1 Do Now: Do Now: How is a window screen similar to a cell How is a window screen similar to a cell membrane? membrane? 1. 1. What are some things that can pass through a What are some things that can pass through a window screen? window screen? 2. 2. What are some things that cannot pass What are some things that cannot pass through a window screen? through a window screen? 3. 3. The cell is surrounded by a cell membrane, The cell is surrounded by a cell membrane, which regulates what enters and leaves the which regulates what enters and leaves the cell. Why is it important to regulate what cell. Why is it important to regulate what moves into and out of a cell? moves into and out of a cell? Cell Membrane Cell Membrane (Plasma Membrane) (Plasma Membrane) Chapter 7: Section 7 Chapter 7: Section 7-3 Electromagnetic energy Label the Diagram Label the Diagram In 1972, Singer and Nicolson In 1972, Singer and Nicolson Cell membrane Cell membrane - made of scattered made of scattered proteins proteins and and lipids lipids that make up the that make up the phospholipid bilayer. phospholipid bilayer. Cell Membrane: Cell Membrane: Fluid Mosaic Model Fluid Mosaic Model Fluid meaning movement. Fluid meaning movement. Phospholipids move Phospholipids move Figure 7.5 B Fluid Viscous Unsaturated hydrocarbon tails with kinks Saturated hydro- Carbon tails (b) Membrane fluidity Proteins can move (drift) inside the bilayer Proteins can move (drift) inside the bilayer EXPERIMENT Researchers labeled the plasma membrane proteins of a mouse cell and a human cell with two different markers and fused the cells. Using a microscope, they observed the markers on the hybrid cell. Membrane proteins Mouse cell Human cell Hybrid cell Mixed proteins after 1 hour RESULTS CONCLUSION The mixing of the mouse and human membrane proteins indicates that at least some membrane proteins move sideways within the plane of the plasma membrane. +
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1
Do Now:Do Now:
How is a window screen similar to a cellHow is a window screen similar to a cell
membrane?membrane?1.1. What are some things that can pass through a What are some things that can pass through a
window screen?window screen?
2.2. What are some things that cannot pass What are some things that cannot pass through a window screen?through a window screen?
3.3. The cell is surrounded by a cell membrane, The cell is surrounded by a cell membrane, which regulates what enters and leaves the which regulates what enters and leaves the cell. Why is it important to regulate what cell. Why is it important to regulate what moves into and out of a cell?moves into and out of a cell?
Do you think the Do you think the cell membranecell membrane will allow will allow
smaller molecules or larger molecules smaller molecules or larger molecules to pass to pass through without through without using energy? using energy?
The passage of small molecules through the cell The passage of small molecules through the cell membrane.membrane.
No ENERGY USED!!!!!!!!!!No ENERGY USED!!!!!!!!!!
Examples: H20, C02, O2Examples: H20, C02, O2
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Facilitated DiffusionFacilitated Diffusion
Are Are protein channelsprotein channels that allow diffusion of that allow diffusion of molecules to travel across the cell membrane.molecules to travel across the cell membrane.
NO ENERGY USED!NO ENERGY USED!
Example: GlucoseExample: Glucose
EquilibriumEquilibrium
ConcentrationConcentration of the solute is the of the solute is the SAMESAMEthroughout both sides.throughout both sides.
Molecules of dye Membrane (cross section)
Net diffusion Net diffusion Equilibrium
Molecules of Dye
HIGH TO LOW CONCENTRATION
Keeps passing back & forth
OsmosisOsmosis
TheThe diffusiondiffusion of water through a selectively of water through a selectively
�� The process of taking material into the cell by The process of taking material into the cell by means of pockets by the cell membrane.means of pockets by the cell membrane.
�� A vacuole is formed inside the cytoplasm.A vacuole is formed inside the cytoplasm.
�� Used for LARGER molecules.Used for LARGER molecules.
�� ENERGY is USED !!!!!!!!!!!!!!!!ENERGY is USED !!!!!!!!!!!!!!!!
Active TransportActive Transport
3. 3. ExocytosisExocytosis (out)(out)
�� The process where a vacuole surrounding The process where a vacuole surrounding a material fuses with the cell membrane, a material fuses with the cell membrane,
forcing the contents out of the cell.forcing the contents out of the cell.
��Used for LARGER molecules.Used for LARGER molecules.
��ENERGY is USED!!!!!!!!!!!!ENERGY is USED!!!!!!!!!!!!
Endocytosis & ExocytosisEndocytosis & Exocytosis
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Analyze: Analyze: Endocytosis or Exocytosis?Endocytosis or Exocytosis?
2 Types of Endocytosis2 Types of Endocytosis
1.1. PhagocytosisPhagocytosis�� Means “cell eating”Means “cell eating”�� The cytoplasm extends & surrounds a particle & The cytoplasm extends & surrounds a particle &
package it within a food molecule.package it within a food molecule.
2. Pinocytosis2. Pinocytosis�� Means “Cell Drinking”Means “Cell Drinking”
��The process where tiny pockets are formed filled with liquid The process where tiny pockets are formed filled with liquid along the cell membrane.along the cell membrane.
��Then pinch off to form a vacuole inside the cell.Then pinch off to form a vacuole inside the cell.