key area 2.2 - cellular respiration

Question 1

cellular respiration

Answer 1

• a series of enzyme controlled reactions that releases energy energy
• yields energy
• converts the chemical energy stored in glucose into the chemical energy stored in ATP

Question 2

ADP

Answer 2

• low energy molecule composed of adenosine and two phosphate groups
• adenosine diphosphate

Question 3

ATP

Answer 3

• adenosine triphosphate
• high energy molecule of adenosine and three phosphate groups
• ATP transfers chemical energy from respiration to anabolic pathways and other cellular processes

Question 4

ATP synthase

Answer 4

• enzyme which catalyses the synthesis of ATP

Question 5

dehydrogenase

Answer 5

• enzyme that removes hydrogen ions and high energy electrons from the respitory substrate
• then used in the synthesis of ATP

Question 6

glucose

Answer 6

• respiratory substrate which provides energy for the regeneration of ATP

Question 7

phosphorylation

Answer 7

• the addition of phosphates to molecules

Question 8

phosphorylation word equation

Answer 8

ADP + Pi => ATP

Question 9

fermentation

Answer 9

• form of cellular respiration which involves the partial breakdown of glucose in the absence of oxygen

Question 10

fermentation in animals

Answer 10

glucose => lactate + energy

Question 11

fermentation in plants and yeast

Answer 11

• glucose => ethanol + CO2 + energy

Question 12

NAD

Answer 12

• coenzyme which carries hydrogen and electrons from glycolysis and the citric acid cycle to the electron transport chain

Question 13

stages in respiration

Answer 13

• glycolysis
• citric acid cycle
• electron transport chain

Question 14

process of glycolysis

Answer 14

occurs in the cytoplasm
energy investment phase
- 2ATP phosphorylate glucose to form intermediate molecules

energy pay off phase
- the conversion of intermediate molecules into pryruvate molecules producing 4ATP
- there is a net gain of 2ATP
- dehydrogenase enzymes remove hydrogen ions and electrons, which combine with the coenzyme NAD to form NADH
- if oxygen is present NADH transports hydrogen to the electron transport chain

Question 15

citric acid cycle

Answer 15

• occurs in the central matrix of mitochondria
• if oxygen is available, pyruvate is broken into an acetyl group which then combines with coenzyme A to be transferred to the citric acid cycle as acetyl coenzyme A
• during this CO2 is released and NAD forms NADH
• the acetyl group from Coenzyme A combines with oxaloacetate to form citrate
• enzyme controlled reactions then convert citrate back into oxaloacetate generating ATP
• CO2 is released
• dehydrogenase removes hydrogen ions and electrons so NAD forms NADH to carry hydrogen ions and high energy electrons to the electron transport chain

Question 16

electron transport chain

Answer 16

• occurs in the inner membrane of the mitochondria
• series of carrier proteins attached to the inner mitochondrial membrane
• hydrogen ions and electrons from NADH are transferred to the ETC
• they separate, the high energy electrons are passed down transport chains to release energy
• the energy allows hydrogen ions to be pumped across the membrane
• the return flow of hydrogen ions rotates part of the membrane protein ATP synthase which catalyses the synthesis of ATP
• oxygen in final acceptor of electrons and hydrogen ions, as they come to the end of the ETC, combining to form water

Question 17

co-enzyme A

Answer 17

• substance that carries an acetyl group into the citric acid cycle as acetyl-co enzyme A

Question 18

intermediate

Answer 18

• substance in a metabolic pathway between the original substrate and the end product