Section 3-3, 3-4, 3-5 “Movement across the cell membrane” Write everything that is underlined
3.3 KEY CONCEPT: The cell membrane is a barrier that separates a cell from the external environment.
Cell membranes are composed of two phospholipid layers. It forms a boundary between inside and outside of the cell …and controls passage of materials cell membrane outside cell inside cell
The cell membrane is made of a phospholipid bilayer. There are other molecules embedded in the membrane. The fluid mosaic model describes the membrane. cell membrane protein cholesterol carbohydrate chain protein channel
How many layers is the cell membrane made up of? 1 2 3 4
The cell membrane is selectively permeable (only certain things get through) like a screen door
3.4 KEY CONCEPT: Materials move across membranes because of concentration differences.
Passive transport does not require energy There are two types of passive transport: diffusion osmosis
Diffusion: Molecules move down a concentration gradient “From an area of high concentration to low concentration”
Osmosis is the diffusion of water There are three types of solutions: isotonic, hypertonic, hypotonic
What is passive transport? Does not require energy to move materials Requires energy to move materials Depends on your definition of movement Only sometimes does it use energy
What is/are the different types of passive transport? Diffusion Isotonic Osmosis A and C
Diffusion is the movement of materials from an area of ___________ concentration to ______ concentration Low to High High to High Low to Low High to Low
Osmosis it the diffusion of ___________ Materials Sugar Water Amino acids
Facilitated diffusion: diffusion through transport proteins Some molecules can only diffuse through transport proteins. Facilitated diffusion: diffusion through transport proteins
3.5 KEY CONCEPT: Cells use energy to transport materials that cannot diffuse across a membrane.
Active transport requires energy to move a substance against its concentration gradient (from LOW to HIGH) Passive transport requires no energy from the cell Active transport is powered by chemical energy (ATP) Cells use active transport to maintain homeostasis
A cell can import and export large materials or large amounts of material in vesicles during the processes of endocytosis and exocytosis. Endocytosis is the process of taking material into the cell – also called Phagocytosis
Exocytosis is the process of expelling (pushing out) material from the cell
What is the difference between active transport and passive transport? Active requires energy and passive does not Passive requires energy and active does not Passive moves big materials into the cell and active does not B and C
What does the following picture show? Endocytosis Exocytosis Diffusion Osmosis