ATP and respiration

Question 1

When is ATP produced

Answer 1

made when energy is available from respiration and the light dependant reactions of photosynthesis.

Question 2

how and why is controlled release of energy required

Answer 2

glucose is Brocken down in controlled steps by enzymes.
This allows small amounts of energy to be released to prevent against over heating by uncontrolled release. And is released gradually to phosphorylate ADP to ATP.

Question 3

what enzyme causes brekadown of ATP to ADP

Answer 3

ATPase

Question 4

What reaction is endergonic -energy used

Answer 4

to produce ATP

Question 5

what enzyme causes phosphorylation of ADP to ATP

Answer 5

ATP synthetase.

Question 6

Where is ATP producede in organisms

Answer 6

either- cristae /inner membrane of mitochondria.
or on the thylakoid membranes of chlorplasts.

Question 7

what is chemiosmosis

Answer 7

flow of protons down an electrochemical gradient through ATP synthetase .

Question 8

describe chemiosmosis in ATP flow

Answer 8

ATP is produced as protons (H+) flow across the inner membrane down their electrochemical gradient to a lower conc. They move via the enzyme ATP synthetase in stalked particles. The down=ward movement releases energy used to form ATP.

Question 9

Explain the proton gradient/pump process.

Answer 9

H+ pumped from one side to a another- creating a proton gradient.
The energy to pump the protons come from energy being released from electrons flowing down a series of electron carriers in an electron transport chain. Each carrier is at a lower energy level than previous.
protons then flow back across membrane down their electrochemical gradient via ATP synthetase.

Question 10

describe substrate phosphorylation

Answer 10

phosphate groups transferred directly from phosphate compounds e.g in cytoplasm during glycolysis and Krebs cycle.

Question 11

describe oxidative phosphorylation

Answer 11

occurs in mitochondria during aerobic respiration as electrons are transported down the electron transport chain.- requires oxygen.

Question 12

advantages of ATP

Answer 12

-easily hydrolysed by 1 enzyme ATPase to release energy -is efficient
-rleseases energy in useable amounts.
-inert-no osmotic effects
-easily transported across membranes and into cytoplasm
- readily formed by phosphorylation.

Question 13

how is mitochondria adapted for respiration

Answer 13

-intermembrane spaces is small to quickly accumulate protons.
-matrix has appropriate enzymes and PH for krebs cycle.
- inner membranes contain ETC and ATP synthetase for oxidative phosphorylation.
-cristae highly folded to increase surface area.
-outer membrane contains transport proteins for shuttling pyruvate into mitochondria.

Question 14

where does glycolysis occur

Answer 14

cytoplasm

Question 15

describe process of glycolysis (4 marks)

Answer 15

glucose is phosphorylated creating a glucose diphosphate. The hexose diphosphate (glucose diphosphate) then splits as it becomes unstable by phosphorylation into triose phosphate -3c sugar.
hydrogens is removed from triose phosphate , which allows =NAD to become reduced (NADH)
-pyruvate is then formed and 2 ATP is formed by substrate level phosphorylation.

Question 16

what are the products of glycolysis

Answer 16

-2 ATP
-2 NADH
-2 pyruvate

Question 17

what happens to the pyruvate after created in glycolysis

Answer 17

moves into mitochondria by diffusion down a conc gradient into matrix. This leads to link reaction which allows the conc gradient to be maintained.

Question 18

describe the process of the link reaction (3 marks)

Answer 18

-pyruvate decarboxylated and dehydrogenated, NADH produced
-all that remains of each pyruvate is a 2 carbon acetate molecule which combined with coenzyme A producing acetyl coenzyme A.

