Microbiology- Chapter 8 (Microbial Metabolism)

Front 1

Describe what metabolism is.

Back 1

× Collection of ALL biochemical reactions that take place within cells of an organism
× The ultimate function of metabolism is to reproduce the organism

Front 2

What are the two classes of chemical reactions in metabolism.

Back 2

× ANABOLISM:
-Building of complex molecules from simpler ones
- Process by which all cell is built up
- Energy requiring process (endergonic processes)

× CATABOLISM
- Process by which complex molecules are broken down into simpler ones- energy broken down into simpler ones- energy released (exergonic processes)

Front 3

What are the processes of metabolism?

Back 3

× Nutrient uptake
× Conversion of nutrients into cell components
× Conversion of nutrients into energy
× Excretion of waste products
× *compounts are taken in, converted, and some are made into waste and excreted

Front 4

What are Enzymes.

HINT: chemical reactions within the cell are directed by enzymes

Back 4

× Protiens that catalyze (accelerate) chemical reactions
× They are specific; they catalyze a single type of chemical reaction
× During the reaction they do not permanently change (*so they can start a new reaction) and can be reused
× The enzyme molecule is bigger then a substrate molecule and serves as physical site for reaction

Front 5

How do enzymes work?

Back 5

× They catalyze the reaction by lowering activation energy
× Activation energy is the energy needed to disrupt the stable chemical bonds

Front 6

Name the parts of the enzyme structure.

Back 6

× Apoenzyme (protien)

× Cofactor- non protein (metal ion

× Coenzyme- organic molecule( Type of cofactor) (vitamins)

× Cofactor or coenzyme placed together with apoenzyme make holoenzyme( Conjugated enzyme)

Front 7

What is an active site of an Enzyme?

Back 7

× Tertiary and quaternary structure provide the active site- the site where the substrate binds (groove)

Front 8

Describe enzyme-substrate interaction.

Back 8

× Substrate and enzyme make a temporary union
× Substrate is inserted into the active site
× The process is reversible

Front 9

What are the roles of coenzymes.

Back 9

× Removes of donates atoms from or to a substrate
× Electron carriers (remove electrons from the substrate; transfer them to other molecules)
× Many enzymes are vitamins
× Most important enzymes:
- Nicotinamid adenin dinucleotide (NAD+)—catabolic reaction
- Nicotinamid adenin dinucleotide phosphate (NADP+)—anabolic reactions
- Derrives of B vitamin

Front 10

What do vitamin deficiencies prevent?

Back 10

it prevents the honoenzyme from being formed.

Front 11

Describe the mechanism of enzymatic action.

Back 11

× Enzyme attaches to the substrate at the active site
× Enzyme-substrate complex is formed
× Substrate molecule is transformed—products of the reaction are released
× The unchanged enzyme can start a new reaction
× *example shown… fructose is the substrate being placed within the enzyme biphosphate aldolase

Front 12

What are the 6 types of enzymes based on mode of action.

Back 12

× Hydrolases- breaking of bonds with addition of water
× Isomerases- rearrangement of atoms
× Ligases- joining of two molecules with the removal of water
× Lyases- removal or adding of groups of atoms without hydrolysis
× Oxidoreductases- transfer of electron from one substrate to another
× Transferases- transfer of functional group

Front 13

Explain synthesis reaction in metabolism.

Back 13

× Synthesis
 Anabolic reactions in which two molecules are united into a new bigger molecule
- This dehydration reaction (ATP used and H20 molecule is released)

Front 14

Explain hydrolysis (digestion) reaction in metabolism.

Back 14

× Hydrolysis
- Digestion of macroMolecules
- Breaking the bonds require an imput of H20 (*one water molecule is added)

Front 15

Describe oxidation-reduction reactions

Back 15

× Oxidation- removal of electrons (+energy)
Note: Compound that looses electron is oxidized.

× Reduction- gain of electrons
Note: Compound that receives electron is reduced.

× These reactions are always coupled
× *once electrons are removed they must be attached to another… so oxidation always happens around the same time as reduction

Front 16

Describe enzymes sensitivity to their environment.

Back 16

× Environmental factors affect the activity of the enzymes
× The enzymes are unstable in extreme conditions (high temperatures, extreme pH, osmotic pressure)
× These conditions cause- Denaturation- the shape of the enzyme molecule is changed

Front 17

Why is denaturation bad for enzymes?

Back 17

It changes the shape of the enzyme molecule, so it prevents substrate from attaching.

Front 18

Describe Ribozymes in metabolism.

Back 18

× Some RNA molecules called ribozymes can act as a catalyst
× Active on RNA strands only
× Removes sections of RNA joining together the remaining pieces

Front 19

What are the two types of enzyme control?

Back 19

- Constitutive- present in constant amounts
- Regulated- their concentration is regulated by two different things

Front 20

In enzyme regulated control, what are the two ways of regulated control.

Back 20

× Direct control:
o Competitive inhibition
o Noncompetitive inhibition

× Control of enzyme synthesis
o Enzyme repression
o Enzyme induction

Front 21

Describe competitive inhibition.

Back 21

× Substances with similar structure as the real substrate bind to the enzyme's active site, preventing substrate to bind.

Front 22

Describe noncompetitive inhibition.

