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The Cell Membrane. A. Phospholipid. 1. They have a polar head that is hydrophilic (water-loving). 2. They are made of nonpolar tails that are hydrophobic (water-fearing). B. Phospholipid Bilayer.
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A. Phospholipid 1. They have a polar head that is hydrophilic (water-loving). 2. They are made of nonpolartails that are hydrophobic (water-fearing).
B. Phospholipid Bilayer 1. The plasma membrane is made of 2 layers of phospholipids with polar heads pointing out and nonpolar tails pointing in.
C. 3 Proteins in the Membrane • Transport protein: act like doors or channels that allow molecules to pass through the membrane. (Cell phone) • Receptor proteins: transfer information to the inside of the cell. (Texting) • Recognition proteins or glyco-proteins. These are name tags. (caller ID)
D. Selectively Permeable Membrane Only certain molecules are allowed to pass freely.
So how do materials move in and out of a cell? 1. Passive transport – NO energy A. Simple Diffusion (Osmosis) B. Carrier-facilitated Diffusion 2. Active transport – needs energy
A. Simple Diffusion • No energy is needed. Molecules move from an area of high concentration (where there are many molecules) to an area of low concentration (where there are less molecules). • Molecules spread out evenly and reach an equilibrium.
B. Osmosis 1. Osmosis is the Diffusion of WATER. Water molecules move from an area of high concentration (where there are many water) to an area of low concentration (where there are less water). 2. NO energy needed!
1. Water moves by diffusion.2. Membrane is selectively permeable.
Dictionary says: “Facilitate: to make easier; to help something happen” So who facilitates in the cell membrane?
C. Facilitated Diffusion • The TRANSPORT PROTEINS move molecules, they are facilitators or helpers. • No energy needed because molecules are moving from a higher concentration (lots of molecules) to a lower concentration (few molecules).
Active Transport • Transport Proteins move or pump molecules by using energy. • Why is energy needed? • Molecules move from a low concentration (few) to a higher concentration (many).
What do you know? Use your notes to help!!
Name differences between simple diffusion & facilitated diffusion.
The Cell
Name a structure found in eukaryotes but not in prokaryotes.
Nucleus, Organelles
Are plants and animal cells eukaryotic cells or prokaryotic cells?
Acts as a boundary between the cell and its environment. Controls what enters and leaves the cell
A jelly-like substance in the cell that holds the organelles in place
It contains the DNA. Control center for the cell
Which type of cell transport (active or passive) requires no energy?