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Overview of Cells
• Prokaryotes vs Eukaryotes
• The Cell Organelles
• The Endosymbiotic Theory
Prokaryotic Cells
• Archaea
• Bacteria
• Come in many different shapes and sizes
 .5 µm – 2 µm, up to 60 µm long
• Have large surface to volume ration
– nutrients from outside can easily
reach all parts of the cell
Eukaryotic Cells
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Protists
Fungi
Animal Cells
Plant Cells
• Like prokaryotic cells, eukaryotic cells come in many different shapes
and sizes, but have the same basic set of organelles
• Multicellular organisms (fungi, plants and animals) have specialized
eukaryotic cells that each perform a particular job and all work together
for the benefit of the organism
Eukaryotic Cells
Common Organelles
– Plasma membrane
– Nucleus
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Chromatin (DNA)
Nucleolus
Nuclear Envelope
– Ribosomes
– Rough Endoplasmic
Reticulum (rough ER)
– Smooth Endoplasmic
Reticulum (smooth ER)
– Golgi Apparatus
– Centrioles
– Mitochondria
– Cytoskeleton
– Vesicles, Peroxisomes, Lysosomes, Small Vacuoles
Eukaryotic Cells
Organelles only found in Plants
– All those in animal cells except
Centrioles
– plus
 Cell Wall
 Chloroplasts
 Large Vacuoles
– The cell wall and
vacuoles help plant
cells maintain a rigid
shape (keep plant from
drooping)
Organelles
• Organelles are the parts within a cell that have specific functions
• Prokaryotic cells (e.g. bacteria) are smaller and less complex
(fewer organelles) than eukaryotic cells.
Eukaryotic Cells
Prokaryotic Cells
Plant Cells
– Plasma Membrane
(eukaryotic)
– Plasma Membrane
– Cytoplasm
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Cytoplasm
Cell Wall
DNA (no nucleus)
Ribosomes
– Nucleus
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Chromatin (DNA)
Nucleolus
Nuclear Envelope
– Cell Wall
– Chloroplasts
– Vacuole
Ribosomes
Vesicles, Peroxisomes, Lysosomes
Rough Endoplasmic Reticulum
Smooth Endoplasmic Reticulum
Golgi Apparatus
Centrioles
Mitochondria
Cytoskeleton
Organelles
Polysaccharides
Organelles are made of:
• Proteins – made of amino acids
• Lipids – made of fatty acids
• Carbohydrates - polysaccharides
made of sacharides (sugars)
• Nucleic Acids (DNA and RNA)
– made of nucleotides
Proteins (Polypeptides)
Lipids
Nucleic Acids
Components found in all cells
Plasma Membrane
• Made of a Phospholipid Bilayer
• Various proteins, lipids, and sugars float in membrane
• Semipermeable
 Small hydrophobic molecules pass easily through
 Contains pores that enable water and very small ions to pass through
 large molecules must pass through channel proteins
Components found in all cells
Plasma Membrane
 Eukaryotic cells also membrane-bound internal
organelles composed of lipid bilayer membranes
• Nuclear Envelope
• Golgi Apparatus
• Endoplasmic Reticulum (rough and smooth)
• Mitochondria
• Chloroplasts (in plants)
• Vesicles, Lysosomes, Peroxisomes & Vacuoles
Components found in all cells
Cytoplasm
• The fluid that fills cells and surrounds the organelles
• Consists of:
• Water (mostly)
• Proteins (e.g. hormones and enzymes)
• Small Molecules (e.g. ions)
Components found in all cells
DNA
• Prokaryotic Cells
• May be linear or circular
• Contained in the nuclear region (nucleoid)
• May also include short, circular plasmids
• Eukaryotic Cells
• Longer (approx. 9 feet per cell in humans),
coiled around histone proteins to help pack it
into the cell
• Always linear
• Contained in the nucleus
• Known as chromatin when relaxed and
chromosomes when condensed (supercoiled)
Components found in all cells
Ribosomes
• Float freely in the cytoplasm of prokaryotic and eukaryotic cells
• Also coat the rough ER of
eukaryotic cells
Components found in all cells
Ribosomes
• Build proteins using instructions encoded in DNA
Components found in all cells
Ribosomes
• Build proteins using instructions encoded in DNA
• Complex of protein and rRNA forming two subunits
Purple = Proteins
Blue = rRNA of small subunit
Grey = rRNA of large subunit
Components found only in Eukaryotic Cells
Nucleus
• Nuclear Envelope
 double membrane
 nuclear pores allow RNA to exit
• Chromatin – “relaxed” DNA
• Nucleolus – where ribosomes are assembled