03 bio+210+fq+2014+ch+5+metabolism

8/10/2019 03 BIO+210+FQ+2014+Ch+5+Metabolism

1/36

Metabolism: broken down into two components:

(1) Catabolism: degrading or breaking down larger molecules

to smaller components and generates energy.

(2) Anabolism (biosynthesis): building larger molecules from

smaller ones. Anabolic reactions require energy and use

energy generated by catabolic reactions.


2/36

Enzymes

Act as biological catalysts to increase the rate of a

reaction

only act with one or a few specific substrates

enzymes are not altered by the chemical reaction

they catalyze


3/36

Chemical reactions require energy to break/form chemical

bonds

Enzymes do not add energy, they lower the energy of activationand allow the reaction to proceed more rapidly


4/36

Environmental factors that affect the activity ofan enzyme:

Temperature, pH, and salt concentration


5/36

Functional protein Denatured protein


6/36

Allosteric Regulation

Regulates production of product (controlsmetabolic activity)

Regulatory molecule binds to allosteric site ofenzyme


7/36


8/36

Feedback inhibition

A chemical pathway is shut down by buildup of a product that acts on allosteric site of

enzyme


9/36

Scheme of metabolism:

Key pathways

Glycolysis

Tricarboxcylic acid cycle

Fermentation

Pathways are catabolic and provide

Energy

Reducing power

Precursor metabolites


10/36

Role of Adenosine triphosphate (ATP):

it is chemical energy used by the cell to do work


11/36

Acetyl-CoA

Pyruvic acid

(or derivative)

Formation of

fermentation

end-products

2 Pyruvic acid

GlucoseGL

YCOL

YSIS

Respiration Fermentation

KREBS

CYCLE

Electrons


12/36

Substrate phosphorylation

Uses chemical energy to add a phosphate ion to a moleculeof ADP

Occurs in glycolysis and Krebs cycle

Oxidative phosphorylation

Uses energy from proton motive force to add a phosphateion to ADP

Photophosphorylation

Uses radiant energy from sun to phosphorylate ADP toATP

Occurs in photosynthesis

Where ATP is generated:


13/36

Glycolysis (Embden-Myerhoff Pathway)

oxidizes one glucose to two pyruvate

Pathway generates

Two 3-C pyruvate molecules Net gain of two ATP

Two molecules of NADH (reducing power)


14/36

Role of electron carriers:

Three different types of electron carriers NAD

+(Nicotinamide adenine dinucleotide)

FAD (Flavin adenine dinucleotide)

NADP+

(Nicotinamide adenine dinucleotide phosphate)

These listed above are all oxidized forms

Reduced forms represent reducing power (energy in bonds)

These listed below are all reduced forms

NADH

FADH2

NADPH


15/36

Alternatives to Glycolysis

Yield fewer molecules of ATP than glycolysis

Two pathways:

Pentose phosphate pathway generates

net gain of two molecules of NADPH one molecule of ATP

Entner-Doudoroff pathway generates

net gain of two molecules of NADPH one molecule of ATP


16/36

Transition step:

links Glycolysis to Tricarboxylic Acid Cycle

Modifies 3-C pyruvate from glycolysis toform acetyl-CoA

NAD+is reduced to NADH

This modification occurs twice for oneglucose


17/36

Pyruvic acid

Decarboxylation

Acetate

Coenzyme A

Acetyl-coenzyme A

(acetyl-CoA)

Respiration Fermentation

Transition step:

links Glycolysis to

Tricarboxylic Acid

Cycle


18/36

Tricarboxylic acid cycle (TCA)

uses pyruvate formed in glycolysis and pentosephosphate pathway (remember pyruvate is modified toform Acetyl-CoA)

cycle turns twice to complete oxidation of one glucosemolecule

T i b li


19/36

Acetyl-CoA

Oxaloacetic acid

Malic acid

Fumaric acid

Succinic acid

Succinyl-CoA

-Ketoglutaric acid

Isocitric acid

KREBS

CYCLE

Citric acid

OOH

OOH

OOH

OOH

OOH

HOO

OOH

OOH

OOH

OOH

OOH

OOH

OOH

OOH

OOH

OOH

OOH

Tricarboxylic

Acid

Cycle

Substrate

phosphorylation


20/36

Tricarboxylic Acid Cycle (also known as Krebs Cycle):

Completes the oxidation of glucose

Uses Acetyl-CoA (generated using pyruvate formed during

glycolysis)

Releases CO2

Cycle turns once for each Acetyl-CoA

Two turns for each glucose molecule

For each glucose molecule, the cycle generates

2 ATP 6 NADH

2 FADH2


21/36

What happens to the molecules of

NADH and FADH2?

