Cell Theory

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Cell Theory

• All living things are made of cells
• Cells are the basic unit of life
• Cells today come only from other living cells

Robert Hooke first saw cells in 1665
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The Structure of a Cell

• All cells have
• Plasma membrane
• Cytosol
• DNA
• Ribosomes

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Two Major Types of Cells

• Prokaryotic
• No membrane bound organelles
• Make up Domains Archaea and Eubacteria
• Eukaryotic
• Membrane-bound organelles
• Make up Kingdoms Plantae, Animalia, Protista, and
  Fungi

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A prokaryotic cell
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Overview of an animal cell
Cytoplasm everything inside the cell but the
nucleus
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Overview of a plant cell
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Cell size
The human body has over 5 billion cells. The
largest animal is the blue whale, Balaenoptera
musculus. It is known to reach lengths over 100
feet (30 meters) and weigh 120 tons.
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Cell size
So, why arent there organisms composed of one
really big cell?
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Surface Area and Volume
Surface area of a sphere 4?r2 Volume of a
sphere (4/3) ?r3 So as a sphere gets bigger,
its volume increases faster than its surface
area
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Figure 7.5 Geometric relationships explain why
most cells are microscopic
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Lets look at the interior of Eukaryotic cells

• Nucleus
• Ribosomes
• Endomembrane System
• Nuclear envelope
• Endoplasmic Reticulum
• Golgi Apparatus
• Vesicles
• Lysosomes
• Vacuoles
• Other organelles mitochondria, chloroplasts,
  peroxisomes
• Cytoskeleton

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DNA? RNA ? protein a diagrammatic overview of
information flow in a cell
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Figure 7.9 The nucleus and its envelope 
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Figure 7.10 Ribosomes
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Figure 7.11 Endoplasmic reticulum (ER)
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In the rough ER, proteins are modified by the
addition of a carbohydrate group
H2N
COOH
Protein
Now GLYCOPROTEIN
Carbohydrate group
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Figure 7.12 The Golgi apparatus
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THE SECRETORY PATHWAY A MODEL
RNA
1. Proteins are synthesized in the RER
Rough ER
2. Protein exits RER in a vesicle.
cis face of Golgi apparatus
3. Protein travels through the cisternae of the
Golgi apparatus.
4. Protein enters a secretory vesicle that fuses
with cell membrane.
trans face of Golgi apparatus
Plasma membrane
5. Protein is secreted from cell.
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Figure 7.13 Lysosomes
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Figure 7.14 The formation and functions of
lysosomes (Layer 1)
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Figure 7.14 The formation and functions of
lysosomes (Layer 2)
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Figure 7.14 The formation and functions of
lysosomes (Layer 3)
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Figure 7.15 The plant cell vacuole 
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Figure 7.16 Review relationships among
organelles of the endomembrane system