Figure 2.18. Copyright © 2010 Pearson Education, Inc. Collision Theory The collision theory states...

Figure 2.18

Copyright © 2010 Pearson Education, Inc.

Collision Theory

The collision theory states that chemical reactions can occur when atoms, ions, and molecules collide

Activation energy is the amount of energy needed for them to collide ‘hard’ enough to disrupt electronic configurations and produce a chemical reaction

Reaction rate is the frequency of collisions with enough energy to bring about a reaction.

Reaction rate can be increased by enzymes or by increasing temperature or pressure

Copyright © 2010 Pearson Education, Inc.Figure 5.4a

The Mechanism of Enzymatic Action

Copyright © 2010 Pearson Education, Inc.Figure 5.7a–b

Enzyme Inhibitors: Competitive Inhibition


Enzyme Inhibitors: Competitive Inhibition Example-Sulfa drugs (sulfonamides) Discovered in the 1930s


Oxidation-Reduction Reactions

Oxidation: Removal of electrons. The general process of electron donation to an electron acceptor is also referred to as oxidation even though the electron acceptor may not be oxygen.

Reduction: Gain of electrons Redox reaction: An oxidation reaction paired with a

reduction reaction

Copyright © 2010 Pearson Education, Inc.Figure 5.9

Oxidation-Reduction


The Generation of ATP

ATP is generated by the phosphorylation of ADP


3 Ways ATP is Produced in Living Cells

1. Substrate-Level Phosphorylation. Occurs during glycolysis (or alternate pathway) during

a. Fermentation (in Microbes and our own skeletal muscle cells and brain Cells)

b. Respiration: Glycolysis and Krebs Cycle 2. Oxidative Phosphorylation

Occurs during respiratory e- transport chains (aerobic or anaerobic)3. Photophosphorylation. Occurs during photosynthesis


Substrate-Level Phosphorylation

A chemical reaction where a phosphate group is transferred from one molecule to ADP. This requires a specific enzyme that can transfer the phosphate from this specific molecule to ADP.

This is how the process of FERMENTATION produces ATP.


Oxidative Phosphorylation

Energy released from transfer of electrons (oxidation) of one compound to another (reduction) is used to generate ATP in the electron transport chain

An electron transport chain(ETC) couples a chemical reaction between an electron donor (such as NADH) and an electron acceptor (such as O2) to the transfer of H+ ions across a membrane, through a set of mediating biochemical reactions. http://en.wikipedia.org/wiki/Electron_transport_chain


Photophosphorylation

Light causes chlorophyll to give up electrons. The electrons go through a process similar to what happens during respiration (an electron transport chain and chemiosmosis). This process releases energy used to bond a phosphate to ADP producing ATP.

The ATP produced is used to produce food molecules (sugars-glucose).


Glycolysis

The oxidation of glucose to pyruvic acid produces ATP and NADH


Representative Biological Oxidation

Copyright © 2010 Pearson Education, Inc.Figure 5.12, steps 1–5

Preparatory Stage of Glycolysis

2 ATP are used Glucose is split to form 2 glucose-3-phosphate

Copyright © 2010 Pearson Education, Inc.Figure 5.12, steps 6–10

Energy-Conserving Stage of Glycolysis

2 glucose-3-phosphate oxidized to 2 pyruvic acid 4 ATP produced 2 NADH produced


Preparatory Step Intermediate between Glycolysis and Krebs Cycle Pyruvic acid (from glycolysis) is oxidized and

decarboyxlated


The Krebs Cycle


Chemiosmotic Generation of ATP


Pathway Eukaryote Prokaryote

Glycolysis Cytoplasm Cytoplasm

Intermediate step Cytoplasm Cytoplasm

Krebs cycle Mitochondrial matrix Cytoplasm

ETC Mitochondrial inner membrane Plasma membrane

Comparing Eukaryotic and Prokaryotic Cellular Location of Catabolic Processes


A Summary of Respiration

Aerobic respiration: The final electron acceptor in the electron transport chain is molecular oxygen (O2).

Anaerobic respiration: The final electron acceptor in the electron transport chain is not O2. Yields less energy than aerobic respiration because only part of the Krebs cycles operates under anaerobic conditions.


Electron Acceptor Products

NO3– NO2

–, N2 + H2O

SO4– H2S + H2O

CO32 – CH4 + H2O

Anaerobic Respiration


Fermentation

FERMENTATION Scientific definition: Releases energy from oxidation of organic molecules Does not require oxygen Does not use the Krebs cycle or ETC Uses an organic molecule as the final electron acceptor


Types of Fermentation


Catabolism of Organic Food Molecules


Photosynthesis

Conversion of light energy into chemical energy (ATP) and nutrients (glucose)

Overall Summary Reaction? Compare and Contrast: Oxidative Phosphorylation

and Photophosphorylation.


Photosynthesis

Oxygenic:

Anoxygenic:

2 2

6 12 6 2 2

6 CO + 12 H O + Light energy

C H O + 6 H O + 6 O

2 2

6 12 6 2

6 CO + 12 H S + Light energy

C H O + 6 H O + 12 S


Nutritional Type Energy Source Carbon Source Example

Photoautotroph Light CO2 Oxygenic: Cyanobacteria plantsAnoxygenic: Green, purple bacteria

Photoheterotroph Light Organic compounds

Green, purple nonsulfur bacteria

Chemoautotroph Chemical CO2 Iron-oxidizing bacteria

Chemoheterotroph Chemical Organic compounds

Fermentative bacteriaAnimals, protozoa, fungi, bacteria.

Metabolic Diversity among Organisms


Amphibolic Pathways

Figure 2.18. Copyright © 2010 Pearson Education, Inc. Collision Theory The collision theory states...

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