Cell Structure and Function

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Chapter 7

• Cell Structure and Function

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7.1 The Discovery of Cells

• Robert Hooke
• Discovered 1st cell
• Observed dead cork cells
• Named the cell basic unit of living organisms

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Anton van LeeuwenhoekLooked at described the
1st living cell
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The Cell Theory

• Matthias Schleiden Thomas Schwann
• Schleiden ? Botanist
• Schwann ? Zoologist
• Developed the cell theory
• All life forms are made from one or more cells.
• Cells only arise from pre-existing cells.
• The cell is the smallest form of life.

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Two basic cell types

• Prokaryote
• Before a nucleus (NO Nucleus)
• Single-celled
• Eukaryote
• Has a nucleus
• Unicellular or multicellular
• Contained organelles (membrane bound structures)

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A.
B.
Which one is a prokaryotic cell? Is B. a plant or
an animal cell?
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7-2 Eukaryotic Cell Structure

• Contain Organelles which means little organs.
• Each cell contains Cytoplasm which holds all of
  the organelles.

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Nucleus Control center of the cell
Contains DNA
Has a nuclear envelope Nucleolus
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Ribosomes make proteins
most numerous organelle in the cell
Found on and off of ER
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Endoplasmic Reticulum Two types of ER
Smooth (no ribosomes) Rough (has
ribosomes)
Smooth makes and transports lipids Rough
transports proteins
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Golgi Apparatus Stores and
packages chemicals
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Lysosome Stomach of the cell
Vacuole that contains
digestive enzymes
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Mitochondria Powerhouse of the
cell
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Chloroplast Capture sunlight and convert it
into chemical energy in a process called
photosynthesis
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7-3 Cell Boundaries

• All cells are surrounded by a cell membrane (also
  called a plasma membrane).
• Some cells are surrounded by a cell wall
  (especially plant cells).
• Both serve as a boundary between the cell and its
  environment.
• The Cell membrane is semi-permeable.

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The Plasma Membrane

• FUNCTIONS
• Controls what enters and leaves the cell
  (maintaining homeostasis with selective
  permeability)
• Protects the cell
• Also the cell walls main function!!

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PM continued

• PM is made of a bilayer of phospholipids!!
• Two ends to a phospholipid
• Hydrophilic
• Hydrophobic
• Two types
• Saturated
• Unsaturated

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Fluid Mosaic Model (PG. 182)
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Random movement of Molecules

• Robert Brown Brownian Motion
• Molecules are in a constant state of motion
• Gas fast movement
• Liquid medium movement
• Solid slow movement
• Molecules move from high concentrations to low
  concentrations because of a concentration
  gradient.

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Diffusion Through Cell Boundaries

• Diffusion the movement of particles from and
  area of high concentration to low concentration
• Osmosis is the diffusion of water

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Diffusion
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Three types of solutions (Pg. 186)

• Isotonic concentrations on both sides of the
  plasma membrane are equal
• No net movement
• Hypertonic concentration of dissolved
  substances outside the cell are higher than
  inside
• Water moves out ? Cell Shrinks
• Hypotonic concentration of dissolved substances
  inside the cell are higher than outside
• Water moves in ? Cell Swells

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Two types of transport

• Passive Transport
• Move with the concentration gradient
• NO energy required
• Simple Diffusion
• Osmosis
• Facilitated Diffusion

• Active Transport
• Move against the concentration gradient
• Energy REQUIRED
• Endocytosis
• Pinocytosis (drinking)
• Receptor-mediated endocytosis
• Phagocytosis (Eating)
• Exocytosis