Biology: Chapter 9: Catabolism

Front 1

How does most life on earth acquire energy?

Back 1

Photosynthesis (directly or indirectly) followed by cellular respiration. These processes form a cycle on which life depends.

Front 2

Respiration

Back 2

Complete breakdown of organic fuel, produces more ATP.

Front 3

Fermentation

Back 3

Incomplete breakdown of organic fuel, produces less ATP.

Front 4

What happens to the organic fuel in catabolism?

Back 4

It is oxidized.

Front 5

Oxidation

Back 5

Loss of electrons.

Front 6

Reduction

Back 6

Gaining of electrons.

Front 7

What do redox reactions involve?

Back 7

A transfer of electrons.

In the picture, the energy is formed from the potential energy of the electrons.

Front 8

What stores energy?

Back 8

Electrons
Fats
Carbs
Fats store more energy than carbs.

Front 9

Is ATP synthesis exergonic or endergonic?

Back 9

Endergonic, it requires energy to make ATP. The energy comes from the substrate.

Front 10

Is cellular respiration exergonic or endergonic?

Back 10

Exergonic.

Front 11

Before H's are transferred... where are they first transferred to?

Back 11

Coenzymes.

Front 12

Coenzymes

Back 12

Small molecule required by some enzymes.
Like the substrate:
--Bind to the enzyme
--Chemically altered
Serve as 'molecular handles'
Ex: NAD+, FAD, Coenzyme A

Front 13

Main coenzyme is NAD+ (nicotinamide adenine dinucleotide)

Back 13

carries hydrogen
-- specifically: 2e− + 1 p+
reduced form is: NADH
KEY: little energy is lost!
a "dinucleotide‟

Front 14

Cellular Respiration overview

Back 14

glucose has HIGH ENERGY electrons
glucose is oxidized by oxygen
e−+ p+ (hydrogen) are transferred to oxygen
H‟s FIRST transferred to NAD+ making NADH

Front 15

Four Stages of Cellular Respiration

Back 15

1) Glycolysis
2) Pyruvate Oxidation
3) Citric Acid Cycle
4) Electron Transport

Front 16

Overview of Stages 1-4

Back 16

(1-3) catabolize glucose through oxidations, makes a little ATP
-- many NAD+s are reduced
(4) electrons are transferred, makes most ATP
-- NADHs are oxidized

Front 17

In Stage 1: Glycolysis

Back 17

10 step pathway
Begins in cytosol
Breaks glucose into 2 smaller molecules.

Front 18

Energy Investment Phase (uses ATP): Steps 1-5 in Glycolysis

Back 18

Step 1: Two reactants: glucose and ATP. Product: ADP.
Step 2: Converts glucose to fructose.
Step 3: Use ATP to phosphorylate the sugar. Phosphofructosekinate (PFK)
Step 4: Glycolysis (breaks sugar into DHP and G-3-P)
Step 5: Converted DHP into G-3-P so there is now 2.

Front 19

Energy Payoff (creates ATP): Steps 6-10 in Glycolysis

Back 19

Step 6: 2 G-3-P + 2NAD+ -> 2NADH + 2H+
G-3-P is oxidized.
Step 7: Makes ATP
Step 8: Rearranging molecule
Step 9: Catabolizes
Step 10: Makes more ATP.
Final product: pyruvate.

Front 20

Substrate-level phosphorylation

Back 20

Making ATP by transferring a phosphate from an organic substrate, to ADP.

Front 21

Tabulation of glycolysis

Back 21

2 Pyruvate
4 ATP per glucose
2 produced per G-3-P
Net: 2 ATP per glucose
Other products: 2 NADH per glucose

Front 22

In Stage 2: Pyruvate oxidation

Back 22

Pyruvate is transported into the mitochondrial matrix.
Three step pathway.
Catalyzed by a complex of enzymes.
Coenzyme A receives the acetyl group.

Front 23

In Stage 3: Citric Acid Cycle

Back 23

Eight Step Pathway
A Cycle
Completes glucose catabolism
Hans Krebs

Front 24

Citric Acid Cycle (cont.)

Back 24

Acetyl CoA + oxaloacetate -> citrate
made 4 ATP, 10 NADH, 2 FADH2
1 ATP per cycle
-686 kcal/mol
Most of the harvested energy from glucose in NADH now
NADH is oxidized by an electron transport chain

Front 25

ATP synthase

Back 25

Makes ATP. Embedded into the membrane of the mitochondria. Power provided by proton gradient.

Front 26

In Stage 4: Electron Transport

Back 26

A 'chain' of proteins within the inner membrane
Includes 4 complexes
Several 'cytochrome proteins'
Chain preforms a series of redox reactions: electron transport chain

Front 27

Electron Transport (cont.)

