Week 3: Metabolism (continued)

Define oxidation

removal of electrons

Define reduction

gain of electrons

What is a redox reaction?

an oxidation reaction paired with a reduction reaction

In biological systems, what element are electrons usually associated with?

Hydrogen

what is “phosphorylation”

is it the addition of phosphate to a molecule of ADP to make ATP

What are the 3 main types of phosphorylation?

• oxidation phosphorylation

• photophosphorylation

• substrate level phosphorylation

What is oxidative phosphorylation and what is its distinguishing factor?

when electrons are trasnferred from one electron carrier to another along the Electron Transport Chain on a membrane that releases energy to create ATP

• always going to be on a membrane and include the etc

What is photophosphorylation and what is its distinguishing trait?

light energy converted to chemical energy during transfer of electrons (oxidation) form chlorophyll as they pass through system of carrier molecules

• only phosphorylation that includes light energy

What is substrate level phosphorylation and how can it be distinguished?

ATP is generated when high-energy PO4- is added to ADP

• does not include light energy or occur along a membrane

What is carbohydrate catabolism and what are the three steps?

The breakdown of carbohydrates to release energy; typically occurs in

three principle stages

• Glycolysis

• Krebs cycle

• Electron transport chain

What is glycolysis?

A metabolic pathway where the cell captures energy from glucose by breaking a 6-carbon molecule into 2 3-carbon molecules. It uses 2 ATP to start and makes 4 ATP (net 2 ATP) as well as 2 pyruvic acids and 2 NADH molecules per glucose molecule.

What is the Krebs Cycle?

Pyruvic acid made from glycolysis is oxidized down through a series of oxidations and the energy is released into NAD (which then becomes NADH after being reduced) and FAD into FADH. Fully oxidized carbons are released as carbon dioxide. There is 1 molecule of ATP made for each molecule of pyruvic acid through substrate level phosphorylation.

What is the Electron Transport Chain?

A way of extracting the remaining energy left in glucose. It uses NADH and FADH created from glycolysis and Krebs cycle. The protons sent to the ETC are sent through ATP synthase, which created atp through oxidative phosphorylation. Oxygen is final electron acceptor and binds with remaining H+ to create water (only in aerobic environments)

How much net ATP is created during Glycolysis? Krebs cycle? Total?

Glycolysis: 2 ATP net

Krebs Cycle: 2 ATP net

Total: 38 ATP (36 ATP net)

Why is glycolysis substrate level phosphorylation but the ETC is oxidative phosphorylation?

ETC occurs within a membrane, glycolysis does not.

What is anaerobic respiration?

a type of cellular respiration that produces energy without using molecular oxygen. (yields less energy than aerobic)

In simple words, what is the purpose of fermentation?

To recycle NADH back into NAD+

besides carbohydrate catabolism, what are the two other ways mentioned into the Krebs cycles

Protein catabolism and Lipid catabolism

What is the role of ATP synthase in the ETC?

ATP synthase functions as a rotary enzyme that converts ADP to ATP. As protons enter the enzyme, they rotate it. The spinning motion provides the physical energy needed to attach a phosphate group to ADP, creating ATP.