BSC1005 - Cellular Respiration

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Terms to Know in This Chapter:

glycolysis [glie COL eh siss]

aerobic [a ROBE ik]

pyruvate [PIE rue vate]

anaerobic [an ah ROBE ik]

fermentation [fur men TAY shun]

Adenosine Triphosphate (ATP) [ah DEN oh seen] [tri FOSS fate]

Nicotinamide Adenine Dinucleotide (NAD) [nick oh TIN ah mide] [ADD uh neen] [die NEW klee oh tide]

yeast (sing.)

ethyl alcohol [ethel] [AL co hall]

lactic acid [LAK tick]

muscle fatigue

glucose [GLUE cose]

glucose-6-phosphate

fructose-6-phosphate [FRUCK tose]

fructose-1,6-biphosphate

phosphoglyceraldehyde (PGAL) [FOSS foe GLIS er al dee hide]

dihydroxyacetone phosphate (DHAP) [DIE high drox ee ASS eh tone]

1,3-biphosphoglycerate [bi FOSS foe GLIS er ate]

3-phosphoglycerate

2-phosphoglycerate

phosphoenolpyruvate (PEP) [FOSS foe EE noll PIE rue vate]

Kreb's cycle

coenzyme A

acetyl-Co-A [uh SEE till]

citrate [SIH trate]

isocitrate [EYE so SIH trate]

carbon dioxide [die OX ide]

alpha ketogluterate [key toe GLUE tah rate]

succinyl-CoA [SUCK sih nil]

Guanosine Triphosphate (GTP) [GUAN oh seen]

succinate [SUCK sih nate]

fumarate [FUM ah rate]

oxaloacetate (OAA) [ox AL oh ASS eh tate]

Flavin Adenine Dinucleotide (FAD) [FLAY vin] [ADD uh neen] [die NEW klee oh tide]

electron transport system

NADH dehydrogenase [dee high DROG eh nase]

quinone [QUI noan] or ubiquinone [you BICK kwee noan]

cytochrome b,c1 complex

cytochrome c

cytochrome oxidase [OX eh daze]

oxygen

oxidative phosphorylation

What You Need to Know:

You should be able to:

1. explain why you cannot simply break glucose down in one large step,
2. explain the three pathways of glucose metabolism,
3. explain the overall result of glycolysis, especially into what glucose is broken into, how many ATP's are produced, where in the cell it occurs, and under what conditions (aerobic or anaerobic),
4. explain the overall result of the Kreb's cycle to include the major products (hydrogen, ATP, and carbon dioxide), where in the cell it occurs, and under what conditions (aerobic or anaerobic),
5. explain the overall events of the electron transport system to include the products (ATP and water), where in the cell it occurs, under what conditions, and where NADH and FADH₂ feed into the system,
6. distinguish between aerobic and anaerobic respiration,
7. explain the three possible fates of pyruvate after glycolysis,
8. explain fermentation and how it differs between plant and animals,
9. give the bi-products of plant and animal fermentation,
10. explain how acetyl-CoA is formed, what is necessary for its formation, what is oxidized, what is reduced, and to where acetyl-CoA feeds,
11. give the intermediates of the Kreb's cycle, explain where CO₂, NADH + H, and FADH₂ are released, where ATP is produced, and explain why it is called a cycle,
12. give the electron acceptors in the electron transport system and explain where ATP is produced and name the final electron-hydrogen acceptor, and,
13. explain how many ATP's are produced total in glycolysis, Kreb's cycle, and electron transport system.

Exercises: Fill in the Blank.

