Chapter 3- Aerobic Cellular respiration

Question 1

Aerobic cellular respiration

Answer 1

• phosphorylates ADP into ATP by breaking down glucose and moving electrons (oxidation and reduction reactions)
• breaks down glucose into 38 ATPs
• 4 catabolic processes:
  1. Glycolysis
  2. Pyruvate manipulations
  3. Krebs cycle
  4. Oxidative phosphorylation

Question 2

Glycolysis

Answer 2

• glucose → 2ATP + 2NADH + 2pyruvate
• occurs in the cytosol
• anaerobic (does not require oxygen), it is used in fermentation also!
• extracts and uses high-energy electrons as glucose is broken down, to reduce NAD+ into NADH, which may travel to ETC for more ATP production.

Question 3

Substrate-level phosphorylation

Answer 3

-transfers a phosphate group to ADP and generates ATP in glycolysis

Question 4

GTP (Guanosine triphosphate)

Answer 4

-RNA nucleoside triphosphate like ATP

Question 5

Flavin Adenine Dinucleotide (FAD)

Answer 5

-electron carrying coenzyme like NAD+

Question 6

Fermentation

Answer 6

anaerobic pathway to oxidize NADH back to NAD⁺ so glycolysis can continue to make ATP.

Question 7

Lactic acid fermentation

Answer 7

• regenerates NAD⁺ from NADH by reducing pyruvate into lactic acid.
• NADH transfers electron to pyruvate regenerating NAD+. This forms lactic acid/lactate

Question 8

Cori Cycle

Answer 8

• converts lactate back to glucose when oxygen is available again.
• transports lactate from the myocyte (muslces) through the bloodstream to hepatocytes (liver cells).
• Lactate can then oxidize back into pyruvate which can form glucose through gluconeogensis.

Question 9

Gluconeogensis

Answer 9

• creates new glucose from pyruvate
• energy investment of 6 ATP is required
• Glucose is broken down as oxygen is available again

Question 10

Hepatocytes (liver cells)

Answer 10

• contain an enzyme that undoes hexokinase reaction of glycolysis
• Liver is the only organ that can release glucose into the bloodstream.

Question 11

Alcohol fermentation

Answer 11

• it regenerates NAD+ for glycolysis to make 2 ATPs, similar to lactic acid ferm.
• However, electrons from NADH will not reduce the pyruvate
• Instead, pyruvate is decarboxylated to lose carbon as CO2.
• Left over molecule acetaldehyde will be reduced by NADH into ethanol, which oxidizes NAD+.
• Done by Yeast and produces ethanol found in alcohol.

Question 12

Glycolysis (look at written notes for details)

Answer 12

-converts glucose into 2 pyruvates + 2ATP + NADH

Question 13

Pyruvate manipulation (look at written notes for details)

Answer 13

-converts 2 pyruvates into 2CO2 + 2NADH + 2acetyl-CoA

Question 14

Krebs Cycle (look at written notes for details)

Answer 14

-converts 2 acetyl CoA into 4CO2 + 6NADH + 2FADH + 2GTP

Question 15

Oxidative phosphorylation (look at written notes for details)

Answer 15

-converts electron carries NADH and FADH into ATP and H2O

Question 16

Obligate Aerobes

Answer 16

-only perform aerobic
respiration, need
oxygen to survive.

Question 17

Obligate anaerobes

Answer 17

-only undergo anaerobic

respiration, will die in presence of oxygen

Question 18

Facultative anaerobes

Answer 18

-can do aerobic, anaerobic respiration, or fermentation
-prefers aerobic respiration
because it generates the most ATP.

Question 19

Microaerophiles

Answer 19

• only perform aerobic respiration

- but high amount of oxygen is harmful to them

Question 20

Aerotolerant organisms

Answer 20

-only undergo
anaerobic respiration or fermentation, but
oxygen is not poisonous to them.

Question 21

Alternative Sources of Energy Generation

Answer 21

• other types of carbohydrates, fats, and proteins can be modified to enter cellular respiration at various stages for energy generation.
• carbohydrates are the preferred energy source since they are easily catabolized and are high yield (4kcal/gram)

Question 22

Glycogenolysis

Answer 22

-the release of glucose-6-phosphate from glycogen, a highly branched polysaccharide of glucose.

-Disaccharides
can undergo hydrolysis to release two carbohydrate monomers, which can enter glycolysis.

Question 23

Glycogensis

Answer 23

-the conversion of glucose into glycogen to be stored in the liver when energy and fuel is sufficient.

Question 24

Fats as source of energy generation

Answer 24

• present in the body as triglycerides
• Lipase enzyme digest fats into free fatty acids and alcohols through process of lipolysis.
• the digested parts are then absorbed by enterocytes in the small intestine and reform triglycerides.

Question 25

Adipocytes

Answer 25

-cells that store fat (triglycerides) -have hormone-sensitive lipase enzymes to help release triglycerides back into circulation as lipoproteins or as free fatty acids bound by a protein called albumin.

Question 26

Chylomicrons

Answer 26

- are lipoprotein transport structures formed by the fusing of triglycerides with proteins, phospholipids, and cholesterol. - They leave enterocytes and enter lacteals. (small lymphatic vessels that take fats to the rest of the body)

Question 27

Low-density lipoproteins (LDLs)

Answer 27

-low density of proteins, unhealthy because they transport cholesterol to the peripheral tissues, causing vessel blockage.

Question 28

High-density lipoproteins (HDLs)

Answer 28

-high density of proteins, healthy because they bring cholesterol to the liver to make bile.

Question 29

Glycerol in the liver

Answer 29

-can be converted to enter glycolysis or make new glucose via gluconeogensis in the liver.

Question 30

Free fatty acids

Answer 30

-undergo beta-oxidation to be converted into acetyl-CoA. -Beta-oxidation requires an initial investment of ATP, but then is continuously cleaved to yield two-carbon acetyl-CoA molecules (which can be used in the Krebs cycle for ATP generation) and electron carriers (NADH + FADH2 - produces more ATP).

Question 31

Proteins as source of energy generation

Answer 31

- least desirable energy source bc the processes to get them into cellular respiration takes a lot of energy - Catabolized when cells are starving due to unavailability of carbs and fats. -They are broken down into amino acids, which must first undergo oxidative deamination (removal of NH3 ) before being shuttled to various parts of cellular respiration. -Ammonia (NH3 ) is toxic, so must be converted into uric acid or urea excreted from the body. EX: humans convert ammonia into urea, which is excreted as urine.