Chapter 5 Microbial Metabolism

A sequence of chemical reactions in a cell 

Metabolic pathway

collision energy needed for a chemical rxn

Activation energy

Frequency of collisions with enough energy to bring about a reaction

Reaction rate

Biological catalysts; not used up in a rxn; lower activation energy→increases rxn rate

Enzymes

Non-protein component of enzymes that accept or donate atoms/electrons. May help enzyme bind to substrate

Cofactor

Organic cofactor derived from vitamins. some are metal ions

Coenzyme

Directly bind to enzyme at active site, block binding of substrate

Competitive inhibition

Bind at another part of enzyme that isn’t active site, but changes the shape of site which prevents substrate binding

Noncompetitive Inhibition

End product of a metabolic pathway allosterically inhibits first enzyme of pathway

Feedback inhibition

Loss of electrons

Oxidation

Gain of electrons

Reduction

An oxidation rxn paired with a reduction reaction, which are always coupled

Redox reactions

Another name for biological oxidations, those hydrogens are passed on to coenzymes

Dehydrogenations

Oxygen is the final electron acceptor in ETC

Aerobic respiration

Inorganic compound is the final electron acceptor in ETC, yields less energy

Anaerobic respiration 

Splitting of sugar. Oxidation of glucose to 2 pyruvic acids. Does not require oxygen. Produces 2 ATP and 2 NADH

Glycolysis

Pyruvic acid is oxidized (forms NADH) and decarboxylated (releases CO2). CoA carries the 2C chain to Krebs cycle (acetyl CoA)

Intermediate step

2 major reactions happen:

decarboxylation (remove carbon) → released as CO2

Oxidation (remove e-/H+) → produce NADH and FADH2

Krebs Cycle

For every 2 molecules of Acetyl CoA…

4; CO2

6; NADH

2; FADH2

2'; ATP

A series of carrier molecules that are oxidized and reduced as electrons are passed down the chain (from higher energy to lower energy molecules, to final e^- acceptor → stepwise- save energy)

Electron transport chain

During ETC, some carrier molecules pick up H+ and pump it across the membrane, which drives what?

Electrochemical gradient of H+ across membrane

Where does ETC happen in prokaryotes?

plasma membrane

Where does ETC happen in eukaryotes?

Inner membrane of mitochondria

Buildup of H+ across membrane; when H+ flows through, energy used to make ATP

ATP synthase

How many ATPs are produced in prokaryotes from carbohydrate catabolism?

38

How many ATPs are produced in eukaryotes from carbohydrate catabolism?

36 

In eukaryotes and prokaryotes, glycolysis happens where?

Cytoplasm

Where does Kreb’s cycle happen in eukaryotes?

Mitochondrial matrix

Where does Kreb’s cycle happen in prokaryotes?

Cytoplasm

Goes through glycolysis; does not need oxygen; no Krebs or ETC; uses organic molecule as final electron acceptor; produces 1-2 ATP quickly

Fermentation

What is second step of fermentation after glycolysis?

Recycles NAD+ to continue glycolysis

Produces lactic acid

Lactic Acid fermentation

Produces ethanol + CO2

Alcohol fermentation

glycerol and fatty acids get metabolized by lipase through beta-oxidation

Lipid catabolism

amino acids get converted by protease through deamination, decarboxylation, dehydrogenation, or desulfurization

Protein catabolism

complex polysaccharide made for long-term energy storage

Glycogen

Complex polysaccharide for cell structure

Peptidoglycan

energy from light feeds into ETC (in membranes of chloroplasts)

Light-dependent reaction

Fixing carbon into organic molecules

Carbon fixation

Energy source for phototrophs

Light

Energy source of chemotrophs

inorganic or organic compounds

Carbon source of autotrophs

CO2

Carbon source of heterotrophs

organic carbon source

Use organic carbon source; energy and carbon source is same → glucose. Most medically-important microbes

Chemoheterotroph

Uses CO2 as a carbon source. Energy source is inorganic compounds

Chemoautotroph

Use light as energy source and CO2 as carbon source

Photoautotroph

Use light as energy and organic carbon source

Photoheterotroph