Bio 1080 Chapter 9 Cellular Respiration

Front 1

autotrophs

Back 1

class of organisms that are able to produce their own organic molecules through photosynthesis

Front 2

heterotrophs

Back 2

class of organisms that live on organic compounds produced by other organisms

Front 3

cellular respiration

Back 3

a process used by ALL organisms to extract energy from organic molecules

Front 4

energy is contained

Back 4

within the bonds of molecules

Front 5

oxidation

Back 5

loss of an electron

Front 6

reduction

Back 6

gain of an electron, reduces the positivity of an atom/ion

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OIL RIG

Back 7

Oxidation Is Loss, Reduction Is Gain

Front 8

degree of electron sharing

Back 8

some redox reactions do not exchange electrons, they change the degree of electron sharing in covalent bonds

Front 9

adding hydrogens

Back 9

reduction

Front 10

removing hydrogens

Back 10

oxidation

Front 11

follow the hydrogens

Back 11

to determine/understand where oxidation and reduction has occurred

Front 12

dehydrogenations

Back 12

lost electrons are accompanied by hydrogen ions, therefore what is actually lost is a hydrogen atom (1 electron, 1 proton)

Front 13

NAD+

Back 13

an electron carrier, accepts 2 electrons and 1 proton to become NADH (reversible reaction)

Front 14

aerobic respiration

Back 14

final electron receptor is oxygen (O2)

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anaerobic respiration

Back 15

final electron receptor is an inorganic molecule (not O2)

Front 16

fermentation

Back 16

final electron receptor is an organic molecule

Front 17

electron carriers

Back 17

soluble, membrane-bound, move within membrane, easily oxidized and reduced

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[NAD+] + 2 electrons + 1 proton =

Back 18

NADH

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substrate-level phosphorylation

Back 19

transfer high-energy phosphate group directly to ADP from another molecule

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oxidative phosphorylation

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ATP sythase uses energy from a proton (H+) gradient to make ATP

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stages of oxidation of glucose

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1. gycolysis 2.pyruvate oxidation 3. krebs cycle 4. electron transport chain 5. chemiosmosis

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ATP powers cellular work, 3 main kinds

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mechanical, transport, chemical

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ATP hydrolysis drives

Back 23

endergonic reactions in cells

Front 24

APT hydrolysis drives endergonic reactions in cells in two ways

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1. By coupling exergonic reactions with endergonic reactions so over all ⌂G<0

2. By phosphorylating substrates and making them more reactive

Front 25

energy release

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is always associated with the loss of electrons and so metabolism really is ALL ABOUT THE ELECTRONS

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glycolysis

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10-step biochemical pathway that occurs in the cytosol

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glycolysis

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6-carbon glucose broken down into two 3-carbon molecules of pyruvate

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glycolysis

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net production of 2 ATP molecules by substrate-level phosphorylation and 2 NADH produced by the reduction of NAD+

Front 29

2 phases of glycolysis

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energy investment phase and energy payoff phase

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energy investment phase of glycolysis

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two molecules of ATP are consumed, glucose is phosphorylated twice

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energy payoff phase of glycolysis

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sugar is split to form 2 pyruvate molecules, 2 molecules of NAD+ are reduced to NADH, four molecules of APT are formed by substrate-level phosphorylation (net gain 2 ATP)

Front 32

NADH must be recycled to NAD+ by either

Back 32

aerobic respiration or fermentation

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aerobic respiration

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occurs when oxygen is available as the final electron acceptor

Front 34

fermentation

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occurs when oxygen is not available and an organic molecule is the final electron acceptor

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fate of pyruvate

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depends of oxygen availability

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pyruvate + oxygen is present

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pyruvate is oxidized to acetyl-CoA which enters the Krebs cycle

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pyruvate + oxygen not present

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pyruvate is reduced to oxidize NADH back to NAD+ (byproduct is lactate)

Front 38

oxidation of pyruvate occurs

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in the mitochondria in eukaryotes, in the plasma membrane in prokaryotes

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pyruvate dehydrogenase

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a mutienzyme complex which catalyzes the reaction of pyruvate oxidation

Front 40

oxidation of one pyruvate molecule yields

Back 40

1 CO2, 1 NADH, 1 Acetyl-CoA (consisting of 2 carbons from pyruvate attached to coenzyme A)... Acetyl-CoA procedes to Krebs cycle

