plasma_membrane 2 automation

Business Access : 

Business Access The World in Our Hands Let’s Create Something New

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Dr. B. Roach 2010 Business Access Biology 101 Arrow will appear below in gray on the transport bar

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The Plasma Membrane and Homeostasis

Homeostasis – Maintaining a Balance : 

Homeostasis – Maintaining a Balance Cells must keep the proper concentration of nutrients and water and eliminate wastes. The plasma membrane is selectively permeable – it will allow some things to pass through, while blocking other things.

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Homeostasis – Maintaining a Balance Some things can pass through the cell and other items cannot.

Structure of the Plasma Membrane : 

Structure of the Plasma Membrane Lipid bilayer – two sheets of lipids (phospholipids). Found around the cell, the nucleus, vacuoles, mitochondria, and chloroplasts. Embedded with proteins and strengthened with cholesterol molecules.

What is a Phospholipid? : 

What is a Phospholipid? It’s a pair of fatty acid chains and a phosphate group attached to a glycerol backbone. Polar (water-soluble) heads face out and the nonpolar fatty acids hang inside. Polar Head Nonpolar fatty Acids

Membrane Proteins : 

Membrane Proteins 1. Determine what particles can pass through the membrane. 2. Serve as enzymes (may speed reactions). 3. Act as markers that are recognized by chemicals and molecules from the inside and the outside of the cell (the immune system).

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cytoskeleton cholesterol membrane protein carbohydrate chains outside the cell interior of cell

Cellular Transport : 

Cellular Transport Diffusion – movement of particles from an area of high concentration to an area of low concentration. Caused by Brownian motion (movement of particles because of the movement of their atoms). Continues until an equilibrium is reached (no gradient). Dynamic equilibrium – particles move freely and are evenly distributed.

Cellular Transport [2] : 

Cellular Transport [2] Passive transport – no energy is needed to move particles. Facilitated diffusion – embedded proteins act as tunnels allowing particles to “fall” through.

Cellular Transport [3] : 

Cellular Transport [3] Active transport – energy is needed to move particles. Carrier proteins – embedded proteins change shape to open and close passages across the membrane. Endocytosis – taking something into the cell. Exocytosis – expelling something from the cell.

Passive & Active Transport : 

Passive & Active Transport Click the above box to view a video explanation of Active & Passive Transport Click on box to play

So, What is Osmosis? : 

So, What is Osmosis?

Osmosis : 

Osmosis Diffusion of water across a selectively permeable membrane. Occurs until water is balanced on both sides of the membrane.

Diffusion : 

Diffusion Click the above box to view a video explanation of Diffusion Click on box to play

Cell Concentrations : 

Cell Concentrations Hypertonic solutions – more dissolved solute. Hypotonic solutions – less dissolved solute. Isotonic solutions – the same dissolved solute.

Overcoming Osmosis : 

Overcoming Osmosis Contractile vacuoles – expel excess water from bacterial cells that live in water. Turgor pressure – water pressure in a plant cell. Loss of turgor pressure causes wilting (plasmolysis).

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This Completes Section #1