Photosynthesis and Cellular Respiration

Standard Cell Biology 1F

Students know useable energy is captured from sunlight by chloroplasts and is stored through the synthesis of sugar.

At the end of this lesson…

Students will know all energy on Earth comes from the sun

Students will be able to create a flow map illustrating photosynthesis

What is Energy?

Energy is the ability to do work or grow

All Energy on the earth comes from the sun

Plants and animals get their energy in different ways.

ATP: Energy for Cells

ATP is the unit of energy for all cellsATP= Adenosine

TriphosphateATP releases energy when the bond between the second and third phosphate groups is broken, forming a molecule called adenosine diphosphate (ADP) and a free phosphate group.

Photosynthesis

Photosynthesis is the process plants use to make energy for themselves

Photosynthesis uses the energy from the sun to make glucose and take carbon from the air (CO2 ) to use for growth

Photosynthesis

• Photosynthesis takes place in the chloroplasts of plant cells. • Chloroplasts contain the pigment Chlorophyll, which absorbs

certain wavelengths of light. • What is the closest equivalent of a chloroplast in an animal

cell?

Photosynthesis

The Photosynthesis Reaction

Carbon Dioxide and water combine in the presence of sunlight to make glucose (a sugar) and oxygen gas.

Why is light necessary? Why are plants necessary for photosynthesis to occur?

Photosynthesis Occurs in 2 steps:

1. Light Dependent Reactions Takes in water Gives off energy

molecules called ATP

Gives off Oxygen

2. Calvin CycleTakes in Carbon

Dioxide– Gives off glucose

Light Dependent Reactions:

• Chloroplasts capture light energy

• Takes place in the Thylakoid (Stack of membranes in chloroplast)

• Require water and sunlight• Water is split, releasing

hydrogen ions• Hydrogen ion is used to

attach a phosphate group to ADP, making it ATP

• Visualizing Light Dependent Reactions

Step 2: The Calvin Cycle

The Calvin Cycle uses carbon dioxide and creates carbohydrates, or glucose.

6 molecules of carbon dioxide are used to create 1 glucose molecule

6 ATP molecules are required to create 1 glucose molecule

Where does the glucose go?

• Glucose is used in plant cells to make starches

• Starches are stored in vacuoles until they are needed later by the plant

• Plants use transport systems like blood vessels to move starches throughout the plant

• To grow, plants combine Carbon that they get from Carbon dioxide and glucose to build new tissues

• Plants are consumed by heterotrophs, who use the starches for their own energy.

How do animals (and plants) get energy?

Animals convert the glucose stored in plants into ATP for their own use

This process is called Cellular respiration

The equation for this process is the OPPOSITE reaction from photosynthesis:

Cellular Respiration takes place in the mitochondria

Occurs in 3 steps:

Cellular Respiration: Oxygen is the Key!

Cellular Respiration

Cellular respiration occurs in three steps:Step 1: glycolysis

Glycolysis means “To break down sugar”Cell breaks down glucose from the food we

eat Turns glucose into pyruvate, which can be

used to make ATPTwo molecules of ATP are made in the

process of glycolysis

Step 2: Krebs Cycle

Most of the energy from the glucose is still contained in the pyruvate.

The Krebs Cycle takes the pyruvate made in glycolysis and creates 2 ATP molecules

Step 3: Electron Transport Chain!

The electron transport chain produces the most ATP in the process of Cellular Respiration

Concentration gradients inside and outside of the mitochondrion create 32 ATP molecules

What are the numbers?

Photosynthesis Cellular Respiration

• Creates a total of 24 ATP molecules

• Creates a total of 36 ATP molecules

Food and ATP

Cellular Respiration

AerobicRequires oxygenGlycolysis, Krebs

cycle and electron transport

28 ATP total

Anaerobic No oxygen Glycolysis

followed by fermentation

4 ATP total

Fermentation (anaerobic)

Lactic Acid Can build up in

skeletal muscle = soreness

In microorganisms, used to make yogurt, cheese and sour cream

Alcohol Fermentation Sugar cane -> rum Wheat -> beer Potatoes -> vodka Grapes -> wine Agave -> tequila Rice -> sake

How does all of the breaking down and building of molecules occur?

ENZYMES!

Enzymes

Enzymes are proteins that help to speed up chemical reactionsProteins are made of chains of amino

acids, which are present in all of our (naturally created) food

There are thousands of enzymes present in every cell of your body

Each enzyme has a specific function Enzyme names usually end in –ase

(such as hydrolase)

Properties of Enzymes

Enzymes are not used up in reactionsThe same enzyme can be used over

and over to combine the same moleculesAn enzyme is like a tool: you can use the

same hammer over and over again to nail together boards.