Post on 08-Jan-2018
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7-2 Cell Structure
Cell Wall Provides structure
and protection for the cell
Mostly carbohydrates Protein fibers
reinforce Found in plants,
fungi, algae, and most bacteria
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Cell Membrane Regulates what goes in/out of a cell
Selectively permeable Fluid Mosaic Model
Made up of a “mosaic” of different molecules Molecules flow laterally
Outsideof cell
Insideof cell(cytoplasm)
Cellmembrane
Proteins
Proteinchannel Lipid bilayer
Carbohydratechains
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Cell Membrane Lipid bilayer
Phospholipids have a polar head and non-polar tail
Polar head is attracted to water (hydrophilic)
Non-polar tail repels water (hydrophobic)
Proteins Carbohydrates
Proteins
Proteinchannel Lipid bilayer
Carbohydratechains
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Lipid Bilayer7-2
7-2 Cell Transport
Diffusion Diffusion is the natural movement of particles from an
area of high concentration to a area of low concentration Spontaneous (needs no energy) Due to random particle motion and collisions
Concentration of solute will eventually reach equilibrium No net diffusion but particles are still moving
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Diffusion7-3
Osmosis Osmosis is the diffusion
of water across a membrane
3 types of solutions:1. Hypertonic- solution
has a higher concentration of solutes than the cell
2. Isotonic- the concentration of solutes is the same inside and outside the cell
3. Hypotonic- solution has a lower concentration of solutes than the cell
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Osmosis7-3
Facilitated Diffusion Uses integral
membrane proteins Channel or Carrier
High Low concentration
Uses no energy Molecule specific
Often for large or polar molecules
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Active Transport Low High concentration
Against concentration gradient Uses energy Larger molecules use
endocytosis (in) and exocytosis (out)
Types of endocytosis: Phagocytosis (solid particles, mostly
food) Pinocytosis (liquids)
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Cell Transport
Passive
Diffusion
Standard Facilitated
Channel Proteins
Carrier Proteins
Active
Molecular
Protein Pumps
Bulk
Endocytosis
Exocytosis
7-4 The Diversity of Cellular Life
Unicellular vs. Multicellular Organisms
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Unicellular Multicellular• Single cell• The most common organisms• Simple• Reproduce quickly
• Many cells• Great variety• Cells perform different tasks (cell specialization)• Evolved from unicellular organisms
Organization in a Multicellular Organism
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Cell Specialization Cells in multicellular
organisms are specialized to perform specific functions
Unique shapes, proteins, and organelle makeup
Stem cells are undifferentiated “blanks” that can become many cell types
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