CELL MEMBRANE Flashcards
what the plasma membrane
Boundary that separates living cells from its surroundings – makes life possible
amphipathic meaning
have both hydrophobic and hydrophilic regions
whats the fluid mosaic
fluid structure with a mosaic of protein embedded - phospholipids can move within the membrane
is the lateral motion in the plasma membrane frequent or non frequent
frequent
is the flip flop across in the plasma membrane frequent or non frequent
non frequent
cholesterol role with the plasma membrane
temperature buffer
- has strong enough hydrophobic interactions to anchor itself within the fatty acid tails - preventing it from becoming too fluid at high temp
- has strong enough hydrophilic interactions to interact with the polar head groups - preventing it from becoming too rigid at low temps
3 Types of protein that make up the mosaic
- integral= inserted into hydrophobic middle
- trans (type of integral protein) = spans the entirety of cell membrane
- peripheral = on surface
6 Protein functions
Transport things across cell surface
Enzymatic activity – break down something / build something up
Signal transduction
Cell–cell recognition
Intercellular joining
Attach to surface
do charged things pass through membrane
no
does O2 + CO2 pass through membrane
yes - will diffuse freely - nonpolar
what is Selective permeability
membrane selects what goes through it
what are transport proteins
allow polar / hydrophilic things to go across membrane (can have hydrophilic channel) - specific for what they transport e.g aquaporins transport water
2 types of transport proteins
Channel
Carrier
what is passive transport
no energy
- uses principles of diffusion (tendency of molecules to spread evenly in space – high -> low conc)
what is active transport and some examples
uses energy (ATP) – goes against conc gradient
- Ion pump – sodium potassium pump – electrogenic pump
- Co-transport – sucrose cotransporter
- Bulk transport
whats osmosis
diffusion of H2O across a semi permeable membrane
whats hypertonic solution
more dissolved in solution outside – H2O moves out (cell = shriveled)
- cell = plazmolyzed in plants
whats hypotonic solution
not much dissolved in solution outside – H2O moves in (cell = lysed)
- healthy state for plant cell – cell wall stops it bursting (cell = turgid)
whats isotonic solution
equal amounts inside and outside of cell - equilibrium
- healthy state for animal cell
- cell = flaccid in plants
whats facilitated diffusion
transport proteins speed up the passive movement of molecules across plasma membrane e.g. channel and carrier proteins
whats Endocytosis and its 3 types
brings things into cell
- Phagocytosis (cellular eating - solid)
- Pinocytosis (cellular drinking - liquid)
- Receptor-mediated endocytosis
whats Exocytosis
takes things out of the cell
whats metabolism
totality of an organisms chemical reactions
- Metabolic pathways begin with a specific molecule and ends with a specific product
whats a catabolic pathway
breaks down complex molecules to simpler compounds, releases energy
whats an anabolic pathway
builds complex molecules, consumes energy
whats bioenergetics
study of how organisms manage energy resources
whats energy and its 2 types
capacity to cause change
- Kinetic - energy of motion
- Potential – energy of position
how does ATP work
ATP adds its phosphate to molecules – makes them higher energy, less stable, greater work capacity
whats thermodynamics and its 2 types
study of energy transformation
- Closed systems – everything is over once reached equilibrium
- Open systems – things keep coming into the system (life is open system – energy of sun keeps coming into it)
2 laws of thermodynamics
- 1st law = energy of the universe is constant
energy can be transferred / transformed but not created - 2nd law = in every energy transfer/transformation, some energy in unusable and lost as heat
what is Lost energy called
entropy - disorder
Gibbs free (G) energy equation
ΔG = ΔH - TΔS
- ΔG - can do work
- ΔH - total energy
- TΔS - cant do work
whats an exergonic reaction
energy released (ΔG < 0)
- spontaneous - reaction NOT driven from input of energy (negative ΔG)
- REACTANTS have greater capacity to do work + are less stable
whats an endergonic reaction
energy required (ΔG > 0)
- non-spontaneous - reaction driven from input of energy (positive ΔG - gets given energy)
- PRODUCTS have greater capacity to do work + are less stable
what does it mean when something has more free energy
- higher G
- Less stable
- Greater work capacity
what does it mean when something has less free energy
- lower G
- More stable
- Less work capacity
what’s the activation energy barrier
energy required for reaction to happen – energy speed bump
- all reactions have them – spontaneous + non spontaneous
how do enzymes lower AEB
Orientating substates correctly
Straining substrate bonds
Providing a favorable microenvironment
Correctly bonding to subsrtate
what 2 factors are enzymes affected by
temp + pH
what 2 chemicals can influence enzyme activity
- Co-factors – non-protein enzyme helpers – inorganic metals or small organics
- Co-enzymes – organic factors
2 types of Enzyme inhibitors
- competitive inhibitors – bind to active site of enzyme
- Non-competitive inhibitors – bind to a place other than active site – cause confromational change making the active site less efficient (allosterie)
what is Allosteric regulation and its 2 types
can inhibit or stimulate enzyme activity – molecule binds to a location and causes a change elsewhere
- Activator - stabilizes the enzyme in active form
- Inhibitor – stabilizes enzyme in its inactive form
what’s a Feedback inhibitor
product of a metabolic pathway shuts down the pathway
