Energy & Metabolism

Energy for life processes Energy is the ability to cause matter to move

or to change

The ability to do work Work for a cell includes

Growth & repair Active transport Reproduction Synthesis of molecules Lots of other stuff!!!

Carbohydrates and lipids are the most important energy sources in foods you eat.

ATP

ATP: is a molecule that transfers energy from the breakdown of food molecules to cell processes

ATP/ADP cycle Energy is released when phosphate bond is broken and a phosphate group is

removed. The bond holding the third phosphate is unstable and easily broken. ATP ADP + Phosphate + Energy Adenosine triphosphate --- adensosine diphosphate Tri= 3; Di= dos= 2 Remember: Energy is in the bonds between phosphates, so if we break a bond

we must get Energy as a product and ATP becomes ADP + Phosphate

ATP/ADP Cycle

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ATP/ADP Cycle- Chemical bonds broken from food add P to ADP ATP; -when you work, ATP ADP + E (to do the work, chemical E in food regenerates ATP (That is why it is referred to as a cycle.)

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- Foods that you eat do not contain ATP that your cells can use.

- First, the food must be digested

- The number of ATP molecules produced depends on the type of molecule that is broken down-carbohydrate, protein, or lipid.

- Lipids store the most energy- fats store about 80% of the energy in your body

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- Plant cells also need ATP

- Plants do not eat their food, they make their own!

- This is done through the process Photosynthesis- plants absorb energy from sunlight and make sugars.

Photosynthesis Captures energy from sunlight to make

sugars that store chemical energy. Therefore, directly or indirectly, the

energy for almost all organisms begins as sunlight!

Plants absorb visible light for photosynthesis-light that we see that appears white but is made up of several colors, or wavelengths, of light.

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https://www.youtube.com/watch?v=eo5XndJaz-Y

Chloroplasts Chloroplasts –the membrane-bound organelles

where photosynthesis takes place in plants. Contain pigments – pigments absorb light

Energy Chlorophyll (green pigment) is a catalyst for

photosynthesis-it absorbs red and blue light; it reflects green light

it transfers light Energy into chemical energy

Chloroplast Has 2 major parts:

1. Thylakoid membrane2. Grana3. Stroma

3 Major Parts of a chloroplast Grana (singular)

Stack of coin-shaped, membrane-enclosed compartments called thylakoids.

Thylakoid membrane: contain chlorophyll, other light-absorbing molecules, and proteins.

Site where light-dependent reactions occur

Stroma: the fluid that surrounds the grana inside a chloroplast.

Site where light-independent reactions

Photosynthesis Chemical Reaction for

photosynthesis:Reactants

Products Water + Carbon dioxide Glucose +

Oxygen

6 H2O + 6 CO2 C6H12O6 + 6 O2

Photosynthesis - Overview Photo = light; synthesis = to make Uses 1% of solar E to convert to chemical E Occurs in 2 steps

Step 1 Light-Dependent Reactions (Light Reactions): Occurs within and across the thylakoid

membraneI. Captures energy from sunlight (pigments absorb light)II. Water (H2O) taken into chloroplast & split Oxygen

(O2) which is released (this is what we breathe-it comes from the water that gets broken down)

III.Energy carried along thylakoid membrane is transferred to molecules that carry energy, such as ATP

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Light Independent Rxn & Calvin CycleStep 2: Calvin Cycle or Dark Reaction or

Light Independent Reaction Occurs in stroma

I. uses energy from the light-dependent reactions to make ___________.

II. Carbon dioxide (CO2) is taken in

III. USED energy creates high-energy sugars (glucose)

IV. Glucose ( C6H12O6) stores some of the energy captured.

PhotosynthesisStage 1 and 2

Stage 3

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The First Stage of Photosynthesis Captures and Transfers Energy.

- Photo- Light-Dependent Reactions - Main function: Capture and transfer energy - Water broken down —> H, electrons, and O2 - Energy carriers- ATP and NADPH

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Photosystem II and Electron Transport

1.) ENERGY ABSORBED FROM SUNLIGHT - Chlorophyll and other light- absorbing molecules in the

thylakoid membrane absorb energy from sunlight. - Energy then transferred to electrons.- High-Energy electrons leave the chlorophyll and enter an

electron transport chain, a series of proteins in the membrane of the thylakoid.

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Photosystem II and Electron Transport

2.) WATER MOLECULES SPLIT-Enzymes break down water molecules -Hydrogen, Oxygen, and electrons are separated from each other.

-Oxygen released as waste.

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Photosystem II and Electron Transport

3.) HYDROGEN IONS TRANSPORTED- Electrons move from protein to protein in the electron

transport chain. - Their energy is used to pump H+ ions inside the thylakoid

against a concentration gradient.- H+ builds up inside thylakoid- Electrons move on to photosystem I.

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Photosystem I and Energy-Carrying Molecules

4.) ENERGY ABSORBED FROM SUNLIGHT

- As in photosystem II, Chlorophyll and other light-absorbing molecules inside the thylakoid membrane and absorb energy from sunlight.

- Electrons are energized and leave the molecules.

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Photosystem I and Energy-Carrying Molecules

5.) NADPH PRODUCED - The energized electrons are added to a molecule called

NADP+, forming a molecule called NADPH.

- NADP+ - functions like ADP

- NADPH- functions like ATP

- NADPH- goes to light- independent reactions.