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Biology IB > C1.2 Cellular Respiration > Flashcards

C1.2 Cellular Respiration Flashcards

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1
Q

Function of ATP

A
  • “Energy currency in cells”
  • Used in many different contexts
  • Constantly recycled
  • Temporary storage of energy
  • Energy transfer between metabolic processes and parts of the cell
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2
Q

Properties of ATP

A
  • Water soluble: moves freely throughout cell cytoplasm and aqueous solutions
  • Cannot simply diffuse across membranes: allows its movement to be controlled via carriers
  • Very reactive: takes part in a large variety of metabolic reactions
  • ATP + H20 –> ADP + Pi + energy : easily reversible to facilitate use and re-use
  • energy released is sufficient for cellular processes with minimal waste
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3
Q

Cellular life processes that require ATP

A

Anabolic reactions:
- Synthesis or larger more complex macromolecules from smaller simpler monomers: endothermic so requires energy
- Each condensation reaction that links a monomer to polymer is coupled to the conversion of ATP to ADP to provide energy

Active transport:
- Pumping substance across a membrane against concentration gradient is not passive and requires energy

Movement of cell components and of the cell itself to another location require energy

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4
Q

Process of adding a phosphate to a molecule (4)

A

Phosphorylation.
- Makes molecules more unstable and more likely to react.
- Hydrolysis of ATP –> ADP + Pi releases energy. (endothermic)
- Many reactions in the body are endothermic so need to be coupled with hydrolysis of ATP that releases energy.

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5
Q

Define Cellular respiration

A

check notes.

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6
Q

Define Cellular Respiration

A
  • Respiration is a complex metabolic process that is carried out by all living organisms.
  • Controlled release of energy from carbon compounds in cells to produce ATP
  • Purpose is to transfer chemical energy in biomolecules into ATP for easier, later use through a series of reactions in a metabolic pathway.
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7
Q

Aerobic respiration in humans (4)

A
  • Involves complete breakdown of glucose to regenerate a net gain of 36 molecules of ATP.
  • Glucose, fats and proteins can be used as substrates.
  • Takes place in the presence of oxygen.
  • Takes place in cytoplasm or mitochondria.
  • Produces water and CO2 as waste products.
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8
Q

Anaerobic respiration in humans (5)

A
  • Involves the partial breakdown of glucose that generates only net 2 ATP.
  • Takes place in absence of oxygen.
  • Only glucose can be used as respiratory substrate.
  • Only takes place in cytoplasm.
  • Produces lactic acid or lactate as waste.
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9
Q

Factors that affect the rate of respiration (4)

A
  • Temperature
  • pH
  • Respiratory substrate concentration.
  • Oxygen concentration.
  • CO2 concentration: CO2 is produced it can form carbonic acid and lower pH
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10
Q

Define Respirometer (4)

A
  • Simple devices which measure the rate of respiration in organisms which respire aerobically.
  • Rate of oxygen consumption is used as an indicator of respiration.
  • Alkaline solution is added to absorb CO2.
  • There will be a decrease in the volume of gas in tube due to oxygen being used in aerobic respiration.
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11
Q

Calculations needed for C1.2 (3)

A

Volume of cylinder, rate = volume of gas consumed/time taken, mean rate = add rates together and divide by number of trials.

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12
Q

Structure of Mitochondria (5)

A
  • Intermembrane space.
  • Outer membrane.
  • Inner membrane.
  • Cristae.
  • Matrix.
    check notes diagram.
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13
Q

Function of the structures of Mitochondria (4)

A
  • Inner and outer membrane aides ability to make ATP.
  • Outer membrane is permeable to many small molecules and ions and contains transport proteins (porins).
  • The inner membrane is highly folded into cristae which increases surface area.
  • Matrix is small space and allows high concentration gradients to form which are necessary for respiration.
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14
Q

Function of NAD in aerobic respiration (3)

A
  • Nicotinamide adenine dinucleotide (NAD).
  • functions as a coenzyme.
  • Ability to be reduced and oxidised allows it to perform the critical role of a hydrogen carrier.
  • Used to transfer and use energy incrementally.
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15
Q

First step of aerobic respiration (6)

A

Glycolysis.
- Takes place in cytoplasm.
- Complex set of reactions.
- Glucose is converted to 2 pyruvates.
- Net gain of 2 ATP.
- Formation of 2 NADH (reduced NAD).

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16
Q

4 Stages of Glycolysis (4)

A
  • Stage 1: Uses 2 molecules of ATP to phosphorylate glucose (G6P) - less stable, more reactive.
  • Stage 2: Phosphorylated glucose splits into two glyceraldehyde 3-phosphate (G3P).
  • Stage 3: Each G3P is dehydrogenated to reduce 2NAD into 2NADH.
  • Stage 4: generation of net 2 ATP and 2 pyruvate molecules from each G3P by transferring phosphate to ATP.
17
Q

Second step of aerobic respiration (6)

A

Links reaction.
- Takes place in matrix of mitochondria.
- The two pyruvates from glycolysis enter this stage. 2 pyruvate –> 2 acetate
- For both pyruvate during process: 2 NADH and 2 CO2 produced.
- 2 acetates bind to Coenzyme A to form acetyl-CoA
- CO2 removed as waste product.

