cellular respiration Flashcards by Emily Baker

cellular respiration overview

results in complete oxidation of CO2

4 stages:
1. Glycolysis
2. Pyruvate oxidation
3. Citric Acid Cycle
4. Oxidative Phosphorylation

captures energy released in each reaction in the form of ATP. energy not captured as ATP can be stored as NAHD or FADH2 which go through the electron transport chain during oxidative phosphorylation

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location of glycolysis

cytosol (fluid of the cytoplasm)

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does glycolysis require oxygen?

no!

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how many rxns in glycolysis

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where do the steps of cellular respiration occur in bacteria?

glycolysis, pyruvate processing, citric acid cycle in the cytosol

oxphos in the cell membrane

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where do the steps of cellular respiration occur in eukaryotes

glycolysis - cytoplasm/cytosol

pyruvate processing, citric acid cycle - mitochondria

oxphos - mitochondria

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primary inputs and outputs of each stage of cellular respiration

glycolysis: inputs, glucose; outputs, 2 ATP, 2 Pyruvate

pyruvate processing: inputs, pyruvate; outputs, CO2, acetyl-CoA

citric acid cycle: inputs, acetyl CoA; outputs, CO2, ATP

Oxphos: inputs, NADH, FADH2; outputs, ATP

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substrate-level phosphorylation

when an enzyme catalyzes the transfer of phosphate from a phosphorylated molecule (substrate) to ADP forming ATP

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oxidative phosphorylation

occurs in the mitochondrial membrane (eukaryotes) or cell membrane (prokaryotes) and involves the protein ATP synthase and proton gradient driven ATP phosphorylation

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Phases/ process of glycolyis

phase 1: 2ATP phosphyorylate a 6C sugar w/ 2 negatively charged phosphate groups

phase 2: cleavage phase

6C sugar is cleaved into two 3C molecules
results in glyceraldehyde 3-phosphate and dihydroxyacetone phosphate, dihydroxyactone is then split into 2 glyceraldehyde 3-phosphate molecules, each of which eventually produce 2 atp molecules

phase 3: energy payoff phase
4 ATP made by substrate level phosphorylation
G3P reduced by removal of 4 electrons
2NAD+ become 2 NADH

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inputs and outputs of glycolysis

input - 2 NAD+, 2ATP, glucose

output - 2 pyruvate, 2 NADH, 2 ATP (4 produced throughout but 2 also used so net increase in 2 ATP)

technically AD Pis released as well

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what may NAD+/NADH accept/donate?

NAD+ can accept 2 electrons in the form of hydrogen

NADH can donate 2 electrons

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what may NAD+/NADH accept/donate?

NAD+ can accept 2 electrons in the form of hydrogen

NADH can donate 2 electrons

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fermentation definition

a metabolic process which converts sugars to acids, gases, or alcohol

an alternate pathway following glycolysis

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which cells can ferment?

bacteria, yeast, muscle cells

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by what means does fermentation produce ATP?

substrate level phosphorylation

what are the two types of fermentation?

ethanol fermentation or lactic acid fermentation

lactic acid fermentation

NADH transfers electrons directly to pyruvate, generates lactate as a byproduct (the deprotonated form of lactic acid)

this regenerates NAD+ which can reenter glycolysis

alcohol fermentation

NADH donates donates electrons to a derivative of pyruvate, producing ethanol - TWO STEP PROCESS
releases CO2, regenerates NAD+, form ethanol

pyruvate processing

pyruvate from glycolysis transported into the mitochondria via a carrier protein.

gives up 2 electrons to NAD+ —> NADH
oxidizes one carbon —> CO2

this leaves an acetyl (CH3OH group

transfered to coenzyme A forming acetyl-CoA

NAD+ —> NADH high energy intermediate in this process

substrate inputs and outputs of acetyl CoA synthesis

high energy intermediates of pyruvate processing

pyruvate, acetyl CoA, Coenzyme A, CO2

NAD+ —> NADH

citric acid cycle / tricarboxylic acid cycle / Krebb’s cycle

8 step process

acetyl CoA (2C) joins oxaloacetate (4C) –> citrate (6C)

throughout the cycle, 2 CO2, 3NADH, 1 FADH2, 1 GTP, 3 H+ ions produced

**1ATP produced from GTP, counts as part of cycle

8th step, malate is converted into oxaloacetate which may reenter the cycle

consider, glycolysis produces 2 pyruvate and 2 molecules of acetyl-CoA therefore double the output of a single cycle

summary of all inputs and ouputs of the citric acid cycle (ignoring water) sep into high energy intermediates and substrates etc

substrates etc - in–> acetyl-CoA, CoA, out –> CO2, CoA

high energy - in–> NAD+, FAD, ADP (or GDP), out –> NADH, FADH2, ATP (or GTP)

where does oxidative phosphorylation occur?

the inner membrane of the mitochondria (eukaryotes)

the plasma membrane (eukaryotes/bacteria)

oxidative phosphorylation overall

1. electrons are delivered by high energy intermediates NADH and FADH2 2. energy captured by electrons passed along the electron transport chain in a step down process 3. provides the energy needed to pump protons across mitochondrial membrane (against the concentration gradient) into the intermembrane space 4. proton flow through ATP synthase results in indirect synthesis of ATP

complex I and II in oxidative phosphorylation

complex 1 reduces NADH (prod 1 H+), complex 2 reduces FADH2 (prod 2 H+),

complex III/ transfer from first complexes

Coenzyme Q is CoQH2, transfers electrons from complexes 1 and 2 to complex 3 delivers 2 electrons and 2 protons, transfers them from ubiquinol to cytochrome c and pumps more protons into the intermembrane space

complex IV electron transport chain

cytochrome c carries electrons to complex IV where oxygen is reduced to form water

production of the proton gradient ETC

transport of electrons in complexes I, II, III, IV coupled w transport of protons across the membrane against the proton gradient into the intermembrane space, creating both a concentration and a electrical charge gradient - electrochemical

O2 role in the electron transport chain

the final electron acceptor at the end of the chain from complex IV, therefore TERMINAL ELECTRON ACCEPTOR, and is reduced to water

final production of ATP

the facilitated diffusion of protons along the concentration gradient through ATP synthase (which is made of two components) causes the complex to rotate which thus converts potential energy from the gradient --> kinetic energy / rotational energy which allows for the synthesis of ATP in the mitochondrial matrix

operation of ATP synthase

composed of F1 and F0 subunits, F0 forming a channel that rotates as protons pass through, and F1 using this rotational energy to catalyze the synthesis of ATP

what side of the matrix are the bulk of protein complexes involved in the electron transfer chain located on?

the matrix side

What does DNP do and what effect does it have on the ETC?

embeds itself in the mitochondrial matrix and acts as a channel for H+ to pass through 1. H+ gradient is lost 2. ATP synthesis slows then stops 3. NADH will increase due to increased catalysis of glucose 4. oxygen consumption is increased

why do DNP pill result in weight loss?

Rate of glucose catabolism increases

total cellular respiration process, approx ATP produced by substrate-level phosphorylation vs oxidative phosphorylation

4 by sub level, 28 by oxphos, 32 total

terminal electron acceptor for aerobic cellular respiration + what does it mean about the molecule if it's a terminal electron acceptor

O2 molecule originates in the environmentd

key components of anaerobic cellular respiration

oxygen is not the TEA, alternatively nitrate and sulfate are common inorganic compounds such as H2, H2S are used as electron sources rather than glucose

aerobic vs anaerobic vs fermentation

aerobic - O2 as TEA anaerobic - another electron acceptor ( not TEA ) ex NO3, SO4 fermentation - no O2 or TEA