can pass through the
plasma membrane through diffusion.
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Vacuole
 Is a membrane bound, fluid filled sac inside plant
and animal cells.
Large Vacuole
 Is a membrane bound, fluid filled sac inside plant
and animals cells.
 Occupies much of the volume of a plant cell.
Amyloplast (Starch Grain)
 A membrane bound organelle containing
concentric layers of starch (amylopectin).
READ AND NOTE PAGE 21: Cilia and Flagella