4.1 Chemical Energy & ATP4.2 Overview of Photosynthesis4.3 Photosynthesis in Detail

CELL ENERGY

4.1 Chemical Energy & ATP• Key Concept:• All cells need chemical energy.

The chemical energy used for most cell processes is carried by ATP.

•Molecules in food store chemical energy in their bonds.

Starch molecule

Glucose molecule

ATP transfers energy from the breakdown of food molecules to cell functions.

• Energy is released when a phosphate group is removed.• The breaking of this chemical bond releases energy.• ADP is changed into ATP when a phosphate group is added.

phosphate removed

Organisms break down carbon-based molecules to produce ATP.

•Carbohydrates (details) are the molecules most commonly broken down to make ATP.• Not stored in large amounts (so it needs to be made all the time)• Up to 36 ATP can come from one glucose moleculetriphosphateadenosine

adenosine diphosphate

tri=3

di=2

• Lipids (details) store the most energy.• 80% of the energy in your body• About 146 ATP from one triglyceride•Proteins (details) are the least likely to be broken down to make ATP.• Amino acids are not usually needed for energy•Have about the same amount of energy as a carbohydrate

Organisms break down carbon-based molecules to produce ATP.

A few types of organisms do not need sunlight and photosynthesis as a source of energy.

• Some organisms live in places that never get sunlight (deep in the ocean for example).• Chemosynthesis is…• chemical energy is used to build carbon-based molecules.• Similar to photosynthesis• Uses chemical energy instead oflight energy

4.2 Overview of Photosynthesis• Key Concept:• The overall process of photosynthesis produces sugars that store chemical energy.

4.3 Photosynthesis in Detail• Key Concept:• Photosynthesis requires a series of chemical reactions.

Photosynthesis•The process of photosynthesis captures energy from sunlight and converts it into sugar.•This process happens in organisms called autotrophs or producers. (Need to make their own food)•This process takes place in and organelle called the chloroplast.•The chloroplast has a green pigment in it called chlorophyll that is responsible for capturing the light energy.

Photosynthesis in plants occurs in chloroplasts.

•Photosynthesis takes place in two parts of the chloroplast.•Grana (thylakoids)•Light-dependent reactions(aka Light Reactions)

•Stroma•Light-independent reactions (aka Dark Reactions; aka Calvin Cycle)

chloroplast

stroma

grana (thylakoids)

How does photosynthesis work?

•The first stage of photosynthesis is called the Light-Dependent Reactions/ Light Reactions.

1. (Sun) light is captured by the chlorophyll in the thylakoid.

2. Energy is transferred along the thylakoid membrane and water is broken down. Oxygen (from the broken apart water) is released.

3. Energy is transferred to ATP and NADPH. (Both are energy carrying molecules that will transfer energy to the second stage of photosynthesis.)

How does photosynthesis work?

•The second stage of photosynthesis is called the Light-Independent Reactions/ Calvin Cycle/ Dark Reactions.

1. ATP and NADPH carry energy from the thylakoid to the stroma to begin the next reaction.

2. Carbon dioxide is added from the atmosphere to help make sugar.

3. A molecule of glucose is formed. This molecule stores some of the energy captured from the sun.

1

2

3

4

5

6

97

8Light-independent reactions(Calvin Cycle)

Contains: chlorophyll and other light-absorbing molecules

Photosynthesis Equation6CO2 + 6 H2O + sunlight C6H12O6 + 6 O2

C6H12O6

granum (stack of thylakoids)

thylakoid

sunlight

1 six-carbon sugar

6H2O

6CO2

6O2

chloroplast1

2

43

energy

stroma (fluid outside the thylakoids)

Photosynthesis Inputs

•Sunlight•Needed for Light Reactions•Splits apart water

•Water (H2O)

•Needed for Light Reactions•Hydrogen from water becomes the hydrogen in glucose

•Carbon dioxide (CO2)

•Needed for Dark Reactions (Calvin Cycle)•Becomes the carbon and oxygen in glucose

Photosynthesis Outputs

•Oxygen (O2)

•Given off from Light Reactions•Comes from water splitting apart

•Glucose (C6H12O6)

•Given off from Dark Reactions (Calvin Cycle)•Comes from putting CO2 and H (from water) together

•Photosynthesis Song

Enzymes control the process of photosynthesis. • Factors like temperature will make the rate/ speed of photosynthesis drop.• This happens because change in temperature denatures enzymes (changes their shape) and makes them not able to function. • Draw a graph of what temperature does to the rate of photosynthesis:

• How does this relate to the change of seasons?