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TOPIC 11: Metabolism: How the cell obtains energy - Coggle Diagram
TOPIC 11: Metabolism: How the cell obtains energy
Metabolism
Metabolic path is divided into 2
Anabolic pathway
will lead to the synthesis of more complex molecules from simpler molecules
will build
Catabolic pathway
will lead to break down of complex molecules to simpler molecules
will break down
Energy will be produced & can be stored in the form of ATP or Electron carrier (ex: NADH, FADH2, NADPH)
Three stages of metabolism
FIRST: consume/ digestion ; breaking down large macromolecules to simpler molecules (Catabolic pathways)
in the form of amino acids (protein), simple sugars (polysaccharides), fatty acids & glycerol (fats)
SECOND: break down those smaller molecules to acetyl CoA
THIRD: completely oxidize those acetyl CoA to make more ATP in the mitochondria
Glucose & fatty acids are two main sources of energy in ATP production of cells
so after food digestion, glucose will be oxidized & to make ATP
( ATP is the direct energy molecule are cell can use to do cellular work, DNA replication, translation)
Glucose
Energy
ATP production
Glucose or fatty acids have energy since they contain covalent bonds - a matter of electrons
Oxidative reactions
leading to molecule breakdown
catalyzed by oxygen or dehydrogenase
removal of electrons (in the form of H)
aka
Redox reaction
always happen spontaneously and involves change in the e- state of reactants
Focus on the movement of electrons
leading to catabolic pathway
ex: aerobic respiration= oxidative reaction= is glucose
Reductive reaction
Addition of electron (in the form of H)
Leading to molecular build up
catalyzed by reductase or hydrogenase
leads to anabolic pathway
Carbon
Carbon always forms covalent bonds
is going to be gaining or losing of H or Oxygen
Carbon gaining H= carbon is reduced ( causing the sharing of electrons to be equal; carbon having electrons closer)
carbon gaining Oxygen = carbon is oxidized (bc the oxygen has the electrons closer)
most reduced carbon form = CH4
most oxidized form of carbon = CO2
= carbon is completely oxidized
carbon loses Oxygen = carbon is reduced
Over view of ATP synthesis
Substrate phosphorylation
requires high energy molecules
can only sustain for a short amount of time
Used for emergency
making ATP using a high energy molecule
occurs very fast
phosphoenolpyruvate is our high energy molecule
will donate the phosphate to the ADP to make ATP; at the same time it will become pyruvate
Oxidative phosphorylation
involve oxidation of organic molecule
ex: if your organic molecule starts w/ glucose it needs to go through glycolysis to make pyruvate, then get into mitochondria to become farther oxidized = Acetyl CoA
then entering the TCA cycle (citric acid cycle) to be further oxidized generating a lot of electrons
those electrons are stored in NaDH or FADH then they will be further used to be oxidized
through that process it will donate bc the NaDH is oxidized becoming NaD+ or FADH2 = 2electrons
those 2e- will be donated to the electron transport chain protein located in the inner membrane of the mitochondria so the e- are transported among those etc proteins
these process will help process energy bc they are ,moving from a higher concentration to a lower concentration generating energy to pump H ions from lumen of the mitochondria to the space b/w the inner membrane & outer membrane of the mitochondria
2 more items...
generates a large amount of ATP ( a lot more than substrate ph.)
