Unit 2 Flashcards
metabolism
sum of all chemical reactions that occur in the cell
anabolism + catabolism
metabolic pathway
a sequential series of chemical reactions in living cells; each reaction is catalyzed by a unique enzyme
anabolism
process of using energy to build large molecules from smaller molecules
ex. photosynthesis, synthesis of macromolecules
catabolism
process of breaking down compounds into smaller molecules to release energy
ex. cellular respiration
energy
the ability to do work
kinetic energy vs potential energy
energy of motion vs stored energy
when energy is transferred from one place to another, that is called _____
work
1st law of thermodynamics
energy cannot be created or destroyed, but it can be transformed from one type into another and transferred from one object to another
all energy is accounted for
energy cannot be lost or disappear
chemical energy
potential energy stored in the arrangement of the bonds in a compound
bond energy
measure of the strength or stability of a covalent bond
equal to the minimum amount of energy required to break a particular type of bond
equal to the amount of energy released per mole when a bond is formed
why do free, unbonded atoms have more chemical energy than any compound
because energy is always released when a bond forms
2nd law of thermodynamics
the law of entropy
the entropy of the universe increases with any change that occurs
in every energy transfer or conversion, some of the useful energy in the system becomes unavailable to do work
entropy
measure of disorder
free energy
energy transformations are never 100% efficient. some energy is always lost to the environment, which leads to an increase in entropy.
energy that is not lost, or the portion left that is available to do (useful) work in the given system is free energy.
how are changes in free energy produced
chemical reactions break some bonds and form new ones in products
exergonic reactions
chemical reaction that releases energy
spontaneous and involves a decrease in free energy
products of reaction contain less free energy than reactants (delta G is negative)
endergonic reactions
chemical reaction that requires energy
not spontaneous, and involves an increase in free energy, gains free energy
products of reaction contain more free energy than reactants (delta G is positive)
adenosine triphosphate (ATP)
adenine, phosphate, 3 phosphate groups
last phosphate is unstable
large quantity of energy is released when ATP becomes ADP plus inorganic phosphate P
redox reactions, electron transfers
transfer of electrons/ redox reactions during chemical reactions releases energy stored in organic molecules which is used to synthesize ATP
oxidation vs reduction
loss of electrons from one substance vs addition of electrons to another substance
the ______ form of a molecule is always at a higher energy level than the _________ form
and why
reduced, oxidized
because electrons that pass from one atom to another carry energy with them
electron carriers
compounds that pick up electrons from energy-rich compounds and then donate them to low-energy compounds
an electron carrier is recycled
all organisms require energy for
active transport cell division movement production of biomolecules reproduction temperature regulation
how does ATP store energy
a lot of stored energy in each bond
bonding of negative P groups is unstable > spring loaded > P groups “pop off” easily & release energy
why is ATP unstoreable
too reactive
transfers P too easily
only short term storage
digest organic molecules to get…
raw materials for synthesis
fuels for energy
how do we harvest energy from fuels
digest large molecules into smaller ones
break bonds and move electrons from one molecule to another
as electrons move they “carry energy” with them
that energy is stored in another bond,
released as heat or harvested to make ATP
how do we move electrons in biology
electrons cannot move alone in cells
they move as part of an H atom
oxidation and reduction in terms of energy
oxidation - exergonic, releases energy
reduction - endergonic, stores energy
cellular respiration
The process by which mitochondria break down
glucose to make ATP
two types: aerobic and anaerobic
aerobic respiration
requires oxygen and carried out by plants, animals, and some bacteria
anaerobic respiration
requires no oxygen and carried out by yeast, some bacteria, and sometimes animals
3 overall goals of cellular respiration
-to break the bonds between glucose to result in
carbon dioxide (producing 6 CO2)
-to move H atom electrons from glucose to oxygen to
form water (producing 6 H2Os)
-to trap as much free energy as possible released in the form of ATP (ultimate goal) accomplished through substrate-level phosphorylation and oxidative phosphorylation
substrate-level phosphorylation
ATP is formed directly in an enzyme-catalyzed reaction
a phosphate-containing compound (PEP or GDP) transfers a phosphate group directly to ADP, forming ATP
This type of energy transfer occurs in glycolysis and in
the Krebs cycle
oxidative phosphorylation
ATP is formed indirectly
involves sequential redox reaction, with oxygen being the final electron acceptor
More complex
Yields more ATP than substrate-level phosphorlation
cellular respiration stages and changes
Stage 1: Glycolysis – a 10 step process occurring
in the cy p to lasm
Stage 2: Pyruvate Oxidation – a one-step process
in the mitochondrial matrix
Stage 3: The Krebs cycle – an 8 step cyclical
process in the mitochondrial matrix
Stage 4: Electron transport and chemiosmosis – a
multistep process in the mitochondrial cristae
The ETC consists of:
4 protein complexes: NADH dehydrogenase complex, complex II, cytochrome bc complex, cytochrome c oxidase complex
2 mobile electron carriers: ubiquinone/coenzyme Q, cytochrome C
ATP synthase
protons enter the matrix through proton channels associated with ATP synthase (ATPase)
for every H+ that passes through, enough free energy is released to create 1 ATP from the phosphorylation of ADP
chemiosmosis
a process that uses energy in a hydrogen ion gradient across the inner mitochondrial membrane to drive phosphorylation of ADP to form ATP
regulation of aerobic respiration
feedback inhibition
speeding up aerobic respiration
high levels of ADP
low levels of citrate
both act on phosphofructokinase (PFK)
slow down aerobic respiration
excess ATP (acts on PFK) accumulation of citrate (acts on PFK) excess NADH (acts on pyruvate dehydrogenase)
lipid catabolism
2nd energy source
triglycerides are digested into fatty acids and glycerol
glycerol can be converted to G3P (glyceraldehyde-3-phosphate) and enter glycolysis
fatty acids undergo beta oxidation (same process as pyruvate oxidation) and enter Krebs cycle
protein catabolism
first go through deamination where amino groups are removed and converted to ammonia waste product
amino acids are oxidized and can enter as pyruvate, acetyl units, or molecules in Krebs cycle
total yield of ATP from cellular respiration
2 ATP from glycolysis
2 ATP from krebs cycle
4 ATP from NADH formed during glycolysis
6 ATP from NADH formed during pyruvate oxidation
22 ATP from NADH and FADH2 formed during Krebs cycle
total of 36
