LSU BIO 1201 EXAM 2 QUESTIONS AND
ANSWERS 100% CORRECT
why are membranes called phospholipid bilayers? - ANSWER-phospholipids have
hydrophilic head and hydrophobic tail, hydrophobic face inside of cell making 2 layers
what is meant by fluid mosaic? - ANSWER-Mosaic of proteins drifting laterally in fluid
bilayer of phospholipids
how are membranes adjusted for different temperatures? - ANSWER-membrane fluidity
adjusted by changing the ratio of unsaturated to saturated fatty acids
how do the relative amounts of saturated and unsaturated fats change? - ANSWER-if
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? - ANSWER-not too solid, not too fluid
why is fluidity an important property? - ANSWER-preserves membrane function
when equilibrium is reached in diffusion: does the net movement of molecules stop? -
ANSWER-yes
what is meant by hypertonic? - ANSWER-lower water potential; more solutes dissolved;
tend to gain water via osmosis
what is meant by hypertonic? - ANSWER-higher water potential; fewer solutes
dissolved; will tend to lose water via osmosis
isotonic - ANSWER-equivalent water potential; equal number of solutes; no note
movement of water
in which direction does water flow? - ANSWER-osmosis and the direction of net water
movement
what are aquaporins? - ANSWER-channel proteins which facilitate water diffusion
through the membrane
Henrique and Hanson performed experiments with pigs and examined the effects on the
relative amounts of saturated and unsaturated fats. What did they find? - ANSWER-
, found 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? - ANSWER-small
nonpolar molecules, gases, steroid hormones, and water
what is simple diffusion? - ANSWER-down the concentration gradient; does not require
supplied energy; does not use a carrier molecule
what is facilitated diffusion? - ANSWER-down the concentration gradient; employs
carrier molecule; does not require supplied energy
what is active transport? - ANSWER-work must me done; must use supplied energy;
employs carrier molecule
for which transport processes are carrier molecules involved? - ANSWER-facilitated
diffusion and active transport
which transport processes require the input of additional energy? - ANSWER-active
transport
what is a semi-permeable barrier? - ANSWER-only some types of molecules pass
through
when equilibrium is reached in diffusion: does movement of molecules stop? -
ANSWER-no
marine bony fish are...? - ANSWER-hypotonic to seawater
how do enzymes work? - ANSWER-they position the reactants in a conformation more
favorable for the chemical reaction to occur
what aspects of the energetics do enzymes change? - ANSWER-enzymes lower
activation energy barrier ΔG⧧
what aspects of energetics do enzymes not affect? - ANSWER-they do not reverse an
energetically unfavorable reactions; they do not make a reaction go uphill
how are substrates lured into the active site? - ANSWER-positively 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? -
ANSWER-Siren song= positively charged arginine sidechain
Negatively charged substrate= Odysseus' men
Circe= active site
ANSWERS 100% CORRECT
why are membranes called phospholipid bilayers? - ANSWER-phospholipids have
hydrophilic head and hydrophobic tail, hydrophobic face inside of cell making 2 layers
what is meant by fluid mosaic? - ANSWER-Mosaic of proteins drifting laterally in fluid
bilayer of phospholipids
how are membranes adjusted for different temperatures? - ANSWER-membrane fluidity
adjusted by changing the ratio of unsaturated to saturated fatty acids
how do the relative amounts of saturated and unsaturated fats change? - ANSWER-if
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? - ANSWER-not too solid, not too fluid
why is fluidity an important property? - ANSWER-preserves membrane function
when equilibrium is reached in diffusion: does the net movement of molecules stop? -
ANSWER-yes
what is meant by hypertonic? - ANSWER-lower water potential; more solutes dissolved;
tend to gain water via osmosis
what is meant by hypertonic? - ANSWER-higher water potential; fewer solutes
dissolved; will tend to lose water via osmosis
isotonic - ANSWER-equivalent water potential; equal number of solutes; no note
movement of water
in which direction does water flow? - ANSWER-osmosis and the direction of net water
movement
what are aquaporins? - ANSWER-channel proteins which facilitate water diffusion
through the membrane
Henrique and Hanson performed experiments with pigs and examined the effects on the
relative amounts of saturated and unsaturated fats. What did they find? - ANSWER-
, found 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? - ANSWER-small
nonpolar molecules, gases, steroid hormones, and water
what is simple diffusion? - ANSWER-down the concentration gradient; does not require
supplied energy; does not use a carrier molecule
what is facilitated diffusion? - ANSWER-down the concentration gradient; employs
carrier molecule; does not require supplied energy
what is active transport? - ANSWER-work must me done; must use supplied energy;
employs carrier molecule
for which transport processes are carrier molecules involved? - ANSWER-facilitated
diffusion and active transport
which transport processes require the input of additional energy? - ANSWER-active
transport
what is a semi-permeable barrier? - ANSWER-only some types of molecules pass
through
when equilibrium is reached in diffusion: does movement of molecules stop? -
ANSWER-no
marine bony fish are...? - ANSWER-hypotonic to seawater
how do enzymes work? - ANSWER-they position the reactants in a conformation more
favorable for the chemical reaction to occur
what aspects of the energetics do enzymes change? - ANSWER-enzymes lower
activation energy barrier ΔG⧧
what aspects of energetics do enzymes not affect? - ANSWER-they do not reverse an
energetically unfavorable reactions; they do not make a reaction go uphill
how are substrates lured into the active site? - ANSWER-positively 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? -
ANSWER-Siren song= positively charged arginine sidechain
Negatively charged substrate= Odysseus' men
Circe= active site