They are used in respiration through their

donation of electrons to the electrontransport chain for the generation of ATP


22/36

Respiration in prokaryotes

Respiration is either aerobic or anaerobic

Oxygen acts as acceptor in aerobic respiration

Alternate acceptors used in anaerobic respiration

Uses NADH and FADH2to generate ATP through theprocess of oxidative phosphorylation:

uses electron transport chain

Generates proton motive force

uses ATP synthase with proton motive force to synthesize ATP


23/36

FMN

NADH

from glycolysis,

Krebs cycle,

pentose phosphate

pathway, and

Entner-Doudoroff

pathway

FADH2

fromKrebs cycle

Ubiquinone

Cyt c2

Cyt b

Cyt c


24/36

Cyt cCyt aCyt a3

ATP synthase


25/36

ATP synthase:

Harvest energy from proton motive force to

phosphorylate ADP to ATP

One NADH produces 3 molecules ATP

One FADH2produces 2 molecules of ATP


26/36

ATP from oxidative phosphorylation: (starting with 1 glucose

molecule)

Maximum theoretical yield = 34 ATP

From glycolysis

2 NADH 6 ATP

From conversion of pyruvate to acetyl coA (transition step)

2 NADH 6 ATP

From Krebs Cycle

6 NADH 18 ATP

2 FADH2 4 ATP


27/36

ATP from cellular respiration: (starting with 1 glucose molecule)

Maximum theoretical yield = 38 ATP

From glycolysis

2 NADH 6 ATP

and 2 ATP (subs. phosphory.) From conversion of pyruvate to acetyl coA (transition step)

2 NADH 6 ATP

From Krebs Cycle

6 NADH 18 ATP

2 FADH2 4 ATP

and 2 ATP (sub. phosphory.)


28/36

Respiration

Anaerobic respiration is less efficient

Oxygen does not act as terminal electron

acceptor

Alternate acceptors are used: e.g. nitrate, sulfate,carbonate


29/36

Fermentation

Used by organisms that cannot respire

is a partial oxidation of glucose

ATP generated only in glycolysis

Recycles NADH (the NAD+

from fermentation feeds

back into glycolysis to form more NADH)

Fermentation pathways use pyruvate or derivative as

terminal electron acceptor

F t ti


30/36

Pyruvic acid

Lactic acid Acetaldehyde

Ethanol

What are the terminal

electron acceptors used in:

-Lactic acid fermentation?

-Ethanol fermentation ?

Fermentation

Glucose


31/36

Glucose

Pyruvic acid

Swiss cheeseCheddar cheese,

yogurt, soy sauce Wine, beer

Nail polish

remover,

rubbingalcohol

Propionibacter ium

Aspergi l lus

Lactobaci l lus

Streptococcus

Saccharomyces

Clostr id ium

Fermentation

examples

Ph t th i


32/36

Photosynthesis

Use sunlight energy to power synthesis of

organic compounds from CO2

Photosynthesis has two distinct stages

Light dependent reactions

Converts light energy to chemical energy

Light independent reactions Uses energy from light reactions to

produce organic compounds


33/36

Photosynthetic organisms have light capturing pigments

Chlorophyll plants, algae and cyanobacteria

Bacteriochlorophylls

purple and green photosynthetic bacteria

Accessory pigments:carotenoids and phycobilins carotenoids found in eukaryotes and prokaryotes

phycobilins found only in cyanobacteria

Photosynthesis


34/36


35/36

Phototrophs: organisms that harvest the energy of

sunlight to power synthesis of organic compounds.

Chemoorganotrophs: organisms that obtain energy by

degrading organic compounds.


36/36

Chemolithotrophs

Chemolithotrophs: organisms that use reducedinorganicchemicals as source of energy

Organisms fall into four groups

Hydrogen bacteria

Oxidize hydrogen gas

Sulfur bacteria

Oxidize hydrogen sulfide

Iron bacteria

Oxidize reduced iron

Nitrifying bacteria

Two groups

One oxidizes ammonia to nitrite

One oxidizes nitrite to nitrate

03 bio+210+fq+2014+ch+5+metabolism

Documents