Does
not
require an high energy molecule like phosphoenopyruvate
requires the oxidation of the organic molecules
metabolism; how cells obtain energy
Two stages of glucose catabolism
Glycolysis
occurs in cytoplasm (in the cytosol) in both eukaryotes & prokaryotes
Final product = ATP & pyruvates
after glycolysis pyruvates are generated & some ATP are also synthesized
under aerobic conditions pyruvates in eukaryote cells will enter mitochondria
first: pyruvate will be oxidized to acetyl CoA
then acetyl CoA will enter the citric acid cycle
Steps of glycolysis
1: one glucose will requires ATP to make 6-phosphate become fructose 6-phosphate
2: another ATP will be used to = fructose 1,6-bisphoshate
as of now 2 ATP have been consumed
3: this molecule will be split becoming 2 three carbon molecules
one of them had to be converted to become 3 carbon molecule
4: the two 3 carbon molecules become oxidized = NADH ( bc electrons are donated to NAD+ become NADH)
5: important bc its the first step during glycolysis can synthesis ATP called 1,3-biphosphoglycerate (high energy molecule)
1,3-biphosphoglycerate will make one of these 3 carbon will make one ATP
1 more item...
6 carbon atoms in the glucose molecule
all ATP synthesis are though substrate phosphorylation
Overall equation of Glycolysis
Glucose + 2ADP + 2Pi + 2NAD+ -----> 2 pyruvate + 2ATP + 2NAHDH+ 2H+ + 2H2O
Citric acid (Krebs or TCA) cycle
has 3 carbonic acids very important during the cycle
Citric acid cycle occurs in the mitochondria; more specific its in the
LUMEN
of the mitochondria
this will lead us to the final oxidation of the carbon to be completely oxidized becoming CO2 CO2
Ex:
stepwise oxidation of sugar in cell
inside of cell it moves very slowly
under aerobic condition the Sugar + oxygen, will go through glycolysis first, generating a pyruvate and pyruvate will enter mitochondria ; & under aerobic condition will become further oxidized to make CO2 & H2O
Small activation energies overcome by body temperature
free energy stored in activated carrier molecules
we do this in cell bc if we would burn it in one step we would create too much heat making the cell not be able to function
during oxidative phosphorylation we will make more ATP; so when we do that step by step cells can use those energy molecules to make more ATP
In lab setting ( direct burning of sugar)
we can place glucose (sugar) & O2 in a test tube and burn it in one step making CO2 & H2O
large activation energy overcome by the beat from a fire
all free energy is released as heat & none is stored
Aerobic respiration:
C6H12O6 + 6O ---> 6CO2 +6H2O
The structure of NAD+ (an electron carrier) & NADH
NAD+; is positively charged
then NADH; addition hydrogens
so when NAD+ is reduced to NADH how many electrons are being received ?
2 electrons; one is to make neutral the positive charge and the other one is from the hydrogen
Glycolysis can be regulated
metabolic regulation
Covalent modifications
addition or removal of phosphate
a general mechanism for changing the activity of enzymes
to regulate the enzyme activity; some enzymes will not have enzyme activity until a phosphate group is added or some enzymes will not have activity until the phosphate is removed
Allosteric modulation
the activity of the enzyme can be inhibited or stimulated by a compound that binds to site
the major enzyme can be regulated allosteric modulation is called phosphofructokinase
inhibited by ATP, NADH, citrate, & phosphoenolpyruvate ; this enzyme will be inhibited when ever we have too many ATP already
Will be activated by ADP; bc it means we need to convert all those ADP into ATP
Pyruvate is a key compound
very important molecule during glycolysis (pyruvate is our product) ; pyruvate sits at the junction b/w anaerobic & aerobic pathway
w/out oxygen, pyruvate undergoes fermentation
with Oxygen presence aerobic respiration occurs
reverse glycolysis synthesis glucose again called
Gluconeogenesis
even if we don’t consume glucose, our cells can use other organic molecules to make glucose through gluconeogenesis
Fermentation
for most cells fermentation will occur and create lactate acid
glucose after glycolysis will make 2 pyruvate
then those 2 pyruvate will go through fermentation
under go anaerobic condition; if oxygen not present they will be oxidized and create lactic acid
why is fermentation necessary?
is to make NAD+ ; bc we need to get rid of NADH ;will make us sore;
certain cell will not go through fermentation
like yeast cells; instead they will give you CO2 & ethanol ( they make ethanol instead of lactic acid)