Lecture 16 Notes

In animals periodic access to food and in plants periodic access to light requires that

special forms of "food" storage. (typically, sugar and fats) i'm assuming that he meant to say that these food storages are made or something. idk

Step 5 (written)

A phosphate molecule from solution displaces the CoA, forming a high energy phosphate linkage to succinate. This phosphate is then passed to GDP to form GTP. (In bacteria and plants, ATP is formed instead.)

Step 1 (written)

After the enzyme removes a proton from the CH3 group on acetyl CoA, the negatively charged CH2- forms a bond to a carbonyl carbon of oxaloacetate. The subsequent loss by hydrolysis of the coenzyme A (CoA) drives the reaction strongly forward

Step 2 (written)

An isomerization reaction, in which water is first removed and then added back, moves the hydroxyl group from one carbon atom to its neighbor

Step 7 Reactants/Intermediate/ Products What's given off Enzyme

Fumarate (add water) ----> malate Enzyme: fumarase

Glycogen can be readily converted to

G1P which is converted to G6P

Step 3 (written)

In the first of four oxidation steps in the cycle, the carbon carrying the hydroxyl group is converted to a carbonyl group. The immediate product is unstable, losing CO2 while still bound to the enzyme

Step 8 (written)

In the last of four oxidation steps in the cycle, the carbon carrying the hydroxyl group is converted to a carbonyl group, regenerating the oxaloacetate needed for step 1

What happens in Aerobic conditions? (long answer) Slide 17

In the presence of oxygen, many organisms convert pyruvate to an activated form of acetate know as acetyl CoA. In this reaction, pyruvate is oxidized (with NAD being reduced to NADH) and decarboxylated (liberation of a carbon atom as CO2). Acetyl CoA then becomes the substrate for aerobic respiration, where NADH is oxidized back to NAD+ by molecular oxygen

Summery of what happens after glycolysis under Aerobic conditions

In the presence of oxygen, many organisms convert pyruvate to an activated form of acetate known as acetyl CoA. In this reaction, pyruvate is both oxidized (with NAD being reduced to NADH) and decarboxylated (liberation of a carbon atom as CO2), Acetyl CoA then becomes the substrate for aerobic respiration, where NADH is oxidized back to NAD+ by molecular oxygen *Slide 8

Step 6 (written)

In the third oxidation step in the cycle, FAD removes two hydrogen atoms from succinate

Two types of Fermentation

Lactate Fermentation Alcohol Fermentation

Step 4 (written)

The a-ketoglutarate dehydrogenase complex closely resembles the large enzyme complex that converts pyruvate to acetyl CoA (pyruvate dehydrogenase). It likewise catalyzes an oxidation that produces NADH, CO2, and a high-energy thioester bond to coenzyme A (CoA)

Step 7 (written)

The addition of water to fumarate places a hydroxyl group next to a carbonyl carbon

Summery of what happens after glycolysis under Anaerobic conditions

When oxygen is absent, pyruvate is reduced so that NADH can be oxidized to NAD, the form of this coenzyme required in reaction Gly-6 glycolysis. Common products of pyruvate reduction are B) lactate (in most animal cells and many bacteria) C) ethanol and CO2 (in many plant cells and in yeast and other microorganisms) *Slide 8

What happens under Anaerobic conditions? (long answer) Slide 17

When oxygen is absent, pyruvate is reduced so that NADH can be oxidized to NAD, the form of this coenzyme required in reaction Gly-6 of glycolysis. Common products of pyruvate reduction are lactate (in animal cells and many bacteria) or ethanol and CO2 (in many plant cells and in yeasts and other microorganisms)

Step 1 Reactants/Intermediate/Products What's given off Enzyme

acetyl CoA + oxaloacetate <-----> S-citryl-CoA intermediate ---> Citrate + HS-CoA + H+ Enzyme: citrate synthase

In organisms that can grow anaerobically, pyruvate is converted to

acetylaldehyde and then into ethanol and CO2. NAD+ is regenerated

Under anaerobic conditions pyruvate is converted to

alternate products such as alcohol + CO2 (e.g., yeast) and lactate (e.g., in muscle) [NADH gives up e-s to make available NAD+ for additional ATP synthesis]

The ATP system serves as a way of ______

conserving and releasing energy in a cell

Seeds often contain large excesses of ____ and ___ to accommodate prolong periods prior to germination (and they make nutrient rich food)

fats and starch

While animals readily convert sugars to ______, they cannot convert FAs to ___; therefore FAs are _____ and converted into ____

fats; sugar; oxidized directly; acetyl-CoA *slide 29

Pyruvate generated via glycolysis may alternatively enter ________ under anaerobic conditions

fermentation pathways

for short term storage, glucose can be stored in the form of ____, which is what.

glycogen - a granular branched polysaccharide in cytoplasm (e.g., liver, muscle)

Other primary inputs (e.g., sugars and glycerol) may enter the ______ and are typically converted into ______

glycolysis pathway; converted into an intermediate in the main pathway *slide 4 and 5