18
Q

Third step of aerobic respiration (8)

A

Krebs cycle.
- Takes place in matrix of the mitochondria.
- 1 x Acetyl CoA enters into the Krebs cycle so that there are two cycles.
- Acetyl CoA combines with oxaloacetate to form citrate - CoA released to be reused in link reaction
Per cycle:
- Creates 3 reduced NAD
- Creates 1 reduced FAD.
- Creates 1 ATP.
- Releases 2 molecules of CO2.
- Completes the breakdown of the original glucose.

19
Q

Factors that determine the amount of ATP that can be generated

A

How much hydrogen is available from the broken down molecule.
- More hydrogen = More reduced NAD.
- More reduced NAD = more proteins can be transported across the inner mitochondrial membrane.
- More ATP can be generated.

20
Q

Lipids as respiratory substrates.

A
  • When lipid molecules is set to be respired, it is broken down to glycerol and fatty acids.
  • Glycerol can be used in glycolysis.
  • Fatty acids can be broken into acetyl groups and through the links reaction, becomes units of acetyl CoA.
  • Lipids cannot be used in anaerobic respiration.
21
Q

For 1 glucose molecule…

A
  • 2 Pyruvates are formed.
  • Net of 2 ATP and 2 NADH (reduced NAD) made.
  • Each pyruvate makes 1 CO2 and 1 NADH and make Acetyl CoA.
  • Then during Krebs cycle, each Acetyl CoA creates 2 CO2, 3 NADH, 1 ATP, and 2 FADH2.
22
Q

Electron Transfer Chain/ Oxidative Phosphorylation

A
  • Takes place in the inner mitochondrial membrane and intermembrane space.
  • creates approx. 34 ATP.
  • Produces water which is a waste product excreted from energy.
23
Q

Components of the Electron Transport Chain

A
  • 4 transmembrane proteins
  • 2 electron carriers
24
Q

Electron Transport Chain process: NADH and FADH

A
  • Reduced NAD (NADH) is delivered to the first protein of the ETC.
  • Here it splits: NADH –> NAD+ + H+ + 2e-
  • The two electrons are passed along electron carriers
  • These electrons power the H+ ions being pumped across the membrane into the intermembrane space
  • Reduced FAD (FADH) works in a similar fashion but delivers electrons to the second protein.
25
Q

Explain Chemiosmosis and role of ATP-synthase

A
  • The pumping of the H+ across the membrane, creates a concentration gradient
  • The intermembrane space is very small so the concentration is even greater
  • This gradient is key to generating large amounts of ATP.
  • The H+ only has one route back across the Inner mitochondrial membrane: through the ATP-synthase (specialized protein channel)
  • As the H+ pass through ATP-synthase, it rotates ATP and generates energy to convert ADP to ATP
26
Q

Explain the role of Oxygen in the ETC

A
  • Once electrons pass along the ETC, they must go somewhere.
  • O2 splits and each oxygen molecule joins with 2e- and 2H+ to form two water molecules.
  • If no oxygen is present, NAD+ and FAD+ cannot be recycled and used again. In the absence of oxygen, hydrogen carriers cannot transfer energized electrons to the chain and ATP production is halted.
27
Q

Features of Anaerobic respiration

A
  • Produces a lot less ATP (compared to aerobic)
  • When oxygen is lacking or in short supply, anaerobic respiration can provide the cell with a source of ATP
  • Takes place in cytoplasm
  • Only glycolysis takes place
  • Creates 2 ATP and 2 NADH (reduced NAD)
28
Q

Steps of Anaerobic respiration in animals

A
  • Glucose (6C) will break down into pyruvate (3C)
  • In the process, releases net 2 ATP and 2 NADH
  • Pyruvate is converted into lactate in animals: this happens in the cytosol (liquid part of cytoplasm)
29
Q

Steps of Anaerobic respiration (yeast)

A
  • Glucose (6C) will break down into pyruvate (3C)
  • In the process, releases 2 ATP
  • Pyruvate is converted into ethanal by decarboxylation
  • Ethanal –> Ethanol (reduced by NADH): happens in cytosol
  • Ethanol and CO2 produced
30
Q

Carbohydrates as respiratory substrates

A
  • Broken down into monosaccharides
  • These enter glycolysis
  • Can be respired aerobically and anaerobically
  • Compared to lipids, lower energy yield per gram

Biology IB (10 decks)

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