Microbial Metabolism

Energy

Metabolism the chemical processes occurring within a living cell or organism that allow it to get and use energy. anabolic (building up or synthetic) catabolic (tearing down or degradative)

Anaerobic metabolism - occurs without oxygen. Aerobic metabolism - requires free oxygen (which functions as the final electron acceptor during the generation of ATP).

Metabolic pathways 1. Substrates enter the reaction 2. End products remain after the reaction 3. In some cases intermediates are formed

Energy - the ability to do work Types include: 1. Kinetic - energy that is associated with motion 2. Potential - energy that is stored as is available for use. Chemical potential energy is stored in the bond between atoms of a molecule or compound. 3. Thermal- heat energy

LAWS OF THERMODYNAMICS

The First Law of Thermodynamics states that energy can neither by created or destroyed but it can change from one form to another The Second Law of Thermodynamics states that during transformations, some or all of the energy is spontaneously converted from more ordered forms to less ordered forms (thus entropy or disorder increases).

Energy Transfer

Entropy

The ultimate source of energy for life on Earth is the Sun. Energy transfer is not complete (most is lost as heat remember entropy increases) from one tropic (feeding) level to another. Thus energy is a limiting resource

Energy flow

ATP (adenosine triphosphate) the universal energy currency of all cells energy is stored within the bonds of this energy intermediate (ADP + Pi ATP) The formation of ATP occurs by a process known as phosphorylation (oxidative or substrate-level)

Enzymes Part I Organic catalysts [a substance which speeds up a reaction that would normally occur and that is not used up in the reaction)]. Nearly all enzymes are proteins Work by lowering the activation energy required for a reaction to proceed Promotes a reaction by serving as a physical site upon which one or more substrates can be positioned for various activities

Enzymes Part II Each enzyme is associated with a specific substrate and thus we have a “lock and key” mechanism. Can lose their catalytic abilities if they are denatured (the shape changes and they no longer “fit” the substrate). So they are limited by factors e.g., temperature and pH Some are exoenzymes that catalyze reactions outside of the cell and other enzymes are endoenzymes that catalyze reactions inside of the cell. Some enzymes are constitutive which are always present, and others are induced which are not always present.

Respiration and Fermentation

Aerobic Respiration Occurs in the presence of Oxygen Oxygen acts as the final electron acceptor The cpe in glucose is transferred into cpe in ATP The glucose is dismantled during the steps of aerobic respiration: glycolysis, prep for the Kreb’s cycle, Kreb’s cycle, and ETS Carbon and oxygen are lost as CO2 The hydrogens are used in the ETS for ATP formation

Glycolysis

Prep for the Kreb’s cycle

Kreb’s cycle

Electron Transport System

http://video. google. com/videosearch http://video.google.com/videosearch?hl=en&q=oxidation%20reduction%20reaction&gbv=2&ie=UTF-8&sa=N&tab=iv#q=glycolysis&hl=en&emb=0 http://video.google.com/videosearch?q=cellular+respiration+animation&www_google_domain=www.google.com&hl=en&emb=0&aq=2&oq=cellular+respiration#

Fermentation

http://video. google. com/videosearch http://video.google.com/videosearch?q=fermentation&hl=en&emb=0&aq=f#q=fermentation+animation&hl=en&emb=0&start=20

Photosynthesis The ultimate source of biological energy - the Sun Plants, some protists, and some prokaryotes capture sunlight energy with photosynthetic pigments 1. Chlorophyll which is found in chloroplasts is the most common pigment. It appears green because it absorbs light of colors other than green and allows green light to be reflected and thus detected by other organisms. 2. There are also accessory photosynthetic pigments that make plants appear yellow and orange. The primary photosynthetic organs of plants are leaves ( know thylakoids, stroma, granuum, and inner and outer membranes)

Chloroplast

Thylakoid

Photosynthesis: 12H2O +6CO2 sunlight energy> 6O2 +C6H12O6 + 6H2O

Light dependent reactions Light absorption. Photochemical reactions involve the trapping of light. Light energy excites pigment molecules and causes an electron to be freed which begins moving through an ETS. There are two photosystems [Photosystem I (with chlorophyll a absorbing lightwaves of 700 most efficiently; P700) and Photosystem II (also with chlorophyll a but absorbing lightwaves of 680 most efficiently; P680)] that are involved in capturing the energy and the beginning of electron transfer.

Electron transfer. The electron that is excited in Photosystem I is sent along the ETS to NADP+ and as another electron is passed to NADP+, the latter is reduced to NADPH (a coenzyme and energy intermediate) which carries electrons. Now light energy absorbed by Photosystem II is transferred into an electron thus exciting it and causing it to be sent to P700 (of Photosystem I) which can now absorb more light energy because of the replaced electron (note that Photosystem II has electrons replaced from split water molecules which also results in the formation of O2).

Light Independent Reactions Chemiosmotic synthesis of ATP. This is the final phase of energy capture and involves the movement of the hydrogen ions along a series of membrane proteins with the release of energy and finally the synthesis of ATP from ADP. Carbon fixation 1. Carbon fixation occurs when a gas (CO2) is incorporated into a solid (e.g., a carbohydrate) 2. During energy capture the energy and the hydrogen needed for carbon fixation are required. 3. Carbon fixation involving atmospheric CO2 occurs during the reactions of the Calvin-Benson Cycle

http://video. google. com/videosearch http://video.google.com/videosearch?hl=en&q=photosynthesis%20light%20absorption&ie=UTF-8&sa=N&tab=iv#q=photosynthesis+animation&hl=en&emb=0 http://video.google.com/videosearch?hl=en&q=photosynthesis%20light%20absorption&ie=UTF-8&sa=N&tab=iv#q=Calvin+Benson+cycle+animation&hl=en&emb=0

Metabolism - the chemical processes occurring within a living cell or organism. These include anabolic (building or synthetic) and catabolic (tearing apart or degradative) reactions

Energy - the ability to do work Kinetic - energy that is associated with motion Potential is energy that is stored and ready for use. Chemical potential energy is stored in the bonds between the atoms of a molecule or compound

Laws of Energy 1. The First Law of Thermodynamics states that energy can neither be created nor destroyed, but it can change from one form to another. 2. The Second Law of Thermodynamics states that during energy transformations, some or all of the energy is spontaneously converted from more ordered forms to less ordered forms (entropy or disorder increases).

The universal energy currency is ATP (adenosine triphosphate) The universal energy currency is ATP (adenosine triphosphate). Energy is stored within the bonds of the energy intermediate (know the equation associated with ATP).

Enzymes An enzyme is an organic catalyst [a substance which speeds up a reaction that would normally occur and that is not used up in the reaction)]. Nearly all enzymes are proteins Enzymes work by lowering the activation energy required for a chemical reaction to proceed (fig. 6.5) An enzyme promotes a reaction by serving as a physical site upon which one or more substrates can be positioned for various activities Each enzyme is associated with a specific substrate and thus we have a “lock and key” mechanism. Enzymes can lose their catalytic abilities if they are denatured (the shape changes and they no longer “fit” the substrate). Thus enzymes are limited by factors such as temperature and pH Some enzymes are exoenzymes that catalyze reactions outside of the cell and other enzymes are endoenzymes that catalyze reactions inside of the cell. Some enzymes are constitutive which are always present, and others are induced which are not always present.

Glycolysis

Photosynthesis