Exam 3 Study Guide Flashcards
What two components are cell membranes composed of?
Phospholipids and Proteins
Which Component provides the cell membrane with its structure?
Phospholipids
Which component provides the cell membrane with its functions?
Proteins
What part of a phospholipid is hydrophobic? and Hydrophilic?
Tail, Head
Sketch a phospholipid in your brain
2 tails, glycerol head with phosphate group attached and maybe choline or serine
Name other lipids found in cell membranes
Cholesterol, Phosphoatidylserine, galactocerebroside
Can lipid molecules exchange places with their neighbors such as flip flopping?
Yes but its rare bc hydrophilic heads have to cross hydrophobic tails
More unsaturated (double) bonds in the hydrocarbon tails lead to membranes being more _________. Why?
Fluid because bent tails do not pack in as tightly together
What does the inclusion of cholesterol do to the fluidity of the lipid bilayer?
Makes it less fluid
The cytosolic face of a cell membranes faces ____. the non-cytosolic face of the cell membrane faces _____
IN, OUT
Glycolipids tend to be found on which face of the plasma membrane?
Non-cytosolic face
Transporter Proteins
Transport molecules (Na+ pump)
Ion Channel Proteins
Act as a pore and allow ions to leave cells (K+ leak channel)
Anchor Proteins
Integrins anchor cell membrane
Receptor Proteins
PDGF receives signal and transmits it to the inside
Enzyme Proteins
Amylase-> breaks down carbs
Transmembrane Proteins
Span the length of the lipid bilayer
Mono-layer Associated Proteins
Associated within one layer of the membrane
Lipid Linked Proteins
Lipid is attached to protein
Protein Attached Proteins
Protein attached to protein
What are the two main classes of proteins that move molecules across the membrane?
Channel Proteins and Carrier Proteins
Which proteins move substances by changing their conformation?
Carrier Proteins
Which proteins move substance through pores?
Channel Proteins
Where are the higher levels of Na+, K+, and Cl- in the cell?
K+ is in the cell, Na+ and Cl- are found outside of the cell predominately
How do carrier proteins and channel proteins discriminate between substances to be moved?
Carrier proteins bind only to specific ligands
Channel proteins do this by allowing ions through of a specific size and charge
Define passive transport. What proteins (carrier or channel) carry out passive transport?
Passive transport does not require the input of external energy and can only move molecules down a concentration gradient. Channels are passive, carrier proteins can be passive or active.
Define active transport. What proteins- carrier and or channel carry out active transport?
Active transport requires energy input and moves molecules against a concentration gradient
What is meant by the term “Electrochemical Gradient?”
Electrical forces coupled with chemical gradients
What do we call movement of one type of molecule across the membrane? Two molecules in the same direction? Two molecules in opposite directions?
Uniport, Symport, and Antiport
Describe the steps in the function of the Na+ K+ Pump. What is the result on Na+ and K+ ion concentrations and the cell membrane?
Na+ binds, pump phosphorylates itself hydrolyzing ATP, conformational change occurs and Na+ is ejected, K+ binds, pump dephosphorylates itself, pump returns to OG conformation and K+ is ejected
Result is High Extracellular Na+ and High Intracellular K+
How does the electrochemical gradient affect the movement of Na+ and K+
Both electrical and chemical gradients want to move Na+ in. Electrical wants to move K+ in while chemical gradient wants to move K+ out
What occurs during an action potential and the propogation of an action potential from one nerve cell to another?
Cell has negative resting potential because of higher concentrations of negative ions inside. High Na+ concentration outside, High K+ concentration inside. Concentration gradient wants to push K+ ions out, electrical gradient want to push K+ ions in.
Once action potential starts, Na+ voltage gated ion channels open and Na+ rushes in depolarizing local spot of membrane. Due to Na+ electrochemical gradient, Na+ rapidly rush in changing local membrane potential to positive 40 mV, switching Na+ channels to inactive state. Solwer K+ Voltage gates channels are activated by voltage change in membrane potential and K+ leaks out returning membrane to resting potential. Voltage change then switches the Na+ back to OG state and K+ channels back to closed state. Meanwhile, Na+/K+ ion pump (active carrier protein) works to return ion concentrations to OG gradients