Back 22

× Interact with another part of the enzyme- allosteric site
× Causes changing the shape of the active site

Enzyme with 2 sites, active site and regulatory site. Enzymes are regulated by binding of molecules other than the substrate in their regulatory site.

Front 23

What are the two controls of enzyme synthesis.

Back 23

x Repression
- The excess of the end product suppresses the synthesis of enzyme
× Induction
- Presence of a particular substrate induces the synthesis of the relevant enzyme

Front 24

What are the two types of energy transactions?

Back 24

- Exergonic- release of energy
× X + Y ---enzyme---> Z+ Energy (release)
- Endergonic- consumption of energy
× Energy + A + B --- Enzyme---> C

Front 25

What is catabolism?

Back 25

getting materials and energy
× Glucose is the most frequent nutrient used for obatining energy
× There are three metabolic pathways which glucose is transformed
- Glycolysis
- Aerobic respiration (Krebs cycle) ( Electron transport chain)
- Anaerobic respiration (fermentation)

Front 26

What are the 3 stages of respiration of glucose?

Back 26

× Glycolysis
× The krebs cycle
× Electron transport chain system

Front 27

Where does gyclolysis occur?

Back 27

×Occurs in cytoplasm of most cells

Front 28

Describe the proces of glyclolysis.

Back 28

× Involves splitting of a six-carbon glucose
× Direct transfer of phosphate between two substrates- substrate level phosphorylation
× Net gain of
- Two ATP molecules
- Two molecules of NADH
- Pyruvic acid

× Three-carbon molecules are oxidized to
- Two molecules of pyruvic acid
- 2 NAD 1 NADH+
- 4 ATP formed
- Energy balance of glycolysis = 2 ATP

Front 29

What is substrate level of Phosphorilation?

Back 29

× High energy P directly transferred from a substrate to ADP
× C-C-C~P + ADP -------> C-C-C+ATP

Front 30

Describe the krebs cycle (tricaboxylic acid cycle).

HINT: pg.228

Back 30

× A series of biochemical reaction in which chemical energy is released stop by step
× Starting compound is pyruvic acid (from glycolysis) which Is transformed into Acetyl CoA
× Acetyl CoA is decaboxilated (loss of CO2 molecule) and entered into tricarboxylic acid cycle
× The reduced coenzymes are formed NAHH+ and FADH2 (energy stored)- enter the Respiratory Chain



× In this cycle ATP, NADH, and FADH are formed
× NADH and FADH enter the electron transport chain

Front 31

Describe the electron chain transport.

Back 31

× Sequence of carrier molecules that can be oxidized and reduced
× Located in plasma membrane of prokaryotic cells of in mitochondria in eukaryotic cells
× Energy is released by transfer of electron from hgih energy to lower energy compounds
× Protons (H+) are actively pumped out

Front 32

What is the net yield of ATP of glycloloysis, krebs cycle and electron chain transport.

Back 32

Glyclolysis= 2 ATP
Krebs= 2 ATP
Electron chain= 34 ATP

TOTAL= 38

Front 33

What is chemoiosmosis?

Back 33

As the electron transport carriers shuttle electrons, they actively pump hydrogen ions (protons) into the outer compartment of the mitochondrion.

× Acumulated protons (H+) from outer compartment diffuse through the ATP synthase to inner compartment
× Rotation of the ATP synthase causes bonding of ADP and Pi --> ATP
× Cytochrome aa3 catalizes the reaction between H+ and O2 --> H2O

Front 34

What is anaerobic respiration?

Back 34

 Fermentation

Front 35

Describe fermentation.

Back 35

× Further oxidation of Pyruvic acid (obtained in glycolysis) without the presence of 02
× Partial oxidation without the presence of O2
× Final product is organic molecule (not H20)
× Only small amounts of ATP is revovered
× Different bactreia perform different types of fermentation

× Final product: lactic acid, ethanol, propionic acid, CO2, H2, acetic acid, etc.

Front 36

What is photosynthesis?

Back 36

× light energy --> ATP, NADPH = Synthesis of organic molecules

Front 37

Describe photosynthesis.

Back 37

× Conversion of light energy into chemical energy
× Present in plants and photosynthetic bacteria and algae- Photoautotrophs
× Chemical energy used for conversion of CO2 into reduced carbon compounds (sugars)

Front 38

WHat are the two stages of photosynthesis.

Back 38

× 1. Light dependent stage (reactions)
- (light energy converted into ATP- photophosphorilation
*when you convert light into ATP*
- Light --> Chlorophyll--> e- --> electron transport chain ---chemiosmosis-->ATP
- Electrons from chlorophyll are replaced by electrons from water
× 2. Light independent stage (reactions)
- (ATP produced in the previous stage is used to reduce CO2 into sugars)

*light independent reactions gets the energy made in the first stage and breaks it down into glucose*

Front 39

What is osygenic and anoxygenic?

Back 39

× Osygenic- plants, algae, cyaenobacteria
6CO2+ 12H20+ Light Energy = C6H12O6 + H20 + 6O2

602= end product

× Anoxygenic- *is* purple sulgur, and green sulfur bacteria
6CO2+ 12 H2S + Light energy = C6H12O6 +H20+ 12S

12S= End product