UNIT 2.2

Question 1

cellular respiration is

Answer 1

the process of oxidising food molecules, like glucose to carbon dioxide and water. the energy released is trapped in the from of ATP

Question 2

glycolysis - happens in cytoplasm (break down of glucose)

Answer 2

• phosphorylation of glucose, require 2 ATP mols (energy investment stage)
  = it turns ATP to ADP
• more ATP molecules are regenerated that were used during EIS
• another intermediate is phosphorylated
• dehydrogenase strips hydrogen and electrons and passes to the coenzyme NAD = this is taken to ETC
  = G produces 2 pyruvate and 2 ATP (energy payoff phase)

Question 3

citric acid cycle - happens in the matrix of the mitochondria

Answer 3

• pyruvate diffuse from the cytoplasm to the mitochondria - carbon as a waste
• the molecule that remain is a 2 carbon acetate group which combines with coA to form acetyl coenzyme A
• further hydrogen ions and high energy electrons are released and become bound to NAD to form NADH
• each acetyl coA combines with oxaloacetate to form a oxaloacetate to form a molecule called citrate (6 carbon)
• each carbon is lost in the cycle as carbon dioxide, hydrogen ions and high energy electrons are released
• hydrogen ions and electrons become bound to NAH to form NADH = used in the next stage

Question 4

electron transport chain

Answer 4

• hydrogen ions and electrons transferred to the coenzyme NAD during the previous stages, G and CAC are passed in to the ETC and used to drive ATP synthase
  -hydrogen ions and electrons are realised from NAD +1
• the H.E.E cascade down the ETC and release their energy
• this energy is used to pump H.I across the inner mit mem
• the return flow of the ions rotates part of the membrane protein ATP synthases
• this causes the generation of ATP
• the final electron acceptor is oxygen it combines with low energy electrons and hydrogen ions to form water

Question 5

fermentation

Answer 5

takes place in cytoplasm when there is no oxygen available, only in glycolysis it can take place - other pathways do not need oxygen anyway
- involves partial breakdown of sugar with the production of only a little energy = 2 ATP
- glucose (6c) to pyruvate
in animals = lactic acid 3c
plants = ethanol 2c and carbon dioxide 1c