Cell Membrane Flashcards
(15 cards)
What is the main function of the cell membrane?
Maintain homeostasis. Control the transport of nutrients/waste between the cell and the extracellular space.
What do sterols do and how?
Maintain the fluidity of the cell membrane, by restricting the movement of phospholipids and proteins in the lipid bilayer.
Which sterol is in the cell membrane each for plants, animals and fungi?
Plants: sitosterol, Animals: cholesterol, Fungi: ergosterol
(pronounced si-to-sterol, er-go-sterol)
Describe the arrangements of phospholipids in the bilayer.
Hydrophilic head, hydrophobic tails. Tails face the inside of the bilayer, heads face the water on either side of the membrane.
HINT: based on what factors?
How is the cell membrane ‘selectively permeable’?
Only certain materials are transported, based on particle size, electric charge, and whether the material is hydrophobic or hydrophilic.
Three types of transport across the cell membrane.
Simple diffusion, facilitated diffusion, active transport.
What is the cell membrane made of?
Lipids (phospholipids & sterols), protein and carbohydrates
What does semi-permeable mean?
Has lots of tiny holes, so small particles can pass through but not big ones (although proteins can help large molecules move through)
Integral vs peripheral proteins (position & function).
Integral: span through entire membrane. Transports larger molcules across the membrane. Peripheral: don’t span through entire membrane, sometimes attached to integral proteins. Transport & communication.
What are glycoproteins?
Proteins with carbohydrates (short chains of sugars) attached.
What do glycoproteins do?
Serve as recognition signals for other cells.
Describe the membrane in terms of the fluid mosaic model.
Fluid: cell membrane flows like a liquid. Mosaic: bilayer contains protein & carbohydrate molecules.
What carbohydrate is in glycolipids and glycoproteins?
Glycocalyx
What are the main things that enter a cell?
Gases, nutrients, water
Why is the cell membrane important?
Is a barrier to most substances, so materials can be concentrated inside cells or excluded from cells, which allows chemical reactions to take place.
