Micro 276 exam 3

factors that determine ΔG (3)

1) intrinsic properties of a reaction 2) [ ]'s of reactants and products 3)environmental factors

functions of fermentation (3)

1) preserves food 2)improves digestibility 3) adds nutrients and flavors

how does aerobic benzoate catabolism work

1)enzymes remove substituents: Cl, N 2)makes catechol intermediate: benzene ring with 2 adjacent hydroxyl groups 3)ring cleaved and breaks down to pyruvate making NADH 4)acetyl coA goes to TCA cycle and respiration

structure of NADH

ADP and nicotinamide at end instead of 3rd phosphate group

Acetic acid fermentation is produced from

Acetobacter who converts alcohol to acetic acid in the presence of oxygen (e.g.,vinegar).

oxidized form of NADH

NAD+

reduced form of NADH

NADH

examples of energy carriers

NADH, FADH2, ATP

function of pyruvate dehydrogenase complex

removes co2 from pyruvate making acetyl coA

main products of PPP

ribulose 5 phosphate 1 ATP NADPH NOT NADH

amphibolic pathways include enzymes that

run in either direction in which is determined by key enzymes that operate only in catabolic or anabolic direction

yeasts are

single celled proteins

why does glycolysis need to be regulated?

so that reactions go forward only when cell needs energy not when cell is trying to synthesize glucose

why are aromatic molecules more difficult to digest than sugars

stability of ring structures

environmental factors that determines ΔG

temperature, pressure, ionic strength (salt concentrations)

standard conditions for ΔG^o

temperature: 298 K pressure: 1 atm concentrations: 1 M

conditions for ΔGo′ in living cells

temperature: 298 K pressure: 1 atm concentrations: 1 M ph: 7

under what conditions cells will favor the ED pathway

the ED pathway is common among facultative anaerobes and even more common among aerobes

entropy is based on

the number of states of a system such as the number of possible conformations

if ΔG> 0

the reaction will go in reverse

The random distribution of molecules at uniform concentration represents

the state of maximum entropy

Ethanolic fermentation contributes

to the production of ethanol and co2 without lactic acid

lactic acid fermentation: what gets converted, microbes involved, food made

turns glucose to lactic acid lactic acid bacteria example: lactobacillus, streptococcus kimchi and sauerkraut

how is nori made?

use red algae (Porphya) which are cultured in enclosed tanks distributed on nets in estuaries cultures grow until hang heavy from the nets harvest for processing into sheets sheets get toasted and turns green

Martin Kamen experiment of TCA cycle

used trace isotopes: 14 C to figure out which 2 C's of acetyl coA removed as CO2

examples of food made from ethanolic fermentation by yeast

wines, beers, vodka, whiskey, brandy, and bread

chemotrophy

yields energy from electron transfer between chemicals.

phototrophy

yields energy from light absorption

Gibbs free energy change equation

ΔG= ΔH−TΔS

Bacteria and archaea use 3 main routes to catabolize glucose

1) Embden-Meyerhof-Parnas (EMP) pathway aka glycolysis 2) Entner-Doudoroff (ED) pathway 3) Pentose phosphate pathway (PPP)

how does Anaerobic benzoate catabolism work

1) benzene and naphthalene incorporates co2 = carboxylate group of benzene 2) use ATP because CO2 is a weak oxidant 3)carboxylate + HS CoA = benzyl coA 4)NADH reduces to hydrogenate ring breaking aromaticity

3 main catabolic pathways

1. Fermentation 2. Respiration 3.Photoheterotrophy

input of EMP pathway

2 ATP

Overall reduction of NAD+ consumes

2 H atoms to make NADH.

NADH carries ___ times as much energy as ATP

2-3

summarize Krebs cycle

2-carbon acetyl results in outputs of 2 CO2, 3 NADH, 1 FADH2, and 1 ATP (or GTP) molecules made by substrate-level phosphorylation

output of EMP pathway

4ATP molecules, 2 NADH molecules, and 2 pyruvates

amphibolic

Catabolism provides energy for anabolism, and pathways which involve both destructive and constructive metabolism

Initial step of amino acid degradation is one of 2 kinds:

Decarboxylation (removals of co2) = amine Deamination (removal of nh3) = carboxylic acid that get degraded by TCA cycle

How does ED and EMP differ in ATP yield?

EMP: hydrolyzes two ATP to phosphorylate glucose twice and recovers four ATP by metabolizing two triose-phosphates through lower glycolysis, yielding two ATP total ED: invests one ATP in phosphorylation and recovers two (glucose is cleaved into only one fermentable product) yielding one ATP per glucose

enzymes unique to EMP and ED

EMP: pfk ED: edd and eda

under what conditions cells will favor the EMP pathway

Energy-deprived anaerobes overwhelmingly rely upon the higher ATP yield of the EMP pathway

why is magnesium an essential nutrient for all living cells?

