TOPIC 7: Respiration Flashcards
Locations of all reactions in respiration
-Glycolysis = Cytoplasm
-Link reaction = Matrix of mitochondria
-Krebs cycle = Matrix of mitochondria
-Oxidative phosphorylation = Utilises proteins found in membrane of the cristae
Outline the stages of glycolysis
- Glucose (6c) gets phosphorylated to form fructose biphosphate
- This molecule then splits into 2xTriosphosphate via lysis
- NAD+ is oxidated to form 2 NADH
- 4ADP is dephosphorylated to form 4ATP
- 2xPyruvate (3c) is formed
Explain the link reaction
- Pyruvate is decarboxylated and dehydrogenated to form Acetate (2c)
- Acetate (2c) then combines with Co-enzyme A to produce Acetyl CoA
-Links glycolysis and Krebs cycle
-No ATP is produced
-For every one glucose molecule, this reaction happens twice
-CoA transports acetyl to Krebs cycle
-Pyruvate + NAD+ CoA —–> Acetyl CoA + reduced NAD + CO2
Explain the Krebs cycle
- Oxoacetate (4c) joins with acetyl (2c) to produce Citrate (6c)
- Citrate is decarboxylated to become a 5c compound
- Citrate is then converted back to oxoacetate through a series of redox reactions
-4c molecule has to be made at the end for the cycle to repeat
-Makes an ATP molecule
-Phosphate gets activated in the matrix. Joins ADP to make ATP molecule
During which of the following processes is ATP formed? (1)
A) Glycolysis and the electron transport chain only
B) Glycolysis and the Krebs cycle only
C) Glycolysis, the Krebs cycle and the electron transport chain only
D) Glycolysis, the link reaction, the Krebs cycle and the electron transport chain
C - Glycolysis, the Krebs cycle and the electron transport chain only
Explain why some ATP is broken down during glycolysis (2)
-The breakdown of ATP donates phosphate to glucose. (Production of fructose biphosphate)
-ATP supplies energy to break down the glucose
-To produce phosphorylated 3-carbon compounds E.g. GALP and GP
The electron transport chain occurs in the cristae of the mitochondria. The electron transport chain involves a number of carrier molecules
Explain the role of these carrier molecules in the electron transport chain (3)
-Receive hydrogen from reduced NAD to allow NAD to be oxidised
-Break hydrogen into hydrogen ions and electrons
-Electrons transferred by a series of redox reactions
-Energy released is used to pump hydrogen ions in intermembranal space
Explain why ATP is required for Glycolysis (3)
-Hydrolysis of ATP
-Provides energy for the reaction as the reaction requires energy
-Provides phosphate group for phosphorylation
Glycolysis is inhibited by acidic conditions
Devise an investigation to determine the effect of acidic conditions on the initial rate of reaction of phosphofructokinase (4)
-Use PH buffers at a range of PH values below 7
-Provide and excess of ATP
-Use phosphofructokinase at an appropriate concentration
-Control enzyme concentration / temperature
-Measure quantity of phosphofructokinase measured per minute
Which of the following is transferred to a molecule of FAD to form reduced FAD?
A) Two oxygen atoms
B) Two hydrogen atoms
C) One oxygen atom and one hydrogen atom
D) One water molecule
B - Two hydrogen atoms
Explain the need for reduced NAD to be oxidised in a mitochondrion (2)
-So that hydrogen can be delivered to the electron transport chain
-To allow ATP synthesis
-To regenerate NAD
Name two molecules needed for aerobic respiration that can move into the mitochondria (2)
-Pyruvate
-Oxygen
-Reduced NAD / ADP
The outer mitochondrial membrane is not permeable to hydrogen ions (H+)
Explain the importance of this feature of the membrane (4)
-To stop hydrogen ions diffusing out of the mitochondria into cytoplasm
-Therefore maintaining a high concentration of the H+ ions in the intermembrane space
-So H+ ions can move down the concentration gradient
-By Chemiosmosis
-To synthesise ATP
Cells produce lactate during anaerobic respiration. Lactate travels in the blood to the liver.
Liver cells can absorb lactate from the blood
Deduce what happens to the lactate in these cells (3)
-Lactate is oxidised to form pyruvate
-Pyruvate is converted to glucose
-Glucose is used in respiration
State the function of ATPase in aerobic respiration (3)
-H+ flows through ATP synthase
-Down electrochemical gradient
-Sufficient energy is released
-Allow {ADP + Pi to join / ATP to form} ;
-Down H+ concentration gradient
-Phosphorylation of ADP
ATP synthase
-An enzyme that catalyses the formation of ATP using adenosine diphosphate (ADP) and inorganic phosphate (Pi).
Describe the fate of reduced NAD in aerobic respiration (4)
-Reduced NAD from glycolysis enters mitochondria
-Moves to inner membrane of mitochondrion
-Becomes oxidised to NAD+
-As electrons / transferred to electron transport chain
-Hydrogen ions are pumped into membrane space
-(NAD) returns to Krebs cycle/ matrix
Explain how the pH of the blood of a sprinter is returned to its original level after a race (5)
-Low pH is due to acid in the blood
-Lactate taken to liver
-Oxygen debt
-With production of NAD
-Pyruvate converted to glucose
-Pyruvate into mitochondria
-Chemoreceptors detecting change in pH
-Increased nerve impulse rate from medulla / breathing rate / heart rate
-Dissolved CO2 from blood diffuses into alveoli
What is the electron transport chain?
A series of proteins embedded in the inner membrane of the mitochondria
Another name for hydrogen ions
PROTONS
Explain the process of the electron transport chain
-NADH gives electrons to the first electron carrier which releases energy
-This energy is used to pump hydrogen ions across the membrane from the matrix to the intermembrane space
-Builds a high concentration of hydrogen ions in the intermembrane space, H+ ions move down the concentration gradient
-The last carrier is oxygen, which accepts electrons and hydrogens from the matrix to form water
-ATP synthase allows the high conc of hydrogen ions to move from intermembrane space to the matrix via facilitated diffusion
-This produces ATP
The hydrogen (H) from the Krebs cycle enters the electron transport chain and oxidative phosphorylation occurs.
Explain what is meant by the term oxidative phosphorylation (3)
-Electrons being passed along the electron transport chain
-Losing energy
-used to add a phosphate to ADP to make ATP
-ATPase
-Chemiosmosis
-Oxygen as the final acceptor
Explain the role of oxygen in human respiration (4)
-Final acceptor of electrons (and H+) (in the electron transport chain)
-In oxidative phosphorylation
-ATP is synthesised
-(presence of oxygen) allows oxidation of (reduced) NAD
State one difference between the structure of pyruvate and the structure of the acetyl group in acetyl CoA (1)
Pyruvate has 3 carbons compared to 2 carbons in acetyl
