5.1 Energy & PhotosynthesisChapter 9

Energy: All organisms require energy for

survival All energy in food ultimately comes from

the sun

Energy: How do we get it? Make it! Autotrophs

Organisms that make their own food (glucose) using energy from the sun

Examples: plants, algae & some bacteria

Energy: How do we get it? Eat it! Heterotrophs

Organisms that eat plants or animals to get energy

Examples: animals & fungi

Energy: What’s it all for? Why do organisms need energy?

To move, breathe & reproduce

Why do cells need energy? Active transport, cell division & make

biomolecules

Where does energy come from? Food: Carbs – quick energy; Lipids – long

term energy

Energy Molecules:

ATP

ADP

Energy Molecules: ATP ATP (adenosine triphosphate)

1 ribose (sugar) molecule 3 phosphate groups Adenine (nitrogenous base)

Energy Molecules: ADP ADP (adenosine diphosphate)

1 ribose (sugar) molecule 2 phosphate groups Adenine (nitrogenous base) Created when ATP loses energy & a

phosphate

Energy Molecules

So what happens? ATP ADP

Bond between 2nd & 3rd phosphate is broken

Energy is released Energy can be used by the cell

So what happens? ADP ATP

Energy is stored when 3rd phosphate adds to ADP

How do cells get ATP? Break down carbohydrates & lipids

Creates energy – energy used to make ATP

Where do animals get carbohydrates & lipids from? Their FOOD

That food is produced by autotrophs in the process of photosynthesis

Photosynthesis Ability to

capture light energy from the sun and change it into chemical bond energy while making oxygen

Photosynthesis Equation

6CO2 + 6H2O + Light energy C6H12O6 + 6O2

Photosynthesis Questions: Where does it occur in plants? What are the reactants? How do the reactants get into the plant? What are the products? What happens to the products?

Location? In the chloroplast of plant cells

Where does it occur?

Chloroplast structure:

Thylakoids:Sacs of membrane with pigment molecules

Grana:Stacks of thylakoids

Stroma:Liquid surrounding thylakoidsContains enzymes for PS

Photosynthesis process Occur in two steps:

Light-dependent reactions Purpose: Make energy for light-independent

reactions Light-independent reactions

Also called Calvin cycle Purpose: Use energy from light reactions to make

glucose

Light-dependent Reactions

Light-independent

Reactions

Glucose

thylakoid Electrons

Photosynthesis process:light-dependent reactions

Location: Thylakoids1.Light energy is absorbed by chlorophyll2.Energy used to make ATP3.Electrons are stored for Calvin Cycle

Photosynthesis process:light-dependent reactions4. Water is split to produce oxygen and

hydrogen atoms 2H2O + Light 2H2 + O2

Oxygen is released as a product

Photosynthesis process:light-dependent reactions

Used:

Light energy

H2O

Made:

ATP

electrons

Oxygen (product)

Light-independent rxns

Photosynthesis process:light-independent reactions Called Calvin cycle

No light required!

Location: Stroma of chloroplast

Photosynthesis process:light-independent reactions

1. ATP broken apart to release energy ATP ADP + P + energy

2. Energy used to bond electrons with CO2 to make glucose

1. Equation: CO2 + H2 C6H12O6

3. ADP goes back to light reactions to get recharged

Turned back into ATP

Photosynthesis process:light-independent reactions

Used:

CO2

ATP (from light rxns)

Electrons (from light rxns)

Made:

GLUCOSE !!!

Photosynthesis review: Where did the CO2 come from?

How did water enter the plant?

What absorbed the sunlight?

What reactant is used in the light-independent reactions?

Photosynthesis questions: What is made in the light-dependent

reactions that is used in the light-independent reactions?

What reactant is responsible for making oxygen?

Photosynthesis questions Where do the light-dependent reactions

take place?

Where do the light-independent reactions take place?

What is the final product of the light-independent reactions?

H

Factors that influence PS Rates Lack of water

Example/Adaptation: Desert plants/conifers (pines): waxy

coating and “needle” leaves to reduce water loss

Factors that influence PS Rates Temperature: influences enzymes

involved in the PS reactions What is the best temperature?

Factors that Influence PS rates Intensity of light (varies by plant)

Excess UV rays/sunlight can decrease PS