Most enzyme binding sites forATP actually bind Mg 2+-ATP

energy carriers

Molecules that gain/release small amounts of energy in reversible reactions

Explain how genomic studies have contributed to our understanding of microbial catabolism

Prokaryotic glycolytic strategy correlates with the availability of non- glycolytic energy sources genomes sequence of microbiome determines ability to digest common foods

bacterium involved in propionic acid fermentation

Propionibacterium, Lactobacillus, Streptococcus

cofactor

a substance (other than the substrate) whose presence is essential for the activity of an enzyme.

photoautotrophy

absorption with CO2 fixation

photoheterotrophy

absorption without CO2 fixation

how does fermentation preserve food?

accumulated waste products of fermentation inhibit the growth of most organisms

aromatic compounds are catabolized to

acetate through different pathways such as the catechol pathway

Competitive inhibitors bind to the _______ site of an enzyme, while noncompetitive inhibitors bind to an ___________ site.

active; allosteric

ATP stands for

adenosine triphosphate

why is glucose oxidized in a series of steps instead of a single step?

all energy released at once would dissipate at heat without building biomass which is inefficient for cell function and biosynthesis

EMP and ED share

all reactions of lower glycolysis: G3P to pyruvate

holoenzyme

apoenzyme + cofactor

key feature of NADH

aromatic

ATP contains

base (adenine) sugar(ribose) three phosphates

why can't most bacteria be eaten?

because small cells contain high proportions of DNA/ RNA in which nucleic acids contain purines that humans digest and convert into uric acid which can't be metabolized because humans lack urate oxidase build of uric acid causes gout and kidney stones

how does fermentation improve digestibility?

break downs fibrous macromolecules and tenderizes producers making it easier for humans to digest

how do microbes compensate for the low efficiency of fermentation

by consuming large quantities of substrate and excreting large quantities of products

substrates for microbial metabolism

carbohydrates, lipids, peptides, aromatic compounds

photoheteroptrophy

catabolism is conducted by light catalyzation

aerobic benzoate catabolism

catabolism via sequential oxidation steps needing ETC that terminates w O2

sugar and sugar derivatives like amines and acids are

catabolized to pyruvate

propionic fermentation is responsible for

characteristic flavor of Swiss cheese

categorize microbes based on how they acquire energy (3)

chemotrophy phototrophy syntrophy

Respiration

complete breakdown of organic molecules with electron transfer to a terminal electron acceptor such as O2

Spirulina

cyanobacteria classified as a single celled protein or edible microbe of high food value

identify different types of fermented foods

dairy: cheese, yogurt soy: miso, tempeh vegetative products: sauerkrat, kimchi coffee, chocolate, alcohol

Chemolithotrophy

energy from inorganic compounds rock eating"

Chemoorganotrophy

energy from organic compounds

Δ H represents

enthalpy

Δ S represents

entropy

Yeasts are the predominant organisms for

ethanolic fermentation

Pyruvate and other intermediary products of sugar catabolism are

fermented of further catabolized into CO2 an H2O via TCA cycle

lignin

forms key structural support of trees and woody stems

acetic acid fermentation is produced from

from the acetic acid bacteria (AAB) species.

lipids and amino acid are catabolized to

glycerol and acetate

enthalpy

heat energy absorbed or released as reactants become products at constant pressure

Apoenzyme

inactive enzyme that is activated by cofactor

regulation of pyruvate dehydrogenase complex

induced when carbon sources are plentiful and repressed under starvation and low oxygen

2 ways glycerol enters catabolism

intermediate in glycolysis broken down into acetate

under what conditions cells will favor the PPP pathway

intermediates from the PPP are used for the biosynthesis of nucleotides and amino acids. Therefore, this glycolytic pathway may be favored when the cell has need for nucleic acid and/or protein synthesis

propionic fermentation turns

lactic acid to propionic acid

Examples of aromatic compounds

lignin and benzoate derivatives

Under physiological conditions, ATP always forms a complex with

mg 2+

how does fermentation add nutrients and flavors?

microbial metabolism generates vitamins (B12) and flavors like esters and sulfur compounds

recall types of microbes that are edible

mushrooms, marine algae, yeasts, Spirulina

In order for a reaction to proceed, ∆G must be: a) positive b) negative c) neutral

negative

NADH stands for

nicotinamide adenine dinucleotide

syntrophy

one species' acquisition of energy from the products of another species' metabolism

3ways fatty acids enter catabolism

oxidative break down = acetyl groups which enter TCA when a terminal electron acceptor is available enters fermentation enters anaerobic syntrophy

electron acceptor

oxidizing agent

Anaerobic benzoate catabolism

oxygen not available to conduct conversation of forming carboxylate and introduction of hydroxyl groups

fermentation

partial breakdown of organic food without net electron transfer to an inorganic terminal electron acceptor

The more disordered, the more _____Δ S

positive, catabolic reaction

If ΔG< 0

process may go forward

electron donor

reducing agent