Back 27

The chain is oxidized by oxygen
Flavoprotein in complex I -> cytochromin 3 in complex IV

Front 28

Electron Transport (cont.):
The last redox reaction (for 2 NADH):
4e- + 4H+ + O2 -→ 2H20

Back 28

Energy poor, greater electronegativity.
Consumed ALL reactants.
Generated: both chemical byproducts, 4ATP per glucose
Electrons are at an energy minimum in water.

Front 29

What do the chain proteins transfer?

Back 29

Protons, across the inner membrane, creating a proton gradient (energy). Use the energy of redox.
Used to make ATP by the enzyme ATP synthase.

Front 30

Chemiosmosis

Back 30

Using a proton gradient to make ATP.

Front 31

Oxidative phosphorylation

Back 31

Making ATP from ADP and Pi, powered by redox reactions of an electron transport chain.

Front 32

Electron transport chain + chemiosmosis = ?

Back 32

Oxidative phosphorylation

Front 33

Path of Energy Flow

Back 33

Front 34

Final ATP tabulation

Back 34

Glycolysis: 2
Citric acid cycle: 2
Oxidation phosphorylation: 26
Total: 30

Front 35

How efficient is cellular respiration?

Back 35

32%-40%. Pretty efficient.

Front 36

What if the oxidizing agent 02 is unavailable?

Back 36

They can't get rid of electrons.
1) Chain fills with e-, stops functioning
2) NADH has no oxidizing agent. Can't make NAD+, becomes depleted
3) The solution is fermentation

Front 37

Two types of fermentation

Back 37

Lactic acid, and alcohol fermentation.

Front 38

Fermentation

Back 38

A catabolism without O2 (incomplete)
Derive ATP from glycolysis only
Oxidize NADH using pyruvate
Microorganisms do this in an oxygen deprived environment.
We do this in our muscles.

Front 39

What runs cellular respiration?

Back 39

Bacteria and yeast

Front 40

What fuels cellular respiration?

Back 40

Carbs- fructose, sucrose, maltose, lactose, starch
Fats- fatty acids, glycerol
Proteins- amino acids

Front 41

How is cellular respiration regulated?

Back 41

Through the enzyme PFK (phosphofructosekinase).

Front 42

PFK

Back 42

Catalyzes the third step of glycolysis
Has allosteric sites
Can be positively or negatively regulated
Controlled by feedback inhibition

Front 43

What can PFK be shut off by and promoted by?

Back 43

Shut off by: ATP & citrate
Promoted by: ADP & AMP

Front 44

Coenzymes may be made from __________. An example is NAD+, which is made from nicotinic acid or niacin.

Back 44

Vitamins.

Front 45

What coenzyme is used as an oxidizing agent during the first three stages of cellular respiration?

Back 45

NAD+

Front 46

How many different enzymes run the citric acid cycle?

Back 46

8

Front 47

Which of the first three stages of cellular respiration does NOT produce ATP?

Back 47

Pyruvate oxidation.

Front 48

Which of the first three stages of cellular respiration does not produce NADH?

Back 48

All produce NADH.

Front 49

Enzymes or other proteins involved in a metabolic pathway may be LOCALIZED so that they function more efficiently or in specialized capacities. The following are examples from cellular respiration:

Back 49

-the enzymes of pyruvate oxidation are bound together into a multi-enzyme
complex
-citric acid cycle enzymes are located in the mitochondrial matrix
-electron transport chain proteins and ATP synthase are embedded in the inner membrane of the mitochondria

Front 50

What type of gradient is created across the mitochondrial inner membrane during the last stage of cellular respiration?

Back 50

Proton gradient.

Front 51

In which subcellular compartment specifically are protons concentrated during cellular respiration?

Back 51

Mitochondrial intermembrane space. A mitochondrion only has TWO membranes and TWO aqueous compartments.

Front 52

The TRANSFORMATION of the energy of a proton gradient into the energy of ATP is a demonstration of the _______

Back 52

First law of thermodynamics.

Front 53

In addition to being an enzyme, ATP synthase is a _____.

Back 53

Membrane transport protein.

Front 54

The following reaction occurs during cellular respiration:
1, 3-bisphosphoglycerate + ADP → 3-phosphoglycerate + ATP

The reaction shown occurs _____.

Back 54

During glycolysis.

Front 55

This reaction is an example of _____.

Back 55

Substrate level phosphorylation.

Front 56

ATP is made in the above reaction because energy is provided by _____.

Back 56

1, 3-bisphosphoglycerate.

Front 57

The synthesis of ATP by the enzyme ATP synthase works differently than the reaction above, and involves the flow of protons across the mitochondrial inner membrane THROUGH the enzyme itself. This movement of protons is best termed as _____.

Back 57

Facilitated diffusion.