Chap. 2 Sec. 2: Respiration

CHAP. 2 – SEC. 2: RESPIRATION

The food you eat provides you with chemical potential energy.

It is chemical potential energy because the energy is not immediately converted to use.

To convert the food to energy, it must go through the following steps:

1. The food must be digested which means breaking food down into smaller molecules.

2. The small molecules pass out of your digestive system and directly into your bloodstream.

3. Once it your bloodstream, it travels to your cells.

4. Once inside the cells, the molecules are transformed into energy through a process called cellular respiration.

I. STORING & RELEASING ENERGY

The reason that food is not immediately converted into energy is because your body usually does not need the

1 energy right away. The energy from food is stored in the cells for later use.

Plants save the energy made in photosynthesis in the form of carbohydrates: starches (potatoes) and sugars (celery).

When plant needs energy, it breaks down the carbohydrates and the process of breaking down the carbohydrates releases energy.

II. RESPIRATION

After you eat a carbohydrate, your body stores the energy in it as glucose (a type of sugar).

If you need the energy in the glucose, your body breaks down the sugar in a process called CELLULAR RESPIRATION.

III. THE RESPIRATION EQUATION

C6H12O6 + 6O2  6CO2 + 6H2O + energy glucose oxygen Carbon water dioxide The glucose comes from storage in the cells and from the food animals consume.

2 The oxygen comes from the air animals breathe in or water for aquatic organisms.

Notice that the raw materials in cellular respiration are the output products of photosynthesis.

Notice that the output products of photosynthesis are the raw materials for cellular respiration.

IV. TWO STAGES OF RESPIRATION

A. FIRST STAGE

This takes places in the cytoplasm of the cells where large glucose molecules are broken down into smaller ones.

Only a small amount of energy is released when the glucose molecules are broken down.

B. SECOND STAGE

The second stage takes place in the mitochondria.

Small molecules are broken down into even smaller molecules in the mitochondria.

3 Oxygen is required in this stage and a great deal of energy is released.

Hence, why mitochondria are called the cell’s powerhouse.

C. THE PRODUCTS OF CELLULAR RESPIRATION

The products or results of cellular respiration are energy, carbon dioxide, and water.

Energy gets used immediately by the body.

Carbon dioxide and water diffuse out the cells and out of the body when you breathe out.

When you breathe in, you take in oxygen – a needed material to undergo cellular respiration.

V. COMPARING PHOTOSYNTHESIS & RESPIRATION

The equation for photosynthesis is the opposite for cellular respiration.

4 Together, the two energy cycles keep the levels of oxygen and carbon dioxide in balance.

However, in today’s climate, too much carbon dioxide is being produced by humans, animals, and machines.

Plants and trees are being cut down and cannot consume all the carbon dioxide or give us the oxygen we need to live.

As a result, excess carbon dioxide is sticking to our atmosphere causes the earth to heat up – known as global warming.

The electromagnetic waves that come to earth normally bounce back into space.

With a thickening atmosphere, it is trapped on the earth causing the earth to heat up.

VI. FERMENTATION

There are organisms on this earth that can obtain energy from food WITHOUT USING OXYGEN.

These organisms obtain energy from a process called fermentation.

5 The amount of energy released from each glucose molecule during fermentation is much lower than the amount released during respiration.

A. ALCOHOLIC FERMENTATION

This is fermentation in yeast and other single celled organisms.

It is called alcoholic fermentation because alcohol is released as a product when the sugars are broken down.

Also released are carbon dioxide and energy.

Fermentation is important to bakers and brewers.

For bakers, carbon dioxide causes the bread to rise and creates air pockets.

For brewers, carbon dioxide is the source of the bubbles in beer and the alcohol is the basis for the all alcoholic drinks.

6 B. LACTIC-ACID FERMENTATION

There are times when you push your body so hard that cellular respiration cannot keep up and give you the energy you need.

When your body lacks the oxygen it needs to undergo cellular respiration, it will switch to fermentation.

You feel fermentation as a painful, burning sensation in your muscles.

The burning is caused by the product of fermentation called LACTIC ACID.