Cell Surface Membrane Flashcards
Module 1
Roles of a cell surface membrane
Partially permeable barrier
Site of chemical reaction
Site of cell communication
What are cell surface membranes made of
Phospholipid bilayer, glycoprotein, glycolipids, proteins, cholesterol
What is a phospholipids structure
Polarised Hydrophilic head and hydrophobic tail
What is amphipatic
When some parts are charged and some arent
What happens to phospholipids in water
They form Liposomes and micelles
What is a phospholipid bilayer
When the polar heads of phospholipids are attracted to water and the hydrophobic tails are repelled
What are the parts of the fluid mosaic model
Glycoproteins, channel proteins, phospholipid bilayer, extrinsic protein
What are integral protiens
Span the whole width of the membrane
Many are carrier molecules or channels
Help transport ions, sugars and amino acids
Some are receptors for hormones and neurotransmitters, or enzymes
What are glycoproteins
proteins with attached carbohydrate chains
What are peripheral proteins
Proteins confined to the inner or outer surface of the membranes
May act as receptors, involved in cell signalling or chemical reactions
Glycoproteins and glycolipid function
Acts as receptor sites - involved in cell signalling
Assist in binding cells together
What is cholesterol
Controls membrane fluidity and permeability
More cholesterol = less fluid and less permeable
Important in keeping membranes stable at normal body temp
What are factors affecting membrane permeability
Solvents, temperature, detergents
How do solvents effect membrane permeability
Solvents dissolve lipids in membrane
Some solvents increase permeability more than others
How does temperature affect membrane permeability
low temp - little KE so phospholipids very close together, ice crystals may form and pierce the membrane
Mid temp - temp increases, KE increases, phospholipids move apart
High temp - bilayer starts to melt, H2O expands and puts pressure on membrane, proteins denature
What is the detergents effect on membrane permeability
Increases permeability by removing lipids from the membrane or forming stable pores in the membrane
What is cell signalling
how cells communicate with other cells
need messenger/signal molecules and receptors on cell surface membrane
What do drugs do to cell communication
Block receptors so receptor cells cant work
What does poisons do cells
Toxins produced bind with receptor cells in human muscle cells, stopping muscles from working properly and causing paralysis
What is Diffusion
The passive processes that includes the movement of molecules from a region of higher concentration to a region of lower concentration down a concentration gradient
What is Net movement
Overall movement of molecules
What factors effect the rate of diffusion
Temp, conc grad, s.a, nature of diffusing molecule
What particles can undergo simple diffusion
Lipid based molecules (fat soluble, steroid hormones)
Very small molecules (CO2 and O2)
What particles need facilitated diffusion
Large molecules, charged particles
