Cellular Respiration and Metabolism

EOTC and Student IDs

• For the EOTC, a student ID or tech student ID is required.

• Student IDs are free and available at the entrance with the glass wall door.

Hydroubic Oxidation Step

• Inputs: Pyruvate

• Outputs: Acetyl CoA, Carbon Dioxide (CO_2), NADH

• Every time a carbon is removed, hydrogens are also removed.

• NAD^+ accepts hydrogens to become NADH.

• The carbon attaches to another oxygen, forming CO_2.

• NADH is one of the three outputs.

Intermediate Electron Carrier

• NAD^+ carries two electrons and one proton (H^+).

• Two hydrogen atoms are associated with it, but one proton doesn't fully attach; electrons do.

Glycolysis

• Glycolysis involves 10 steps (awareness is sufficient, memorization not required).

• Starting Point: Glucose

• End Products: Pyruvate, ATP, NADH

Pyruvate Oxidation (Transition Step/Glucose Oxidation)

• Task requirements for each step:

  • Inputs

  • Outputs

  • Location

  • Amount of outputs (Some, A lot)

  • So far, outputs are just "some".

Krebs Cycle

• Inputs: Acetyl CoA, NAD+, ADP

• Outputs: CO_2, NADH, ATP

• Acetyl CoA is broken in half, hydrogens removed and attached to NAD^+ to make NADH.

• Carbons leave with oxygen as CO_2.

• A little ATP is made.

• The cycle runs twice.

• No need to memorize intermediate names.

• Understanding Krebs cycle forms a foundation for the rest of biology and science.

ATP Production So Far

• ATP production is currently "some".

• Glycolysis: Glucose (6 carbon) is split into two pyruvates.

• ADP becomes ATP.

• Glycolysis means "cutting sugar".

• Transition Step/Pyruvate Oxidation: One carbon is cut off each pyruvate, and coenzyme A is attached.

• Acetyl CoA is a two-carbon molecule.

• Two CO_2 molecules are released.

• \text{NAD}^+ becomes NADH (hydrogens are transferred).

• Don't worry about the numbers; it's all just "some".

Krebs Cycle (Review)

• Inputs: Acetyl CoA, NAD+, ADP

• Outputs: CO_2, NADH, ATP

• FAD (flavin adenine dinucleotide) is another intermediate electron carrier.

• FAD picks up two protons and two electrons to become FADH_2.

• Glucose molecule is completely oxidized.

• All carbons and oxygens have left as CO_2.

• All hydrogens are now associated with intermediate electron carriers (NADH or FADH_2).

• Only a little ATP produced so far (yield of four ATP).

• 10 NADH and 2 FADH_2 are produced.

Electron Transport Chain (ETC) and Chemiosmotic Phosphorylation (CP)

• Oxygen will be used in step four.

Location of Glycolysis: Cytosol

• Pyruvate oxidation, we're just gonna say mitochondria.

• Krebs cycle location: Matrix (deepest, darkest center of the mitochondria)

Electron Transport Chain

• A chain of enzymes that transport electrons.

• Structure: Outer membrane, inner membrane, intermembrane compartment, matrix.

• Inner membrane looks more like a bacterial membrane, outer membrane looks more like a eukaryotic membrane.

• Intermediate electron carriers NADH and FADH_2 are used.

• Protons and electrons are separated.

• Electrons are at a higher energy state.

• Energized electrons power pumps (active transport).

• Protons (H^+$) are pumped across into the intermembrane compartment.

• Electrons reduce energy, transfer to the next one, and so on.

• Around halfway, FADH_2 starts dumping theirs in.

• At the end, electrons are at ground state (lowest energy possible).

• A proton gradient is generated (higher concentration on one side of the membrane).

Oxygen's Role

• Something with high electronegativity is needed to attract and bind ground state electrons.

• Oxygen has extremely high electronegativity and can accept even ground state electrons.

• If oxygen is not present, those electrons sit there, and the whole process shuts down.

• Krebs and pyruvate oxidation will eventually stop because there's too much NADH and FADH_2.

• As soon as you run out of oxygen, this shuts down and you quickly lose this gradient.

Location of Electron Transport Chain

• Inner membrane of the mitochondria

Function

• To transport protons using the power of electrons (a proton pump).

• If oxygen is present, the final electrons combine with oxygen and some hydrogens to form H_2O, which leaves the mitochondria.

