cellular metabolism Flashcards
metabolic pathways
series of steps to alter molecules
anabolic pathways
build molecules, requires energy
catabolic pathways
break down molecules, releases energy
energy is the ability to
create change
KE
energy of movement
thermal energy
energy of heat due to random molecule movement
electrical energy
energy of charged particles
chemical energy
energy stored in covalent bonds
1st rule of thermodynamics
energy cannot be created or destroyed
2nd law of thermodynamics: energy transformation…
energy transformation increases entropy (disorder)
processes that decrease entropy require
require energy
biological systems are highly ordered which means
they require a lot of energy to maintain, and lose a lot of energy as heat
Gibbs free energy measures
energy of chemical reaction
Gibbs free energy
energy available to do work
+ Gibbs free energy
reaction requires energy and universe becomes more organized
negative gibs free energy
reaction releases energy and universe becomes less organized
why is negative Gibbs free energy more stable than positive?
*More stable because disorder in the universe is always trending towards randomness and disorder
*Since they change less, they have less ability to do work (they just want to sit there since they are so stable)
exergonic reaction: change in free energy is …
G < 0
in exergonic reactions:
reactants have ____ energy than products?
reactions ____ energy?
reaction is ______?
Reactants have more energy than products
Releases energy
Reaction is spontaneous
in endergonic reactions: change in free energy is
G > 0
in endergonic reactions:
reactants have ____ energy than products?
reactions ____ energy?
reaction is ______?
less; require; non spontaneous
what happens if cells reach equilibrium?
they will die
three main categories of work that cells do:
chemical reactions, transporting things, and mechanical.
chemical work (by cells)
powering endergonic reactions
transport work (by cells)
pumping substances up concentration gradients
mechanical work (by cell)
move the cell or nearby structures
to do work, cells use
adenosine triphosphate (ATP)
ATP is composed of
Nucleotide (adenine) attached to 3 phosphates
energy currency of cells
ATP
smallest unit of energy in the cell
ATP
- ATP hydrolysis
-phosphates can be removed via hydrolysis
*Releases energy and creates ADP (adenosine diphosphate)
- phosphorylation
phosphate released from ATP hydrolysis is transferred to another molecule, creating a phosphorylated intermediate
Couples exergonic ATP hydrolysis with endergonic reaction
phosphorylation
Coupled reactions are still exergonic if
ATP releases more energy than endergonic reaction uses
- regenerating ATP
Phosphate can be added to ADP via dehydration to recreate ATP
regenerating ATP requires
energy
primary purpose of cellular respiration
to create ATP
activation energy
energy needed (IN) to start reaction
____reactions require energy to start
exergonic
catalysts function
decrease activation energy
enzyme are biological ….
catalyst proteins
enzyme names end in
-ase
___ lowers the activation energy of reactions
catalysts
catalysts are not
used up by the reaction
enzyme structures
large proteins with complex shape
substrate
reactant that enzyme acts on
enzyme substrate complex
enzyme attached to substrate preparing to catalyze reaction
active site
location on enzyme that fits substrate
enzyme specificity
enzymes only fit ONE substrate and catalyze ONE reaction
the 3D shape of the protein determines
its function
denaturing
hostile/incorrect environmental conditions cause protein to lose/change shape and therefore its function
rising temps and enzymes:
Rising temp increases enzyme activity (why we get fevers when we are sick)
too high temperatures and enzymes:
Too high temps begin denaturing enzyme and lowers activity
many enzymes have optimal function at pH of
6-8
cofactors
additional molecules that enzymes need to function
facts to know about cofactors (the molecules that enzymes need to function)
Not a part of the enzyme
Usually bind to the enzyme
Not used up in reaction
coenzyme is a type of
cofactor
coenzymes are made by
living things (such as vitamins)
enzyme inhibitors
reduce or block enzyme function
enzyme inhibitors do not
destroy or damage enzymes
competitive enzyme inhibitors:
- Fill active sites
- Compete with substrate
noncompetitive enzyme inhibitors:
- Do not bind in active site
- Change enzyme shape
why must cells be able to control their metabolic pathways?
store enzymes for quick activation later
super charge enzymes for burst increase in reaction rate
keep enzymes from wasting energy on unneeded molecules
Allosteric regulation: allosteric site
binding site that is not the active site
Allosteric activation
allosteric molecule improves enzyme shape to increase enzyme function
Allosteric inhibition
(noncompetitive inhibition) allosteric molecule makes proper shape difficult to achieve to reduce enzyme function
Feedback inhibition:
Metabolic product inhibits pathway
grouping enzymes in the same pathway…
increases function
enzymes in compartments allows
control of local conditions
Cellular respiration
break down of molecules to release energy
two kinds of cellular respiration
aerobic respiration and anaerobic respiration
aerobic respiration
uses oxygen to release energy
anaerobic respiration
does not use oxygen to release energy
oxidation
loss of electrons (increase oxidation number)
reduction
electrons are gained
redox reactions release
energy
why is oxygen used in cellular respiration?
Oxygen pulls electrons strongly, giving electrons to oxygen results in a stable, low energy system
Reactions that increase stability are
exergonic
Cellular respiration (aerobic) oxidizes organic molecules to
release energy from them
reducing electron carriers moves energetic electrons to
electron transport chain
electron transport chain receives electrons from
electron carriers
Stages of cellular respiration
- Glycolysis
- Citric acid cycle
- Oxidative phosphorylation
where does glycolysis occur?
cytoplasm
how many ATP does glycolysis require for activation?
2
respiration steps: how many net ATP from glycolysis
2 ATP
respiration steps: how many net ATP from citric acid cycle
2 ATP
respiration steps: how many net ATP from oxidative phosphorylation
26 or 28
respiration steps: how many net ATP TOTAL
30 or 32
what happens to electron transport chains without oxygen
- Electron carriers cannot deliver electrons
- Electron carriers become full of electrons
- Electron carriers cannot pick up electrons in glycolysis
- Glycolysis ceases
- No ATP is made via substrate-level phosphorylation
fermentation is a type of
anaerobic respiration
main function of fermentation
empty electron carriers without electron transport chain to allow glycolysis to continue
___ ATP are produced via substrate level phosphorylation
2
lactic acid fermentation
Electrons are given to pyruvate and forms lactate
Empties electron carriers (regenerates NAD+)
Glycolysis can continue
lactic acid fermentation only occurs in
in bacteria, fungi, and animals
Alcohol fermentation (anaerobic)
CO2 is removed from pyruvate to form acetaldehyde
Acetaldehyde takes electrons to become ethanol
Empties electron carriers and regenerates NAD+
Glycolysis can continue
fermentation produces ___ ATP while aerobic respiration produces ___ ATP.
2, 32
both aerobic respiration and fermentation use
glycolysis
fermentation does not need
oxygen
chloroplast location
highest location in leaves
chloroplast location
