C1.2 Cellular Respiration Flashcards
(30 cards)
Function of ATP
- “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
Properties of ATP
- 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
Cellular life processes that require ATP
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
Process of adding a phosphate to a molecule (4)
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.
Define Cellular respiration
Controlled release of energy from organic compounds in cells to form ATP.
Define Cellular Respiration
- 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.
Aerobic respiration in humans (4)
- 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.
Anaerobic respiration in humans (5)
- 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.
Factors that affect the rate of respiration (4)
- Temperature
- pH
- Respiratory substrate concentration.
- Oxygen concentration.
- CO2 concentration: CO2 is produced it can form carbonic acid and lower pH
Define Respirometer (4)
- 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.
Calculations needed for C1.2 (3)
Volume of cylinder, rate = volume of gas consumed/time taken, mean rate = add rates together and divide by number of trials.
Structure of Mitochondria (5)
- Intermembrane space.
- Outer membrane.
- Inner membrane.
- Cristae.
- Matrix.
check notes diagram.
Function of the structures of Mitochondria (4)
- 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.
Function of NAD in aerobic respiration (3)
- 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.
First step of aerobic respiration (6)
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).
4 Stages of Glycolysis (4)
- 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.
Second step of aerobic respiration (6)
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.
Third step of aerobic respiration (8)
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.
Factors that determine the amount of ATP that can be generated
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.
Lipids as respiratory substrates.
- 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.
For 1 glucose molecule…
- 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.
Electron Transfer Chain/ Oxidative Phosphorylation
- Takes place in the inner mitochondrial membrane and intermembrane space.
- creates approx. 34 ATP.
- Produces water which is a waste product excreted from energy.
Components of the Electron Transport Chain
- 4 transmembrane proteins
- 2 electron carriers
Electron Transport Chain process: NADH and FADH
- 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.
