Regents Biology 2009-2010

Cellular Respiration

Harvesting Chemical Energy

ATP

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Section Objectives:

Compare and contrast cellular respiration and fermentation.

Explain how cells obtain energy from cellular respiration.

Ch.8.3

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CO2 + H2O + heat fuel

(carbohydrates)

O2

“Burn fuels” to make energy combustion

making heat energy by burning fuels in one step

ATP

ATP + CO2 + H2O (+ heat)

aerobic respiration

making ATP energy (& some heat) by burning fuels

in many small steps

food

(carbohydrates)

O2

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Energy needs of life

Animals are energy consumers

What do we need energy for?

synthesis (building for growth)

reproduction

active transport

movement

temperature control (making heat)

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Where do we get energy?

Energy is stored in organic molecules

carbohydrates, fats, proteins

Animals eat these organic molecules food

digest food to get

fuels for energy (ATP)

raw materials for building more molecules

carbohydrates, fats, proteins, nucleic acids

ATP

Regents Biology 2009-2010

ATP

What is energy in biology?

Whoa! HOT stuff!

Adenosine TriPhosphate

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Harvesting energy stored in food

Cellular respiration

breaking down food to produce ATP

in mitochondria

using oxygen

“aerobic” respiration

usually digesting glucose

but could be other sugars,

fats, or proteins

C6H12O6 6O2 ATP 6CO2 6H2O + + +

glucose + oxygen energy + carbon + water dioxide

O2

food ATP

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What do we need to make energy? The “Furnace” for making energy

mitochondria

Fuel

food: carbohydrates, fats, proteins

Helpers

oxygen

enzymes

Product

ATP

Waste products

carbon dioxide then used by plants

water

O2

food

ATP

Make ATP! Make ATP!

All I do all day… And no one even notices!

enzymes

CO2 H2O

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Mitochondria are everywhere!!

animal cells plant cells

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Can’t store ATP too unstable

only used in cell

that produces it

only short term

energy storage carbohydrates & fats

are long term

energy storage

Using ATP to do work?

A working muscle recycles over

10 million ATPs per second

ATP

ADP

work

Whoa! Pass me the

glucose & oxygen!

Adenosine DiPhosphate

Adenosine TriPhosphate

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make energy

A Body’s Energy Budget

eat

food

synthesis

(building)

• energy needed

even at rest

• activity

• temperature

control

{ • growth

• reproduction

• repair { storage

• glycogen

(animal starch)

• fat {

ATP

1

2

3

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Cellular Respiration

The first stage, glycolysis, is anaerobic—no oxygen is required.

The last two stages are aerobic and require oxygen to be completed.

SUMMARY EQUATION:

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STAGES OF CELLULAR RESPIRATION

Respiration occurs in three main stages

GLYCOLYSIS KREBS

CYCLE

ELECTRON

TRANSPORT CHAIN

High-energy

electrons carried

by NADH

Mitochondrion

Cytoplasmic

fluid

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Glycolysis [Glyco=sweet, sugar lysis = to split] s: a series of chemical reactions in the cytoplasm of a cell that

break down glucose, a six-carbon compound, into two

molecules of pyruvic acid, a three-carbon compound

produces only two ATP molecules for each glucose molecule broken down. (4-2=2)

2 molecules of NADH are formed

Glucose 2 Pyruvic acid

2ATP

2ADP 4ADP + 4P

4ATP

2NAD+

2NADH + 2H+

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Transition

Phase.

Before citric acid cycle and electron transport chain can begin, pyruvic acid undergoes a series of reactions in which it gives off a molecule of CO2 and combines with a molecule called coenzyme A to form acetyl-CoA.

Pyruvic

acid

Acetyl CoA

(acetyl

coenzyme A)

CO2

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The citric acid cycle • also called the Krebs

cycle, is a series of chemical reactions in that the molecule used in the first reaction is also one of the end products.

• For every turn of the cycle, one molecule of ATP and two molecules of carbon dioxide, 3 NADH, 1 FADH2 are produced.

• For a total of 2ATP,6 NADH,& 2 FADH2

• Occurs in mitochondrial matrix

CO2

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The electron transport chain In the electron transport chain, the carrier molecules NADH and

FADH2 gives up electrons that pass through a series of

reactions. Oxygen is the final electron acceptor forming water.

This sets up a H+ (proton) gradient

Allow the protons

to flow through ATP synthase which synthesizes ATP (ADP +

Pi = ATP)

the electron transport chain adds 32 ATP molecules

to the four already produced during glycolysis &

citric acid cycle

Occurs in the inner mitochondrial membrane

occurs

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What if oxygen is missing?

No oxygen available = can’t complete

aerobic respiration

Anaerobic respiration

also known as fermentation

alcohol fermentation

lactic acid fermentation

no oxygen or

no mitochondria (bacteria)

can only make very little ATP

large animals cannot survive

O2

yeast

bacteria

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Anaerobic Respiration Fermentation

alcohol fermentation

yeast

glucose ATP + CO2+ alcohol

make beer, wine, bread

lactic acid fermentation

bacteria, animals

glucose ATP + lactic acid

bacteria make yogurt

animals feel muscle fatigue

O2

Tastes good… but not enough energy for me!

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Alcoholic fermentation

used by yeast cells and some bacteria to produce CO2 and ethyl alcohol

glucose -> pyruvic acid-> 2 ethyl

alcohol + 2 CO2

2ATP

GLYCOLYSIS

FERMENTATION

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Lactic acid fermentation

Glucose->pyruvic acid -> 2 lactic acid 2ATP GLYCOLYSIS FERMENTATION used to make cheese and yogurt ~ in humans during strenuous exercise not enough oxygen from blood “oxygen debt” ~ lactic acid accumulates in muscle; leads to fatigue and pain Will be converted back to pyruvic acid in liver

Regents Biology 2009-2010

Got the energy…

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