Chapter 7 UTD Biology

autotrophs

harvest sunlight and convert radiant energy into chemical energy

heterotrophs

live off the energy produced by autotrophs

how do heterotrophs extract energy

digestion and catabolism

cellular respiration reactions

oxidations, dehydrogenations

dehydrogenations

lost electrons are accompanied by hydrogen (what is actually lost is a hydrogen atom)

overall cellular energy harvest

-Dozens of redox reactions take place
-Number of electron acceptors including NAD+
-end with high-energy electrons from initial chemical bonds losing much of their energy and transferring it to a final electron acceptor

cellular respiration

cells harvest energy by breaking bonds and shifting electrons from one molecule to another

aerobic respiration

final electron acceptor is oxygen

anaerobic respiraton

final electron acceptor is inorganic molecule (not oxygen)

fermentation

final electron acceptor is an organic molecule

goal of respiration

produce ATP

what form is energy released from oxidation reactions in? Where is it converted to ATP?

electrons which are shuttled by electron carriers to the electron transport chain, that's where the energy is converted to ATP

Redox reactions

electrons release some of their energy as they pass from a donor molecule to an acceptor molecule, free energy is available for cellular work

substrate-level phosphorylation

transfer phosphate group directly to ADP during glycolysis

oxidative phosphorylation

ATP synthase uses energy from a proton gradient

electron carriers (4)

soluble, membrane-bound, move within membrane, easily oxidized and reduced, carry either just electrons or both electrons and protons

NAD+ needs what to become NADH

2 electrons and a proton

aerobic respiration free energy per mol of glucose

-686

enzyme for oxidative phosphorylation

ATP synthase

how is energy derived in oxidative phosphorylation

proton gradient formed by high energy electrons during oxidation of glucose, energy depleted electrons are then donated to oxygen

glycolysis location

cytosol

pyruvate oxidation and citric acid cycle location

mitochondrial matrix

electron transfer system location

inner mitochondrial membrane

4 stages of oxidation of glucose

glycolysis, pyruvate oxidation, kreb's cycle, electron transport chain

Glycolysis overall

breaks 6 carbon glucose into 2 molecules of 3-carbon pyruvate, 2 ATP and 2 NADH produced

glucose priming part 1 of glycolysis

cleavage and rearrangement

substrate level phosphorylation part 2 of glycolysis

oxidation, ATP generation

what reactions in glycolysis require energy

1 glucose is broken to 2 g3ps

energy releasing reactions in glycolysis

G3P to Pyruvate (produce 2 nadh and 2 atp)

How does pyruvate enter the mitochondria?

active transport

what does oxidation of 1 pyruvate generate

1 CO2, 1 acetyl-CoA, 1 NADH

What enters the citric acid cycle?

Acetyl CoA, but the coenzyme A is stripped leaving the 2 carbon acetyl

fate of pyruvate with O2

oxidized to acetyl-coA which enters krebs cycle

fate of pyruvate without O2

reduced in order to oxidize NADH to NAD+ (fermentation)

how does pyruvate become acetyl-coA

it is decarboxylated

what catalyzes the oxidation of pyruvate in the mitochondria?

a multienzyme complex called pyruvate dehydrogenase catalyzes the reaction

where does oxidation of pyruvate occur in eukaryotes vs prokaryotes?

eukaryotes- mitochondria
prokaryotes- plasma membrane

citric acid cycle products

2 CO2, 3 NADH, FADH2, ATP, oxaloacetate

for glycolysis to continue what must happen

NADH must be recycled to NAD+ by either aerobic respiration or fermentation

After the krebs cycle, what has glucose been oxidized to

6 co2, 4 ATP, 10 NADH, and 2 FADH2

feedback inhibition in glycolysis

phosphofructokinase is allosterically inhibited by ATP and / or citrate

feedback inhibition in pyruvate oxidation

pyruvate dehydrogenase inhibited by high levels of NADH,
citrate synthase inhibited by high levels of ATP

what is the feedback inhibitor for hexokinase?

glucose 6 phosphate

what are the 3 feedback regulators for phosphofructokinase?

ATP and citrate inhibit, AMP promotes

what are the feedback regulators for pyruvate kinase?

fructose-1,6 bisphosphate promotes, ATP and acetyl-coA inhibit

what are the feedback regulators for citrate synthase?

