Membranes
Which side of the membrane is hydrophobic?
the inside
what molecules cannot diffuse through membranes?
ions, large polar molecules
What is the ∆G of an endergonic reaction?
positive
What is the purpose of a branched respiratory chain in bacteria?
allows them to adapt to anaerobic conditions, they can use O2 as a terminal electron acceptor, or to use alternative terminal electron acceptors if oxygen is not available
If a lizard sits on top of a hot rock to warm up, what component of the heat exchange equation is this manipulating?
Conduction, because the surface of the lizard's body is in contact with the surface of the rock and transferring heat
What are the main components of the membrane?
phospholipids, proteins, cholesterol
which direction does osmosis drive the net movement of water across a membrane?
to the side with the higher concentration of solute
do enzymes affect the kinetics or thermodynamics of chemical reactions?
kinetics
In which step of aerobic metabolism is Acetyl-CoA an input?
TCA cycle
Which chlorophyll molecules send electrons to the primary electron acceptor in Photosystem II?
P680 special pair
What is the driving force of lipid bilayer assembly?
Unfavorable hydrophobic interactions of fatty acid tails with water molecules
What will happen to a cell placed in hypotonic solution?
water will flow into the cell, causing it to swell and possibly burst (lyse)
Why do spontaneous reactions not always occur instantaneously?
even though a reaction is spontaneous and favorable, if the transition state is very high in energy (high activation energy) then it would be unlikely for the reaction to proceed without an energy input
Which steps in aerobic metabolism generate ATP?
glycolysis, TCA cycle, and oxidative phosphorylation
What are the two types of photosynthetic organisms?
photoautotrophs (plants, cyanobacteria) and photoheterotrophs (archaea such as Halobacterium salinarum)
What does it mean for a molecule to be amphipathic?
some regions are hydrophobic and some are hydrophilic
What type of transporter is the sodium potassium ATPase? What drives the movement of ions in this case?
active transporter, driven by energy from ATP hydrolysis
Name 2 or more mechanisms by which enzymes lower activation energy of reactions.
1. concentration: create a high local concentration of substrates
2. orientation: holds them in a precise orientation
3. facilitation: speeds reactions using active site "acids" and "bases" or other functional groups (and cofactors)
4. stabilization of transition state: uses binding energy to stabilize the transition state, thereby increasing probability of reaction
compare fermentation as a form of anaerobic respiration to glycolysis in aerobic respiration.
both generate 2 ATP as a result as well as reduced NADH, in glycolysis NADH is a product but in fermentation NADH is oxidized back to NAD+ which generates waste products of ethanol or lactate
At what point in the process of photosynthesis is ATP generated?
by the ETC between photosystem II and photosystem I
How does the membrane maintain fluidity at cold temperatures?
cholesterol and insertion of more unsaturated fatty acid tails prevent tight packing of phospholipids
Bacterial cells have a cell wall and normally are under high turgor pressure. Penicillin weakens their cell wall, which leads to lysis under the high turgor pressure.
Describe the process of feedback inhibition.
the end product of a reaction binds allosterically to the enzyme catalyzing the reaction and inhibits it, so that the amount of product determines the rate at which the reaction will proceed
list four possible terminal electron acceptors
Describe the negative feedback loops that regulate body temperature.
If body temp increases above set point, hypothalamus activates cooling mechanisms such as sweating and blood vessel dilation until body temp returns to set point.
If body temp decreases below set point, hypothalamus activates warming mechanisms such as shivering and blood vessel constriction until temp returns to set point.