B2.1 Membranes and transport Flashcards
What is the main constituent in membranes
phospholipids
The phospholipid bilayer is selectively permable, what does this mean
Some molecules can pass through easily by diffusion or go through a tunnel (facilitated diffusion). Tohers need the energy to get them through
what is the difference between integral and peripheral membrane proteins
The location of which the protein is in the membrane
integral proteins are in between the phospholipids
the peripheral proteins are on the surface of the phospholipid
What is the definition of diffusion
A net movement of particles from an area of high concentration to an area of low concentration until it reaches an equilibrium, no atp required
What types of particles can diffuse through the membrane (simple diffusion)
small non-polar particles, some polar molecules (e.g. water) , non-polar steroids
What are some factors which affect diffusion
concentration, diffusion pathways, temperature (higher temp = more kinetic energy) and surface area
what is facilitated diffusion
Is when ions and charged/polar particles difuse by passing through a membrane (channel) protein. The channels allow only one type of molecule or ion to diffuse them.
Large polar hydrophilic particles require transmembrane proteins fort the transport
The most common are K+ channels
What is osmosis
the diffusion of water molecules which is caused by the differences in the concentration of solutes dissolved in water.
what are aquaporins
Membrane proteins that transport water across cell membranes.
Draw a fluid mosaic model of a membrane structure
Refer to FIgure 14
What does hypertonic mean
more water goes out from the cell, due to the mass amount of water which was firstly in the cell (low solute concentration)
What does hypotonic mean
more water going into the cell, due to the low amount of water which was firstly outside the cell (high solute concentration)
What does isotonic mean
An equal amount of water going in and out of the cell
what does the glycolipid do on the cell wall, what is its function
Glycolipids are involved in cell-cell recognition and communication, serving as markers that allow cells to identify and interact with each other. They are found connected to a phosphate head, shaped in a strand of hexagons
What is the glycoprotein, what does it do, where is it found
Glycoproteins are involved in the cell-cell recognition, they are found connected to a phosphate head, branched hexagons
