BIO Exam 2

What forms of energy are relevant to biology?

electromagnetic (light), chemical energy

Is energy created or destroyed?

No, energy is simply converted into another form of energy.

What is metabolism?

Metabolism is changing molecules into different molecules.

Anabolic

BUILDS larger molecules.

Catabolic

BREAKS DOWN larger molecules into smaller ones.

Is the efficiency typically 100% or less than 100% when Energy is transferred from one molecule to another? What happens to the Energy that is “lost”?

Less than 100%. Energy that is lost is heat, which can then be used to increase temperatures of surrounding molecules. The energy lost can also be used to drive other reactions forward.

What is the source of all life energy on Earth?

The sun. The sun radiates electromagnetic radiation (light) > captured by photosynthetic organisms > chemical energy.

What is exergonic reaction?

The energy leaves the reaction; the products have less energy than the starting molecules.

What is endergonic reaction?

The energy enters the reaction; the products have more energy than the starting molecules.

Is exergonic or endergonic more likely to use ATP hydrolysis?

Exergonic

Where does energy in endergonic reaction typically come from?

Exergonic reaction.

Is photosynthesis endergonic or exergonic?

Photosynthesis is a long series of endergonic reactions where CO2 and H2O are combined and energized until they form an energetic sugar molecule.

Can endergonic reactions occur by themselves? What about exergonic?

No, it needs additional energy from exergonic reaction to actually happen.

Exergonic reactions are spontaneous; they will happen eventually.

What is a catalyst?

Makes reactions easier by lowering the activation energy.Wh

What is activation energy?

Initial energy or the push that starts reactions.

Which reaction requires activation energy?

Both exergonic and endergonic reaction.

Where does activation energy come from?

The kinetic movement of substrates.

What is reaction coupling?

Exergonic and endergonic are coupled reactions because the energy lost in exergonic will end up as one of the products of endergonic reaction.

Are catalysts changed by the reaction?

No. They may change temporarily, but will go back to original state when reaction is done.

What are enzymes?

Catalysts for biological reactions. They are usually made out of protein.

What does substrate and product mean?

The substrate is the starting molecule that the enzyme acts on. The products are what is made after the chemical reaction.

How do enzymes improve rate of reaction?

They lower activation energy and hold substrates in correct position to speed up reaction.

What are enzymes regulated by?

• pH

• inhibitors of molecules

• product of reaction can inhibit its own enzyme to signal it to stop producing said product

Proton gradients are:

• Used to power ATP synthase

• Can be built up across membranes (like dams)

• Protons cannot pass through lipid bilayer

Which is more energetic: CO2 or CH4?

CH4 because carbon is bonded to hydrogen. Bonds to H gets -1 redox. CH4 has -4 redox, which is more than CO2.

Can proton gradients across a membrane store potential energy?

Yes.

What is the starting molecule for Glycolysis? What is the final product of Glycolysis?

The starting molecule for glycolysis is 6-C sugar molecule. The final product of glycolysis is two 3-C pyruvate molecules, 2 NADH, and 4 ATP (2 from each 3-C molecule).

How many ATP are used during Glycolysis? How many ATP are made? What is the "net" gain of ATP from one glucose molecule during Glycolysis?

2 ATP are used during glycolysis to transfer two phosphates to 6-C sugar. 4 ATP are made (2 from each 3-C molecule).

What is NAD+ used for during Glycolysis? What would happen if the cell ran out of NAD+?

NAD+ is used as an electron carrier during glycolysis. If the cell runs out of NAD+, glycolysis will stop because NAD+ is needed in one of the reactions.

What is Fermentation and under what conditions does it occur?

Fermentation ia a process that makes a small amount of ATP and regenerates NAD+ (NAD+ is recovered from NADH) so that glycolysis can continue. This only occurs when there is no oxygen available.

How is Acetyl-CoEnzyme A formed? What can it be used for in a cell?

Acetyl-coenzyme is formed from 3-C pyruvate. The pyruvate becomes oxidized, which converts the pyruvate to Acetyl-CoA (2-C molecule). The products from this process is CO2 and NADH.

In a cell, it is used to help produce ATP in the Krebs Cycle and can also be used to form fatty acids and other molecules.

What happens during the Kreb's Cycle? What are the products of one full turn through the Kreb's Cycle?

Kreb’s Cycle breaks Acetyl-CoA and captures its energy through electron carriers. The products for one full turn of Kreb’s Cycle is 2 CO2, 1 ATP, 3 NADH, and 1 FADH2.

How many ATP, NADH (include FADH2 as equivalent to NADH), and CO2 are made during the Kreb's Cycle?