1. The three steps in glucose metabolism are , , and
2. Respiration that occurs in the presence of oxygen is referred to as while that which takes place in the absence of oxygen is referred to as .
3. Glycolysis results in the production of two molecules of and a net of ATP's.
4. In glycolysis, the first step is for glucose to be converted into by the addition of the phosphate from ATP. (ATP is thus converted to by this addition of phosphate.) Glucose-6-phosphate is immediately changed into by an enzyme called an isomerase. (The reason the enzyme is called an isomerase, is glucose and fructose are of each other.) Fructose-6-phosphate is changed into by the addition of another phosphate from ATP, thus we have actually used up ATP's without making any. Fructose-1,6-biphosphate, a six-carbon molecule, is broken apart into two three-carbon molecules, and . Dihydroxyacetone phosphate is converted immediately into , and PGAL is changed into 1,3 biphosphoglycerate by the reduction of and the addition of a phosphate group (not from ATP). 1,3-biphosphoglycerate is then converted into and at the same time, ADP is converted into ATP. Three-phosphoglycerate is converted into which is converted into . This is converted into pyruvate with the formation of another ATP.
5. Glycolysis takes place in the (cytoplasm, mitochondria)of the cell under conditions (aerobic, anaerobic).
6. Pyruvate, under aerobic conditions, will eventually be converted into . Under anaerobic conditions, pyruvate undergoes .
7. In plants, fermentation results in the formation of and carbon dioxide. In animals, fermentation results in the formation of .
8. Pyruvate, during aerobic respiration, combines with Coenzyme A and , which becomes reduced to form . This feeds directly into the Kreb's cycle.
9. In the Kreb's cycle, acetyl-CoA combines with , a four-carbon compound, to form the six-carbon compound . Citrate is then converted to , an isomer of citrate. This compound is converted into , a five-carbon compound. To go from a six-carbon intermediate to a five-carbon intermediate, is lost at the same time that becomes reduced. Alpha-ketogluterate is converted into , a four-carbon compound when is added and is lost with the reduction of . This four-carbon compound is then converted to at the same time is formed (but immediately converted to ATP). This four-carbon intermediate is changed into and is reduced to form . This intermediate is then converted into , another four-carbon compound that is converted to oxaloacetate and fed back into the Kreb's cycle where it combines with and begins the cycle again.
10. In summation of the Kreb's cycle, ATP's CO₂, and hydrogens are produced for each pyruvate that enters. It takes place in the (cytoplasm, mitochondria) of the cell under conditions. (aerobic, anaerobic)
11. In the electron transport system, NADH + H feeds into which becomes reduced. This transfers the electrons and hydrogen atoms to while at the same time producing 1 ATP. Quinone (Ubiquinione) becomes reduced and passes the electrons and hydrogen atoms to cytochrome complex which becomes reduced as Quinone (Ubiquinone) becomes oxidized. Cytochrome next accepts the hydrogen atoms and electrons and becomes reduced while 1more ATP is generated. Cytochrome c passes the electrons and hydrogen atoms to cytochrome . When this passes the electrons to the final electron acceptor , 1 more ATP is produced. For one NADH + H, ATP's are produced. However, if FADH₂ feeds into the electron transport system, only ATP's are produced because FADH₂ enters at the molecule called instead of NAD dehydrogenase.
12. ATP's total are produced by prokaryotic cells while ATP's are produced by eukaryotic cells during cellular respiration.

Exercises. Multiple Choice. Select the best answer.

1. Glycolysis:
   

   (1) takes place in the mitochondrion.
   

   (2) under aerobic conditions.
   

   (3) produces 4 ATP's net.
   

   (4) both 1 and 2 are correct.
   

   (5) none of these are correct.
   
   

2. Fermentation:

   (1) occurs during aerobic respiration.
   

   (2) takes place in plants.
   

   (3) takes place in animals.
   

   (4) both 2 and 3 are correct.
   

   (5) all of these are correct.
   
   

3. Pyruvate is:
   

   (1) converted into ethyl alcohol under aerobic conditions.
   

   (2) converted into lactic acid under aerobic conditions.
   

   (3) converted into acetyl-CoA under anaerobic conditions.
   

   (4) fed directly into the Kreb's cycle.
   

   (5) none of these are correct.

4. In the Kreb's cycle, GTP is immediately changed into:
   
   

   (1) GDP.
   

   (2) GMP.
   

   (3) ADP.
   

   (4) ATP.
   

   (5) FADH₂.

5. FADH₂:
   

   (1) feeds into Quinone (Ubiquinone) in the electron transport system.
   

   (2) is formed during aerobic respiration in the Kreb's cycle.
   

   (3) is formed when succinate is converted to fumerate in the Kreb's cycle.
   

   (4) both 2 and 3 are correct.
   

   (5) all of these are correct.

6. When one pyruvate molecule feeds into the Kreb's cycle:
   

   (1) 2 ATP's are produced.
   

   (2) eight carbon dioxides are produced.
   

   (3) 16 hydrogen atoms are produced.
   

   (4) one molecule of GTP is formed and converted into ATP.
   

   (5) all of these are correct.

7. This takes place in the cytoplasm under anaerobic conditions.
   

   (1) glycolysis
   

   (2) fermentation
   

   (3) lactic acid production
   

   (4) ethyl alcohol production
   

   (5) all of these are correct

8. The net production of ATP in animal cells is:
   

   (1) 16.
   

   (2) 32.
   

   (3) 34.
   

   (4) 36.
   

   (5) 38.

9. In glycolysis, phosphoenolpyruvate is converted into:
   

   (1) acetyl-CoA.
   

   (2) PGAL.
   

   (3) DHAP.
   

   (4) glucose.
   

   (5) pyruvate.

10. In the Kreb's cycle, alpha-ketogluterate is converted to:

    (1) succinate.
    

    (2) oxaloacetate.
    

    (3) isocitrate.
    

    (4) succinyl-CoA.
    

    (5) fumerate.