C1.2 cell respiration

5 properties of ATP

1. chemically stable at neutral pH levels

   • does not break down and prematurely release energy in cell

2. soluble in water

   • can diffuse freely in cytoplasm quickly

3. unable to diffuse through phospholipid bilayer

   • controlled movement of ATP movement

   • no leakage of ATP out of cell

4. release a quantity of energy

   • energy released is sufficient for wide range of tasks in cell

   • extra energy for transformation to heat

5. quick regeneration

structure of ATP

• base adenine

• ribose

• 3 phosphate

processes that need ATP

• active transport across membranes

• synthesis of macromolecules

• movement of cell components

• movement of whole cell

releasing energy

ATP → ADP + Pi

• hydrolysis

investing/forming energy

ADP + Pi → ATP

• sunlight

• oxidation of foods

• condensation

• phosphorylation

respiration properties?

• oxidation of carbon compounds to release energy

• glucose and fatty acids as principal substrates used

• amino acids can be used

aerobic vs anaerobic respiration in humans

aerobic

• oxygen used

• sugars/lipids used

• 30-32 ATP produced

• CO2 and H2O produced

• happens in cytoplasm and mitochondria

• glucose + oxygen → carbon dioxide + water

anaerobic

• no oxygen sued

• sugars used

• 2 ATP produced

• lactate produced

• happens in cytoplasm

• glucose → lactate

purpose of using alkali in respirometer

absorb CO2 produced by respiration

oxidation vs reduction

Oxidation:

• lose electrons

• gain oxygen

• lose hydrogen (dehydrogenation in cell respiration)

reduction:

• gain electrons

• lose oxygen

• gain hydrogen (accepted by hydrogen carriers in cell)

NAD reaction

• gets reduced

• accepts 2 hydrogen atoms

• NAD⁺+2H → NADH+H⁺

explain the process of glycolysis

1. phosphorylation

• glucose → hexose bisphosphate (unstable)

2. lysis

• hexose bisphosphate → 2 triose phosphate

3. oxidation

• 2 hydrogen removed from each triose phosphate by NAD + H2 → NADH + H+

• pyruvate formed

4. ATP formation

• energy from oxidation of each triose phosphate → converts 2ADP to ATP

summarise the reactants and products of glycolysis

• 1 glucose → 2 pyruvates

• 2 NADs → 2 reduced NADs

• 2 ATP used per glucose ; 4 ATP produced → net yield of 2ATP produced

regenerating NAD in anaerobic respiration

• add hydrogen atom (from reduced NAD) to pyruvate, forming lactate

  • lowers pH of cytoplasm and of blood → anaerobic respiration only used for short period of time → prevent blood pH from dropping too low

NAD regeneration in yeast anaerobic respiration

pyruvate → CO2 + ethanal, ethanal + reduced NAD → NAD + ethanol

application of yeast’s anaerobic respiration

1. CO2 and baking industry

   • yeast in dough uses up oxygen, produces ethanol and CO2

   • CO2 orms bubbles → dough rises, increase volume

   • ethanol produced evaporates

2. ethanol and brewing industry

   • put yeast in a liquid containing sugar with no oxygen → anaerobic respiration

   • ethanol produced and increases in concentration

   • ethanol = toxic to yeast, eventually yeast dies and ethanol production stops

explain the link reaction

1. decarboxylation

• CO2 removed from pyruvate

2. oxidation

• pair of hydrogen removed from pyruvate NAD + H2 → NADH + H+

• remaining acetyl group linked to CoA, forming acetyl-CoA

how to turn fatty acids into acetyl-CoA

• take 2 carbon fragments from fatty acid tail

• convert to acetyl group

• attach to CoA

summary of link reaction

• 2 reduced NAD produced per glucose

• 2 CO2 produced per glucose

explain the krebs cycle

1. oxaloacetate + acetyl-CoA → citrate + CoA

2. citrate + NAD → reduced NAD + CO2 + 5C intermediate

3. 5C intermediate + NAD → reduced NAD + CO2 + 4C intermediate

4. 4C intermediate + ADP + FAD + NAD → reduced NAD + reduced FAD + ATP + oxaloacetate

summary for krebs cycle

1. decarboxylation

   • 4 CO2 produced per glucose

2. dehydrogenation and oxidation

   • 6NAD used per glucose → 6 reduced NAD produced per glucose

   • 2FAD used per glucose → 2 reduced FAD produced per glucose

3. phosphorylation

   • 2 ATP produced per glucose

explain ETC and chemiosmosis

1. reduced NAD supplies 2 electrons to first electron carrier of ETC

   • regenerates NAD (reduced NAD gets converted back to NAD here)

2. electron carrier pass electrons to the next electron carrier → energy released

3. energy used to by electron carriers to pump protons from matrix of mitochondrion to intermembrane space → forms proton gradient

4. protons move down proton gradient from intermembrane space to matrix through ATP synthase

5. proton movement = energy released. ATP synthase uses released energy to convert ADP into ATP

structure of ATP synthase

• rotor that can spin on its axis

• central stalk

• globular region

purpose of the rotor that can spin on its axis

• embedded into inner mitochondrial membrane

• allows protons to diffuse across membrane (acts as a channel protein for them)

  • ATP synthase has binding site on sides of rotor for protons to bind to

  • protons only released into matrix when rotor is in different position after rotation

    • energy for rotation supplied by movement of proton

purpose of central stalk

• projects into matrix

• causes a cycle of conformational changes that allow active sites to produce ATP

summary for one turn of ATP synthase

→ 3 ATP produced

→ 9 protons used

function of oxygen in ETC

accepts protons from matrix and electrons from electron carriers to form water

• the only role of oxygen in respiration is act as a terminal electron acceptor for electron transport chain

• no oxygen = no ETC = no NAD = no link reaction or krebs cycle

lipids vs carbohydrates

lipids:

• higher C:H:O ratio

• larger yield of energy

• beta oxidation to produce acetyl groups for krebs cycle and chemiosmosis

• only for aerobic respiration

carbohydrates:

• lower C:H:O ratio

• lower yield of energy

• glycolysis + link reaction to produce acetyl groups, then krebs cycle and chemiosmosis

• for aerobic and anaerobic respiration