MTC Week 4 Flashcards
what is the structure of a membrane
- carbohydrates:
attaches to lipids and proteins - phospholipids
- protein
- cholesterol: sits next to an unsaturated fatty acid
what is membrane fluidity dependent on and what effect does fluidity have
*Dependent on temperature and composition
*Too fluid = leaky
*Not fluid = no movement or solute passage
how does temperature affect fluidity
Heat: lipids move more, arranging/rearranging
Increased fluidity
Cold: lipids laterally ordered/organized, lipid chains pack together tightly
Decreased fluidity
how does fatty acid chain length affect fluidity
- Long = stiff
Decreased fluidity - Short = less stiff
Increased fluidity
how does double bonds affect fluidity
- saturated = more stiff
decreased fluidity
-unsaturated = less stiff
increased fluidity
how does cholesterol act in membranes of hot and cold temperature
- cholesterol will decrease the fluidity to balance the membrane in a hot environment
-cholesterol will increase the fluidity to balance the membrane in a cold environment
where are carbohydrates, integral proteins, peripheral membrane proteins and cholesterol located on the plasma membrane
- Carbohydrates
– Attached to outer surface of membrane proteins, makes glycoproteins - Integral Proteins
– Some cross the entire bilayer, some only partially - Peripheral membrane proteins
– Do not penetrate bilayer, stay inside cell - Cholesterol
– Interspersed among phospholipid tails in the bilayer, influencing fluidity of fatty acids
true or false: proteins either stay anchored in the membrane or move around
false
what is ECM made of
mixture of collagen, fibronectin, heparin, laminin
what is integrins function
Integrin proteins maintain cell structure via its interaction with the cytoskeleton.
what is osmosis
water moving to the area of higher solute concentration
does not require energy
what happens to the cell in hypertonic, hypotonic and isotonic environments
hypertonic = dehydration
isotonic = no change
hypotonic = cell swelling
are membrane barriers hydrophobic or hydrophillic
hydrophobic
what are some features of simple diffusion
- difference of concentration causes movement
- no energy required
- O2 and CO2 and lipid soluble substances like steroids can cross through
- high to low concentration
what are some features of facilitated diffusion
- requires no energy
- through channel or carrier proteins
channel protein: specific solutes can pass through
carrier protein (are integral proteins):
Requires the transported molecule to bind to a specific carrier protein
The protein goes through conformational change to transfer the bound solute across the membrane
what are aquaporins
water moves through a hydrophilic channel, passively by osmosis
facilitated diffusion
what do Glut1 carrier proteins do
transports glucose into the cell
what are the 2 types of carrier proteins and what do they do
both couple transporters
symporters: moves two substances in the same direction
Ex: Na+/glucose symporter (sodium-glucose linked transporter, SGLT)
antiporters: moves solutes in opposite directions
Ex:Na+/Ca2+ antiporter
present in cardiac muscle cells
what is primary active transport and its features
- requires energy
- ATPase = enzyme that catalyze hydrolysis of ATP to yield ADP + inorganic
phosphate –> releases free energy - phosphate binding to the protein is what causes conformational change
what is secondary active transport and its features
- can only occur if primary active transport took place
- uses energy stored from electrochemical gradient, to move chemicals across the membrane without using ATP
what is the mechanism of action of digoxin
- Inhibits Na/K-ATPase; and raises the intracellular [Na+] and lowers intracellular [K+]
- The Na+/Ca2+ antiporter functions less efficiently with a lower [Na+] gradient, fewer Ca2+ ions are exported causing intracellular Ca2+ concentration increases
- stronger heart muscle contraction
what does the Cystic fibrosis transmembrane conductance regulator (CFTR)
Moves chloride ions outside of the cell
what does a mutation of the Cystic fibrosis transmembrane conductance regulator (CFTR) cause
cystic fibrosis which can cause severe diarrhea as water is being pulled into GI tract due to chemical gradient dysfunction
what are some molecules that cannot pass through the membrane and why
Proteins, polysaccharides, and nucleic acids because they are too large, charged or polar
what are the 3 ways that macromolecules are moved into the cell through endocytosis
phagocytosis
- creates vacuole and “eats”
pinocytosis
- creates vacuole and “drinks”
receptor mediated endocytosis (mediated by surface molecule
