Cellular Respiration Flashcards
what is respiration?
the aerobic breakdown of food molecules to yield cellular energy, ATP
breathing
obtaning O2 from the environment and releasing O2
how do distinguish breathing and respiration?
cellular respiration is the term for respiration
main function of cellular respiration?
releasing energy from the bonds of the biomolecules
representative food molecule for cellular respiration
glucose
is free glucose molecules in our diet?
no- starch is
cellular respiration occurs from the aerobic breakdown from what carbs and biomolecules?
starch and sucrose; proteins and lipids
how much energy can the cell capture when it breaks down down glucose?
about 40% of glucose’s energy and convert into ATP molecules
what happens to the lost energy?
lost to environment as heat
how much of glucose’s energy is captured through anerobic environment?
~20%
where is the energy available to a cell contained?
in the chemical bonds that hold a molecule
is the energy in a bond the same all throughout?
no, some molecules store more chemical energy than others
what biomolecule stores more energy and why?
lipids - more bonds, and hydrocarbons
how does cellular respiration break down glucose?
in a series of steps and taps into the energy carried by electrons
what does cellular respiration do with electrons?
shuttles these electrons through a series of energy-releasing reactions each catalyzed by a specific enzymes
what is the amount of energy released from energy-releasing reactions carried out by electrons?
released in small amounts, not an explosive released of energy when you eat fod
what happens to the small amount of energy released?
some of this released chemical energy as cellular energy/ATP
movement of electrons from one molecule to another
oxidation-reduction
redox reaction
loss of electron
oxidation
gaining of electron
reduction
what does an electron transfer require? how does this relate to redox reactions?
require both a donner and an acceptor, so redox reactions always occur together
what do hydrogen movements represent?
electron transfers because each hydrogen atom consists of an electron and a proton
what is the ultimate electron acceptor?
O2 has a strong tendency to pull electrons away from the other atoms
important coenzyme used in to shuttle electrons in cellular respiration
NAD+
NAD+
nicotinamide adenine dinucleotide
is NAD+ oxidized or reduced?
reduced: NAD+ -> NADH
what role does dehydrogenase play?
enzyme that removes hydrogens from food
ATP stores the potential to react with what?
H2o
when either of the last 2 phosphate bonds are broken, what type of energy is released?
exergonic energy
what is the exergonic energy used for?
be used by the cell for cellular work like metabolism, anabolic and catabolic reactions, movement, growth
spent ATP molecules are?
continuously recycled/phosphates are reattached by eating food
reaction for ATP
ATO+ H2O –> ADP + Pi +free energy (reversible)
layers of mitochondria
outer membrane
intermembrane space
inner membrane
cristae, matrix, ribosome, mitochondrial DNA
what make up the phospholipid bilayer in mitochondria?
outer membrane
intermembrane space
inner membrane
what is cellular respiration also referred to as?
aerobic respiration
how many stages does cellular respiration have
- glycolysis
- formation of acetyl coA
- krebs/citric acid cycle
- ETC (electron transport chain) called chemosis/chemosis synthesis
what are main things to track in cellular respiration?
changes in hydrogen atoms moving through the series of reactions
electron carrier molecules created in cellular respiration
NADH FADH2
what is glycolysis
lysis of glucose
what is glucose?
6 carbon sugar
what does glucose get broken down into?
2 three carbon molecules called pyruvate/pyruvic acid
how many steps of glycolysis have?
10 steps to break down glucose to pyruvate and each step is catalyzed by a different enzyme
how many ATPs are needed in glycolysis?
2
how many ATPs are made in glycolysis?
4
net gain of ATP in glycolysis
2
second product of glycolysis
2 NADH molecules which resulted from the transfer of hydrogen to the electron carrier 2 NAD+
how is the ATP made during glycolysis?
through substrate level phosphorylation
substrate level phosphorylation
when a substrate with a phosphate group and ADP fit into the same active site of an enzyme
then phosphate is removed an added onto ADP creating ATP
summary reaction of glycolysis
C6H12O6 + 2ATP + 2NAD+ –> 2 pyruvate + 4ATP+ 2NADH (net 2 ATP)
where does glycolysis take place?
cytosol
what type of process is glycolysis?
anaerobic - which means that it evolved early
what two options does a cell have after glycolysis?
continue to proceed anaerobically- fermentation
or switch to aerobic cellular respiration
what does the decision to move forward from glycolysis depend on?
cell’s environment depending on whether O2 is available or not
what happens when oxygen is present after glycolysis?
the 2 pyruvate moves to the mitochondrial matrix and combines with 2 coenzyme A to form 2 acetyl coA
what is acetyl coA
2 carbon molecule
how did we go from 3 carbon pyruvate to 2 carbon acetyal coA?
lost 1 carbons in the form of CO2
what is the second product of formation of acteyl coA?
2 NADH
how much ATP is used?
