Chapter 7 - The Cycles of a Cell

Question 1

What are autotrophs?

Answer 1

Converts radiant energy into chemical energy (self feeders)

Question 2

What are heterotrophs?

Answer 2

Live on organic compounds that they consume (fed by others)

Question 3

What is cellular respiration?

Answer 3

The central process in the energy metabolism which involves oxidation of organic compounds and using energy released to form ATP.

Question 4

How is energy extracted from organic mixtures?

Answer 4

By rearranging C–H bonds via oxidation/reduction.

Question 5

What is aerobic respiration?

Answer 5

When the electron acceptor is oxygen.

Question 6

What is anaerobic respiration?

Answer 6

When the electron acceptor is an inorganic molecule other than oxygen.

Question 7

What is fermentation?

Answer 7

When an organic molecule accepts electrons.

Question 8

What is the chemical equation for burning carbohydrates?

Answer 8

C6H12O6 + 6 O2 –> 6 CO2 + 6 H2O + energy (heat and ATP)

Question 9

What makes up NAD+?

Answer 9

Two nucleotides which are nicotinamide monophosphate (NMP) and adenosine monophosphate (AMP) which are joined head-to-head by their phosphate groups.

Question 10

How does NAD+ become NADH?

Answer 10

NAD+ acquires 2 electrons and a proton from the active site of an enzyme and is reduced to NADH.

Question 11

What is substrate-level phosphorylation?

Answer 11

When ATP is formed by transferring a phosphate group directly to ADP from a phosphate-bearing intermediate or substrate.

Question 12

What is oxidative phosphorylation?

Answer 12

When ATP is synthesized by the enzyme ATP synthase, using energy from a proton (H+) gradient.

Question 13

How is the proton (H+) gradient formed?

Answer 13

High-energy electrons removed by oxidation of glucose passes down an electron transport chain.

Question 14

What is the process of Glycolysis?

Answer 14

Converts glucose into 2 3-carbon molecules of pyruvate.

Question 15

Where does glycolysis take place?

Answer 15

In the cytoplasm

Question 16

How many net ATPs does glycolysis yield?

Answer 16

2 ATP

Question 17

How many steps is the first half of glycolysis?

Answer 17

5 reactions

Question 18

What happens in the first 3 steps of glycolysis?

Answer 18

It primes glucose by changing it into a compound that can be readily cleaved into 2 3-carbon phosphorylated molecules.

Question 19

True of False: The first half of glycolysis needs 2 ATP in order to prime glucose.

Answer 19

True: Glycolysis begins by expending 2 ATP to transfer phosphate to each end of the glucose. This produces a 6-carbon molecule with two phosphates.

Question 20

What is formed in the next 2 reactions of the first half of glycolysis?

Answer 20

2 3-carbon monophosphate sugars called glyceraldehyde-3-phosphate (G3P).

Question 21

What is the 2nd to last step of glycolysis?

Answer 21

Each G3P is oxidized transferring 2 electrons and 1 proton to NAD+ forming NADH. A molecule of Pi is added to G3P to produce 1 3-biphosphatoglycerate (BPG).

Question 22

What is the last step of glycolysis?

Answer 22

The phosphate incorporated is transferred to ADP by substrate-level phosphorylation in an exergonic reaction. 2 net ATP is formed

Question 23

How much energy is produced with glycolysis?

Answer 23

14.6 kcal of energy per glucose

Question 24

True or False: Cells contain a large amount of NAD+

Answer 24

False: a cell must oxidize NADH back to NAD+ in order for glycolysis to continue

Question 25

What is the chemical equation for glycolysis?

Answer 25

glucose + 2 ADP + 2 Pi + 2 NAD+ --> 2 pyruvates + 2 ATP + 2 NADH + 2 H+ + H2O

Question 26

Where does the citric acid cycle take place?

Answer 26

In the mitochondria

Question 27

How is pyruvate harvested?

Answer 27

Pyruvate is oxidized to produce a 2-carbon compound and CO2 with the electrons transferred to NAD+ to produce NADH. The 2-carbon compound is oxidized to two molecules of CO2 by the reactions of the citric acid cycle.

Question 28

What is the term of pyruvate's oxidation?

Answer 28

decarboxylation

Question 29

How is acetyl-CoA formed?

Answer 29

By the decarboxylation of pyruvate from cleaving off one of pyruvate's three carbons. The remaining 2-carbon compound is acetyl-CoA.

Question 30

What carbon group is fed into the citric acid cycle?

Answer 30

acetyl-CoA

Question 31

What is acetyl added to?

