Lipids and Membranes Flashcards
What is the reaction type between a fatty acid and glycerol molecule?
Condensation reaction
What is the bond formed between a fatty acid and glycerol?
Ester bond
What are the 3 roles of triglycerides?
Storage, insulation, protection
how do the structure and properties of triglycerides relate to their function?
- High ratio of energy storing bonds to C atoms
- Low mass to energy ratio
- No osmotic affect on the water potential in cells
what it the difference between triglycerides and a phospholipid?
A fatty acid group is substituted for a phosphate group in a phospholipid
What are the 3 functions of the plasma membrane?
- Control transport through a partially permeable membrane
- Act as a receptor site
- Separate cell from outside environment
What molecules do partially permeable membranes not let through?
Water soluble molecules, charged molecules, polar molecules
What are the 2 types of protein found in the membrane?
Extrinsic (in one layer)
Intrinsic (crosses the whole membrane)
What are some examples of polar molecule which need to cross the membrane?
Ions and Glucose
What is the name given to the carbohydrates attached to the proteins in the membrane?
Glycoproteins
What is the function of glycoproteins?
They allow for extra functions in the proteins embedded in the membrane
what is the function of a glycolipid?
Act as recognision sites and maintain the stability of the membrane
Allow cells to attach to one another and thereby form tissues
What is the function of cholesterol in the membrane?
Increase strength and stability by restricting movement of other molecules in the membrane.
Why is the plasma membrane described as fluid mosaic?
Fluid- molecules can move around
mosaic- different types of molecule associated with the membrane
What can the molecules in the fluid mosaic model do?
Move sideways, leave and join membranes
What is Fick’s law?
Rate of diffusion is proprtional to :
[SA x Difference in Conc]/ Membrane thickness
what are some features of facilitated diffusion?
Specific Works down a conc gradient Limited by number of channel proteins Passive Used to transport charged, polar or hydrophillic substances
which substances required channel proteins to cross the membrane?
Ions
What is the definition of osmosis?
The movement of water across a partially permeable membrane down a water potential gradient.
What is crenation?
When water leaves the cell by osmosis and shrinks
What are some examples of active transport?
Uptake of glucose and amino acids in the small intestine
Absorption of mineral ions in plant roots
Exchange of sodium and potassium in neurons