ATP may be generated not only via ______ but also through _____

glycolysis; fermentation or oxidative phosphorylation *slide 6

Step 3 Reactants/Intermediate/ Products What's given off Enzyme

isocitrate ---->oxalosuccinate ---> a-ketoglutarate Given off: NADH + H+, CO2 Enzyme: isocitrate dehydrogenase

If oxygen is present, what happens to pyruvate?

it will become acetyl CoA and proceed to aerobic respiration

In fermentation regeneration of NAD+ yields ____ energy than complete oxidation

less

Step 8 Reactants/Intermediate/ Products What's given off Enzyme

malate ----> oxaloacetate given off: NADH + H+ Enzyme: malate dehydrogenase

In aerobes which use molecular oxygen O2 for growth and reproduction, pyruvate formed during glycolysis is transported into the _____ and then converted

mitochondria converted to CO2 and acetyl- CoA (which is oxidized to H2O + CO2)

Fermentation yields only

modest amounts of energy due to the absence of an external electron acceptor

Sugars and fats are major energy sources for most _________; however, the most useful energy from the oxidation of both kinds of foodstuffs remains stored in______, in which the acetyl group is oxidized to _____(and enters the citric acid cycle).

non-photosynthetic organisms the acetyl-CoA CO2 and H2O *slide 30 also look at slides 31-33

In plants NADPH and ATP are produced by _____ within the cholorplasts; however, the chloroplast membrane is impermeable to both of these carrier molecules.

photosynthesis

Most of the free energy of the glucose molecules is still ____

present in the two molecules of lactate or ethanol molecules

During excess photosynthetic capacity (during the day), chloroplasts convert some of the sugars generated to ____

starch, a polymer of glucose analogous to glycogen in animals

Step 6 Reactants/Intermediate/ Products What's given off Enzyme

succinate ----> fumarate given off: FADH2 Enzyme: succinate dehydrogenase

Step 5 Reactants/Intermediate/ Products What's given off Enzyme

succinyl-CoA ---> succinate + HS-CoA given off: GTP enzyme: succinyl-CoA synthetase

Plants rely heavily on the export of __________ through the same oxidative breakdown of sugars as occurs in animals

sugars from the chloroplasts to mitochondria to generate ATP

Aerobic respiration is

the complete oxidation of glucose to produce carbon dioxide and water in the presence of oxygen (the e- receptor) C6H12O6 + 6O2 ---> 6CO2 + 6H20

Alcohol Fermentation

the end product is ethanol; occur in most plant cells and in microorganisms in yeast

Lactate Fermentaion

the end-product is lactate; occur in some animal cells and many bacteria

In anaerobes, which do not use molecular oxygen, glycolysis is the ______ This is also true for

the main source of the cell's ATP and pyruvate and NADH e-s stay in the cytosol certain tissues in multicellular organisms in which an anaerobic environment may occur (i.e., muscle tissue) *this doesn't make sense but its what's on the slide

Why is fat more important than glycogen for energy storage in animals?

the oxidation of a gram of fat releases ~2X energy as the oxidation of a gram of glycogen. Moreover, there is a 6X difference in the actual mass of glycogen required to store the same amount of energy as fat due to glycogen binding water mass

Fermentation is

the process of energy production in a cell under anaerobic conditions (without oxygen)

Oxygen may be used at a rate greater than _______; the fermentation reactions regenerates _____

the supply in muscle tissue; NAD+ (From step 6 of glycolysis) *slide 11

TAGs stored in fat are hydrolyzed _______

to produce glycerol and fatty acids. FAs are released into the bloodstream

Plants also produce _____

triacylglycerols with varying types and proportions of the class of fatty acid that predominate when compared to animals

Fermentation often results in the accumulation of

waste products such as lactate or ethanol that can be toxic to the cells *picture slide 15

Fat cells (i.e., adiopocytes) store fatty acids in the form of

water insoluble triacylglycerols

____ and ___ are both stored in chloroplasts and serve as reservoirs of energy during periods of darkness

Fat and Starch

the Citric Acid Cycle is also called what?

Tricarboxylic Acid (TCA) Cycle or Kreb's Cycle

Step 4 Reactants/Intermediate/ Products What's given off Enzyme

a-ketoglutarate + HS-CoA ----> succinyl CoA given off: NADH + H+, CO2 Enzyme: a-ketoglutarate dehydrogenase complex

The anaerobic energy-yielding pathways are called

fermentation

One turn of the Citric Acid Cycle produces: and releases:

3 NADH 1 GTP 1 FADH2 releases 2 CO2 molecules *Slide 19 and 20

In fermentation, only about ____% of the free energy potentially available from glucose was obtained

7%

How many steps in the Citric Acid Cycle?

8

Prepare for the Citric Acid Cycle

8 steps you got this doing it twice Slides 20-25

Great Oxygenation Event (GOE) occurred when?

900 million yr or 2.5-2.4 billion years ago

Step 2 Reactants/Intermediate/ Products What's given off Enzyme

Citrate <---> cis-aconitateisocitrate --> isocitrate Enzyme: aconitase