metabolism- lecture #10 & #11 Flashcards
what is ATP to the cell?
currency $$$
what 3 types of cellular work does ATP perform?
chemical work (endergonic/anabolic reactions)
transport work (movement of materials against the concentration gradient)
mechanical work (muscle contraction)
what is rigor mortis and how does it happen?
Rigor mortis is the stiffening of the muscles, this happens because theres no ATP flow in a dead body
what does energy coupling pair together?
energy coupling pairs endergonic reactions ( non-spontaneous) with exergonic reactions (spontaneous)
what is energy coupling?
energy generated from one reaction is used to drive a second reaction
what is ATP hydrolysis? what happens to energy
exergonic water mediated breakdown
energy/heat is released when ATP turns into ADP
are cell conditions standard and what does it mean for hydrolysis?
no, therefore much more energy is available from the hydrolysis as a result
what kind of charge do phosphate groups have?
negative charge
what does the negative charge of the phosphate mean for energy
repulsion of like charge causes energy release when the bonds are cleaved
what do enzymes work to do and what net reaction is created?
couple exergonic reactions with reactions that require energy (endergonic)
creates a net exergonic reaction
what is the process of enzymes coupling
the product (usually a phosphate group) is picked up and used as a reactant in the second reaction (intermediate)
this raises the energy of the intermediate
how is ATP produced
using energy that arises from catabolic reactions in the cell
do anabolic reactions require or produce ATP? what about catabolic reactions
anabolic: require ATP
catabolic: produce ATP
what happens when a reaction reaches equilibrium? what does delta G look like?
it may no longer be used to perform work
delta G = 0
what does cellular catabolism begin and finish with?
begins with: glucose + O2 (high energy)
finishes with CO2 + H20 (low energy)
metabolic processes must be tightly regulated, regulation may
turn the production of an enzyme off (stop transcription of the gene)
regulate the activity of the enzyme post- production
what is the allosteric site
when the allosteric regulatory molecule (inhibitor or activator) binds somewhere where the active site isn’t, that site is the allosteric site
what happens when an allosteric inhibitor binds to an enzyme?
Allosteric enzymes typically have multiple active sites located on different protein subunits.
When an allosteric inhibitor binds to an enzyme, ALL active sites on the protein subunits are changed slightly so that they don’t work as well.
what happens when an allosteric activator binds to an enzyme
Some allosteric activators bind to locations on an enzyme other than the active site, causing an increase in the function of the active site.
what is an example of an allosteric inhibitor?
ATP
-turns off catabolism (produce)
what is cooperativity?
substrate binds to the active site of an enzyme that has many active sites
what happens when cooperativity happens?
triggers a change in shape of all subunits
increases the catalytic activity of the enzyme
what is an allosteric protein that does not work as an enzyme?
hemoglobin
what does hemoglobin do?
works to transport O2 from the lungs to the tissues to the inside of the red blood cells
as the hemoglobin is going through the body you need to load it with tones of oxygen
how does feedback inhibition work?
the end product of a metabolic pathway acts on the key enzyme regulating entry to that pathway, keeping more of the end product from being produced.
how is feedback inhibition behavior observed?
with allosteric inhibitiors
what is an example of a feedback inhibitor?
amino acid isoleucine
what does compartmentalization of the cell do?
creates order in metabolic pathways
______ of the first reaction will be the ________ for the next reaction
product of the first reaction will be the reactant for the next reaction
what is the origin of chemical energy?
the sun
what can be directly catabolized to release energy?
glucose
what will require some processing before they can be catabolized?
proteins, amino acids, lipids, polysaccharides
what happens when theres oxidation of organic molecules? delta G, activation energy
high energy molecules are broken into low energy molecules
(-)delta G
requires enzymes because of high activation energy
what is a loss of electrons?
oxidation
what is a gain of electrons?
reduction
how is energy in organic molecules released?
via electron transfers from one reactant to another
what is a redox reaction?
oxidation and reduction are always coupled
every H+ that gets moved an e- gets moved
what is the reducing agent?
electron donor
what is the oxidizing agent?
electron acceptor
what is the greediest for electrons?
oxygen
do all redox reactions involve the complete transfer of electrons?
no
are C-H covalent bonds polar or non-polar
non-polar
are C-O covalent bonds polar or non-polar
polar
is oxygen an oxidizing agent or reducing agent?
oxidizing agent
what happens when transferring an electron to oxygen?
releases energy
this energy may be used to perform work in the cell
when giving an electron to a molecule that wants it what type of reaction is that?
spontaneous
heavily reduced organic molecules have what potential energy
large potential energy
how is energy harvested through catabolism? what needs to happen and what does it need?
multiple steps
each step has its own enzyme
why does catabolism of an organic molecule not occur in a single step?
causes explosion
energy would not be harvested
energy would be wasted
do we want enzymes to be controlled? why?
yes, because controlling enzymes means to turn them on and off
if we couldn’t control them we would constantly waste energy
why are multiple steps in a transfer good? analogy
if a teacher hands all the papers to you, its overwhelming
if they give to you one by one (multiple steps) its easier
what is NADH
electron carrier that temporarily holds electrons
reduced version
how many electrons does NADH hold?
