How the Cell gets Energy

ENERGY

• Cells need energy because the organism needs energy. Remember, cells do all of an organism’s functions.

• Organisms get their energy by eating foods containing Carbohydrates, Proteins, and Lipids.

• Here’s how it works…..

1. Person eats food

2. Food Passes through the Digestive System

The food is brokendown as it travels through the digestivesystem.

The food is brokendown into smallmolecules.

3. The food molecules get into the blood.

Once throughthe digestivesystem, the food gets intothe arteries &veins.

4. The food molecules get into the cells.

5. The energy inside of the food molecules is released inside the

cell

Today we willlearn how theenergy isreleased so the cell can use it.

Energy is like a Bank Account

• You DEPOSIT energy into your account when you eat food.

• You WITHDRAW energy from your account when your cells perform respiration to break down the food.

RESPIRATION

• The Digestive System converts food into GLUCOSE – a type of sugar.

• RESPIRATION – is the process cells use to break down Glucose into useful cell energy. IT REQUIRES OXYGEN.

• Cells in all living things use respiration

• Animal, Plant, and Bacteria cells all perform respiration.

Don’t get confused

• We often use the words respiration and breathing in everyday life as the same thing.

• WE ARE NOT TALKING ABOUT BREATHING HERE.

• Our definition of respiration is the process cells use to break down glucose into useful cell energy.

Stages of Respiration

There are 2 stages of respiration. Together they make up what we call respiration.

STAGE 1:

• Occurs in the Cytoplasm.

• Molecules of glucose are broken down into smaller molecules. Oxygen is NOT involved and only a small amount of energy is released.

Stages of Respiration

STAGE 2:

• Takes place in the Mitochondria.

• The small molecules from Stage 1 are broken down even smaller. These chemical reactions require oxygen and they release a great deal of energy.

GLUCOSE

A TRANSPORT PROTEIN BRINGS THE GLUCOSE INTO THE CELL

CYTOPLASM

Some energyis released

RESPIRATION: STAGE 1

CYTOPLASM

The glucose is broken down into smaller molecules in the cytoplasm. This gives off a little bit of energy.

MITOCHONDRIA

OXYGEN

WATER

CARBONDIOXIDE

ENERGY

RESPIRATION: STAGE 2CYTOPLASM

CHEMICAL EQUATIONS

• Chemical Equations are quick ways of understanding the chemical reaction that you are studying.

• They always look a certain way.

REACTANTS PRODUCTS

CHEMICAL EQUATIONS

REACTANTS are all the chemicals that go into the reaction. It’s what the process STARTS with. There can be a lot of reactants or only a few. You put a + sign in between them. (LIKE INGREDIENTS FOR A CAKE)

PRODUCTS are all the chemicals that are produced by the reaction. It’s what the process ENDS with. There can be a lot of products or only a few. You put a + sign in between them. (LIKE THE FINISHED CAKE)

THE RESPIRATION CHEMICAL EQUATION

REACTANTS PRODUCTS

C6H12O6 + 6O2 6CO2 + 6H2O + ENERGY

SUGAR + OXYGEN CARBON DIOXIDE + WATER + ENERGY

PHOTOSYNTHESIS & RESPIRATION

PHOTOSYNTHESIS is the process PLANT CELLS use to convert sunlight into sugar.

RESPIRATION is the process ALL CELLS use to convert sugar into useful cell energy.

• These 2 processes are opposite of each other.• For plants, these 2 processes work together.• For animals, we eat food then do respiration.

The Photosynthesis-Respiration Cycle (P-R Cycle)

• Plants use photosynthesis to store sugar inside of them as starch.

• Animals eat plants for their starch (Carbohydrates) and break the sugar inside the plant down using respiration.

• Humans eat those animals for their Carbohydrates and break them down using respiration.

The P-R Cycle

Photosynthesis

Sugar & Oxygen

Carbon Dioxide &Water

Respiration

ENERGYSUN

FERMENTATION

FERMENTATION occurs when energy is obtained from food WITHOUT THE USE OF OXYGEN.

• This process is useful for single-celled organisms that do not live with oxygen.

• Fermentation gives off MUCH LESS energy than respiration.

2 Types of Fermentation

1. ALCOHOLIC FERMENTATION some organisms use this type of Fermentation. The products are Alcohol, Carbon Dioxide, and Energy. YEAST (a fungus) uses this type.

Lactic Acid

2. LACTIC ACID FERMENTATION occurs when the cell has used up the Oxygen already. This type HAPPENS IN YOUR MUSCLE CELLS when you’ve exercised very hard. The products are Lactic Acid and Energy.

• You’ve felt Lactic Acid when your muscles are sore the day after you worked out.