Energy and Glycolysis Flashcards
thermodynamics
the study of energy transformations
1st law of thermodynamics
energy can be transferred and or transformed, but it cannot be created or destroyed (principle of conservation of energy)
exergonic
proceeds with a net release of free energy and is spontaneous; G is negative (reactants > products)
entropy
measure of disorder, or randomness
2nd law of thermodynamics
every energy transfer or transformation increases the entropy of the universe
endergonic
absorbs free energy from its surroundings and is non spontaneous; G is positive (reactants<products)
energy coupling
use of exergonic process to drive an endergonic one -> mediated by ATP
three types of cell work
chemical, transport, mechanical
ATP (adenosine triphosphate)
composed of ribose, adenine and three phosphate groups
- bonds can be broken by hydrolysis (energy released with bonds broken)
- chemical change to lower free energy state
- ATP + H2O -> ADP + Pi
- ATP cycle: catabolism and anabolism
ATP drives endergonic reactions by…
phosphorylation: transferring a P group to some other molecule
- recipient is the phosphorylated intermediate
- leads to a change in a protein’s shape and often its ability to bind to another molecule
- renewable resource by addition of a phosphate group to ADP
catalyst
a chemical agent that speeds up a reaction with out being consumed by the reaction
an enzyme
a catalytic protein
activation energy (Ea)
the initial energy needed to start a chemical reaction
catalysis
speeds up reactions by lowering the Ea barrier
enzyme’s substrate
the reactant that an enzyme acts on
enzyme-substrate complex
enzyme binds to substrate
active site
region on enzyme where substrate binds
induced fit
enzyme change shape due to chemical interactions with the substrate
the active site can lower the Ea barrier by…
- orienting substrates correctly
- straining substrate bonds
- providing a favorable microenvironment
- covalently bonding to the substrate
enzyme saturation increase =
increased reaction speed = increased substrate concentration
photosynthesis generates
O2 and organic molecules, used as fuel for cellular respiration
- cell uses chemical energy stored in organic molecules to regenerate ATP
catabolic pathways yield energy by…
oxidizing organic fuels
aerobic respiration
consumes organic molecules and O2 and yields lots of ATP (occurs without O2)
cellular respiration
includes both aerobic and anaerobic processes
- requires fuel and oxygen
fermentation
a partial degradation of sugars that occurs without O2
redox reactions
chemical reactions that transfer electrons between reactants
oxidation
loses electrons
reduction
gains electrons
reducing agent
electron donor
oxidizing agent
electron acceptor
potential energy stored…
in chemical bonds of sugar, protein and fat molecules
- breaks bonds to make ATP
NAD+ and NADH
the NAD+ picks up an electron from glucose, at which point it becomes NADH. Then NADH, along with another molecule flavin adenine dinucleotide (FADH2) will ultimately transport the electrons to the mitochondria
electron transport chain
electrons passed to increasingly electronegative carrier molecules -series of redox reactions
- electron transfer to oxygen = regenerates ATP
stages of cellular respiration
glycolysis, citric acid cycle, oxidative phosphorylation
glycolysis
breaks down glucose into 2 molecules of pyruvate in cytosol
- can occur with or without O2
pyruvate oxidative and citric acid cycle
complete breakdown of glucose in mitochondrial matrix
oxidative phosphorylation
inner membrane of mitochondria and accounts for most of ATP synthesis (90%)
substrate-level phosphorylation
small amount of ATP formed in glycolysis and the citric acid cycle
glycolysis breaks down glucose into 2 pyruvate, has 2 major phases:
- energy investment phase (-2)
- energy payoff phase (+4)
net yield of glycolysis
2 ATP and 2 NADH per glucose molecule
before the citric acid cycle can begin, pyruvate must be converted…
to acetyl CoA
