Membranes Flashcards
Are phospholipids amphipathic
Yes, the polar heads interact with water, the hydrophobic tails interact with each other to form the lipid bilayer
What are things that affect membrane fluidity
Temperature, Saturated and Unsaturated hydrophobic tails, and Cholesterol
how does unsaturated tails affect the membrane
They are kinked, so they prevent close packing of membrane causing fluidity
how does saturated tails affect the membrane
saturated hydrocarbon tails pack together causing viscosity
how does cholesterol affect the membrane
Happens within animal cells.
At moderate temperature, it reduces phospholipid movement
At low/cold temperatures, it hinders solidification by hindering regular packing of phospholipids
Integral Protein
proteins that penetrate into the membrane
Transmembrane Protein
Transmembrane Protein are integral proteins that go right through the membrane
Peripheral Proteins
Proteins associated with one side of the membrane
Gylcoprotein
Protein with chains of sugars attached in very specific configurations. Found in eukaryotic cellular membranes
Glycolipids
lipids with a carbohydrate (chains of sugars) attached in very specific configurations. Found in eukaryotic cellular membranes
Aquaporin
Channel proteins that allows water through
Passive Transport
The diffusion of a substance across a membrane with no energy investment. Does not use ATP
Diffusion
Movement of particles of any substance
Osmosis
Water moving down its concentration gradient
What it means when a substance diffuses down its concentration gradient?
This means it goes from an area of high concentration to low concentration
Osmolarity
Total concentration of a solution of all solutes in a solution. Expressed in Osm/L
Tonicity
Ability of a surrounding solution to cause a cell to gain or loose water
Hypotonic Solution
The solution has low concentration of solute and high concentration of free water. The cell is lysed
Isotonic Solution
The solution has equal solutes and free water
Hypertonic Solution
The solution has high concentration of solutes and low concentration of free water. Water will leave the cell and the cell will shrink (shrivel)
What is the normal solution for a plant
The normal solution is hypotonic. Cell walls allows the cells to survive without exploding
Four mechanisms by which molecules move across a membrane
Simple Diffusion, Simple Diffusion through a channel, Facilitated Diffusion and Active transport
Simple Diffusion
Movement from higher to lower concentrations straight through the lipid bilayer
Simple diffusion through a channel
Movement from higher to lower concentrations through the pore of an membrane channel protein
Facilitated Diffusion
Movement from higher to low concentrations via a membrane carrier protein
Active Transport
Movement from low to high concentration via a protein transporter. Requires Energy
What are the two types of protein that do facilitated diffusion
Carrier Proteins and Channel Protein
Channel Proteins
Form pores through which specific molecules pass through. Ex. Ion Channels, Aquaporins
Carrier Proteins
First bind,
then the protein changes shape allowing the transported molecule to pass through the membrane. Example. glucose transporter
Protein Pumps
proteins that use the energy stored in ATP to move molecules form a low to high concentration. Ex. Sodium-potassium pump
Electrochemical Gradient
difference in charge across a membrane
Co-transport
Coupled transport of chemical substances (two distinct molecules) across a cell membrane
