How Cells Obtain Energy (.ppsx)

BIO156 Paradise Valley Community College 1

Today’s TopicsEnergy and MetabolismEnzymes, Substrates, & ProductsATP: The Currency of the CellPhotosynthesisEnzymatic PathwaysEnzymatic ControlThree Steps of RespirationFermentationNutritional Pathways

HOW CELLS OBTAIN ENERGY

Chapter 4


PRODUCERS & CONSUMERS

Autotrophsmakes food from inorganic carbon sources (CO2) and energy from the environment

HeterotrophsOrganism obtains carbonand energy from organiccompounds assembledby other organisms

Source: modified from en.wikipedia.org. 2015.Animals, fungi, many

bacteria(Heterotrophs)

Carbon dioxide

Water

Oxygen

Plants, algae, many bacteria (Autotrophs)

OrganicMolecules


PRODUCERS & CONSUMERS

Animals, Fungi, Bacteria

Some bacteriaPhotoheterotroph

Chemoheterotroph

PlantsPhotoautotroph

Many bacteriaChemoautotroph

CO2

Light Light

HeterotrophsAutotrophs

CnH2nOn

EnergySource?

Inorganic Inorganic

EnergySource?

Producers

Carbonsource?

Consumers


PRODUCERS, CONSUMERS & DECOMPOSERS

Most life forms get their energy from the sun.

Plants capture sunlight by photosynthesis. (PRODUCER)

Herbivores eat the plantsfor energy. (CONSUMER)

Carnivores eat theherbivores. (CONSUMER)Decomposition of plantsand animals contribute tonutrient pool.(DECOMPOSER)

“BIOENERGETICS”HEAT

DECOMPOSER

CONSUMERPRODUCER

HEAT


METABOLISM

polymerenzyme

MetabolismThe many physical and chemical processesoccurring within a cell or organism that are necessary for the life.

monomers


SUBSTRATES

An enzyme’s particular substratesbind at its active sites.

SubstrateMolecule(s) specifically acted upon by an enzyme

Active sitePocket (domain) in an enzyme where substrates bind and a reaction occursActive

sites

Substrates


THE ENZYMATIC REACTION

SubstratesEnzyme Product

Active sites

The enzyme is not altered.

ADPPi

ATPATP


A CHEMICAL REACTION

MolecularHydrogen(4 atoms)

MolecularOxygen

(2 atoms)

Water(2 molecules)

ReactantsProducts

2 H2O

∆EO22 H2 +


ENERGY INPUTS AND OUTPUTS

Chemical bonds hold energy.Cells store energy in bonds by runningenergy-requiring (endergonic) reactions.

Cells use energy by runningenergy-releasing (exergonic) reactions.

Energy In+ Energy

OutReactions are reversible.


WHY THE WORLD DOESN’T GO UP IN FLAMES

Molecules release energy when combined with oxygen…

Some energy is required tostart even energy-releasing reactions.

This is called activation energy.

Activation energyMinimum amount of energy required to start a reaction

…but not spontaneously.

Source: modified from www.chem.ucla.edu. 2015.Source: campfiredude.com. 2017.


ACTIVATION ENERGY

Time

Ener

gy

Reactants

Products

1.229 VActivationEnergy (1.229 V)

Difference in energybetween reactants

and products


ATP – THE CELL’S ENERGY CURRENCY

Energy carriers accept energy from energy-releasing reactions and deliver energy to energy-requiring reactions.ATP (Adenosine triphosphate)Main energy carrier between reaction sites in cells

Molecular model variations of ATP


ADENOSINE TRIPHOSPHATE

HOHHOH

Nucleoside

Ribose

Adenine

HOH HOH

Adenosine diphosphateAdenosine monophosphate

Adenosine triphosphateAdenosine

Adenine

Threephosphate

groupsRibose

Twophosphate

groups

AdenineRibose

Pi


HOW MUCH ATP IN THE HUMAN BODY

ATP is enzymatically reduced toADP + Pi (inorganic phosphate).

Then ADP + Pi is enzymaticallyconverted back to ATP.

Every ATP molecule cycles through this reaction ~5,000 times every 24 hours.

8.8 oz.or

250 gramsor

0.2 molesor

~120,000,000,000,000,000,000,000(1.2 x 1023 molecules)

ATP ADP + Pi


ENDERGONIC REACTIONS

Net input of energy: Endergonic reaction

Cells store and retrieve energy by making and breaking chemical bonds in metabolic reactions.Some reactions require a net input of energy.

ADPPi +

Product+

Reactants

enzyme

EnergyIN

ATP


EXERGONIC REACTIONS

Cells store and retrieve energy by making and breaking chemical bonds in metabolic reactions.Some reactions end with a net release of energy.

