Chapter 13 (Book) Intro & Energy Carriers/e- Transport Flashcards
the energy to build cells comes from _______ _______
chemical reactions
enzymes direct the transfer of energy onto _______ such as ___
carriers, ATP
catabolism
breaking down complex molecules into smaller ones to yield energy
organotrophy
organic compounds donate e- to yield energy
heterotroph
organism that uses preformed organic compounds for biosynthesis
lithotrophy
inorganic compounds donate e- to yield energy
phototrophy
light absorption provides e- to yield energy
photoautotrophy vs. photoheterotrophy
photoautotrohpy: light absorption drives CO2 fixation
photoheterotrophy: light absorption w/o CO2 fixation
anabolism
building larger molecules from smaller ones
definition of energy
the ability to do work
ex. flagellar propulsion, maintain ion gradients
entropy
the disorder/randomness of the universe
always increasing
ultimately, the cell’s energy is spent as _____
heat
ex. compost pile 60C
Gibbs free energy change (deltaG)
deltaG = deltaH - TdeltaS
predicts whether a reaction will go forward
shows much much energy is potentially available to do work
negative vs. positive deltaG
negative: the reaction will go forward
positive: the reaction goes in reverse
enthalpy deltaH
heat energy absorbed or released
negative: released
positive: absorbed
entropy deltaS
negative: decrease in entropy
positive: increase in entropy
do we want deltaS to be negative or positive?
positive so it makes deltaG more negative
in general a reaction yields energy for the cell if 2 things
products are more stable than reactants
entropy increases
calorimeter
measures amount of energy (heat) released by a reactions
intrinsic properties of the reaction that affect deltaG
enthalpy
entropy
concentrations/environmental factors that affect deltaG
excess reactants makes deltaG more neg
temp, pressure, ionic strengths
deltaG not prime standard conditions
298K (25C)
1 atm
1M (molar concentrations)
the ______ of energy change is central to all living metabolism
additivity
coupling an energy-yielding rxn to an energy-spending one
how is deltaG related to deltaG not
delta G = deltaG not + RTln[products]/[reactants]
R = 8.315x10^-3 kj/(mol*K)
what is deltaG at equilibrium
0
syntrophy
metabolic relationship between two species
near-zero anaerobic pathways
the random distribution of molecules at steady concentration represents the state of greatest _______
entropy
entropy favors movement of nutrients from ______ to _______ concentration
higher, lower
diffusion
in most environments the concentration of nutrients outside the cell is lower than inside the cell…
so the cell must use energy to transport nutrients into the cell, lowering entropy
3 energy carriers
ATP
NADH
FADH2
what are energy carriers
molecules that gain and release small amounts of energy in reversible reactions
transfer energy
electron donor
a molecule that donates electrons to another molecules
aka. reducing agent
electron acceptor
a molecule that accepts electrons
aka. oxidizing agent
3 parts of ATP
base (adenine)
sugar (ribose)
3 phosphates
ATP complexes with ___
Mg2+
partially neutralizes negative charges of ATP phosphates to stabilize
ATP is formed from ADP by __________
phosphorylation
ADP + Pi + H+ –> ATP + H2O deltaGnot prime = 31 kj/mol
3 ways ATP can transfer energy to cell processes
hydrolysis of Pi
hydrolysis of PPi –> 2Pi
phosphorylation of an organic molecule
phosphotransferase system (PTS)
couple phosphorylation of a sugar to its transport across the cell membrane
how much ATP is made through complete oxidation of glucose
38 ATP
how efficient is complete oxidation of glucose
40-50%
what does NADH stand for and what is it used for
nicotinamide adenine dinucleotide
carry e- from breakdown products of glucose
why is NAD+ relatively stable
aromatic ring delocalizes e-
electron transport system/chain (ETS)
stores energy from e- transfer as an ion gradient across the cell membrane or an organelle
enables production of ATP, motility, nutrient transport
terminal electron acceptor
e- are transferred to this, and the product leaves the cell
3 reasons why different reactions use different e- carriers
different redox levels
different amounts of energy
regulation and specificity
what is the rate of a reaction determined by
activation energy (Ea)
what is activation energy
the input energy required to generate the high-energy transition state on the way to products
catalyst
an agent that lowers Ea and isn’t consumed by the rxn
enzyme
a protein catalyst that lowers Ea by bringing substrates close to each other and correctly orienting them
allosteric site
site on an enzyme that is not the substrate binding site
binding induces a conformational change that increases the rate of the rxn
what is the direction of catalysis of an enzyme dependenton
the concentrations of reactants and products
the presence of absence of allosteric regulators
