LSU Bio 1201 exam 2 Questions &
Answers 100% Correct!!
why are membranes called phospholipid bilayers? - ANSWERSphospholipids have
hydrophilic head and hydrophobic tail, hydrophobic face inside of cell making 2 layers
what is meant by fluid mosaic? - ANSWERSMosaic of proteins drifting laterally in fluid
bilayer of phospholipids
how are membranes adjusted for different temperatures? - ANSWERSmembrane
fluidity adjusted by changing the ratio of unsaturated to saturated fatty acids
how do the relative amounts of saturated and unsaturated fats change? - ANSWERSif
you are in a cold environment you want more saturated fats for your membranes to be
fluid; warm environment you want more saturated fats to make your membranes more
solid
what is meant by membrane fluidity? - ANSWERSnot too solid, not too fluid
why is fluidity an important property? - ANSWERSpreserves membrane function
Henrique and Hanson performed experiments with pigs and examined the effects on the
relative amounts of saturated and unsaturated fats. What did they find? -
ANSWERSfound that membrane fluidity can acclimate to temperature; pigs raised
wearing underwear in a hot room had subcutaneous fats with higher melting point
what types of molecules can move easily across the membrane? - ANSWERSsmall
nonpolar molecules, gases, steroid hormones, and water
what is simple diffusion? - ANSWERSdown the concentration gradient; does not require
supplied energy; does not use a carrier molecule
what is facilitated diffusion? - ANSWERSdown the concentration gradient; employs
carrier molecule; does not require supplied energy
what is active transport? - ANSWERSwork must me done; must use supplied energy;
employs carrier molecule
for which transport processes are carrier molecules involved? - ANSWERSfacilitated
diffusion and active transport
which transport processes require the input of additional energy? - ANSWERSactive
transport
, what is a semi-permeable barrier? - ANSWERSonly some types of molecules pass
through
when equilibrium is reached in diffusion: does movement of molecules stop? -
ANSWERSno
when equilibrium is reached in diffusion: does the net movement of molecules stop? -
ANSWERSyes
what is meant by hypertonic? - ANSWERSlower water potential; more solutes
dissolved; tend to gain water via osmosis
what is meant by hypertonic? - ANSWERShigher water potential; fewer solutes
dissolved; will tend to lose water via osmosis
isotonic - ANSWERSequivalent water potential; equal number of solutes; no note
movement of water
in which direction does water flow? - ANSWERSosmosis and the direction of net water
movement
what are aquaporins? - ANSWERSchannel proteins which facilitate water diffusion
through the membrane
marine bony fish are...? - ANSWERShypotonic to seawater
how do enzymes work? - ANSWERSthey position the reactants in a conformation more
favorable for the chemical reaction to occur
what aspects of the energetics do enzymes change? - ANSWERSenzymes lower
activation energy barrier ΔG⧧
what aspects of energetics do enzymes not affect? - ANSWERSthey do not reverse an
energetically unfavorable reactions; they do not make a reaction go uphill
how are substrates lured into the active site? - ANSWERSpositively charged arginine
sidechain lures the negatively charged substrate into the active site
what are the analogs to these characters in the binding of substrates to enzymes? -
ANSWERSSiren song= positively charged arginine sidechain
Negatively charged substrate= Odysseus' men
Circe= active site
Answers 100% Correct!!
why are membranes called phospholipid bilayers? - ANSWERSphospholipids have
hydrophilic head and hydrophobic tail, hydrophobic face inside of cell making 2 layers
what is meant by fluid mosaic? - ANSWERSMosaic of proteins drifting laterally in fluid
bilayer of phospholipids
how are membranes adjusted for different temperatures? - ANSWERSmembrane
fluidity adjusted by changing the ratio of unsaturated to saturated fatty acids
how do the relative amounts of saturated and unsaturated fats change? - ANSWERSif
you are in a cold environment you want more saturated fats for your membranes to be
fluid; warm environment you want more saturated fats to make your membranes more
solid
what is meant by membrane fluidity? - ANSWERSnot too solid, not too fluid
why is fluidity an important property? - ANSWERSpreserves membrane function
Henrique and Hanson performed experiments with pigs and examined the effects on the
relative amounts of saturated and unsaturated fats. What did they find? -
ANSWERSfound that membrane fluidity can acclimate to temperature; pigs raised
wearing underwear in a hot room had subcutaneous fats with higher melting point
what types of molecules can move easily across the membrane? - ANSWERSsmall
nonpolar molecules, gases, steroid hormones, and water
what is simple diffusion? - ANSWERSdown the concentration gradient; does not require
supplied energy; does not use a carrier molecule
what is facilitated diffusion? - ANSWERSdown the concentration gradient; employs
carrier molecule; does not require supplied energy
what is active transport? - ANSWERSwork must me done; must use supplied energy;
employs carrier molecule
for which transport processes are carrier molecules involved? - ANSWERSfacilitated
diffusion and active transport
which transport processes require the input of additional energy? - ANSWERSactive
transport
, what is a semi-permeable barrier? - ANSWERSonly some types of molecules pass
through
when equilibrium is reached in diffusion: does movement of molecules stop? -
ANSWERSno
when equilibrium is reached in diffusion: does the net movement of molecules stop? -
ANSWERSyes
what is meant by hypertonic? - ANSWERSlower water potential; more solutes
dissolved; tend to gain water via osmosis
what is meant by hypertonic? - ANSWERShigher water potential; fewer solutes
dissolved; will tend to lose water via osmosis
isotonic - ANSWERSequivalent water potential; equal number of solutes; no note
movement of water
in which direction does water flow? - ANSWERSosmosis and the direction of net water
movement
what are aquaporins? - ANSWERSchannel proteins which facilitate water diffusion
through the membrane
marine bony fish are...? - ANSWERShypotonic to seawater
how do enzymes work? - ANSWERSthey position the reactants in a conformation more
favorable for the chemical reaction to occur
what aspects of the energetics do enzymes change? - ANSWERSenzymes lower
activation energy barrier ΔG⧧
what aspects of energetics do enzymes not affect? - ANSWERSthey do not reverse an
energetically unfavorable reactions; they do not make a reaction go uphill
how are substrates lured into the active site? - ANSWERSpositively charged arginine
sidechain lures the negatively charged substrate into the active site
what are the analogs to these characters in the binding of substrates to enzymes? -
ANSWERSSiren song= positively charged arginine sidechain
Negatively charged substrate= Odysseus' men
Circe= active site