Net release of energy: Exergonic reaction

000ATPADP

Pi +

Product+

Reactants

enzyme

EnergyOUT


ADENOSINE TRIPHOSPHATE

Available in Canvas

Khan Academy Link

http://www.khanacademy.org/login?continue=/postlogin?continue=http://www.khanacademy.org/&direct=1


metabolic pathways

ENZYME-MEDIATED REACTIONS

There are metabolic pathways that

allow organisms to grow,reproduce,maintain structures, and respond totheir environments.

Metabolic pathwayEnzyme-mediated reactions by which cells build, remodel, or break down an organic molecule

Source: en.wikipedia.org. 2017.


Each enzyme works bestwithin a characteristic range oftemperature, pH,and salt concentration

IMPORTANCE OF PROTEIN STRUCTURE

Source: Modified from mpibpc.mpg.de. 2017.

When these conditions are not met,hydrogen bonds break,the enzyme changes shape (denatures) andstops working, irreversibly.


ENZYMES, TEMPERATURE, AND pH

normaltyrosinase

Mel

anin

pro

duct

ion

Temperature (Celsius)30°20° 40°

Felis catus, var. Siamese Source: en.m.wikipedia.org. 2016.

temperature-sensitive tyrosinase

Pigment production by the enzyme, tyrosinase


METABOLIC PATHWAYS

reactant

intermediate

productintermediateenzyme

1enzyme

2enzyme

3

Linear Metabolic Pathway

Cyclic Metabolic Pathway reactan

t

intermediate

product

intermediate

enzyme 3

enzyme 1

enzyme 2

All reactions are reversible

All reactions are reversible


Today’s TopicsEnergy and MetabolismEnzymes, Substrates, &

ProductsATP: The Currency of the CellEnzymatic PathwaysEnzymatic ControlPhotosynthesisThree Steps of RespirationFermentationNutritional Pathways

HOW CELLS OBTAIN ENERGY

Chapter 4


Controls over enzymes allow cells toconserve energy and resources …by producing only what they require.

Homeostasis is maintained.

How?1. Feedback inhibition2. Allostery

CONTROL OF METABOLIC PATHWAYS

Source: modified from igbiologyy.blogspot.com. 2015Source: modified from igbiologyy.blogspot.com. 2015


FEEDBACK INHIBITION

Feedback inhibitionMechanism that slows or stops reactions because of some other activity in the overall pathway

intermediateintermediate

Furtherreactionsblockedenzyme 4

enzyme 3

enzyme 2

enzyme 1

product

product product

product

productproductproduct

reactant


Enzyme

Active site

ALLOSTERIC INHIBITION

Allosteric siteA region of an enzyme, other than the active site, that can bind regulatory molecules

Allosteric site

Distorted Active site

Allosteric inhibitor

Substrate

Greek allos (ἄλλος), "other," and stereos (στερεὀς), "solid (object)"


Enzyme

ALLOSTERIC ACTIVATION

Distorted Active

site

Allosteric site

Active

site

Enzyme Enzyme

Allosteric activator

Substrate

Greek allos (ἄλλος), "other," and stereos (στερεὀς), "solid (object)"


INBORN ERRORS OF METABOLISM

Missing or defective enzyme:Phenylalanine hydroxylase (PAH)

Disorder: Phenylketonuria (PKU)Prognosis: mental retardation

Phenylalanine Tyrosine

O2 H2O

enzyme



Disorders: G6P Deficiency, FavismPrognosis: hemolysis, jaundice, renal failureBenefit: protection against malaria

Missing or defective enzyme:Glucose-6-phosphate dehydrogenase

Glucose-6-phosphate (G6P) 6-Phosphogluconate

NAD+ NADH

enzyme



Disorder: Maple Syrup Urine Disease (MSUD)Prognosis: death, retardation, seizures, anorexia

Missing or defective enzyme:BCKDC

(branched-chain alpha-keto acid dehydrogenase complex)

LeucineAcetoacetic acid

acetyl-CoA(cofactor)

+enzyme


PHOTOSYNTHESIS AND RESPIRATION

Earth’s atmosphere was permanently altered by the evolution of photosynthesis some 2.5 billion years ago.

Source: Modified from Cengage. 2015.


CHLOROPHYLL

Chlorophyll HemeSource: Modified from bhavanajagat.com. 2017.


Source: www.123rf.com. 2015.

PHOTOSYNTHETIC PIGMENTS

β-Carotene LycopeneZeaxanthin Fucoxanthin Chlorophylls

Source: nevernotknitting.blogspot.ca. 2015.

Source: MSN Encarta. 2015.



CHLOROPLASTS AND THYLAKOIDS

ChloroplastOrganelle of photosynthesis inplants and some protists

Thylakoid membraneChloroplast’s highly folded inner membrane system

Forms a continuous compartment in the stroma



PHOTOSYNTHESIS

Light-dependen

t reactions

Light- independent

reactions


ADP + Pi

ATP

NADP+

NADPH

CO2Sunlight H2O

O2 H2O

GlucosePThylakoid


OXYGEN AND THE ATMOSPHERE

AnaerobicOccurring in the absence ofoxygen

PhotoautotrophPhotosynthetic autotroph

AerobicInvolving or occurring in thepresence of oxygen

Source: www.breathmd.com. 2015.

