Photosynthesis Big Idea #1 Cellular basis of life

Without the ability to obtain and use energy, life would cease to exist! Energy can be light, heat, electricity, chemical compounds and many other things

Cells use the chemical compound adenosine triphosphate (ATP) as their main source of fuel ADENOSINE PO 4 PO 4 PO 4

How do living things store energy? – Living things store energy through adenosine diphosphate (ADP), which is missing one phosphate group (-PO 4 ) ADENOSINE PO 4 ex.html

– ADP is like a rechargeble battery!

ATP can easily RELEASE AND STORE energy by breaking and reforming bonds between its phosphate (PO 4 ) groups ADP ADENOSINE PO 4 PO 4 PO 4 ATP ENERGY IS STORED!

ADP ADENOSINE PO 4 ATP ENERGY IS RELEASED!

Cells need to produce ATP from the time that they are born – Where do they get the energy to produce ATP? FROM THE CHEMICAL COMPOUNDS FOUND IN “FOOD”!

Heterotrophs get their energy by consuming other living things Autotrophs are organisms that make their own food – Use energy from the sun mostly Mushroom is a heterotroph because it uses organic matter to synthesize energy, just as animals do. Mushrooms cannot photosynthesize.

Plants, algae and some bacteria use light energy from the sun to produce their food.

In the process of photosynthesis, plants convert the energy of sunlight into chemical energy stored in the bonds of carbohydrates

Activity Use a compare/contrast table when you want to see the similarities and differences between two or more objects or processes. Place an “X” in the box next to characteristics that are true of an autotroph or a heterotroph.

X X X X X X

Review – Cells have a basic form of energy called ATP ADENOSINE PO 4 PO 4 PO 4

How many phosphate groups (-PO 4 ) does ATP have? – 3! Where is the energy in ATP stored? – The bonds between adenosine and phosphate!

What is ATP called when it is missing a phosphate group? – ADP! When ADP becomes ATP is energy stored or released? ADP + P  ATP – ENERGY IS STORED!

Where do living things get the energy they need to make ATP? – The “food” they consume. What are organisms that produce their own food called? – Autotrophs.

What is the process called in which autotrophs use the energy of sunlight to produce carbohydrates? – PHOTOSYNTHESIS!

How do plants gather the sun’s energy? – They use light absorbing molecules called pigments – The main pigment in plants is called chlorophyll

Chlorophyll absorbs light well in the blue-violet and red regions of the electromagnetic (EM) spectrum

The electromagnetic spectrum organizes all types of waves in the universe

The light you see is just a small portion of the EM spectrum

Why do we see colors? – Objects REFLECT frequencies of light associated with certain colors.

What color is REFLECTED by the chlorophyll in leaves of plants? – GREEN!

Where does photosynthesis take place? - Inside organelles called chloroplasts

Chlorophyll pigments are located in the chloroplasts, on thylakoid membranes Thylakoids are interconnected and arranged in stacks known as grana

Chlorophyll absorbs EM light and converts it directly into high energy electrons (e - ) Light e-e-

Do electrons just float around by themselves? – No! – They need electron carrier molecules to be transported – In photosynthesis, NADP + is used (nicotinamide adenine dinucleotide phosphate)

This may sound complicated but the job NADP+ does is NOT! – NADP+ accepts and holds TWO high energy electrons (2e - ) and a hydrogen ion (H + ) NADP + + 2e - + H +  NADPH

NADPH then carries the electrons anywhere in the cell that they are needed!

What are some REACTANTS in the photosynthesis process? – 6 Water (H 2 O) molecules and 6 carbon dioxide (CO 2 ) molecules 6H 2 O + 6CO 2 + ?  What else??

LIGHT 6H 2 O + 6CO 2 + LIGHT 

What does photosynthesis produce? – 1 High energy sugar (C 6 H 12 O 6 ) and 6 oxygen molecules (6O 2 ) 6H 2 O + 6CO 2 + LIGHT  C 6 H 12 O 6 + 6O 2

In words: – Carbon dioxide + water + light  sugars + oxygen Why do plants need sugars?

-They use the sugars to produce complex carbohydrates like starches.

Photosynthesis involves 2 sets of reactions: – Light-dependant reactions – Light-independent reactions

Light-dependant reactions – Take place in the thylakoids – Direct involvement of light and light absorbing pigments – This is where ATP is produced

Light-independent reactions – Take place in stroma: the fluid portion of the chloroplast – Use ATP and NADPH from the light-dependant reactions to produce high energy sugars from CO 2 – No light is required

Light dependant reactions – Use energy from sunlight to produce oxygen and convert ADP and NADP + into the energy carriers ATP and NADPH – Takes place in the thylakoids, in photosystems- clusters of chlorophyll and proteins

Photosystem II 1.Pigments (chlorophyll) absorb light 2.Light energy is absorbed by an e-, making the e- energized

3. e - ’s are passed to an electron transport chain- a series of e - carrier proteins that shuttle high energy e - ’s during ATP generating reactions

- the oxygen we breathe comes from a reaction that replaces lost high energy e- with e- from water molecules

– At the end of the e- transport chain, the electrons move into photosystem I

Photosystem I – Some energy of the e- is lost in photosystem II – Pigments use light energy to re- energize the e-

– NADP+ molecules in the stroma pick up e- and H+ to become NADPH

– ATP synthase (a protein in the thylakoid membrane) allows built up H+ to pass out of the thylakoid and make ATP also

Light-independent reactions: the Calvin Cycle – ATP and NADPH are NOT stable compounds – Plants use the energy that ATP and NADPH have stored to make stable high-energy carbohydrate compounds

Calvin Cycle – CO2 enters from the atmosphere and rearranged into different forms of carbon – Energy is harvested from ATP and NADPH 12 CCC 12 ADP 12 NADP+ 12 CCC

– 2 of the 3-carbon compounds make sugars, lipids and amino acids 12 CCC 12 ADP 12 NADP+

– The remaining 3-carbon compounds are converted back to 6 5-carbon compounds and the cycle begins again! 12 CCC 12 ADP 12 NADP+ 10 CCC 6 CCCCC 6 ADP

Photosynthesis can be affected by many things – Temperature – Light intensity – Water availability Ex: C4 plants capture low levels of CO 2 ; corn and sugar cane Ex: CAM plants live in dry climates; cacti