energy from cell

7/28/2019 Energy From Cell

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Copyright 2009 Pearson Education, Inc.

Active Lecture Questions for

Biology: Concepts & Connections, Sixth EditionCampbell, Reece, Taylor, Simon, and Dickey

Chapter 6 How Cells Harvest ChemicalEnergy


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Answer

Some prokaryotic and all eukaryotic cells use oxygen to harvest

energy from food molecules? In what form is that energyavailable to power cell work?

4) ATP molecules.


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Concept Check

The figure above represents an overview of the different processesof cellular respiration. Which of the following correctly identifies thedifferent processes?

1) 1. Glycolysis; 2. Electron transport chain; 3. Krebs cycle

2) 1. Glycolysis; 2. Krebs cycle; 3. Electron transport chain

3) 1. Krebs cycle; 2. Electron transport chain; 3. Glycolysis

4) 1. Electron transport chain; 2. Glycolysis; 3. Krebs cycle


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Answer

The figure above represents an overview of the different processesof cellular respiration. Which of the following correctly identifies thedifferent processes?

2) 1. Glycolysis; 2. Krebs cycle; 3. Electron transport chain


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Cytoplasm

Glucose

FADH2

Mitochondrion

Maximum per glucose:

OXIDATIVEPHOSPHORYLATION

(Electron Transport

and Chemiosmosis)

CITRIC ACIDCYCLE

Electron shuttleacross membrane

2 NADH

2 NADH

2 NADH

6 NADH 2

(or 2 FADH2)

2 Acetyl

CoA

GLYCOLYSIS2

Pyruvate

About38 ATP

about 34 ATPby substrate-levelphosphorylation

by oxidative phosphorylation

2 ATPby substrate-levelphosphorylation

2 ATP


7/26Copyright 2009 Pearson Education, Inc.

6.13 Fermentation enables cells to produce ATP without oxygen

Fermentation is an anaerobic (without oxygen) energy-generating process

It takes advantage of glycolysis, producing two ATP

molecules and reducing NAD+ to NADH

The trick is to oxidize the NADH without passing its

electrons through the electron transport chain to

oxygen





Your muscle cells and certain bacteria can oxidize NADHthrough lactic acid fermentation

NADH is oxidized to NAD+ when pyruvate is reduced to

lactate

In a sense, pyruvate is serving as an electron sink, a

place to dispose of the electrons generated by oxidation

reactions in glycolysis


Animation: Fermentation Overview
http://localhost/var/www/apps/conversion/tmp/scratch_3/06_13FermentationOverview_A.html



Glucose

NADH

NAD+

2

2

NADH2

NAD+2

2 ADP

P

ATP2

2 Pyruvate

2 Lactate

GLYCOLYSIS

Lactic acid fermentation

2




The baking and winemaking industry have used alcoholfermentation for thousands of years

Yeasts are single-celled fungi that not only can use

respiration for energy but can ferment under anaerobic

conditions

They convert pyruvate to CO2 and ethanol while

oxidizing NADH back to NAD+




2 ADP

P

ATP2 GLYCOLY

SIS

NADH

NAD+

2

2

NADH2

NAD+2

2 Pyruvate

2 Ethanol

Alcohol fermentation

Glucose

CO22

released

2

Wine- grapes, water, yeast

Beer- water, malted barley,hops and yeast

Grains make liquors from

mashing and yeast

To Yeast, EtOH is toxic and

secreted to the extracellular

space. If you ferment toomuch, the yeast die and this

limits the proof of what you

are drinking.



Fermentation vats for wine- have one-way valves to release the CO2 but keep out

the oxygen. Fermentation needs to happen without Oxygen.



6.14 EVOLUTION CONNECTION: Glycolysis evolved early in the history of life on Earth

Glycolysis is the universal energy-harvesting process ofliving organisms

So, all cells can use glycolysis for the energy

necessary for viability

The fact that glycolysis has such a widespread

distribution is good evidence for evolution




INTERCONNECTIONS BETWEENMOLECULAR BREAKDOWNAND SYNTHESIS




6.15 Cells use many kinds of organic molecules as fuel for cellular respiration

Although glucose is considered to be the primary sourceof sugar for respiration and fermentation, there are

actually three sources of molecules for generation of

ATP

Carbohydrates (disaccharides)

Proteins (after conversion to amino acids)

Fats




Food, such aspeanuts

ProteinsFatsCarbohydrates

Glucose

OXIDATIVEPHOSPHORYLATION(Electron Transportand Chemiosmosis)

CITRIC

ACIDCYCLE

AcetylCoAGLYCOLYSIS

Pyruvate

Amino acidsGlycerolSugars Fatty acids

Aminogroups

G3P

ATP



Concept Check

1) The electron transport chain is too deeply embedded in themitochondria.

2) The electron transport chain only receives electrons carriedby reduced electron carrier molecules such as NADH.

3) The electron transport chain only receives electrons carriedby oxidized electron carrier molecules such as NAD+.

4) The electron transport chain does not produce ATP.

The figure above represents an

overview of the different entrypathways to cellular respiration when

different macromolecules are digested

for energy production. Why are none

of the digestive products entering the

electron transport chain, directly?


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Answer

2) The electron transport chain only receives electrons carried

by reduced electron carrier molecules such as NADH.

The figure above represents an

overview of the different entrypathways to cellular respiration when

different macromolecules are digested

for energy production. Why are none

of the digestive products entering the

electron transport chain, directly?


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6.16 Food molecules provide raw materials for biosynthesis

Many metabolic pathways are involved in biosynthesis ofbiological molecules

To survive, cells must be able to biosynthesize

molecules that are not present in its foods

Often the cell will convert the intermediate compounds

of glycolysis and the citric acid cycle to molecules not

found in food



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Cells, tissues, organisms

Proteins Fats Carbohydrates

Glucose

ATP needed to drive biosynthesis

CITRICACID

CYCLE

Acetyl

CoA

GLUCOSE SYNTHESIS

Pyruvate

Amino acids Glycerol SugarsFatty acids

Amino

groups

G3P

ATP


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Cytoplasm

GlucoseOxidative

phosphorylation

(Electron Transportand Chemiosmosis)

Citricacid

cycle

Glycolysis

Pyruvate

CO2

ATP

CO2

ATP

NADH and FADH2

Mitochondrion

NADH

ATP


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ATP (a) glucose and

organic fuels

has three stages

producesome

generates

Cellularrespiration

uses

H+ diffusethrough

ATP synthase

by process called

chemiosmosis

energy for

cellular work

uses

(b) (d)

(c)

(f)

(e)

oxidizes

C6H12O6

to pullelectrons down

to

uses pumps H+ to create

H+ gradient

producesmany


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You should now be able to

Explain how photosynthesis and cellular respiration are

necessary to provide energy that is required tosustain your life

Explain why breathing is necessary to support cellularrespiration

Describe how cellular respiration produces energy thatcan be stored in ATP

Explain why ATP is required for human activities



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Describe the process of energy production frommovement of electrons

List and describe the three main stages of cellularrespiration

Describe the major steps of glycolysis andexplain why glycolysis is considered to be ametabolic pathway

Explain how pyruvate is altered to enter the citricacid cycle and why coenzymes are importantto the process



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Describe the citric acid cycle as a metabolicpathway designed for generating additionalenergy from glucose

Discuss the importance of oxidativephosphorylation in producing ATP

Describe useful applications of poisons thatinterrupt critical steps in cellular respiration

Review the steps in oxidation of a glucosemolecule aerobically



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energy from cell

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