Source www.morning-earth.org. 2015.

Source: study.com. 2017.


ANAEROBIC RESPIRATION

Anaerobic Respiration(7% Efficiency)

Glucoseor CO2

Source: www.breathmd.com. 2015.

UnicellularOrganisms


PHOTOSYNTHESIS AND AEROBIC RESPIRATION

Photosynthesis (producers)

Aerobic Respiration (consumers)(42% Efficiency)

CO2 + H2O Glucose + O2

Source www.morning-earth.org. 2015.

Source: study.com. 2017.

Light Energy


EXTRACTING ENERGY

Eukaryotic cells convert the energy of carbohydrate bonds to the energy of ATP by oxygen-requiring aerobic respiration.Aerobic respiration

O2 & carbohydrates(glucose) ATP

Pathwaystarts in the cytoplasm

andfinishes in the mitochondria.

Source: Modified from vestinet.rs. 2017.

2 Pyruvate

Glucose

GLYCOLYSIScytoplasm


AEROBIC RESPIRATION BEGINS

Glycolysis (Respiration, Stage 1, in the cytoplasm)A series of reactions in which glucose is broken down into 2 pyruvates, netting 2 ATP

Glucose

Glycolysis

Pyruvic acid

Pyruvic acidNAD+ NADH


Krebs Cycle (Respiration, Stage 2, in mitochondria)A cyclic pathway that breaks down pyruvate to CO2, netting 2 ATP and many reduced coenzymes.

AEROBIC RESPIRATION CONTINUES

6 CO2

2 Pyruvate Stage 2 of respiration

8 NADH2 FADH2

2 ATP


Aerobic respiration is divided into three steps

1. Glycolysis2. The Krebs cycle3. Oxidative Phosphorylation

In the first two stages, a net of 4 ATP are formed.Coenzymes pick up electrons.In the third stage, electrontransport chain drives ATP synthesis.

ATP + NAD+

Pi + ADP + NADH

Pi + ADP + FADH2ATP + FADH

AN OVERVIEW OF AEROBIC RESPIRATION

NAD+NADHFADH2FADH+


An array of membrane-boundproteins and other moleculesthat accept and give up electrons in sequence

ELECTRON TRANSFER CHAIN

3. Oxidative Phosphorylation

Electron transfer chains (ETC) allow cells to harvest energy in manageableincrements.

Source: Modified from wonderwhizkids.com. 2015.

ATPH2O

ATP

ATP

H2O


FERMENTATION

FermentationAnaerobic pathway thatharvests energy fromcarbohydrates

Alcohol fermentation andlactate fermentation

In fermentation, ATP isformed by glycolysis only.

Net yield of 2 ATP per glucose molecule (7% efficiency)

Fermentation pathways finish in the cytoplasm.

Source: biologyreference.com. 2015.Source: www.chow.com. 2015.


ALCOHOL FERMENTATION

Alcohol fermentationAnaerobic pathway that converts pyruvate to

ethanol and produces ATPExamples: baking, wine & beer productionPyruvate

CO2

Acetaldehyde

Ethanol

NADH

NAD+

enzyme

enzyme


LACTIC ACID FERMENTATION

Lactic acid fermentationAnaerobic pathway that converts pyruvate to lactate and produces ATPExamples: cheese, pickles, kimchi, many

vegetables

NADH NAD+

Pyruvate Lactate

Glycolysisenzyme


LACTIC ACID PRODUCTION IN MUSCLES

Skeletal muscles have two types of fibers: slow-twitch (aerobic)fast-twitch (anaerobic)

Fast-twitch fibers have few mitochondria and rely on lactate fermentation for quick energy.Good for quick, strenuous activity such as sprinting or weight-lifting


ALTERNATIVE ENERGY SOURCES

In humans and other organisms, nutrients enter aerobic respiration at various reaction steps

simple sugars from carbohydrate breakdownglycerol & fatty acids from fat breakdown, andcarbon backbones from amino acids (proteins)

One billion to two billion ATP'screated per minute per cell.

Within the span of twenty-four hours, 1 trillion cells produce about 200 kg of ATP.


Glycolysis

Acetyl-CoA

Glycolysisintermediat

es

ENERGY SOURCES IN THE BODY

Food

Oxidative Phosphorylation

Fatty Acids

Glycerol

Glucose

Pyruvate

Krebs Cycleintermediat

es

NADH

NADH FADH2

Fats Carbohydrates Proteins

KrebsCycle

Acetyl-CoA

Amino acids

How Cells Obtain Energy (.ppsx)

Science

Transcript of How Cells Obtain Energy (.ppsx)