Microbio Exam 1 Week 4

Metabolism

Metabolism

all of the chemical reactions inside a cell

unifying characteristics of all cellular organisms

Catabolism

carbohydrates, lipids, and proteins are chemically broken down

energy is released and transferred to ATP

smaller biomolecules (amino acids, fatty acids, and simple sugars) are produced

Anabolism

uses energy to synthesize macromolecules that make up the cell

Oxidation Reactions

removes electrons from donor molecules leaving them oxidized

loses electrons

electron donor is substance oxidized

Reduction Reactions

add electrons to acceptor molecules leaving them reduced

gaining electrons

electron acceptor is substance reduced

Reduction Potentials and Redox Couples

substances differ in their tendency to donate or accept electrons

expressed as E0 (V)

oxygen is the bottom of the redox tower, the strongest electron acceptor of significance in nature

Common Energy Carriers

originate from B vitamin group and are derivatives of nucleotides

nicotinamide adenine dinucleotide, nicotine adenine dinucleotide, and flavin adenine dinucleotide

Why are Energy Carriers so Important?

provide energy and can be coenzymes

Coenzymes

organic helper molecules required for enzyme action

ex: NADH and ATP: provide high energy electrons or phosphate group and bind to enzymes activating them

Catalysts

speed up a chemical reaction without being permanently altered themselves

lowers the activation energy of a chemical reaction

influenced by local environmental conditions like pH, substrate concentration and temp

Glycolysis

energy investment phase

splits glucose into pyruvate

uses energy from ATP molecules, two phosphorylated 3 carbon molecules (G3P)

energy payoff is gained by oxidizing G3P to pyruvate

net gain from glucose molecule breakdown:

1. two ATP molecules

2. two NAHD molecules

3. two pyruvate molecules

Krebs Cycle/ Tricarboxylic Acid Cycle (TCA)

occurs in cytoplasm of prokaryotes

takes place in mitochondrial matrix of eukaryotes

oxidation of pyruvate to release CO2

many organisms use intermediates from krebs cycle like amino acids, fatty acids, and nucleotides as building blocks for biosynthesis

per turn of cycle:

1. two CO2

2. three NADH

3. one FADH2

4. one ATP or GTP

Cellular Respiration

overall process of catabolism from substrate breakdown to reduction of terminal electron acceptor such as O2

uses glucose to produce ATP

completes catabolism by donating electrons from NADH to ETS in a process that stores energy by pumping proteins (H+) across the membrane to generate a gradient with hydrogen ions

Oxidative Phosphorylation

hydrogen ions return to the cell via ATP synthase, driving the formation of ATP

Electron Transport System (ETS)

series of chemical reactions where electrons from NADH and FADH2 are passed rapidly from one ETS carrier to the next

in aerobic respiration: final electron acceptor is an oxygen molecule (O2) that becomes reduced to water (H2O)

in anaerobic respiration: final electron acceptor is an inorganic molecule other than oxygen, aerobically respiring bacteria switch to nitrate as the final electron acceptor and produce nitrite when oxygen levels are low

Respiration of Glucose with Oxygen

C6H12O6 + 6 H2O → 12 H2O + 6 CO2

can generate a relatively large number of ATP molecules per molecule of glucose, more than fermentation

actual number produced varies on the amount of carbon and oxygen available

Lithotrophs

an alternative route to get electrons for ETS and PMF generation

inorganic, reduced, molecules serve as electron donors instead of organic compounds

ex: ferrous iron (Fe2+), ammonium ion (NH4+), hydrogen gas (H2)

oxygen or alternative gas serves as final electron acceptor for ETS

unique energy pathway used only by some types of bacteria

Fermentation

if respiration doesn’t occur NADH must be re-oxidized to NAD+ for reuse as electron carrier for glycolysis

does not involve the ETS bc it doesn’t directly produce any additional ATP beyond that produced during glycolysis by substrate level phosphorylation

Essential Nutrients

compounds a microbe cannot make itself but must gather from its immediate environment if the cell is to grow and divide

ex: carbon, nitrogen, phosphorous, hydrogen, oxygen, sulfur, magnesium, iron, potassium, and trace elements like cobalt, copper, and zinc

Growth Factors

required by some compounds, must be added to their culture before they grow

Autotrophs

make their own carbon compounds starting with CO2

Heterotrophs

obtain carbon compounds from other organisms

Requirements for Growth

physical: ph, temperature, moisture, hydrostatic pressure, osmotic pressure, and radiation

chemical: availability of carbon, nitrogen, sulfur, phosphorous, trace elements, organic compounds, and oxygen

Psychophiles

cold loving microbes

Mesophiles

moderate temperature loving microbes

Thermophiles

heat loving microbes