Chapter 8 microbial metabolism slides

What is metabolism?

all chemical and physical workings of a cell

What are the two chemical reactions?

Catabolism and Anabolism

What is catabolism?

Degradative; breaks the bonds of larger molecules forming smaller molecules ; RELEASES ENERGY

What is anabolism?

biosynthesis; process that forms larger macromolecules from smaller molecules; requires energy input

What are enzymes?

Biological catalyst that increase the rate of chemical reactions by lowering energy needed

-Not permanently altered in reaction

-Promote a reaction by serving as physical site for specific substrate molecules to position

What are the different types of enzymes?

Simple enzymes

Conjugated enzymes or holoenzymes

Apoenzyme

Cofactors

What are simple enzymes

enzymes that consist of protein alone (Control mechanisms)

What are conjugated enzymes or holoenzymes?

contain protein and nonprotein molecules

What are apoenzymes?

protein portion of enzyme AND ARE THE ACTIVE SITE

What are cofactors in enzymes?

Nonprotein portion of enzyme

What do Apoenzymes do?

Exhibit primary, secondary and tertiary protein organization

(Larger enzymes show quaternary structure

What is the active site(catalytic site) ?

Site for specific substrate binding

What is an apoenzyme?

An enzyme without its cofactor.

What is the active site?

The region of an enzyme where substrate binds.

What is required for a union to occur in an enzyme?

There must be perfect fit between enzyme and substrate

What are metallic cofactors? (Metal ions)

The active enzymes

-Help bring the active site and substrate close together

-Participate directly in chemical reactions with the enzyme-substrate complex

What are coenzymes( organic factors)

-Serve as temporary carrier for some substrates

-Vitamins as the most common

What are exoenzymes?

transported extracellularly, where they break down large food molecules or harmful chemicals

-Cellulase, amylase and penicillnase

What are endoenzymes?

enzymes that function inside the cell; retained intracellularly and function in there

-Most enzymes are endoenzymes

What are constitutive enzymes?

always present, always produced in equal amounts or at equal rates, regardless of the amount of substrate (House keeping enzymes that aid in stuff like digestion)

What are regulated enzymes?

not constantly present; production is turned on (induced) or turned off (repressed) in response to changes in the substrate concentration

What is a condensation reaction?

Forming of glycosidic bonds between two glucose molecules to generate maltose. Requires the removal of water molecule!

What type of reaction is condensation reaction?

anabolic as it produces water as a product

What is a hydrolysis reaction?

Catabolic reaction that breaks down large substrates into smaller molecules

(Breaks peptide bonds between two amino acids)

-Requires the input of water to break bonds!

What influences the activity of an enzyme?

the cell's environment

What has to happen in order for an enzyme to operate?

There needs to constant and exact temperature, pH and osmotic pressure of organisms habitat

What makes enzymes change?

When habitat becomes unstable

What are labiles:

Chemically unstable enzymes

What is denaturation?

Weak bonds that maintain the shape of the apoenzyme are broken

What is the main difference between chemical reactions and biochemical reactions?

Chemical reactions occur instantly due to activation enzyme

Biochemical reactions occur like stairs and are slower

What is a Multienzyme system?

Metabolic pathways usually contain many steps each with an individual enzyme

SLIDE 24

What are the direct controls on the actions of enzymes?

Competitive inhibition

Allosteric inhibition

Noncompetitive inhibition

What is competitive inhibition?

substance that resembles the normal substrate competes with the substrate for the active site

What is allosteric inhibition?

Form of competitive inhibition in special types of enzymes with two binding sites; the active site and the regulatory or allosteric site

-Regulates enzymes via negative feedback from binding of molecules

Non competitive inhibition

Inhibitor binds to entire enzyme substrate complex and prevents the enzyme from completing its action on substrate

Methods of enzyme synthesis control

Enzyme repression

Enzyme induction

What is Enzyme repression? (Turns off enzyme)

automatic suppression of enzyme synthesis when end product builds to excess

-Long response time, but effects last longer

What is Enzyme induction? (Turns on enzyme)

enzymes are made only when suitable substrates are present

-Enables the organism to adapt to nutrients and prevents waste of energy

What is energy?

the capacity to do work or to cause change

What are the forms of energy?

Thermal, radiant, electrical, mechanical, atomic, andchemical

What are cell energenics

Cells manage energy in the form of chemical reactions tha make or break bonds and transfer electrons

What are the two forms of cell energenics

Endergonic reaction

Exergonic reactions

Endergonic reaction

A nonspontaneous chemical reaction, in which free energy is absorbed from the surroundings.

Consume energy

Energy +A + B ------(Enzyme)-----> C

exergonic reaction

A chemical reaction that releases energy

Release energy

X + Y ------(Enzyme)-----> Z+Energy

(Energy released is temporarily stored in high energyphosphate molecules. The energy of these molecules is usedin endergonic cell reactions.)

What are redox reactions?

chemical reactions that transfer electrons between reactants (Always occurs in pairs)

What are electron and proton carriers

-molecules that load and unload electrons and protons (H+)

Ex. NAD, FAD, FMN

Purpose of electron and proton carriers

Repeatedly accept and release electrons and hydrogen to facilitate the transfer of redox energy

Most carriers are coenzymes:• NAD, FAD, coenzyme A, and compounds of the respiratory chain

Oxidized AND Reduced example

NAD+ (OXIDIZED) NADH(Reduced)

What is ATP?