ATP and Citrate inhibit

glucose catabolism

involves a series of oxidation-reduction reactions that release energy by repositioning electrons closer to oxygen atoms- harvested from glucose using NAD+ and FAD+ as electron carriers

ETC

series of membrane bound electron carriers in inner mitochondrial membrane, electrons from NADH and FADH2 are transferred to complexes of the ETC

what does each complex in the ETC have?

a proton pump creating proton gradient

Where is the high H+ concentration?

intermembrane compartment

Where is the low H+ concentration?

matrix

what 3 major complexes serve as electron carriers

I, III, IV

where is complex II

bound to the inner mitochondrial membrane on the matrix side

where do electrons from NADH enter?

complex I

where do electrons from FADH2 enter?

complex II

what mobile electron carriers shuttle electrons between the major complexes

cytochrome c and ubiquinone (coenzyme Q)

cytochromes

proteins with a heme prosthetic group that contains an iron atom that accepts and donates electrons

how are individual electron carriers organized?

high to low free energy (NADH and FADH2 have abundant free energy and are easily oxidized while oxygen is easily reduced)

electron movement is _______ and _________ free energy

spontaneous, releases

what do complexes I, III, and IV do?

actively transport protons from matrix to intermembrane compartment

concentration of H+ in the intermembrane generates an __________ and ____________ gradient across the inner mitochondrial membrane

electrical and chemical

proton-movement force

stored energy produced by proton and voltage gradient, used for ATP synthesis and cotransport of substances to and from mitochondria

atp synthase structure

a basal unit in the inner membrane is connected by a stalk to a headpiece located in the matrix; a peripheral stator bridges the basil unit and headpiece

theoretical yield per glucose for bacteria

38 ATP

theoretical yield for eukaryotes per glucose molecule

36 ATP

theoretical yield of NADH

3 atp

theoretical yield of FADH2

2 atp

actual yield of 1 NADH

2.5

actual yield of FADH2

1.5

actual yield per glucose molecule for eukaryotes

30

why is there a reduced yield?

the proton gradient isn't only used for ATP synthesis, "leaky" inner membrane

E. Racker and W. Stockenius research

showed H+ gradient powers ATP synthesis using membrane vesicles that had a proton pump and ATP synthase; atp was synthesized in light (when protons flowed in to membrane) but not in dark

during fermentation, what supplies ATP

Glycolysis by substrate level phosphorylation

methanogens

CO2 reduced to CH4, found in cows

sulfur bacteria

inorganic sulphate is reduced to hydrogen sulfide

lactate fermentation

converts pyruvate to lactate
occurs in some bacteria, plant tissues, and skeletal muscles

alcoholic fermentation

converts pyruvate into ethyl alcohol and CO2
occurs in some plant tissues, invertebrates, protists, bacteria, and yeast

what does lactate fermentation make

milk, yogurt, dill pickles

what does alcoholic fermentation make

bread and alcoholic beverages

amino acids catabolism

deamination to a molecule that can enter glycolysis or krebs cycle

alanine deamination

pyruvate

aspartate deamination

oxaloacetate

glutamate deamination

a-ketoguterate

catabolism of fats

broken down to fatty acids and glycerol, converted to acetyl groups by beta-oxidation (OXYGEN DEPENDENT)

The respiration of a 6-carbon fatty acid yields

20% more energy than glucose

strict anaerobes

Fermentation is the only source of ATP for bacteria and fungi that lack enzymes to carry out oxidative phosphorylation

facultative anaerobes

can switch between fermentation and full oxidative pathways

examples of facultative anaerobes

e. coli, lactobacillus (used in buttermilk and yogurt), and s. cerevisiae (used in brewing, wine making, and baking), many cell types in higher organisms such as vertebrate muscle cells

strict aerobes

unable to live soley by fermentations and have an absolute requirement for oxygen

strict aerobe example

vertebrate brain cells

abnormal glycolysis

process of higher than normal rates of glycolysis that occurs in most cancer cells, generates large amounts of lactate, aka warburg effect

gloconeogenesis

when energy is not needed by the body, glucose can be synthesized from intermediates (consumes ATP)

Evolution of metabolism

1. Ability to store chemical energy in ATP
2. Evolution of glycolysis
3. Anaerobic photosynthesis using H2S
4. Use of H2O in photosynthesis
5. Evolution of nitrogen fixation
6. Aerobic respiration evolved most recently