2 electrons and H+
what is NAD+?
electrons that travel to go pick up electrons
oxidized version
(empty truck)
process of glucose to H2O (through NAD+)
glucose –> NAD+ –> O2 –> H2O
electrons move from _____ energy end of the chain to the _____ energy end of the chain
high to low
what can FADH2 hold?
2 spots
2H+ and e-
what is aerobic cellular respiration?
requires O2
where does aerobic respiration occur?
glycolysis, intermediate step, TCA cycle and electron transport chain
where does substrate level phosphorylation occur?
glycolysis and TCA cycle
how much ATP does substrate level phosphorylation produce?
4 ATP
where does oxidative phosphorylation take place?
electron transport chain and chemiosmosis
how much ATP does oxidative phosphorylation produce?
28 ATP
where does glycolysis take place?
cytosol
how much ATP does glycolysis require?
2 ATP
how much ATP is produced in glycolysis?
4 ATP are produced but because we invested 2 ATP, 2 ATP are produced at the end of glycolysis
what else does glycolysis produce?
2 NADH + 2H+
what does the chain of 6 carbons turn into? what does this process produce
2 pyruvate (C-C-C) (C-C-C)
produces ATP
how much energy is released during glycolysis?
where does that energy come from? %
25% of available energy is released during glycolysis (some from ATP some from NADH)
how many steps occur in glycolysis?
10 steps each requires a unique enzyme
once pyruvate is produced where is it translocated?
from the cytoplasm into the mitochondrial matrix
in prokaryotes where does the intermediate step take place?
cytoplasm
in the mitochondrial matrix what is pyruvate converted into? how do we get to that product?
coenzyme A gets inserted producing
acetyl-CoA
what is generated when pyruvate is converted into C-C-CoA
2 molecules of CO2
2 molecules of NADH + H+
where does the TCA cycle occur?
mitochondrial matrix
where does the TCA cycle occur in prokaryotes?
cytoplasm
what is the goal of the citric acid cycle?
to oxidize acetyl CoA completely
what are the 8 enzymes in the TCA cycle?
oxaloacetate
citrate
isocitrate
ketoglutarate
succinyl- CoA
succinate
fumarate
malate
if an organism was unable to produce pyruvate what would happen?
GTP (ATP) would not be produced
FADH2 would not be produced
how many photons of light are needed to produce 1 glucose molecule?
48 photons
when using molecules other then glucose to produce energy, what needs to happen?
Amino acids produced from protein breakdown must have amino groups removed before they can enter into cellular respiration
During cellular respiration electrons begin on and are transferred to
glucose to O2
when oxidizing 1 acetyl CoA what is produced?
1 GTP
3 NADH
1 FADH2
what does the TCA cycle produce after cycling twice?
2 GTP
6 NADH
2 FADH2
what is GTP?
ATP but with guanine
what is the first step of the TCA cycle?
acetyl coA (C-C) combines with oxaloacetate (C-C-C-C) forming a 6 carbon structure called citrate
why do 2 carbon get lost in the TCA cycle?
because 2 CO2 are released during the TCA cycle
what is the last step of the TCA cycle?
malate produces NADH when going back to step 1
when does water get inserted into the TCA cycle?
when fumarate makes malate (it needs energy to be able to get to the last step
what holds most of the energy that was made in glucose?
NADH and FADH2
where is the electron transport chain located?
inner mitochondrial membrane
what does pyruvate produce when converting into acetyl coA? what gets inserted?
2 NADH
2 CO2
coenzyme A gets inserted twice
what are the complexes in ETC made of?
mainly of protein
what is needed in order for these complexes to function?
tightly bound prosthetic group
how many NADH enter the ETC?
10
how many ATP are produced per NADH molecule?
2.5 ATP/ NADH molecule
how many FADH2 enter the ETC?
2
how many ATP are produced per FADH2 molecule?
1.5 ATP/ FADH2 molecule
how much ATP in total are produced
32
what is complex I also made out of?
