Chapter 7�

Cell Structure and Function

Section 7.1- Life is Cellular

The Discovery of Cells

Robert Hooke

• Used light microscope to look at cork cells
• Cells reminded him of monk cubicles
• “many little boxes”

The Discovery of Cells

Anton van Leewenhoek

• First to observe living cells
• Invented simple, tiny microscopes

The Cell Theory (pg. 170-171)

“Karyotes”

• Karyote = Nucleus
• Prokaryote
• Pro = Before
• Organisms with out a nucleus
• Bacteria
• Eukaryote
• Eu = True
• Organisms with a true nucleus
• Plants and animals

http://wpcontent.answers.com/wikipedia/commons/thumb/5/5a/Average_prokaryote_cell-_en.svg/400px-Average_prokaryote_cell-_en.svg.png

http://library.thinkquest.org/C004535/media/eukaryote_animal.gif

Section 7.2- Eukaryotic Cell Structure

• The Cell
• Parts of a cell-Organelles

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Basic Parts of a Cell

Comparing Cells

• What are some differences between plant and animal cells?
• What are some similarities?

Nucleus

• “The Brain”
• DNA, surrounded by nuclear envelope, nucleolus- where ribosomes are made

Ribosomes

• “The Construction Company”
• Builds proteins
• Free floating in the cytoplasm or attached to the ER

Endoplasmic Reticulum

• “The Highway” (tubes and sacs)
• Rough
• Produces phospholipids and proteins
• Smooth
• Produces cholesterols

Golgi Apparatus

• “The Post Office”
• Receives proteins from ER
• Modifies, labels and directs proteins to locations in the cell

Lysosomes

• Specialized organelles
• Lysosome- “The Killer or Garbage Truck”
• Breaks down molecules
• Maintains cell’s health by getting rid of non-functioning parts

Vacuole

• Specialized organelles
• Vacuole- “The Storage Center”
• Stores water, nutrients and waste

Mitochondria

• “The Power House”
• Where ATP is produced

Plastids- Chloroplast

• Use light energy to make C6H12O6 and O2
• Thylakoids
• Flattened membranous sacs that contain chlorophyll
• Chlorophyll
• Pigment that absorbs light and captures light energy for the cell

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Cytoskeleton

• “The Infrastructure”
• Cell support
• Microtubule
• Hold organelles in place
• Microfilaments
• Cell movement
• Intermediate Filaments
• Maintain internal shape of cell

Section 7.3- Cell Boundaries

• Cell Diversity
• Basic Parts of a Cell
• Two Basic Types of Cells
• Cellular Organization

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Cell Membrane

• Cell membrane
• Border
• Phospholipid bilayer

Cell Membrane Structure

Selective Permeability

• The cell membrane is “selectively permeable”
• It only allows certain materials to pass when needed
• Some materials may pass through the membrane anytime
• Ex: water, oxygen, carbon dioxide
• Some materials require specialized transport
• Ex: proteins, carbs, large ionic compounds

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Cell Membrane

• Fluid Mosaic Model
• Proteins embedded in lipid bilayer
• Cell surface markers, pumps, channels, receptors

Cell Wall

• rigid layer
• made of cellulose

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Passive Transport

• What does passive mean?
• What does transport mean?

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• Passive Transport
• Movement of substances across a membrane “down” their concentration gradients without using energy

Diffusion

• Net flow from high to low
• Driven by kinetic energy (energy of motion)

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Diffusion

• Semipermeable Membrane
• Concentration Gradient
• Equilibrium
• “simple diffusion”- diffusion across a membrane

High [ ]

Low [ ]

Diffusion Animation

• View Animation here…
• http://www.wiley.com/legacy/college/boyer/0470003790/animations/membrane_transport/membrane_transport.htm

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Osmosis

• Diffusion of water across a membrane
• Direction of osmosis into or out of a cell depends on solute concentrations inside and outside the cell

Animation of Osmosis

Osmosis- Direction of Osmosis

• Salt is the solute
• A solute is a substance that dissolves in a solvent

Isotonic

Hypertonic

Hypotonic

Facilitated Diffusion

• Diffusion that requires the help of carrier proteins

Animation of Facilitated Diffusion

• View an animation here: http://www.wiley.com/legacy/college/boyer/0470003790/animations/membrane_transport/membrane_transport.htm

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Diffusion Through Ion Channels

• Ion channels are membrane proteins that allow only specific ions to pass through.
• Channels can be “open” or “gated”
• If an ion channel is gated, it can be opened by; stretching the cell membrane, a voltage, or a chemical.

Active Transport

• Cell Membrane Pumps
• Movement in Vesicles

Active Transport

• What does active mean?
• What does transport mean?

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• Active Transport
• Movement of substances across a membrane “up” their concentration gradients using energy

Cell Membrane Pumps

• Carrier proteins that move substances from areas of low concentration to areas of high concentration.
• Requires energy
• What molecule furnishes the energy to power the pump?
• View an animation here of the Sodium/Potassium Pump: http://www.wiley.com/legacy/college/boyer/0470003790/animations/membrane_transport/membrane_transport.htm

Sodium-Potassium Pump

• Transports Na+ and K+
• 3 Na+ out of cell / 2 K+ into cell

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*Here’s another animation to look at: http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter6/animations.html#

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How Na+/K+ pump works:

• 3 Na+ ions bind to pump, while pump removes a PO4- from ATP.
• Pump changes shape and releases 3 Na+ out of cell.
• 2 K+ ions bind to pump, while the PO4- is released.
• Pump changes shape and release 2 K+ into the cell.
• Pump is back to original shape to start process again.

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How Na+/K+ pump works:

Animation of Sodium-Potassium Pump

Movement in Vesicles

• What happens if substances are too large to pass through the cell membrane or carrier protein?
• What does the prefix endo- mean?
• What does the prefix exo- mean?
• What does cyto- mean?
• What does –osis mean?

Movement in Vesicles

Endocytosis

• Process by which cells ingest what they need.
• Requires energy
• Cell membrane folds and pinches off to form a vesicle

Endocytosis

• 2 Types
• Pinocytosis
• Endocytosis of solutes and fluids

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• Phagocytosis
• Endocytosis of large particles and whole cells
• Phagocytes

Endocytosis

Movement in Vesicles

Exocytosis

• Process by which cells release unwanted substances.
• Requires energy
• Vesicles fuse to membrane to let substances out of cell

Phagocytosis…the movie!

• Phagocytosis Video: http://www.cellsalive.com/mac.htm

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Exocytosis

• View the endo/exocytosis film here: http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter6/animations.html#

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7.4- The Diversity of Cellular Life

Unicellular or Multicellular Organisms

Unicellular Organisms

• Single cell organism
• Dominate life on Earth

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Multicellular Organisms

• Made up of many cells
• MO depend on communication and cooperation among specialized cells

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• Cell Specialization
• Cells develop differently to perform different tasks

Two Basic Types of Cells

Eukaryote

• Has a nucleus
• Has organelles

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Prokaryote

• Lacks a nucleus
• Lacks organelles

Nucleolus

Cellular Organization