Exam 2 Flashcards
What is a peripheral membrane protein and what is it’s function?
Attached to one end of a membrane (but not inside). Provides support to cytoskeleton (movement of products) by terminating or initiating it’s function. Also works with the extracellular matrix and pass messages to integral proteins. Sometimes have enzyme funciton
What is an integral membrane (transmembrane) protein and what is it’s function ?
Spans completely over the phospholipid bilayer. Integral membranes deal with communication and messages.
Ex. ATP synthase
Intermolecular vs Intramolecular
Intermolecular is interactions between molecules and intramolecular is within a single molecule
What is a disulfide bond? Where does it occur?
Two sulfurs covalently bonded (typically in side chains of amino acids). Often contributes to tertiary and quaternary levels of protein structure.
What are Van der Waals interactions? What does it contribute to in protein structure?
A weak electrical attraction between two nonpolar molecules or parts of a molecule (often through hydrophobic interactions). It contributes to tertiary and quaternary protein structure
What are hydrophobic/hydrophillic interactions?
Weak interactions between nonpolar molecules or nonpolar parts of a molecule when exposed to an aqueous solvent. The water surrounds hydrophobic molecules
What is entropy? What are the trends of entropy?
Quantitative measure of amount of disorder in a system (ex. a group of molecules)
What is Gibbs Free Energy?
The energy of a system that can be converted into work. (Delta G) Can only be measured on how it changes in a reaction
What is the 2nd law of thermodynamics?
The entropy of the universe or any closed system will always increase
What does endergonic mean?
A change in Gibbs free energy that is greater than zero, thus nonspontaneous and requires more energy to occur
What does exergonic mean?
A changes in Gibbs free energy that is less than zero (more energy efficient)
What is permeability?
Tendency to let something pass through it and the rate at which molecules cross the membrane
What does spontaneous mean?
m
What is standard-free energy change?
k
Fluidity of a membrane is determined by..?
Saturation, length of change and cholesterol
How does length of a fatty acid chain change the permeability of a membrane
More permeable membranes have more short, kinked (unsaturated tails)
More nonpermeable membranes have: long straight (saturated tails)
How does cholesterol effect permeability? Why?
More cholesterol = less permeability
Cholesterol brings tails closer to one another, increasing packing density
How does cholesterols impact on permeability help maintain fluidity?
During temperature changes
How does temperature changes effect permeability of a membrane?
It is a temperature buffer. Lower temps = things move slower = less fluidity
What kinds of fats do organisms from tropical zones need to utilize?
Saturated fats: due to the high temperature, these organisms need less fluidity and saturated fats have less kinks and will help maintain that fluidity
What kinds of fats do organisms from temperate zones need to utilize?
Polyunsaturated fats: due to the low temperature, these organisms need more fluidity and unsaturated fats have more kinks that will help in increase fluidity
How does saturation effect permeability?
Saturated fats have less kinks which means more van der waals interactions
However, unsaturated fats are the opposite. The space created by the kink allows for less van der waals interactions
What kind of molecules can easily pass through the cell membrane, why?
Small, non-polar molecules like O2, CO2 and N2 due to being able to interact with the fatty acid tails on the inside of the membrane and because they are small
What molecules need transport proteins to cross a membrane?
Large hydrophillic molecules, ions and water
What is a main characteristic of lipids?
Water-insolubility
What is the main characteristic of carbohydrates?
Must have a carbonyl (C=O) and hydroxyl (-OH) to be considered a carbohydrate
What is a carbonyl?
C=O
What are the bases in DNA
Guanine, Cytosine, thymine and adenine
What are the bases in RNA?
Guanine, cytosine, Uracil and adenine
Do ions need a transport protein? (yes or no) Why?
Yes because they are hydrophilic
How do you know if a nucleic acid will be added
ll