2, but we dont take this into account as it means we dont have ATP to move forward after subtracting 2 from our net gain of 2 from the previous step
summary equation of the formation of acetyl coA?
2 pyruvate + 2 conenzyme A + 2NADH+ –> 2 acetyl coA + 2CO2 + 2NADH
what is the krebs cycle also called?
citric acid cycle
what happens to the carbons during the krebs cycle?
each of the 2 acetyl coA enter this one at a time and all the carbons from acetyl coA will be converted to CO2
where does the krebs cycle occur?
mitochondrial matrix
what type of process is the krebs cycle?
aerobic
how many steps are there in the krebs cycle?
8 steps that are catalyzed by a different enzyme in which ATP is made by substrate level phosphorylation
what does acetyl coA combine with?
oxaloacetate - 4 carbon molecule - to form 6 carbon molecule citric acid
since the cycle starts with 4 carbon oxaloacetate, what should it end with?
same molecule to maintain cycle
how many CO2 are made in the kreb cycle?
2 per cycle, so 4 total
with ONE turn of the krebs cycle, how many ATP made? NADH? FADH2? CO2?
1
3
1
2
how many usable ATPs are there in total after the Krebs cycle?
4
how many NADH do we have after krebs?
2 from glycolysis
2 from formation of acetyl coA
6 from 2 spins of krebs
10 TOTAL
how many FADH2 do we have after krebs?
2 from 2 spins of krebs
2 TOTAL
how many electron carrier molecules are there in total after krebs?
12
where do the electron carrier molecules store their energy?
in their H atoms
what do electron carrier molecules do?
shuttle the hydrogens to the phospholipid bilayer of the inner mitochondrial membrane, including the cristae where they enter the ETC
what happens to NADH and FADH2 when they enter ETC?
they will be split into proton and electron
how are high energy electrons from NADH and FADH2 passed down?
along a series of protein carrier molecules, some being cytochromes - FE containing protein carriers
each carrier molecule hands down electrons until?
they reach final electron acceptor - 1/2 O2
what does the oxygen atom do once it receives electrons?
combines with 2 H+ to form H2O which most is used as a waste product
is it oxidation or reduction when O2 accepts electrons?
reduction
at the same time electrons are being passed along the ETC, what is happening to the protons?
moved through the proton pump into the intermembrane space of mitochondrion creating a gradient with a lot of stored potential energy to do work. also creates an acidic pH in the intermembrane space
what happens to the H+ ions built up in the intermembrane space?
diffused back by facilitated diffusion into the matrix through ATP synthase, enzyme/protein channel
chemiosmosis
diffusion of ions where the ATP synthase spins like a pinwheel and enables ADP with 2 neg charge phosphates to bond with another phosphate group
how many ATP does each NADH make?
3
how many ATP does FADH2 make?
2
total amount of ATP made by NADH? FADH2? total?
30
4
34
where does glycolysis take place? net ATP made? NADH made? FADH2 made?
cytosol
2
2
-
where does formation of acetyl coA take place? net ATP made? NADH made? FADH2 made?
2
-
where does krebs cycle take place? net ATP made? NADH made? FADH2 made?
matrix
2
6
2
where does oxidative phosphorylation take place? net ATP made? NADH made? FADH2 made?
inner membrane cristae
34
0
-
how do anerobic organisms derive energy?
glycolysis is an anaerobic process, so they can make net 2 ATP and reduce 2NAD+ to 2NADH and form 2 pyruvate molecules which are then converted to either lactic acid/lactate or ethanol/ethyl alcohol and CO2
kingdoms that can perform alcoholic fermentation
bacteria, fungi, and plants
what happens to pyruvate in alcoholic fermentation?
pyruvate gets converted into 2 carbon molecule called acetaldehyde and each release a CO2
what is the CO2 released in beer and champgane?
bubbles
what happens to acetaldehyde?
converted to ethanol (drinking alcohol)
what drives the conversion of acetaldehyde to ethanol?
NADH made during glycolysis are oxidized into NAD+
what is the main objective of regenerating NAD+?
glycolysis can keep proceeding when more glucose is added to the system so that 2 ATP can be created in anerobic conditions
waste products of cellular respiration
H20 and CO2
waste product of fermentation?
ethaol
diff between ethanol and H20 and CO2?
ethanol is energy rich
what is the downside of ethanol?
toxic to organisms that produce it
what happens in lactic acid fermentation?
2 three carbon pyruvate are converted into 2 three carbon lactate
how does lactic acid fermentation make ATP? how many?
oxidize NADH into NAD+
2 ATP
what is lactic acid fermentation used for?
make cheese and yogurt
what does lactic acid in muscles create?
cramps
what breaks down lactic acid?
liver
how to stop muscle cramps?
increase O2 intake so lactic acid can be converted back into 2 pyruvates and reenter aerobic cellular respiration