• 1 ATP

• 3 NADH

• 2 CO2

• 1 FADH2

If it counts for the whole glucose:

• 2 ATP

• 8 NADH (NADH + FADH2)

• 4 CO2

What is the final electron acceptor in the Mitochondrial Electron Transport Chain?

Oxygen.

What are the two membranes of the Mitochondria called? What are the compartments inside the Mitochondria and what are they used for?

The two membranes of the mitochondria are called inner membrane (has folds called cristae) and outer membrane.

• Inner membrane = ETC + ATP synthase → makes ATP

• Intermembrane (between the outer and inner membrane) which is used for creating a proton gradient by storing H+ to power ATP synthase.

• Matrix = Krebs cycle

How many CO₂ are made during Glycolysis?

0

What will happen to Acetyl-CoA if the cell already has an abundance of ATP?

It will likely be used to make fats.

At the end of The Citric Acid Cycle, where are all the Carbon atoms from the original glucose or what is the original glucose completely broken down into?

CO2.

At the end of The Citric Acid Cycle, where are the electrons that we removed from Glucose?

NADH or FADH2. The electrons will also be used to make water from O2.

What is a purpose of the Electron Transport Chain in Mitochondria?

To use energy in the electrons from NADH (or FADH2) to create a H+ gradient across the inner membrane.

The complete oxidation of Glucose to 6 CO₂ through cellular respiration produces about how many ATP?

32 ATP.

The major protein complexes involved in the Mitochondrial Electron Transport Chain, and the ATP synthase, are located where?

Inner membrane.

What is Pi?

Inorganic phosphate.

What does it mean for an atom/molecule to be reduced?

They gain electrons.

What does it mean when atoms/molecules are oxidized?

They lose electrons.

Which is the oxidized and the reduced form: NADH and NAD+

NADH is the reduced form, NAD+ is the oxidized form.

How does ATP turn into ADP and Pi?

ATP becomes hydrolyzed.

What is the connection between ATP hydrolysis and endergonic reactions?

ATP hydrolysis can be coupled up with other endergonic reactions to drive their reactions forward.

List the steps of glycolysis:

1. Energy requiring/priming steps: 2 ATP are used to attach two phosphates (Pi) to 6-C sugar. The 2 ATP used becomes ADP.

2. Cleavage reaction: 6-C sugar gets split to 3-C sugar with phosphate on each.

3. Energy releasing: 3-C sugar gets converted to 3-C pyruvate. Results in 2 NADH and 4 ATP (1 NADH and 2 ATP from each 3-C pyruvate).

Glycolysis happens to how many glucose?

Happens once to one glucose.

For animals, what does fermentation produce?

2 lactate. F

For yeast and plants, what does fermentation produce?

2 ethanol and CO2.

What redox state = more energy in molecule?

More negative redox.

What is redox state for bond of the following: H, O, C.

H = -1 (more energy if C is bonded to H)

O = +1 (less energy if C is bonded to O)

C = 0

Where does cellular respiration start?

Starts in the cytoplasm but mainly occurs in mitochondria.

What is glucose good and not good for?

Good for storing and transporting energy. Not good for driving reactions.

Where does ATP store energy?

ATP stores energy in the bonds between phosphates. This can be hydrolyzed to be used by enzymes to drive other reactions forward.

What is the equation of cellular respiration?

C6 H12 O6 + 6O2 + ~32 ADP + ~32 Pi —→ 6CO2 + 6H2O + ~32ATP

Where does glycolysis occur?

In the cytoplasm and can occur with or without O2.
Makes a small amount of ATP.

Where does the Krebs Cycle occur?

In the mitochondria (matrix) and requires O2.
Makes a small amount of ATP.

Where does Electron Transport Chain/ATP Synthase occur?

In the inner membrane of mitochondria and requires O2.
Produces a bulk of ATP.

What powers ATP synthase?

The proton / H+ gradient.

What is the source of electrons in the Electron Transport Chain of Cellular Respiration?

NADH and FADH2 carries electrons to ETC.

What is the Electron Transport Chain doing that will allow the Mitochondria to make ATP?

1. ETC concentrates H+ in intermembrane space.

2. H+ flows back to matrix through ATP synthase as ADP + Pi ——> ATP (powered by the proton gradient potential energy).

3. Oxygen accepts electrons and combines with H+ to form water.

How is ATP made in the Mitochondria? About how many ATP are made from each Glucose molecule if it is fully Oxidized to CO2 and Water?

NADH and FADH2 brings electrons to ETC to help concentrate H+ in the intermembrane space. H+ flows back to matrix through ATP synthase and makes ATP with oxygen accepting electrons to make water. Around 32 ATP are made.