cellular respiration Flashcards
why do we breakdown our food stepwise and not just combust it?
we’re interested in energy storage- when we break it down stepwise, we produce ATP, which we can use to store energy
what are the 2 ways to make ATP?
- 2 ways to make ATP:
- Chemiosmotic synthesis- happens more at end of process
- Substrate level phosphorylation- this is just the enzyme step that makes ATP
what is chemiosmotic synthesis?
an enzymatic reaction process to make ATP where the energy comes from a proton concentration gradient. this is the pumped hydro of energy production, utilizes a rotor to place p’s on ADP’s
how is ATP synthase related to chemiosmosis?
ATP synthase is the enzyme that makes ATP by chemiosmosis. It allows protons to pass through the membrane and uses the free energy difference to phosphorylate adenosine diphosphate (ADP), making ATP.
how do you get chemiosmotic synthesis going?
- in mitochondria, have a bunch of protons in intermembrane space. Low concentration gradient inside makes protons flow in.
substrate level phosphorylation
Enzyme destabilizes bond with inorganic phosphate and substrate to remove the substrate and add the extra phosphate to ADP to create ATP. the delta G of removing P from PEP is so negative, that it drives the positive delta G of adding P to ADP.
what is the big picture behind cellular respiration? why do we do it?
- Take sugars with O2 and oxidize it in a bunch of small steps to get carbon dioxide and water
- Do it in small steps to harvest the energy and use it for other purposes
- GOAL: convert all the energy from small steps into creating ATP which can be used everywhere in the body
high level- what is glycolysis, why is it crucial to evolution? where in cell does it occur?
A series of steps to break down the large macromolecules into their subunits. Present in all living things (evidence of one common ancestor.) Can occur without oxygen so we think it evolved before our atmosphere had free oxygen.
- Happens in the cytoplasm of cells
in glycolsis, what do you start with and what do you end with?
INS: Glucose, NAD+, 2 ADP
OUTS: 2 Pyruvate, 2 Net ATP, 2 NADH
draw out glycolysis process starting from glucose and including correct end processes

describe how the cell can regulate cell resp? and is this competitive or non competitive?
- If there is a lot of ATP around, it can inhibit (turn down) the phosphofructokinase enzyme
- If there is a lot of ADP and Citrate, it can turn up the phosphorfructokinase enzyme
- This is non-competitive inhibition (allosteric)—the inhibitor changes the form of the enzyme
where does chemiosmotic synthesis occur?
in the mitochondria
why would humans use a process of fermentation?
When you exert yourself you do not supply oxygen fast enough to break down pyruvate : begin to pile them all up . You also use up all the NAD+ you make too
what does fermentation allow us to do?
Fermentation allows us to use organic molecule to accept electrons from NADH so we can regenerate NAD+ so glycolysis can continue to run
what are the phases of cellular respiration and the options?
- glycolysis (doesn’t require O2).
- with O2: pyruvate oxidation , krebs cycle, ETC, chemiosmosis
- without O2: fermentation, -> glycolysis
theoretical total and % yield of ATP for all of cellular respiration?
36 ATP
- 38% efficiency in converting heat to energy
what is our energy % yield through glycolysis
2%
Q: If after glycolysis, oxygen is present, additional breakdown continues in the ____
mitochondrion
The entire goal for a yeast cell is to recycle ___ into ____to continue glycolysis
NADH into NAD+
inputs and outputs pyruvate oxidation
ins: 2 pyruvate, 2 NAD+
outs: 2 acetyl coA, 2 CO2, 2 NADH
describe pyruvate oxidation and where it occurs
- Once it enters mitochondrial matrix, Oxidation of pyruvate by pyruvate dehydrogenase (removes electrons which is an oxidation step)
- Pyruvate dehydrogenase is a multi-subunit enzyme complex
in the presence of oxygen, pyruvate is converted to:
acetyl CoA
a large, multi-subunit enzyme complex that links glycolysis and the citric acid cycle under aerobic conditions:
pyruvate dehydrogenase
acetyl CoA is:
- the fuel for the citric acid cycle
in the absence of oxygen (anaerobic conditions), pyruvate is converted into:
- lactic acid or ethanol
pyruvate is converted into acetyl CoA usually in: (what kind of activity? what kind or organism?)
resting muscle activity in higher organisms
the citric acid cycle takes place in what part of the cell?
in the mitochondria
where must pyruvate be transported to be aerobically metabolized?
into the mitochondria
why is glycolysis inefficient?
it captures only a fraction of the energy inherent in a glucose molecule as ATP
what does the pyruvate dehydrogenase complex produce and capture?
it produces CO2 and captures high-transfer-potential electrons in the form of NADH
the citric acid cycle processes:
the two-carbon acetyl unit to 2 molecules of CO2 while generating high-energy electrons that can be used to form ATP
the high-potential electrons produced in the citric acid cycle are transferred to oxygen to form water in a series of oxidation-reduction reactions called the:
electron transport chain
the electron transport chain is highly (ender/exergonic) allowing it to produce ___
exergonic, and the released energy is used to synthesize ATP (oxidative phosphorylation)
the conversion of pyruvate into acetyl CoA consists of 3 steps:
1) decarboxylation
2) oxidation
3) the transfer of the resultant acetyl group to CoA
describe start to end cellular respiration
The process that releases energy (ATP) by breaking down glucose.
cytoplasm: glucose -> 2 pyruvate, 2 ATP, 2 NADH via glycolysis
Mitochondrial membranes: pyruvate -> acetyl coA via pyruvate oxidation Pyruvate Dehydrogenase, a large multi-subunit enzyme complex
Mitoochondrial membranes: krebs cycle -> 1 turn generates 3 NADH, 1 GTP, 1 FADH2, 2 molecules CO2 note: FAD is just Another electron-carrying cofactor
ETC: uses NADH to produce ATP, O2, H2O
Alcoholic Fermentation
Type of anaerobic respiration used by organisms such as yeast to recycle products of glycolysis. Alcohol and Carbon Dioxide made, NO additional ATP made. Used in making beer, bread and wine

