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 / FAD to allow NAD / FAD 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 the energy storage molecule adenosine triphosphate (ATP) using adenosine diphosphate (ADP) and inorganic phosphate (Pi).
