Chapter 9 - cellular Respiration

Question 1

what is fermentation?

Answer 1

partial degradation of sugars or other organic fuel that occurs without the use of oxygen

Question 2

glycolysis

Answer 2

initial/partial breakdown of glucose (regardless of O2)

Question 3

what is aerobic respiration?

Answer 3

consumes organic molecules and O2 (final electron acceptor) to yield ATP via the electron transport chain (very efficient!)

Glucose →(glycolysis) → pyruvate → acetyl CoA

Question 4

what is anaerobic respiration?

Answer 4

similar to aerobic respiration but instead of O2, another inorganic molecules (such as NO3, SO3, or CO2) is used as the final electron acceptor (less efficient than O2 but better than fermentation)

produces a limited amount of ATP (no ETC)

Question 5

how is NADH formed?

Answer 5

2 hydrogen atoms and 2 e- are taken from glucose/food

1 hydrogen atom, 2 e- are bonded to NAD+

Question 6

how is NADH formed in cellular respiration?

Answer 6

1) hydrogen that reacts with oxygen is derived from an organic molecule, not H2
2) electron transport chain is used to break the fall of the electrons to oxygen into several steps

Question 7

what is the electron transport chain?

Answer 7

it consists of a number of molecules mostly proteins, built into the inner membrane of the mitochondria of eukaryotic cells

electrons removed from glucose are shuttled by NAHD to the higher energy end of the ETC and at the lower energy end O2 captures these electrons along with H+, forming water

exergonic rxn

Question 8

what is the path of an electron during cellular respiration?

Answer 8

glucose –> NADH –> ETC –> oxygen

Question 9

what are the stages of cellular respiration?

Answer 9

1) glycolysis
2) pyruvate oxidation/citric acid cycle
3) oxidative phosphorylation

Question 10

where does glycolysis occur?

Answer 10

cytosol

breaks down glucose into two molecules of pyruvate

pyruvate then enters the mitochondrion and is oxidized to a acetyl CoA

acetyl CoA enters citric acid cycle where the breakdown of glucose to CO2 is competed

(in prokaryotic cells this happens in the cytosol too)

Question 11

what is oxidative phosphorylation?

Answer 11

th energy released at each step of the chain in the formation of NADH and then the ETC and formation of water is stored in a form the mitochondria can use to make ATP from ADP - this mode of ATP synthesis is called oxidative phosphorylation because it is powered by the red reaction of the electron transport chain

Question 12

what is substrate level phosphorylation?

Answer 12

when ATP is directly formed in a few reactions of glycolysiss and the citric acid cycle when an enzyme transfers a phosphate group from a substrate to ADP

substrate = m-c generated as intermediate during catabolism of glucose

Question 13

glycolysis

Answer 13

• can occur with or without oxygen!
• no CO2 released, # of carbon is conserved!
• substrate-level phosphorylation
• energy investment phase (-2ATP) and energy payoff phase (+4ATP, +4NADH)
• net: 2 ATP, 2 NADH/glucose

glucose –> 2pyruvate + 2H2O

if O2 is present, pyruvate oxidation, citric acid cycle, and oxidative phosphorylation can happen`

Question 14

what is pyruvate oxidation?

Answer 14

1) pyruvate enters mitochondria via active transport on carrier protein
2) carboxyl group of pyruvate turns into CO2
3) NAD+ –> NADH
4) Acetyl CoA (goes into Krebb’s)

exergonic reactiion
occurs in mitochondria

Question 15

what is the citric acid cycle?

Answer 15

net/glucose: 6NADH, 2FADH2, 2ATP, 4CO2 released

occurs in the presence of O2 
happens in mitochondrial matrix
All carbons from glucose are lost as CO2
acetyl CoA enters Krebb's cycle 
ATP made through substrate-level phosphorylation

Question 16

where is the electron transport chain?

Answer 16

inner membrane of the mitochondria
(in plasma membrane of prokaryotic cells)

inner membrane is folded to form cristae to increase SA providing space for thousands of ETC

Question 17

what is the ETC?

Answer 17

most components of the chain are proteins which exist in multi protein complexes

prosthetic groups (nonprotein components) are tightly bound to these proteins to aid in catalytic functions of certain enzymes

Multiprotein complexes in the inner membrane of the mitochondrion alternate accepting and donating electrons

Electrons lose free energy as they go down the ETC and are finally passed to O2, forming H2O

This energy is used to pump H+ across the membrane

Electrons are passed through a number of proteins including cytochromes, eventually reaching to O2, forming H2O. With each electron transfer, H+ is pumped across the membrane.

H+ moves back across the membrane from inter membrane space to mitochondrial matrix, passing through ATP synthase, which uses the exergonic flow of H+ to drive phosphorylation of ATP (chemosis)

Question 18

what is oxidative phosphorylation?

Answer 18

Couples electron transport to ATP synthesis

Question 19

what is the proton-motive?

Answer 19

The H+ gradient in ATP synthase is referred to as a proton-motive force, emphasizing its capacity to do work

Question 20

what is the energy flow of cellular respiration?

Answer 20

glucose –> NADH/FADH2 –> ETC –>proton-motive force –> ATP

Question 21

what is fermentation?

Answer 21

Redox reactions that regenerate NAD+
occurs in cytosol
2ATP/glucose

Coupled with glycolysis, cells are able to produce ATP without the use of oxygen

Pyruvate (or a derivative) acts as the final electron acceptor - it’s reduced!

glycolysis –> pyruvate then NADH is turned into NAD+ and lactate and ethanol are produced

the NAD+ then cycles back into glycolysis to form NADH and ATPg

Question 22

what is feedback regulation?

Answer 22

The most common mechanism for metabolic control

Intermediates of the pathways can inhibit glycolysis

Control by regulating the activity of enzymes at strategic points in the catabolic pathway

AMP (means low ATP) with activate glycolysis