2.1 The Structure

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2.1The Structure Functions of Eukaryotic
Cells
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Cells

• Smallest living unit
• Most are microscopic

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Defining a Cell

• A cell is a confined system of potentially self
  perpetuating linked organic reactions that are
  catalyzed step-wise by enzymes.

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Principles of The Cell Theory

• All living things are made of 1 or more cells
• Smallest living unit of structure and function of
  all organisms is the cell
• All cells arise from pre-existing cells
• (this principle discarded the idea of
• spontaneous generation)

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Cell Size
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Small Cells have a large Surface Area-to-Volume
Ratio. Why?
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Why are S.A./Vol. Ratios Important?

• Surface area represents the access available to
  and from a cell for supplies.
• Volume represents how much has to be supplied.
• The more access you have to supply each unit of
  volume, the more efficient the cell is.

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Characteristics of Living Cells

• Very complex
• Very small
• Self-replicating
• Autonomous/semiautonomous
• Homeostatic

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There are 2 Cell Types

• Prokaryotic
• Eukaryotic

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Prokaryotic Cells

• First cell type on earth (chemosynthetic)
• All are single celled (ie Bacteria)

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Prokaryotic Cells

• No membrane bound structures inside
• Nucleoid instead of nucleus (region of DNA
  concentration).
• Organelles not bound by membranes

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Eukaryotic Cells

• Internal membrane bound organelles
• Cytoplasm (cytosol, organelles molecule ions
  ) for metabolism
• Cell Membrane (Phospholipid bilayer)
• Can be Single or Multi-celled

Protozoan
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Eukaryotic Animal Cell
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Animal Cell Micrograph
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Eukaryotic Plant Cell
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Plant Cell Micrograph

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Cytoplasm

• Viscous fluid containing organelles
• components of cytoplasm
• Interconnected protein filaments fibers
• Fluid cytosol
• Organelles (not nucleus)
• storage substances

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Nucleus

• Control center of the cell
• Contains nucleoplasm
• Wrapped by a nuclear envelope which is a double
  membrane.
• Nuclear pore complexes form openings in nuclear
  envelope
• Contains
• Chromosomes (DNA)
• Nucleolus

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Nucleus Micrograph
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Chromosomes (DNA)

• Hereditary material
• Chromosomes
• - DNA proteins
• Short, thick strands
• form for cell division
• Chromatin
• - DNA proteins
• long, thin strands
• form for interphase
• DNA is transcribed translated into protein to
  express hereditary traits

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Nucleolus

• Non-membrane bound
• Contains RNA proteins
• Most cells have 2 or more.
• Directs synthesis of RNA
• Forms ribosomes

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End of Part 1!