• It may get used by another chemical reaction that needs water.

Steps

• NADH and FADH_2 donate their electrons to the electron transport chain.

• It's a series of pumps where energy from the electrons pumps protons from the matrix into the intermembrane space.

Inputs and Outputs

• Inputs: NADH, FADH2, Oxygen (O2)

• Outputs: NAD^+$, FAD, Water (H_2O)

• NADH is oxidized to NAD^+$.

• FADH_2 is oxidized to FAD.

• Oxygen is reduced to H_2O.

• No ATP is produced in this step at all only potential energy of proton gradient is established.

Chemiosmotic Phosphorylation

• Chemiosmosis is the diffusion of protons.

• Phosphorylation is adding a phosphate group to ADP.

• We phosphorylate ADP to ATP using the diffusion of protons.

• 1 ADP + 1 Phosphate = ATP

• It takes three protons to go through to make one ATP.

• ATP synthase (the enzyme involved) has moving parts and spins.

• The force of it spinning smashes the ADP and P together.

• This process continues as long as we have a proton gradient.

ATP and Plant Cells

• ATP made in chloroplasts in plant cells is only used by the chloroplasts.

• Plant cells also have mitochondria.

• They send the glucose made in the chloroplast over to the mitochondria to make ATP for the rest of the cell.

ATP Production

• Glycolysis – Makes some ATP (substrate level phosphorylation)

• Pyruvate Oxidation – No ATP made.

• Krebs Cycle – Low ATP (substrate level phosphorylation)

• Electron Transport Chain – No ATP made

• Chemiosmotic Phosphorylation – Makes lots of ATP

Substrate level Phosphorylation Explanation

• Glycolysis and Krebs cycle make ATP through substrate-level phosphorylation.

• Enzymes in glycolysis and Krebs are classic enzymes with substrates and active sites.

• vs chemiosmotic phosphorylation, which is different and simpler. ATP synthase here. You form, spin, and smash ADP and P together.

• ATP and P are inputs, and ATP is the output.

• No oxygen is used directly in this step.

• The energy used is the physical flowing of the protons through the ATP synthase.

• Protons act as water going over a dam to make the wheel spin.

Direction, what molecules is needed, and types of phosphorylation

• The reaction step goes from the intermembrane compartment back to the matrix.

• The enzyme ATP synthase is embedded in the inner membrane.

• No ATP is used for step 5, but it makes ATP.

• The process is dependent on oxygen but it is not part of this reaction step.

• The protons were previously attached to NADH and FADH_2$$.

• They were originally attached to glucose.

• Glucose became pyruvate, and pyruvate became Acetyl CoA

• There will be questions to name which type fo reaction from substrate and non-substrate level reaction will be ATP generated.

Carbon Dioxide Molecules

How did carbon molecules enter your body?

• They were in glucose, which came from food.

Other Points

• Matrix is the center space.

• Mitochondria carries out the majority of cellular respiration.

• Phosphorylation of ADP to ATP is endergonic and anabolic.

• Individual membrane sacs that contain chlorophyll are thylakoids.

• Stacks of thylakoids are called grana. Stroma is the liquid interior inside chloroplasts.

• Examples of autotrophic organisms: cactus and algae.
  Fungus is not one because it's not photosynthetic.

Metabolism of Various Biomolecules

What if you don’t have glucose?

• If it’s a carbohydrate other than glucose, then you just break it down to pyruvates

• Mitochondria work with pyruvate not exactly directly with glucose.

Lipids

• Carbohydrates is best for the utilization, thus lipids only broken down during restrictive diet where it forces you to run out of carbs.

• You burn the oat log and you set your fire going.
  *The body knows how to respond once you trigger with oat log and set your fat stores to burn.

• Step is called beta oxidation in oxidation of lipids and or the burning of lipids as a means of energy.

Proteins

• When runs out of lipids will switch to using proteins, which is also when the life raft is activated.

• Called deamination when converting protein chain to what is needed by the body. There is no enzymes that can convert nitrogen.

Bacteria Does Not Have Mitochondria!

*Bacteria do not have mitochondria, which is called a cellular respiration baceria.
Outer membrane in black and inner membrane red.
This is the Baceria, so will make NADH and FADH2.
Uses this outer membrane like the inner membrane of mitochondria