IB Biology Cellular Respiration C1.2

Out of IB Bio textbook 🌱

What macromolecule is ATP?

Nucleotide

What properties of ATP make it suitable for energy transfer?

1. Soluble in water

2. Stable at neutral pH

3. Controlled movement due to inability to diffuse out of a cell

4. Third phosphate can easily be removed

5. Hydrolyzing ATP to ADP and phosphate releases only a small amount of energy, just enough for cell to use

What 3 main activities require energy from ATP?

1. Synthesizing macromolecules

2. Active transport against the concentration gradient

3. Movement within the cell and of the cell as a whole

Where can energy come from?

Cell respiration, photosynthesis, chemosynthesis (oxidizing inorganic substances)

Oxidation

The loss of electrons

What happens during respiration?

Carbon compounds are oxidized to create energy, which is used to produce ATP

What main carbon compounds are oxidized in respiration?

Glucose and fatty acids

Gas exchange

Oxygen enters cells through the plasma membrane while carbon dioxide exits cells

Aerobic respiration equation

C6H12O6 +O2 = CO2 + H2O + ATP (catabolic reaction)

Anaerobic respiration in humans equation

C6H12O6 = lactate + ATP

Anaerobic respiration in yeast equation

C6H12O6 = ethanol + CO2 + ATP

Advantage of anaerobic respiration

Produces ATP rapidly over a short period of time

Oxygen debt

The oxygen that it takes to break down lactate buildup after anaerobic respiration has occurred

Reduction

Gain of electrons, happens at the same time as oxidation

NAD

Electron carrier that can easily accept and lose electrons. Links oxidation and reduction in cells during cellular respiration

How are substances oxidized in respiration?

2 hydrogen atoms are removed (one electron and one proton)

NADH

NAD after it has accepted 2 electrons and one of the two protons from oxidized substances

Glycolysis

First stage of cellular respiration, glucose or monosaccharide is the reactant. In the cytoplasm, glucose is converted to pyruvate by a chain of reactions. Produces a small yield of 2 atps per glucose

How is reduced NAD converted to NAD in anaerobic reactions?

Hydrogen is transferred from NADH to pyruvate, converting it into lactic acid (lactic fermentation)

How is anaerobic respiration in yeast different from normal anaerobic respiration?

Reduced NAD is converted to NAD through conversion of pyruvate into ethanol and CO2. (ethanol/alcoholic fermentation)

Link reaction

Connects glycolysis and the krebs cycle; pyruvate is oxidized into CO2 and H2O which yields much more ATP than anaerobic respiration. Initial reaction is conversion of pyruvate to a 2-carbon acetyl group. Takes place in the matrix of mitochondria

3 steps of a link reaction

1. Decarboxylation: CO2 is removed,3-carbon pyruvate is converted to 2-carbon molecule

2. Oxidation: 2 electrons removed and accepted by NAD to produce reduced NAD

3. Binding: acetyl group is bound to coenzyme A, a carrier molecule

Krebs cycle

Acetyl groups are oxidized in a series of reactions that take place in the matrix. Acetyl groups are fed to the cycle when coenzyme A transfers the group to oxaloacetate, creating citrate. The goal of the reaction is to remove two carbons from citrate to produce oxaloacetate again through decarboxylation reactions where CO2s are removed. Released energy is held by the removed electrons, which are carried by NAD or FAD to the electron transport chain.

Electron transport chain

Proteins acting as election carriers receive and transfer the electrons from the Krebs cycle.

How does substrate concentration affect rate of respiration?

As the amount of substrate increases, so does the rate of respiration, until it plateaus at the maximum activity.

How does yeast concentration affect rate of respiration?

As yeast concentration increases, so does the rate of respiration until it plateaus at maximum activity.

How does pH affect rate of respiration?

Starts off low, then gradually increases until pH reaches 4.7, and then decreases as pH gets more basic. Denatures around pH of 6

How does the temperature affect respiration rate?

Graph looks like a craggy mountain; gradually goes up until it reaches 20C then goes up fast until it peaks at around 43C then goes down steeply then more gradually.