Lecture 2 Old Notes Flashcards
What are the three components of plasma membranes?
Lipids, proteins and sugars
What is the bulk of the membrane made of? (hint: 2 of something)
Lipid bilayer
How do you make hydrophobic proteins stay in the lipid bilayer?
Using nonpolar amino acids
Why would small, charged ions be unable to cross the phospholipid bilayer?
If there is a gradient
What two things make sodium move?
Electric gradient and concentration gradient (electrochemical gradient)
What objects use passive diffusion to cross a membrane?
Small, uncharged molecules and gases
Passive diffusion is inversely proportional to what? Directly proportional to what?
Inversely proportion to the radius of the molecule and the viscosity of the membrane; directly proportional to the area of the membrane, temperature and electrochemical
What is a flux?
The amount an item moves per unit of time
What type of molecule is needed to help sodium move down an electrochemical gradient?
A protein
What are the two ion channel examples for facilitated diffusion?
Voltage-gated sodium channels and ligand-gated channels
What is meant by a sodium gradient is indirectly couple to the hydrolysis of ATP as a form of active transport?
The sodium ion is let in and they energy released is used to do work for some other purpose
What forms of transportation can be saturated?
Active transport and facilitated diffusion, due to not enough transport proteins being available for transport
Endocytosis and exocytosis are examples of what kind of transport?
Across (bulk) transport
What type of particles are brought into the cell by cell invagination (i.e. endocytosis)?
Large particles, such as the invagination of osteoclasts
Pinocytosis is not necessarily about moving liquid into the cell, but rather what?
Trying to remove part of the membrane
By what process are most neurotransmitters and polypeptide hormones released from cells?
Exocytosis
All cells have 3 functions they have to perform; what are they?
Survive, detect what is in the environment, response to what is detected in said environment
Cell membranes are stabilized by what two types of bonding?
Hydrophobic interactions and Van der Waals interactions
How does increasing the membrane fluidity influence the survival of the cell?
It increases the survivability of the cell
What three factors contribute to increasing membrane fluidity?
Shorter fatty acid chains, more unsaturated fatty acids, and less cholesterol
What are the three primary types of lipids?
Phospholipids, glycolipids and cholesterol
What is the most abundant type of lipid?
Phospholipids
What two functions do glycolipids have, which are related to “recognition”?
Cell to cell recognition and signal recogition
Where are sulfatides (a subclass of glycolipids) commonly found in?
Neuronal cell membranes
Where are gangliosides (a type of glycolipids) abundant?
Nerve endings
Where is cholesterol found in a cell?
In the central core of the lipid bilayer
Where are sugars mostly located in a cell membrane?
The outer leaflet
What is a glycocalyx?
It is a polysaccharide layer on the cell membrane (made from sugars)
What is the function of sugars for the cell?
They are used to recognize signals outside the cell, such as from a nearby cell; think “recognition”
What constitutes a glycoprotein? Where is it found?
It is made of an oligosaccharide attached to a protein, and is found on the outer leaflet.
What are three functions of glycoproteins?
Receptors, hormones, and used as a structural molecule (i.e. collagen)
