Micro Chapter 5: Microbial Nutrition and Metabolism

the sum of all the chemical processes carried out by living organisms

reactions that require energy to synthesize complex molecules from simpler ones

needed for growth, reproduction, and repair of cellular structures

reactions that release energy by breaking complex molecules into simpler ones that can then be reused as building blocks

provides an organism with energy for its life processes, including movement, transport, and the synthesis of complex molecules (anabolism)

allows energy to be captured in high-energy bonds in ATP and similar molecules

found in all catabolic reactions

the loss or removal of electons

the gain of electrons

self-feeding

other-feeding

use carbon dioxide to synthesize organic molecules

photosynthesis

obtain energy from light

obtain energy from oxidizing simple inorganic substances such as sulfides and nitrites

get their carbon from ready-made organic molecules, which they obtain from other organisms, living or dead

obtain chemical energy from light

obtain chemical energy from breaking down ready-made organic compounds

oxidation of glucose to pyruvic acid

conversion of pyruvic acid to ethyl alcohol, lactic acid, or other organic compounds

oxidation of pyruvic acid to carbon dioxide and water

C₆H₁₂O₆ + 6O₂ -----> 6CO₂ + 6H₂O + energy

6CO₂ + 6H₂O -------> C₆H₁₂O₆ + 6O₂

a series of chemical reactions in which the product of one reaction serves as the substrate from the next

capture energy in a form cells can use

make the complex molecules that form the structure of cells, enzymes, and other molecules that control cells

ATP molecules

act as catalysts in biochemical reactions

energy required to start a reaction

cells would raise the temperature enough to denature proteins and evaporate liquids

binding site

the substance on which the enzyme acts

catalyze only one type of reaction, and most act on only one particular substrate

intracellular enzymes, act within the cell that produced them

extracellular enzymes, are synthesized in a cell but cross the cell membrane to act in the periplasmic space or in the cell's immediate environment

protein portion of an enzyme

a nonprotein organic molecule bound to or loosely associated with an enzyme

vitamins

pantothenic acid

niacin

usually an inorganic ion, such as magnesium, zinc, or manganese

competes with the substrate from the active site

attach to the enzyme at an allosteric site,which is a site other than the active site

a kind of reversible non-competitive inhibition that regulates the rate of many metabolic pathways

• 1) Temperature
• 2) pH
• 3) concentrations of substrate, product, and enzyme

the rate at which an enzyme catalyzes a reaction

• 1) Substrate-level phosphorylation (the transfer of phosphte froups from ATPs to glucose)
• 2)Breaking of a six-carbon molecule (glucose) into two three-carbon molecules
• 3)The transfer of two electrons to the coenzyme NAD
• 4)The capture of energy in ATP

the addition of a phosphate group to a molecule, often from ATP

two molecules of pyruvic acid and two molecules of reduced NAD (NADH)

pentose phosphate pathway

pyruvic acid is subsequently metabolized in the absence of oxygen

pyruvic acid is converted directly to lactic acid, using electrons from reduced NAD

used in making cheeses

carbon dioxide is released from pyruvic acid to form the intermediate acetaldehyde, which is quickly reduced to ethyl alcohol by electrons from reduced NAD

metabolizes two-carbon units called acetyl groups to CO₂ and H₂O

acetyl CoA

• -the oxidation of carbon
• -the transfer of electrons to coenzymes
• -the substrate-level energy capture

the process leading to the transfer from substrate to O₂

• 1) accepting electrons from an electron donor and transferring them to an electron acceptor
• 2) conserving for ATP synthesis some of the energy released during the electron transfer

energy is captured in high-energy bonds as P_i combines with ADP to form ATP

ADP is converted to ATP by a large ATP-synthesizing complex called ATP synthase

a major contribution to the understanding of how ATP is formed during the electron transport

34 ATPs

19 times!

• Light strikes the freen pigment chlorophyll a in thylakoids of chloroplasts. Electrons in the chlorophyll become excited (raised to a higher energy level).
• Products= ATP and NADPH

occurs in the stroma of chloroplasts

can yield enegy or building blocks for synthetic reactions

form channels through the outer membrane

the ability of an organism to emit light (appears to be a by-product of aerobic metabolism)