3.1 and 3.3-ATP and Rspiration

Question 1

what is ATP often referred as?

Answer 1

the universal energy currency
-it provides energy to all organisms for all reactions

Question 2

how is ATP able to carry out its function?

Answer 2

-it releases energy in small usable quantities to avoid waste
-it’s easily hydrolysed to release energy
-it’s chemically inert to other processes

Question 3

where is ATP often created?

Answer 3

the inner membrane of mitochondria

Question 4

why is ATP so important?

Answer 4

-process/reactions require energy (muscle contraction/protein synthesis/active transport)

Question 5

how is ATP made?

Answer 5

protons flow down the electrochemical gradient through ATP synthase (contained in stalked particles)
this movement is the source of potential energy required to break the bond between the 3rd and 2nd phosphate group. this process allows the phosphorylation of ADP to ATP and the release of energy.
-this process is called chemiosmosis

Question 6

describe the stages of oxidative phosphorylation in mitochondria

Answer 6

1) hydrogen atoms are picked up and taken to the ETC
(matrix)
2)the inner mitochondrial membrane is the location of the ETC

3)high energy electrons are released into the ETC and provide energy to the proton pumps which then allow the active transport of protons from the matrix into the inter membrane space, creating a electro-chemical gradient

4)protons flow down the concentration gradient through the ATP synthase complexes (stalked particles) through the process f chemiosmosis. this potential energy formed allows the oxidative phosphorylation of ADP to release on phosphate group and form ATP

Question 7

describe the stages of phosphorylation in chloroplast

Answer 7

1) the process of the ETC akes place in the thylakoid membrane

2)electrons are exited by photons and provide energy to the proton pumps allowing protons to be pumped across the membrane

3)the thylakoid space is where the protons are pumped to, forming an electro-chemical gradient

4) protons flow through the stalked particles (containing ATP synthase) from the thylakoid space into the stroma

5)ADP is phosphorylated into ATP

6) protons enter the stroma and combine with electrons and NADP to form NADPH which will then be used in the Calvin cycle

Question 8

describe the stages of the Electron Transport Chain

Answer 8

1)reduced NAD acts as a hydrogen carrier and releases 1 proton and 1 high energy electron into the ETC

2)electron passes through proton pumps in a series of redo reactions (pumps 1,3,5 only)

3)provides energy to actively transport protons from the matrix into the intermembrane space

4)an electro-chemical gradient is formed

5)the final proton pump is re-oxidised when the oxygen (the final acceptor) accepts the electron

6)chemiosmosis occurs–>protons flow down the concentration gradient through the staled particles and oxidative phosphorylation occurs to convert ADP to ATP

Question 9

why is oxygen so important in these processes?

Answer 9

-acts as a final acceptor of electrons allowing re-oxidation of the final proton pump allowing them to continue pumping protons to maintain the electro-chemical gradient
-NAD is also re-oxidised allowing them to take in more hydrogen atoms so that glycolysis,krebs, and link can continue

Question 10

describe the stages of glycolysis

Answer 10

1)it occurs in the cytoplasm

2)one molecule of glucose is phosphorylated by two molecules of ATP

3) 6C phosphate molecule is formed which is then split into 2 trios phosphate molecules

4) each molecule is then dehydrogenase’s and results in the phosphorylation of 2 ADP molecules

5) 2 molecules of pyruvic acids are formed

Question 10

describe the stages of Links Reaction

Answer 10

1)occurs in the mitochondrial matrix and occurs x2 for each glucose molecule

2)each pyruvate us decarboxylated and dehydrogenated

3)a molecule of NAD is reduces

4)the remaining 2 carbon fragments (acetyle group) binds to coenzyme A forming acetyle coenzyme A

Question 11

describe the stages of Krebs Cycle

Answer 11

1)occurs in the mitochondrial matrix and X2 for each glucose molecule

2)the acetyle group passes the 2C group to the krebs cycle, linking to a 4C molecue (forming a 6C molecule)

3)2 decarboxylation reactions occur

4)3 dehydrogenations also occur -reducing 3 NAD molecules

5)a single substrate-level phosphorylation occurs

6)further dehydrogenation occurs to reduce one molecule of FAD

7)the 4C molecule is regenerated

Question 12

how many ATP molecules are phosphorylated for each NAD?

Answer 12

3

Question 13

how many ATP molecules are phosphorylated for each FAD?

Answer 13

2

Question 14

why does temperature in the mitochondria rise?

Answer 14

excess kinetic energy from the movement of protons is lost as heat

Question 15

how might inhibitors /toxins interfere with the production of ATP by the ETC

Answer 15

they can bind to the proteins, preventing movement or release of high energy electrons so no electro-chemical gradient formed

no gradient->no oxidative phosphorylation->no ATP=death

Question 16

what is meant by an uncoupler?

Answer 16

it removes the link between the action of the ETC and the stalked particles

Question 17

what effect will an uncoupler have on oxygen consumption?

Answer 17

it will increase as an increase rate of respiration could be required to produce reduced NAD more rapidly to release enough energy to meet the demand of out theoretical yield

Question 18

what effect will an uncoupler have on body temperature?

Answer 18

temperature of the mitochondria will increase as a higher proportion of the kinetic energy form chemiosmostic movement of protons will be released as heat

Question 19

why would a drug lead to weight loss if they ‘uncoupled’ the ETC and ATPase

Answer 19

more substrate would be respired to produce the same amount of energy as less ATP is yielded per molecule of glucose. this means more respiratory substrate would be used in respiration than ingested. alternative substrates such as fats/proteins would be used. leading to weight loss

Question 20

aerobic respiration

Answer 20

involves the breakdown of glucose in the presence of oxygen. releeasing large amounts of energy to produce sufficient amounts of ATP by oxidative phosphorylation

Question 21

anaerobic respiration

Answer 21

the incomplete breakdown of glucose in the absence of oyxygen, releasing little amounts of energy and aking small amounts of ATP by substarte level phosphorylation

Question 22

what is cyanide?

Answer 22

a non-competitive inhibitor
it prevents electrons and proton from passing onto oxygen to form water. this means that the gradient is not maintained and chemiosmosis stops

Question 23

what happens when oxygen is not the final acceptor? (animals and yeast)

Answer 23

without oxygen Krebs and Link stop as NAD/FAD cannot be re-oxidised nd cannot pick up more hydrogens

animals-glycolysis will still continue, however pyruvate will become the final acceptor. Lactate is formed

yeast-pyruvate is decarboxylated to rpoduce ethanal which becomes the final acceptor for hydrogen. ethanol and carbon dioxide are the final products

Question 24

what is an alternative respiratory substrate?

Answer 24

when glucose molecules have been completly depleted, lipids and amino acids can be used as an alternative

Question 25

why is lipid used as an alternative to glucose?

Answer 25

they are hydrolused into fatty acids and glycerol by lipase. glycerol is comverted into 3C compounds (trios phosphate) and enter glycolysis. fatty acids are very long hydro-carbon chains which are split into 2C molecules and feed into krebs cycle as acetyleCoA

Question 26

why are amino acids used as an alternative to glucose?

Answer 26

hydrolysed unt their constituents (amino acids) which are deanimated (remove amino group) in the liver forming keto acid and ammonia. some jeto acids are fed into glycolysis via pyruvate and some are fed into krebs via acetyle CoA.

amino acids are only used as an energy source in severe circumstances (starvation

Question 27

how do you calculate the respiratory quotient (RQ)?

Answer 27

number of molecules of CO2 produced / number of molecules of O2 consumed