Question 19

what are the products of link recation

Answer 19

-Acetyl conzyme A
-c02
-NADH

Question 20

where does the krebs cycle occur

Answer 20

matrix or mitochondria

Question 21

describe the process of krebs cycle (6 marks)

Answer 21

-Each acetyl CO A (2C) combines with a 4C molecule producing a 6C molecule. Tjhis regenerates the CO A and cycle begins again. The 6C compound is dehydrogentaed to rpoduce NADH and decarbolylated to prouduce C02 and a 5 carbon intermediate. Compounds used in krebs cycle containc ompoiunds used in other processes.
This 5C carbon compound is dehydrogenates to produce 2x NADH and one FADH. It is also decarboxylated to produce a 4c carbon molecule.

Question 22

what are the overall products of the krebs cycle from one acetyl coenzyme A

Answer 22

-2x C02.
-3x NADH
-1x FADH

Question 23

importance of krebs cycle

Answer 23

-coenzyme has to be regenerated to allow the continuity of link reaction.
-4c molecule needs to be regenerated to accept the 2c carbon compound entering the Krebs cycle.
-intermediate compounds can be used elsewhere e.g to make fatty acids.
-the FADH and NADH are formed to enter the electron transport chain to produce more ATP by oxidative phosphorylation.

Question 24

what is the final stage of respiration

Answer 24

oxidative phosphorylation

Question 25

where does oxidative phosphorylation occur

Answer 25

inner membrane of mitochondria.

Question 26

whatb aheppns to the reduced FAD and NAD molecules

Answer 26

hydrogens removed by dehydrogenases in the matrix.
-hydrogen atoms split into protons and electrons which are accepted by electron carriers in the cristae membrane to start an electron transport chain.

Question 27

why is 02 needed?

Answer 27

is the final acceptor of electrons as they leave the ETC.

Question 28

what does cyanide do?

Answer 28

respiratory inhibitor of enzymke that catalyses the addition of hydrogen to form water.

Question 29

what is the equation that cyanide can inhibit (the proudction of water .

Answer 29

4H+ + 4 e- +02 —-2H20

Question 30

what does each NADH molecule produce

Answer 30

3 ATP

Question 31

what does each FAD produce

Answer 31

2 ATP

Question 32

what is the ATP energy budget in respiration

Answer 32

38 ATP molecules are produced.
-2 ATP in glycolysis by substrate level phosphorylation
-2 ATP in krebs cycle - substrate level
-34 ATP in oxidative phosphorylation -10 NADH (2 glycolysis and 2 link reaction 6 krebs cycle)=30 ATP
2 FADH-krebs cycle

Question 33

why is max yield of ATP never achieved (2 marks)

Answer 33

-loss of substances by leaky membranes
-movement of pyruvate and ATP into matrix uses some energy.

Question 34

what happens in anaerobic resporation

Answer 34

takes place in cytoplasm - pyruvate does niot enter mitochondria.
-krebs cycle stops.
-hydrogen carriers cant unload hydrogen.
-glycolysos wouyld also stop if all NAD stayed reduced as no NAD would be regenerated to accept more H+
-hydrogen combines with pyruvate forming lactate/ethanol.
-pyruvate is reduced to lactate, done by regenerating NADH to NAD.
-pyruvate reduced to ehtanol and co2 when 2NADH becomes 2 NAD .

Question 35

what is produced in anaerobic respiration

Answer 35

-2 ATP

Question 36

what respiratory substances can enter the Krebs cycle as an intermediate compound.

Answer 36

carbohydrates, lipids and proteins

Question 37

how are lipids used as a respiratory substance

Answer 37

hydrolysed into fatty acids and glycerol.
-glycerol converted to triphosphate and enters glycolysis.
-fatty acids spilt into 2c acetate fragments and enter Krebs cycle as acetyl co A.

Question 38

how are proteins used as a respiratory substance

Answer 38

hydrolysed into amino acids.
- these are taken to liver and deaminated forming keto acids and ammonia. Some keto acids are converted to pyruvate and others into acetyl co A or other intermediates in Krebs cycle.

Question 39

what is a respirometer

Answer 39

measures rate of respiration typically measuring oxygen consumption and carbon dioxide output. e.g using soda lime to absorb co2.