1
Q
cell membrane
A
- plasma membrane
- semipermeable phospholipid bilayer
- fat soluble easily cross
- fluid mosaic model
- selectively regulate traffic into and out of cell
- intracellular and intercellular communication and transport
- cellular receptors
- contains proteins, lipid rafts
- glycoprotein coat - carb associated with membrane protein
2
Q
Fluid mosaic model
A
- phospholipids move in the plane of membrane
- lipid rafts - attachment points for biomolecules
- help with signaling
- Proteins and lipid rafts move within membrane
- flippases - help “flip” between layers
- can change composition of membrane to accomodate biosignaling and adjust cellular receptors
3
Q
Fattyy Acids and Triacylglycerols in membrane
A
- fatty acids - hydrocarbon with carboxylic end
- unsaturated - one or more double bonds, liquid at room temp
- important for fluidity
- most come from triglycerol in diet, through intestine via chylomicrons
- unsaturated - one or more double bonds, liquid at room temp
- triglycerides - storage lipids, 3 fatty acid chains esterified by glycerol
- saturated fats decrease fluidity
- unhealthy fats that are found in animal products
4
Q
Phospholipids
A
- glycerophospholipid
- substitute a fatty acid chain in a triglycerol for a phosphate group
- micellles - aka liposomes - due to hydrophobic interactions
5
Q
Sphingolipids
A
- hydrophilic region and 2 fatty acid tails
- ceramide
- sphyingomyelins
- cerebrosides
- gangliosides
- varie based on different hydrophilic groups on head
6
Q
Cholesterol and Steroids in Membrane
A
- steroids derived from cholesterol
- cholesterol keeps membrane fluid
- hydrophilic and hydrophobic regions
- high temps - prevent movement
- low temp - prevent crystal structures to increase fluidity
- high concentration in membrane
7
Q
Waxes in membrane
A
- very hydrophobic
- more likely in plants than animals
- waterproofing and protective property
8
Q
Proteins in membrane
A
- integral proteins - associated with interior, mostly hydrophobic
- transmembrane proteins - completely through
- transporters, channels, receptors
- embedded protein - only interior or only exterior
- transmembrane proteins - completely through
- membrane-associated proteins -
- peripheral proteins
- electrostatic interaction, lipid rafts, attach to other protein
- intracellular and associated with other structure
9
Q
Carbohydrates in Membrane
A
- attached to proteins on extracellular surface
- signaling
- recognition molecules
- ABO antigens differ by carbohydrate sequence on sphingolipids
10
Q
Cell Adhesion Molecules (CAM)
A
- proteins that allow cells to recognize each other
- differentiation
- development
11
Q
Gap Junctions
A
- direct cell to cell communication
- connexons - alignment and interaction of pores
- connexin - makes pores
- water and solutes movement between cells
12
Q
Tight Junctions
A
- prevent leaking into space between cells
- paracellular route
- epithelial cells for water tight protection
13
Q
Desmosomes
A
- bind adjacent cells
- anchor to cytoskeleton
- interaction between transmembrane proteins associated with intermediate filaments inside adjacent cells
- epithelial tissue
14
Q
simple diffusion
A
- substrate moves down concentration gradient directly across the membrane
- particle must be freely permeable to the membrane
- energy dissipated as the gradient decreases
15
Q
Osmosis
A
- water moves from low to high solute concentration regions
- Important when impermeable solute
- hypotonic solution- low surrounding conc, cell is higher conc
- swell
- hypertonic solution- high surrounding conc, cell is lower conc
- shrivle
- isotonic
- net movement is zero
- water can still move, but net is zero
- osmotic pressure - aka colligative property
- conc of dissolved particles
- Π = iMRT
- Π : osmotic pressure
- M - molarity
- R - ideal gas constant
- T temperature (K)
- i - van’t Hoff factor
- number of particles from a molecules (NaCl = 2)
16
Q
Facilitated Diffusion
A
- simple diffusion for molecules that are impermeable to the membrane
- large, polar, charged
- integral membrane protein
- transporters and channels
- carriers - only open to one side of the membrane at a time
- channels - open or closed confirmation
17
Q
Active transport
A
- net movement against conc gradient
- requires energy
- primary active transport - use ATP or other energy molecule
- transmembrane ATPase
- Secondary active transport - coupled transport
- use energy from a different molecule going down its gradient
- symport - both molecules same direction
- antiport - molecules in different directions
18
Q
Endocytosis
A
- cell membrane engulfs material and brings into cell
- pinocytosis - fluids and dissolved particles
- phagocytosis - large solids, bacteria
- vesicle-coating proteins
19
Q
Exocytosis
A
- secretory vesicles fuse with membrane and release material out of cell
- neurotransmitters in synapse
20
Q
Membrane Potential
A
- electrochemical difference between interior and exterior of the cell
- membrane potential (Vm)
- resting is -40 and -80 mV
- sodium-potassium pump (Na+/K+ ATPase)
- regulate membrane potential
- Nernst Equation used for membrane potential
- E = RT/zF * ln ([ion outside]/[ion inside])
21
Q
Sodium Potassium Pump
A
- maintain low Na+ and high K+ in the cell
- 3 Na+ out and 2 K+ in
- removes a positive charge and maintains negatice potential
- leak channels for both ions
- more permeable to K+ than Na+
22
Q
A
23
Q
Mitochondrial Membrane
A
- Outer mitochondrial membrane - highly permeable with large pores
- Intermembrane space
- Inner mitochondrial membrane - mroe restricted permeability
- cristae - infoldings, increase surface area
- increase ETC and ATP synthesis
- encloses matrix
- citric acid cycle makes electron carriers
- cristae - infoldings, increase surface area
MCAT Biochemistry
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