IB HL BIO: 8.2 Cell respiration HL!!

The role of oxygen in this process:

*Oxygen is needed to bind with the free protons to form water to maintain the hydrogen gradient so chemiosmosis can continue*. Oxygen acts as a final electron acceptor in the mitochondrial electron transport chain allowing further electrons to enter the chain.

What does a reduction reaction involve?

- gain of electrons - loss of oxygen - gain of hydrogen - results in many C-H bonds - results in a compound with a higher potential energy

What does an oxidation reaction involve?

- loss of electrons - gain of oxygen - loss of hydrogen - results in many C-O bonds - results in a compound with lower potential energy

Hydrogen carriers!

A hydrogen carrier is an organic macromolecule that transports atoms of hydrogen from one place to another inside a cell or from cell to cell for use in various metabolical processes.

What is Kreb's cycle?

A sequence of reactions where energy is generated during the process of aerobic respiration. It consumes oxygen, producing carbon dioxide and water as waste products, and converting ADP to ATP. Consists of 3 segments: Segment A, B and C.

What are electron carriers?

THey are substances that can accept and give up electrons required. They often link oxidations and reductions in cells.

How many decarboxylations are there in the Krebs cycle? How do you know?

TWO DECARBOXYLATIONS. carbon dioxide is removed.

How many times must the Kreb's cycle run and why?

the cycle turns TWICE per glucose molecule because it was converted to two pyruvate molecules.

Oxidative phosphorylation

The use of oxygen to oxidize NADH to generate ATP through a mechanical reaction. Occurs during electron transport chain.

Segment C

Two additional oxidations generate another NADH and an FADH2 and generate the original 4C oxaloacetate.

What are the 4 main stages of glycolysis? (GLYCOLYSIS IS PLOA LOL)

*Phosphorylation*: when a phosphate molecule attaches to the 6 carbon sugar. *Lysis*: the glucose-6-phosphate is split into two molecules of trios phosphate *Oxidation*: trios phosphate is being oxidised and NAD is being reduced. *ATP production*: the phosphate groups are removed by an enzyme and passed to ADP from ATP. And pyruvate is produced. just remember the diagram lol

Products of glycolysis:

2 NADH 2 pyruvate molecules 2 ATP

End products of the link reaction:

2 molecules of acetyl Coenzyme A carbon dioxide 2 NADH

Products of kreb's cycle:

6 NADH's 2 FADH2 2 ATP 4 CO2's

What happens to pyruvate after?

As long as oxygen is present, the pyruvate can now be used in the Krebs Cycle. Before entering the Krebs cycle, 1) the pyruvate will have carbon removed in the form of carbon dioxide (known as decarboxylation) 2) Oxidation will occur when hydrogen atoms are removed and accepted by NAD+.

Discuss how cell respiration involves the oxidation and reduction of compounds.

As organic molecules are broken down through catabolic reactions, a transfer of electrons occurs which releases energy stored in the organic molecules which is used to synthesize ATP.

What is chemiosmosis?

Chemiosmosis is the movement of ions across a selectively permeable membrane, down their electrochemical gradient. It involves the removal of energetic electrons from NADH and FADH2 to drive proton pumps.

What is Coezyme A?

CoA is a carrier that accepts acetyl groups that are produced through metabolism and brings them in for use during the Krebs cycle.

Pathway of glycolysis

Glucose to glucose-6-phosphate to fructose-6-phosphate to fructose 1,6 biphosphate. That splits into 2 trios phosphate and then into 2 three carbon pyruvate.

What is glycolysis?

Glycolysis is the first stage of cell respiration when glucose is the substrate being oxidized. It occurs in the cytoplasm and is catalysed by enzymes. During glycolysis, a hexose sugar is partially oxidized which produces a small yield of pyruvate and ATP. This can occur with or without the presence of oxygen

Know how to draw a mitochondria & annotate parts and functions.

Know functions for: Mitochondrion Outer mitochondrial membrane Inner mitochondrial membrane Cristae Intermembrane space Matrix Ribosome DNA

Segment B

Oxidation reactions produce NADH. Citrate gives of two molecules of CO2 in separate decarboxylation reactions forming a new 4C compound. 1 ATP is directly generated for each acetyl group fed in.

What is phosphorylation?

Phosphorylation is the addition of a phosphoryl group (PO32−) group to a molecule. Phosphorylation makes a molecule unstable which means it is more likely to react. The first reaction in glycolysis includes phosphorylation: Glucose yields Glucose-6-phosphate where ATP is converted into ADP.

Segment A

Pyruvate from glycolysis is oxidized into an acetyl group that feeds into the citrate cycle. 2C acetyl group combines with 4C oxaloacetate to produce 6C compound citrate.

The link reaction!! What happens in it?

Pyruvate is transported from the cytoplasm to the mitochondrial matrix. 1: the carboxyl group is removed and released as carbon dioxide (decarboxylation) 2: the 2 carbon molecule is oxidized & hydrogen atoms are removed and accepted by NAD+. 3: the oxidized 2 carbon molecule is attached to Coenzyme A to form acetyl CoA

What is an electron transport chain?

The electron transport chain is a chain of electron carriers, mostly proteins, embedded in the inner membrane of the mitochondria.

Summary of oxidative phosphorylation through chemiomosis:

The hydrogen carriers provide electrons to the electron transport chain. The hydrogen atoms split, to release 2 electrons which pass from carrier to carrier, releasing energy. Three of the carriers use this energy to transfer protons across the inner mitochondrial membrane from the matrix to the intermembrane space. As electrons continue to flow along the chain, more & more protons are pumped across the inner mitochondrial membrane. So, a concentration gradient of protons builds up creating a store of potential energy. Protons then flow through the ATP synthase down their concentration gradient, releasing energy which is used by ATP synthase to phosphorylate ADP. The total amount of electron carriers from glycolysis, link reaction and kreb's cycle are: 10 NADH and 2 FADH2.

Substrate Level Phosphorylation

The synthesis of ATP by the direct transfer of phosphate group from a substrate to ADP. Instead of phosphate coming from ATP, it is coming from a molecule and given to ADP to form ATP. Occurs in glycolysis and TCA cycle.