Cellular Respiration

You feel weak when you are hungry because food serves as a source of

energy.

How does the food you eat get converted into a usable form of energy for your cells?

Chemical Energy and Food

Calorie – amount of energy needed to raise a

temperature of 1 gram of water by 1 degree Celsius

Cells use all sorts of molecules for food, including

fats, proteins, and carbohydrates.

The energy stored in these molecules varies

because their chemical structures, and therefore

their energy-storing bonds, differ.

Cells break down food molecules gradually and use

the energy stored in the chemical bonds to produce

compounds such as ATP that power the activities

of the cell.

Where do organisms get

energy? Food = chemical

energy

It provides living

organisms with

chemical building

blocks they need to

grow and reproduce

ATP = organic

molecule containing

high energy bonds

powers most cell

activities

Cellular Respiration Overview

Cellular Respiration: Transformation of

chemical energy in food into chemical

energy cells can use

ATP energy

Overall Reaction:

C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP

Glucose + Oxygen Carbon dioxide + Water + Energy

ATP Reminder!ATP = adenosine triphosphate.

This is the compound that directlysupplies the energy to do cellular work.

How ATP Works

The release of one of the phosphate groups makes energy available to do cellular work.

ATP energizes other molecules by transferring one phosphate group.

Cellular Respiration has

Many Steps!

1) Glycolysis

2) Krebs cycle

3) Electron transport

chain

Oxygen and Energy Aerobic- process that requires

oxygen

Some parts of Cellular Respiration

need Oxygen

Both take place in mitochondria

Makes 36 ATP molecules

Anaerobic- process that does

not require oxygen

Some parts don’t need oxygen

Takes place in cytoplasm

Makes 2 ATP molecules

What do you notice?

Cellular Respiration

C6H12O6 + O2 CO2 + H2O + ATP

Photosynthesis

CO2 + H2O + Light C6H12O6 + O2

Photosynthesis vs. Cellular

Respiration The reactants of cellular

respiration are the products

of photosynthesis and vice

versa.

The release of energy by

cellular respiration takes

place in plants, animals,

fungi, protists, and most

bacteria.

Energy capture by

photosynthesis occurs only in

plants, algae, and some

bacteria.

ATP and Glucose Most cells have only a small amount of ATP (enough

to last for a few seconds of activity)

ATP is very efficient at transferring energy but it is not very good at storing energy over long periods of time.

It is more efficient for cells to store energy in a molecule such as glucose.

A glucose molecule has more than 90 times the chemical energy of a molecule of ATP

If our body needs to store energy for longer, we store it as fat

Energy and Exercise

Quick bursts of energy body uses ATP

present in muscles

Exercise longer than 90 seconds cellular

respiration is the only way to continue

generating a supply of ATP

You need oxygen for this

You need to breath!

Cramps while Exercising?

If you don’t get enough oxygen from breathing

your body switches to Lactic Acid Fermentation

Lactic Acid Fermentation gives us energy but

causes lactic acid to build up in our muscles

This causes cramps!

In order to get rid of the

lactic acid you must get

oxygen Breath!

Fermentation

What happens when oxygen isn’t around?

Fermentation

Fermentation – makes energy

from food without oxygen

Alcoholic Fermentation –

yeast and other organisms use

alcoholic fermentation to get

energy

Makes cheese, bread, beer, etc!