FMN (flavoprotein)
what does FMN do?
accepts electrons
what does FMN do with these electrons?
moves them to Fe-S
what does Fe-S do?
transfers electrons to ubiquinone
how are electrons produced to travel through the ETC?
produced from NADH –> NAD+
produced from FADH2 –> FAD+
what does ubiquinone do with the electrons from complex I and II
carries electrons to complex III
what is complex III also called?
cytochrome reductase
what is included in the structure of cytochrome reductase?
iron
what is the last electron carrier called?
cytochrome a3 or complex IV
what does complex IV do?
transfers electrons to O2
what does O2 do?
picks up H+ from the mitochondrial matrix forming water
what is the equation to form H2O?
2e- + 2H+ + 1/2 O2 —> H2O
where does FADH2 enter the chain? how many electrons does it contribute?
enters chain at complex II
contributes 2e-
why is complex II worth less ATP?
because it enters the chain later
when is H+ pumped into the inter-membranous space?
complexes I, III and IV
why can complex II not pump H+ across?
not transmembrane
what does the H+ gradient provide?
proton motive force that can be used to produce ATP
what can the energy stored in the gradient be used to do?
cellular work
what movement from the proton gradient is used to drive cellular work?
movement of pyruvate from the cytoplasm into the mitochondria
movement of ATP into the cytosol after production in the ETC
how many H+ ions need to be pumped through chemiosmosis for 1 ATP to be produced?
4H+ need to be pumped
what has a higher pH, intermembrane space or mitochondrial matrix?
mitochondrial matrix (pH=7.8)
intermembrane space (pH=7)
what would happen if the ETC stopped?
you won’t be able to make enough ATP and you’ll die
what does aerobic cellular respiration consist of?
glycolysis, intermediate step, TCA cycle and ETC
when does fermentation occur?
in the absence of oxygen
is fermentation ever a primary means of energy production?
yes. in some prokaryotes
what are the 2 types of fermentation?
alcohol fermentation
lactic acid fermentation
what happens before fermentation?
glycolysis then fermentation
what is the product of alcohol fermentation?
produces ethanol
what is the product of lactic acid fermentation?
lactic acid
does fermentation use ETC
no.
what is the process of alcohol fermentation?
normal glycolysis
pyruvate (C-C-C)
CO2 steams of creating a 2 carbon enzyme
called acetaldehyde (C-C)
NAD+ is produced
acetaldehyde turns into ethanol (C-C-OH)
NAD+ goes back to beginning of glycolysis for process to restart
how much ATP and NADH is produced in fermentation?
more then 2 ATP
2 NADH
(from glycolysis)
where does fermentation occur?
in the cytoplasm of prokaryotes and eukaryotes
what happens to NADH in fermentation? why does this happen?
NADH is oxidized back to NAD+
so that glycolysis can continue to produce energy for the cell
what creates alcohol fermentation?
bacteria and yeast
what is lactic acid fermentation used by?
fungi and bacteria
human skeletal muscle switches to lactic acid fermentation when O2 is limited, how does this process work?
lactic acid is sent to the liver
converted to pyruvate
enters into the intermediate step for normal catabolic processing
what happens after pyruvate is made in glycolysis? lactic acid fermentation
pyruvate converted into lactic acid
what’s another process used in the absence of oxygen?
anaerobic respiration
does anaerobic respiration use ETC?
yes!
due to the absence of O2, what is used instead?
instead of O2, SO4
instead of water, H2S
is any energy available from anaerobic respiration?
yes, just less energy avaliable
what happens to obligate anaerobes in the presence of O2?
killed in the presence of O2
what do obligate anaerobes use for energy production?
fermentation or anaerobic respiration
what are facultative anaerobes?
can grow under conditions with or without oxygen but prefer aerobic conditions
is free glucose common?
no
what are commonly consumed as energy?
disaccharides, proteins and lipids
how does glycogen release free glucose for cell respiration?
glycogen is easily cutdown into glucose
what can amino acids be used for?
anabolic reactions
protein synthesis
how can amino acids be used for ATP production? (5 steps)
amino acids go through deamination
amino group gets cut off
pyruvate (C-C-C) produced
can go directly into intermediate step
amino group gets peed out
glycerol can be converted into what?
glycerol can be converted into C-C-C
what can fatty acids be synthesized from?
acetyl coA
what do fats store?
large quantities of energy
therefore, worth large quantities of NADH, FADH2 and GTP in the TCA cycle
why is it more difficult to loose weight?
1 gram of fat stores twice as much energy as 1 gram of sugar
is all food that enters the body catabolized?
no, some must be used in order to build molecules required by the body
what do anabolic reactions consume?
ATP
what is released when the molecule is catabolized?
ATP
order of highest energy production to lowest
(aerobic, fermentation, anaerobic)
aerobic, anaerobic, fermentation
what type of process is movement of protons across complex I from the mitochondrial matrix into the inter-membranous space?
endergonic
