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Cell Features
Robert Hooke
 1665
 Observed cork “little boxes” called cells
 Crude microscope
Anton van Leeuwenhoek
 1675
 Observed pond water
 Living creatures
 “Animalcules”
The Cell Theory
 1. All living things are made of One or more cells.
 2. Cells are the basic units of structure and function in
organisms.
 3. All cells arise from existing cells.
Why must cells be small?
 100 trillion cells in the body
 Cells surface-area to volume ratio must be high
 Small cells can exchange substances easier
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Common cell features to ALL cells (5 total)
 1. Cell membrane (Plasma membrane)
 Regulates what enters and leaves the cell (gases, nutrients,
wastes)
Cell Membrane
Common Features
 2. Cytoplasm
 Houses the contents of the cell
Cytoplasm
Common Features
 3. Cytoskeleton
 Microscopic fibers that give the cell shape
Cytoskeleton
Common Features
 4. Ribosomes
 Where proteins are made in the cell
Ribosomes
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 Where proteins are made in the cell
Ribosomes
Common Features
 5. DNA
 Stores genetic information
DNA
Prokaryotes
 Single celled organism
 No nucleus, no Membrane-bound Organelles
Prokaryotes
 Early prokaryotes lived 3.5 billion years ago
 Modern prokaryotes are bacteria
Bacteria cell parts
Draw a Bacteria Using the Diagram below
Bacteria Cell parts
 Cell wall (composed of polysaccharides & Amino Acids)
 Cell (Plasma) Membrane
 Flagella - enables movement
 DNA - in circular ring
 Capsule - enables it to cling to almost anything
Eukaryotes
 Includes all plant and animal cells
 Can be single celled organism or multicellular (made up of
many cells)
Eukaryotes
 Some have Flagella or cilia for movement
 Has a nucleus and internal compartments called organelles
 Organelle “little organs” Which carry out specific activities
Organelle groups
 Organelles for making Proteins
 Organelles for supporting the cell
 Organelles for Producing energy for the cell
 Organelles for breaking down and storing wastes
Organelles for making proteins include
 Nucleus - “brain” directs all activities
 ER - smooth & Rough - Membrane system that move proteins
 Ribosomes - proteins are made on these
 Golgi Apparatus - packaging & distribution “post office”
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 Ribosomes - proteins are made on these
 Golgi Apparatus - packaging & distribution “post office”
Nucleus, ER, Ribosomes and Golgi
Organelles for supporting the cell
 Cell Membrane - Outer boundary of the cell, Controls what
goes into and out of the Cell.
 Cell Wall (plant cell) - surrounds cell membrane in plant cells
Cell Membrane
cell wall
Organelles that produce energy
 Mitochondria - Provides the energy the cell needs
“powerhouse”
 Chloroplast (In plant cells Only) - Site of photosynthesis
Mitochondria and Chloroplast
Organelles that breakdown & Move & Store
 Lysosomes - Digest waste products “Garbage collectors”
 Vesicles - “vehicles” of the cell carry substances
 Central Vacuole (plant cell) - storage site for water
Lysosomes, Vesicles, Central Vacuole
Cell Membrane
 Selectively permeable
 Made up of phospholipids (2 fatty acids bonded to a
phosphate)
 Draw Phospholipid
Lipid Bilayer
 Form a lipid bilayer
 Polar heads that are hydrophilic (interact with water)
 Nonpolar tails that are hydrophobic (repel water)
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 Because of this some molecules are able to pass directly
through the cell membrane and others need to travel through a
protein embedded in the membrane.
Protein function
 Proteins embedded in the membrane have different functions:
 Cell surface markers
 Receptor proteins
 Enzymes
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 Enzymes
 Transport proteins
Cell Surface Markers
 Cell-surface marker - help other cells recognize their cell types
Receptor Proteins
 Receptor protein - recognize and bind specific substances the
cell needs
Enzymes
 Enzymes - involved in Many reactions in the cell, Help to
speed up reactions.
Transport Proteins
 Transport Proteins Aid the movement of substances into and
out of the cell that can’t go directly through the cell membrane
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