CHAPTER 9

CELLULAR RESPIRATION & FERMENTATION

Summary of Photosynthesis &

Cellular Respiration

How much energy is stored in

food?

Energy stored in food is expressed in units

of CALORIES.

Calorie: the amount of energy needed to

raise the temperature of 1 gram of water

by 1 degree Celsius.

Cells use all sorts of molecules for food-Fats, proteins, carbohydrates) Each of these molecule stores a different

amount of energy because its chemical structure 1g fat ~ 9000kilocal. (~9calories) 1g of carbohydrates ~ 4000kilocal. (4calories) 1g of protein ~ 4000kilocal. (4calories)

Composition of Some Common Foods

Food Protein (g) Carb(g) Fat (g)

Apple, 1

medium

0 22 0

Bacon, 2 slices 5 0 6

Chocolate bar 3 23 13

Eggs, 2 whole 12 0 9

2% milk, 1 cup 8 12 5

Potato chips, 15

chips

2 14 10

Skinless

roasted turkey,

3 slices

11 3 1

• Serving Size on label:

• Calories per serving:

• Total Fat grams per serving:

• Calories in your serving:

• Total Fat grams in your serving:

Cellular Respiration

process that releases energy from food in the

presence of oxygen.

C6H12O6 + 6O2 6CO2 + 6H2O + 36 to 38 ATP

Glucose + oxygen carbon + water+ energy

dioxide

How do I get energy from the food I

ate?

Food that you eat is converted to glucose

The glucose is split to release energy from it

through a process known as GLYCOLYSIS.

GLYCOLYSIS splitting glucose

Takes place in the Cytoplasm

Anaerobic process (Doesn’t Use Oxygen)

HARVESTING CHEMICAL ENERGY

Glycolysis Summary

Note Glycolysis: •Starts with 2ATP •Ends with 4ATP •Net Yield= 2ATP •The end product of glycolysis is PYRUVIC ACID •PYRUVIC ACID can follow 2 different pathways depending on the presence or absence of oxygen

TWO TYPES OF

RESPIRATION

Aerobic Respiration

When cells make ATP

by breaking down

organic compounds in

the presence of

oxygen.

Anaerobic Respiration

When cells make ATP

by breaking down

organic compounds in

the absence of

oxygen.

Note: ATP can be made with or without oxygen but more is yielded with oxygen

Fermentation (Anaerobic

Respiration)

Absence of oxygen

No ATP is produced but NAD+ is

generated

NAD+ helps to keep glycolysis going to

make more ATP

2 common fermentation pathways produce

lactic acid & alcohol (depending on the

enzyme used)

Lactic Acid Fermentation in

Foods

In lactic acid

fermentation, an

enzyme converts

pyruvic acid into a

carbon compound

called LACTIC ACID

Important in the

manufacture of food

products such as

yogurt & cheese

Quick Energy (90 seconds or less)

For short quick bursts of

energy, the body uses

ATP already in the

muscles.

This ATP supply usually

lasts for about 90

seconds; just enough to

reach a 200 or 300 meter

sprint

Lactic Acid Fermentation in

Muscles

A quick sprint

builds up lactic

acid in the cell’s

cytosol and causes

oxygen debt.

This reduces the

ability of the cells

to contract

resulting in muscle

fatigue, cramps &

pain

Lactic Acid Fermentation in

Muscles (cont.) Heavy breathing

after the race repays

the oxygen debt.

When oxygen

becomes available,

lactic acid is

eventually

transported to the

liver through the

blood where it is

converted to pyruvic

acid

Long-Term Energy (more than 90

seconds)

For long term energy, cellular respiration is the only way to continue generating a supply of ATP.

Cellular respiration releases energy more slowly than fermentation does, which is why well-conditioned athletes have to pace themselves during a long race or over the course of a game.

Your body stores energy in muscles and other tissues in the form of a carbohydrate called glycogen.

This stores of glycogen usually lasts for about 15-20 minutes of activity

After 15-20 mins, your body begins to breakdown other stored molecules, such as fats for energy.

This is one reason

aerobic exercises

such as running,

dancing, swimming

are beneficial for

weight control.

Some organisms

such as bears,

count on energy

stored in fat to get

them through long

periods without

food.

ALCOHOLIC FERMENTATION

Used to convert

pyruvic acid to

ETHYL ALCOHOL

(ethanol)

Some plant cells

and unicellular

organisms ex.

Yeast use this

process.

ALCOHOLIC FERMENTATION

Basis for wine &

beer making

industries

Basis for bread

making (the

alcohol evaporates

during baking)

What are the Stages of

Cellular Respiration?

Glycolysis

The Krebs Cycle

The Electron Transport Chain

Copyright Cmassengale

Where Does Cellular

Respiration Take Place?

It actually takes place in two parts of the cell:

Glycolysis occurs in the Cytoplasm

Krebs Cycle & ETC Take place in the Mitochondria

Krebs Cycle Summary

Krebs Cycle when pyruvic acid is broken

down into CO2 in a series of energy

extracting reactions.

Also known as the citric acid cycle because

citric acid is the first compound formed.

Produces two ATP

Takes place in matrix of mitochondria

Electron Transport Chain (ETC)

Summary

ETC uses high-energy electrons from glycolysis and Krebs Cycle to convert ADP to ATP.

34 ATP & H2O are Produced

Occurs Across Inner Mitochondrial membrane

Cellular respiration (Glycolysis, Krebs

Cycle, and ETC) releases 36-38

molecules of ATP per molecule of glucose.

SUMMARY OF CELLULAR RESPIRATION

P

Pyruvic Acid

Electron Transport Chain

Animation