Front 41

krebs cycle

Back 41

oxidizes the acetyl group from pyruvate, occurs in the matrix of the mitochondria, 9 steps

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Acetly-CoA + oxaloacetate ----> citrate

(2 carbons) (4 carbons) (6 carbons)

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first step of the krebs cycle

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remaining steps of Krebs cycle

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release 2 molecules of CO2, reduce 3 NAD+ to 3 NADH, reduce 1 FAD to FADH2, produce 1 ATP, regenerate oxaloacitate

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Kreb cycle has to run _______ for each glucose

Back 44

twice

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feedback inhibition for Krebs cycle

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Krebs cycle can be turned off at multiple points based on the abundance or scarcity of ATP and NADH

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ATP and NADH in abundance

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Krebs cycle slows

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ATP and NADH are scarce

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Krebs cycle speeds up

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glycolysis-->pyruvate oxidation-->Krebs cycle=

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glucose has been oxidized to 6 CO2, 4 ATP, 10 NADH, and 2 FADH (these electron carriers proceed to the electron transport chain)

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electron transport chain (ETC)

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a series of membrane-bound electron carriers embedded in the inner mitochondrial membrane

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energy lost with each transfer in the ETC

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used to pump protons (H+) across the membrane from the matrix to the inner membrane space of the mitochondria

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protein gradient

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between the intermembrane space and the matrix of the mitochondria, makes up the ETC

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NADH produces _____ ATP

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three

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FADH2 produces _____ ATP

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two

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FADH2 produces less ATP

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because electrons enter ETC later and pump only two protons into the intermembrane space

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chemiosmosis

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higher negative charge in matrix attracts the protons (H+) back from the intermembrane space to the matrix, and so the accumulation of protons in the intermembrane space drives protons into the matrix via diffusion

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during chemiosmosis, most protons move back to the matrix through ____________

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ATP synthase

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ATP synthase

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a membrane-bound enzyme that uses the energy of the proton gradient to synthesize ATP from ADP - Pi

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ATP synthase structure

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an enzyme complex consisting of ATPase "knob" component and a membrane-bound, proton-transporting base component, connected by a "stalk"

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ATP synthase function

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protons flow through transport protein and cause the stalk to spin, as the knob spins with the stalk, it's subunits change shape in a way that catalyzes the phosphorylation of ADP to ATP

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actual yield per glucose for eukaryotes

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30 ATP per glucose

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theoretical yield per glucose for eukaryotes

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38 ATP per glucose

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reduced yield of ATP due to

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"leaky" inner membrane (some protons enter outside of ATP sythase), use of the proton gradient for purposes other than ATP sythesis (pyruvate transport)

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___% of available energy from glucose is harvested by the cell

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32

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regulation of respiration

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occurs by feedback inhibition, when a step with in glycolysis is allosterically inhibited by ATP and citrate

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high levels of NADH inhibit ______ ______________

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pyruvate dehydrogenase

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high levels of ATP inhibit ________ _________

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citrate synthase

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anaerobic respiration

Back 67

use of inorganic molecules (other than O2) as final electron acceptor- many prokaryotes use sulfur, nitrate, carbon dioxide or even inorganic metals

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fermentation

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use of organic molecules as final electron acceptor

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methanogens

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CO2 is reduced to CH4 (methane), found in diverse organisms including bacteria that live in cows- anaerobic

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sulfur bacteria

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inorganic sulphate (SO4) is reduced to hydrogen sulfide (H2S), early sufate reducers set the stage for evolution of photosynthesis

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fermentation

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(2 kinds) reduces organic molecules in order to regenerate NAD+

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ethanol fermentation

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occurs in yeast, CO2, ethanol and NAD+ are produced

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lactic acid fermentation

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occurs in animal cells (esp muscles), electrons are transferred from NADH to pyruvate to produce lactic acid

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catabolism of protein

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amino acids undergo deamination to remove the amino group, remainder of amino acid is converted to a molecule that enters glycolysis or the Krebs cycle, where high energy electrons are removed and used to make ATP

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examples of catabolism of protein

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alanine is converted to pyruvate, aspartate is converted to oxaloacetate

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catabolism of fat

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fats are broken down to fatty acids and glycerol, fatty acids are converted to acetyl groups by beta oxidation- oxygen dependent process

Front 77

respiration of 6 carbon fatty acid yields ____ more energy than 6-carbon glucose

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