Quiz #4
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Substances move in/out of the cell through the _______
Cell membrane
Cell membrane is
Semi-permeable
Define semi-permeable
Lets only some things in/out
What is the cell membrane made of?
A phospholipid bilayer
What are three characteristics of the phospholipid bilayer?
Flexible, has protein pathways, self-repairs
What are the two parts of a phospholipid molecule?
• Phosphate head • Lipid tail
Define hydrophilic
Likes water
Which part of a phospholipid molecule is hydrophilic?
Phosphate head (faces the outside and inside of the cell)
Define hydrophobic
Doesn’t like water
What part of a phospholipid molecule is hydrophobic?
Lipid tail (hides in the middle of the cell membrane)
What are the two main types of cell transport?
Passive and active
What are the two types of active transport?
• Endo/exocytosis • Protein pumps
What are the three types of passive transport?
• Diffusion • Facilitated diffusion • Osmosis
Describe endocytosis
• Endo - in A molecule is taken into the cell by having a vesicle formed around it
Describe exocytosis
• Exo - out A molecule is deposited out of the cell without breaking the cell membrane
What are protein pumps?
A protein pathway that uses energy (ATP) to push molecules from low to high concentration
What are characteristics of active transport?
• Uses energy (ATP) • L to H concentration
What are characteristics of passive transport?
• No ATP used • H to L concentration • Trying to reach equilibrium
Define diffusion
• Can happen in air or water • Fastest in high temperatures • Only works with small, non-ions
Define facilitated diffusion
• Diffusion with protein pathways • Happens with large or charged molecules (ions)
Define osmosis
• The diffusion of water (H to L) • Solutes don’t move • Changes the cell’s size/shape
Define solutes
Any substance dissolved in water
What are the three situations in osmosis?
Isotonic, hypertonic, and hypotonic
Define isotonic
Equal solutes in and out of the cell