Answer 31

The acetyl groups is added to 4-carbon acid oxaloacetate

Question 32

What does acetyl turn into in the CAC?

Answer 32

It produces citrate

Question 33

What happens to citrate in the CAC?

Answer 33

Citrate converts back to oxaloacetate, generating CO2 and transferring electrons and protons to the electron carriers NADH and FADH2.

Question 34

How many ATP is generated by the oxidation of citrate?

Answer 34

1 ATP

Question 35

True or False: The citric acid cycle produces a lot of ATP but does not produce a lot of NADH.

Answer 35

False: Very few ATP is generated but a large amount of NADH is generated for use in the electron transport chain.

Question 36

How many reactions are in the citric acid cycle?

Answer 36

9 reactions

Question 37

What is the first reaction of the CAC?

Answer 37

Condensation: Citrate is formed by joining acetyl-CoA to oxaloacetate.

Question 38

What happens in reactions 2 and 3 of the CAC?

Answer 38

Isomerization: The hydroxyl (-OH) group of citrate must be repositioned. A water molecules is removed from one carbon and moved to another producing Isocitrate.

Question 39

What is reaction 4 of the CAC?

Answer 39

The first oxidation: Isocitrate is oxidized in a decarboxylation reaction. Yields a par of electrons that reduce NAD+ to NADH. A central carboxyl group splits off to form CO2, produces A-ketoglutarate

Question 40

What is reaction 5 of the CAC?

Answer 40

The second oxidation: A-ketoglutarate is decarboxylated by a multienzyme complex. CO2 is removed and joins to coenzyme A forming Succinyl-CoA. Two more electrons are extracted and reduce another NAD+ to NADH.

Question 41

What is the 6th reaction of CAC?

Answer 41

Substrate-level phosphorylation: The bond of succinyl-CoA is cleaved and drives the phosphorylation of guanosine diphosphate (GDP) forming guanosine triphosphate (GTP). GTP can be converted into ATP. The molecule that remains is succinate.

Question 42

What is the 7th reaction of the CAC?

Answer 42

The third oxidation: Succinate is oxidized to fumarate. FAD is the electron acceptor.

Question 43

What are reactions 8 and 9 of the CAC?

Answer 43

Regeneration of oxaloacetate: a water molecule is added to fumarate to form malate. Malate is oxidized to oxaloacetate and two electrons reduce NAD+ to NADH.

Question 44

How many NADH molecules are formed in the citric acid cycle?

Answer 44

10 molecules

Question 45

How man FADH2 molecules are formed in the CAC?

Answer 45

2 molecules

Question 46

How many net ATP molecules are formed in the CAC?

Answer 46

4 molecules.

Question 47

What is the best method to understand the CAC?

Answer 47

Follow the electrons

Question 48

Where does the electron transport chain take place?

Answer 48

In the inner mitochondrial membrane

Question 49

What is the first to receive the electrons in the ETC?

Answer 49

NADH dehydrogenase

Question 50

What is the carrier called that passes electrons to a protein called the bc1 complex?

Answer 50

Ubiquinone

Question 51

What is the next carrier called that carried electrons to the cytochrome oxidase complex?

Answer 51

Cytochrome C

Question 52

What does the cytochrome oxidase complex do?

Answer 52

It uses 4 electrons to reduce a molecule of oxygen. Each oxygen atom combines with two protons to form water.

Question 53

How does the proton gradient form in the ETC?

Answer 53

The flow of highly energetic electrons induces a change in the shape of proton pump proteins which causes them to transport protons across the membrane.

Question 54

What is chemiosmosis?

Answer 54

The chemical formation of ATP is driven by a diffusion force similar to osmosis

Question 55

How does ATP synthases work?

Answer 55

Most of the protons that re-enter the matrix pass through ATP synthase which uses the energy of the gradient to catalyze the synthesis of ATP from ADP and Pi.

Question 56

How many ATP is produced by NADH?

Answer 56

2.5 ATP

Question 57

How many ATP is produced by FADH2?

Answer 57

1.5 ATP

Question 58

How many ATP is yielded in aerobic respiration?

Answer 58

26-28 ATP

Question 59

True or False: Bacteria have a higher ATP production.

Answer 59

True: Bacteria can produce up to 30-32 ATP.

Question 60

What is produced in alcohol fermentation?

Answer 60

NAD+ and ethanol which is used to create wine.

Question 61

What do muscle cells produce?

Answer 61

Converts pyruvate into lactic acid and regenerates NAD+.