glycolysis- photo- where is it, what’s coming out?

describe how DNP worked in Racker’s experiment
used DNP to create a channel in the mitochondrial matrix that ruined the proton gradient so chemiosmotic synthesis of ATP didn’t work (DNP is uncoupling agent because it uncouples protons gradient from ATP synthase)
- Convert potential energy of gradient into kinetic energy of moving protons, you create heat instead of using the energy to make ATP
- Less ATP available so metabolic rate ramps up so you break down more macromolecules to get more ATP, so you break down fat more rapidly and lose weight
- DNP also overheats you which also ramps your metabolism and KILLS YOU
pyruvate
3 carbon sugar produced when glucose is split during glycolysis
which molecule feeds the ETC?
FADH
how many turns does the kreb cycle do?
- once per pyruvate
oxidation of NADH in ETC forms what products?
NAD+, H2O
describe what happens in the intermembrane space/mitochondrial matrix during ETC
proton pump (converting NADH-> NAD+) creates gradient of H+’s pushing them out into IMS, then H+’s get sucked back into matrix to do chemiosmosis , forming ATP, H2O
what provides the energy to pump protons across membrane in ETC?
electrons harvested from NADH provide this energy to create and pump H+ protons across , forming gradient
what was Racker’s hypothesis?
proton gradient can generate ATP . does experiment using photonabsorbing bacteria to prove it
what’s DNP and why was it used as a weight loss drug?
DNP uncouples synthesis of ATP from proton flow. It generates heat instead of ATP. Then ATP wont synthesize because gradient is missing.
People started taking DNP as weight loss to increase metabolic rate.
white fat versus brown fat? what do they do are where are they found? what does brown fat do that is so special?
- White fat: storage form of fat in body
- Brown fat: mitochondrial rich, found in a few designated spots in body, present in newborn humans (less in adult humans) and small mammals
- Produces an uncoupling agent called thermogenin (protein that acts as channel in membrane to short circuit ATP making so it is designed to produce heat)
when proteins are broken down in cellular resp, what do they turn into?
ammonia and urea
what happens to fats who get cut down for cellular respiration?
- Fatty acids get cut into acetyl CoA and get fed into Krebbs cycle
describe the Endosymbiont Hypothesis
- Fusion event of an ancient bacterium that can do oxidative respiration (mitochondria) with primitive eukaryotic cell
- Became advantageous to both for the eukaryote to provide a home and nutrients for the bacterium and not eat it (this morphed into the mitochondria within eukaryote cells)
draw out and describe oxidative phosphorylation
between the 2 phospholipid bilayers of Mito, you have 2 processes running at the same time: ETC to produce the gradient using NADH, FADH2, and then chemiosmosis to use the gradient to produce ATP . byproducts of this process are H2O and it requires O2.