Metabolic "currency"

Three part molecule consisting of:•

Adenine - a nitrogenous base

• Ribose - a 5-carbon sugar

• 3 phosphate groups

What happens if terminal phosphate is released in ATP

Energy is released

Function of ATP

ATP utilization and replenishment is a constant cycle inactive cells

What is Phosphorylation of glucose by ATP

The metabolic process of introducing a phosphate group into glucose by ATP.

What kind of reaction is Phosphorylation of glucose by ATP

Anabolic

What are the three mechanisms of ATP synthesis?

Substrate-level phosphorylation

Oxidative phosphorylation

Photophosphorylation

What is substrate level phosphorylation?

Transfer of phosphate group from a phosphorylated compound directly to ATP

What is oxidative phosphorylation?

series of redox reactions occurring during respiratory pathway

What is photophosphorylation?

In photosynthetic organisms, utilize the energy of sunlight

What is bioenergetics?

study of the mechanisms of cellular energy release

Includes catabolic and anabolic reactions

Primary catabolism of fuels (glucose) proceeds through a series of three coupled pathways

examples of bioenergetics

Glycolysis

Krebs cycle

Respiratory cycle, or electron transport

Metabolic Strategies

aerobic respiration, anaerobic respiration, fermentation

Examples of Aerobic respiration

Respiration that requires oxygen; glycolysis, the Kreb's cycle,respiratory chain

Examples of Anaerobic respiration

Respiration that does not require oxygen; Glycolysis, the Kreb's cycle, respiratory chain; molecular oxygen is not the final electron acceptor

Examples of Fermentation

What is Aerobic respiration

Series or enzyme-catalyzed reactions in which electrons are transferred from fuel molecules to oxygen as a final electron acceptor

What are cycles that enable Aerobic respiration

Glycolysis

TCA

Electron transport chain

What is glycolysis?

the breakdown of glucose by enzymes, releasing energy and pyruvic acid.

What is the Krebs cycle (TCA)?

second stage of cellular respiration, in which pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions

What is the electron transport chain?

accepts electrons from NADH and FADH; generates energy through sequential redox reactions called oxidative phosphorylation

What is the input of glycolysis?

1 glucose, 2 ATP

What is the output of glycolysis?

2 pyruvate, 2 ATP, 2 NADH

What is the input of the Krebs cycle?

2 Acetyl CoA

What is the output of Krebs cycle

4 CO2, 6 NADH, 2 FADH2, 2 ATP

What is the input of the electron transport chain?

NADH and FADH2

What is the output of the electron transport chain

H2O and ATP (02 is the final electron acceptor)

What is the energy investment stage

the cell uses ATP to phosphorylate compounds of glucose

How much ATP is used in the investment stage

TWO ATP MOLECULES PER STAGE

Gross ATP glycolysis

4 ATP

Net ATP of glycolysis

4 produced - 2 invested = 2 net ATP

what fuels the electron transport chain?

H+

What is the chain of redox carriers in electron transport?

Chain that receives electrons from reduced carriers (NADH and FADH2).

What is the role of ETS in electron transport?

Shuttles electrons down the chain, releasing energy that is captured and used by ATP synthase complexes to produce ATP.

What is the function of the periplasmic space

Folding proteins and storage of protons

The Terminal Step

Oxygen accepts 2 electrons from the ETS and then picks up 2 hydrogen ions from the solution to form a molecule of water. Oxygen is the final electron acceptor

How much ATP is produced in aerobic metabolism

34 ATP

Glycolysis NET SUMMARY

2ATP

2NADHs

2 Pyruvic acids

Transition step NET SUMMARY

2NADHs

2 CO2S

Krebs cycle NET SUMMARY

4 CO2s

6NADHs

2 ATPS

2 FADH2S

Elective transport and oxidative phosphorylation NET SUMMARY

34 ATP

6 H20S

What is anaerobic respiration?

Functions like aerobic respiration except it ultizes oxygen containing ions, rather than free oxygen as the final electron acceptor

Nitrate (NO -3) and Nitrate (NO -2)

What do most obligate anaerobes use?

H+ generated during glycolysis and the krebs cycle to reduce some compound other than O2

What is nitrification?

a process that breaks down ammonia into nitrites or nitrates

Ammonium---->Nitrate

Ammonia nitrication

Ammonium (NH4+) --(Oxidized)----> Nitrate (NO2-)----->(Oxidized)----------> Nitrate (NO3_)

Denitrification (nitrogen cycle)

This is the reverse process of nitrification. During it nitrates are reduced to nitrites and then to nitrogen gas and ammonia.

Nitrate-----> Ammonia

What is fermentation?

Incomplete oxidation of glucose or other carbohydrates in the absence of oxygen

What does fermentation use?

Uses organic compounds as terminal electron acceptors to yield a small amount of ATP

outcome of fermentation

Ethyl alcohol by yeast acting on glucose and formation of acid ,gas and other products by the actions of various bacteria on pyruvic acid

Purpose of fermentation for bacteria

To regenerate NAD+ (Nicotinamide adenine dinucleotide)

What is the advantage of fermentation? (EXAM QUESTION)

To generate ATP

Pathways involved in aerobic respiration

Glycolysis, Krebs Cycle, ETC

GARFIELD

KILLS

ELFS