Chapter 3: Cellular Respiration

Question 1

cellular respiration

Answer 1

1. overall an oxidative, exergonic process
   2.C6H12O6 + O2 = 6CO2 +
   2O + energy
2. during respiration, high energy H atoms removed from organic molecules (dehydrogenation)

Question 2

external respiration

Answer 2

entry of air into lungs and gas exchange between alveoli and blood

Question 3

internal respiration

Answer 3

exchange of gas between blood and the cells + intracellular respiration processes

Question 4

aerobic respiration

Answer 4

1. in the presence of O2 (glycolysis, pyruvate decarb, krebs cycle, oxidative phosphorylation)
2. water is the final product

Question 5

glycolysis

Answer 5

1. decomposition of glucose into pyruvate in CYTOSOL
2. 2ATP added, 2NADH produced, 4ATP produced, 2 pyruvate formed
3. NET= 2ATP + 2 NADH + 2 pyruvate (+2H2O + 2H+)
4. ATP produced here via substrate level phosphorylation=direct enzymatic transfer of a phosphate to ADP, no extraneous carriers needed
5. hexokinase phos’s glucose, important because then it can’t diffuse out and tricks the gradient
6. PFK (enzyme) adds 2nd phosphate, makes fructorse 1,6-biphosphate–this is irreversible and commits to glycolysis, major regulatory point!

Question 6

pyruvate decarboxylation

Answer 6

1. in the mitochondrial matrix
2. pyruvate to Acetyl CoA, producing 1 NADH and 1 CO2 (x2 because 2 pyruvate)
3. NET= 2 NADH + 2 CO2
4. catalyzed by PDC (pyruvate dehydrogenase complex)

Question 7

Krebs Cycle/citric acid cycle/ tricarboxylic acid cycle

Answer 7

1. fate of pyruvate that is produced in glycolysis
2. in Krebs cycle, acetyl CoA merges with oxaloacetate to form citrate, cycle goes w/7 intermediates
3. 3 NADH, 1 FADH2, 1 ATP (via sub phos), and 2 CO2 are produced per turn
4. due to two pyruvate made from 1 glucose in glycolysis so two rounds of TCA cycle occur
5. NET= 6 NADH, 2 FADH2, 2 ATP, 4 CO2
6. takes place in mitochondria matrix (like py. decarb.)
7. CO2 produced here is the CO2 animals exhale when they breathe

Question 8

electron transport chain

Answer 8

1. takes place at the inner membrane/cristae (folds which increase SA for more ETC action)

Question 9

oxidative phosphorylation

Answer 9

1. process of ADP to ATP from NADH and FADH2 via passing of electrons through various carrier proteins
   * ** energy doesn’t accompany the phosphate group but comes from the electrons in the ETC establishing an H+ gradient that supplies energy to ATP synthase

Question 10

process of oxidative phosphorylation

Answer 10

1. NADH makes more energy than FADH2, more H+ is pumped across per NADH (both are coenzymes) —- 3:2 yield
2. final electron acceptor is oxygen-combines with native H+ to form H2O
3. carriers extract energy for NADH and FADH2 while pumping protons into the intermembrane space-ATP synthase uses this gradient (which is a pH and electrical gradient to make ATP as it shuttles H+ back into the inner matrix
4. Coenzyme Q (CoQ)/Ubiquinone is a soluble carrier dissolved in the membrane that can be fully reduced/oxidized, it passes electrons
5. cytochrome C is a protein in the ETC, common in many living organisms, used for genetic relation
6. cytochromes have nonprotein parts like iron (donate/accept electrons, for redox!)
7. Couples exergonic flow of electrons with endergonic pumping of protons across cristae membrane

Question 11

Total ATP production

Answer 11

1. 1 glucose = 36 ATP in eukaryotes
2. prokaryotes= 38ATP
3. not acutal yields, b/c mitochondrial efficacy varies
4. difference because pro. have no mito. so they (unlike eu.) don’t need to transfer pyruvate into mitochondrial matrix (which is done via active transport costing ATP), they use cell membrane for respiration.

Question 12

mitochondria

Answer 12

1. outer membrane=phospholipid bilayer
2. intermembrane space=between inner and outer … where H+ accumulates
3. inner membrane= oxidative phosphorylation in cristae (folds)… holds the ETC consisting of protein complexes, removes electrons from NADH and FADH2 and transports H+ ions fro the matrix to the intermembrane space to go through the ATP synthase where ADP is phosphorylated to ATP
4. matrix= pyruvate to acetly CoA and Krebs cycle

Question 13

chemiosmosis

Answer 13

1. mechanism of ATP generation that occurs when energy is stored in the form of a proton concentration gradient across a membrane
2. Krebs produces NADH/FADH2, they are oxidized (lose electrons), H+ transported from matrix to intermembrane space, pH and electric gradient is created, ATP synthase uses the energy in this gradient to create ATP by letting the proteins flow through the channel
   COMMON QUESTION: about pH changes from these processes; remember that H+ concentration up means pH down.

Question 14

substrate level phosphorylation

Answer 14

1. when phosphate group and its associated energy is transferred from ADP to ATP.
2. the substrate molecule (molecule with the phosphate group) donates the high energy phosphate group.
3. E.g. phosphorylation during glycolysis

Question 15

oxidative phosphorylation

Answer 15

1. when phosphate group is added to ADP to ATP, but the energy for the bond does not accompany the phosphate group
2. instead, elecctrons in the ETC chain of oxidative phos. supply energy … which generate h+ concentration and supplies energy to ATP synthase to generate ATP from ADP and a phosphate group

Question 16

ATP (adenosine triphosphate)

Answer 16

1. an RNA nucleotide (due to its ribose sugar)
2. unstable molecule because the 3 phosphates in ATP are negatively charged and repel one another
3. The change from less stable molecule to more stable always releases energy
4. provides energy for all cells by transferring phosphate from ATP to another molecule

Question 17

anaerobic respiration (cytosol)

Answer 17

1. includes glycolysis and fermentation
2. regenerates NAD+ via O2 which is required for continuation of glycolysis
3. w/o O2, there would be no replenishing–NADH accumulates, cell would die w/ no new ATP so fermentation occurs

Question 18

Alcohol Fermentation

Answer 18

1. occurs in p;ants, fungi (yeast), and bacteria
2. pyruvate to acetaldehyde + CO2, then acetaldehyde to ethanol (and NADH to NAD+)
3. *** acetyladehyde is the final electron acceptor! The final molecule isn’t the final acceptor; acetyladehyde is the final acceptor of the electrons thus forming ethanol! same w/ O being teh final electron acceptor of cellular respiration forming water

Question 19

lactic acid fermentation

Answer 19

1. occurs in human muscle cells, other microorganisms
2. pyruvate to lactate (and NADH to NAD+)
3. Lactate is transported to liver for conversion back to glucose once surplus ATP available
   * ** facultative anaerobes can use oxygen when it’s present (more efficent) but switch to fermentation/anaerobic respiration if is not
   * ** obligate anaerobes cannot live in presence of oxygen