Bellringer – April 16, ) Draw the leaf below. What goes into and out of the PLANT? Label the 5 arrows. 2) In what organelle does photosynthesis take place? 3) Try and write the FULL equation for photosynthesis

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Photosynthesis: Life from Light and Air Honors Biology

Photosynthesis Photo = “light” Synthesis = “to make” Photosynthesis = using light to make something…. What needs to be made during photosynthesis?

Photosynthesis is… When plants convert the energy of sunlight into chemical energy stored in the bonds of carbohydrates Examples of carbohydrates are: – Glucose – Fructose – Sucrose – Starch – Cellulose

2 Types Metabolic Pathways Catabolic pathways – Break down complex molecules into simpler compounds – Release energy Ex: Cellular Respiration A nabolic pathways (“ a dd”) – Build complicated molecules from simpler ones – Sometimes called “biosynthetic pathways” – Consume energy Ex: Building protein from amino acids

Real Life Examples… Exergonic (Exothermic) – Cellular Respiration – Energy (ATP) is released when glucose is broken down Endergonic (Endothermic) – Photosynthesis – Energy (ATP) is NEEDED (consumed) to put together glucose from CO 2, H 2 0 and sunlight –

What is the chemical energy needed by cells? ATP (Adenosine Triphosphate) When energy is needed, ATP is broken down ATP is renewable Energy is released and ATP becomes  ADP + P – ADP (Adenosine Di-phosphate) + P DRAW ME!

P Adenosine triphosphate (ATP) H2OH2O + Free Energy  given off Inorganic phosphate + Adenosine diphosphate (ADP) PP PPP i Sometimes referred to as “high energy” phosphate bonds

– ATP  an “energy currency” Example of Energy Coupling

ADP and ATP ADP stores energy by adding phosphates – Like a rechargeable battery ATP releases energy by breaking bonds between phosphates

Plants are energy producers Like animals, plants need energy to live Unlike animals, plants don’t need to eat food to make that energy Plants make both food & energy – animals are consumers – plants are producers

The Process That Feeds the Biosphere  Photosynthesis  the process that converts solar energy into chemical energy  Who or What?  Plants and other autotrophs  They are producers of the biosphere

2 Types of Autotrophs 1.Chemoautotrophs – Use chemosynthesis to make “food” 2. Photoautotrophs – Use photosynthesis to make “food”

 Plants, some bacteria and algae are photoautotrophs  Use energy of sun to make organic molecules from H 2 O and CO 2  Some worms and bacteria are chemoautotrophs  Use energy from chemicals to make organic molecules

 Photosynthesis  Occurs in plants, algae, certain other protists, some prokaryotes These organisms use light energy to drive the synthesis of organic molecules from carbon dioxideand (in most cases) water. They feed not only themselves, but the entire living world. (a) On land, plants are the predominant producers of food. In aquatic environments, photosynthetic organisms include (b) multicellularalgae, such as this kelp; (c) some unicellular protists, such as Euglena; (d) the prokaryotes clled cyanobacteria; and (e) other photosynthetic prokaryotes, such as these purple sulfur bacteria, which produce sulfur (spherical globules) (c, d, e: LMs). (a) Plants (b) Multicellular algae (c) Unicellular protist 10  m 40  m (d) Cyanobacteria 1.5  m (e) Pruple sulfur bacteria Figure 10.2

Autotrophs vs. Heterotrophs  Heterotrophs  Obtain their organic material from other organisms  They are consumers of the biosphere

Using light & air to grow plants 6CO 2 6H 2 O C 6 H 12 O 6 6O 2 sun energy   glucose + oxygen carbon dioxide sun energy + water + (ATP) Photosynthesis – using sun energy to make ATP – using carbon dioxide & water to make sugar – Takes place in chloroplast – allows plants to grows – makes a waste product oxygen

Chloroplasts: The Sites of Photosynthesis in Plants  The leaves of plants-THEY’RE GREEN!!  major sites of photosynthesis

Chloroplasts Organelle where photosynthesis occurs  Stroma  Dense fluid within chloroplast  Calvin Cycle (Dark reaction) occurs here  Thylakoids  Membranous sac (or “coin”) in stroma  Inside space called thylakoid space  Light reactions occur here  Grana (granum = singular)  Stack of thylakoids (“coins”)  Lumen-inside the thylakoid ****NOTE the difference between stroma and stoma (stomata)

The Equation for Photosynthesis  Photosynthesis converts light energy to the chemical energy of food  Photosynthesis is summarized by this Overall chemical equation 6 6 CO H 2 O + Light energy  C 6 H 12 O O 2

The Nature of Sunlight  Light  a form of electromagnetic energy, which travels in waves and particles (called photons)  Wavelength  distance between crests of waves  Determines type of electromagnetic energy (wavelength & energy are inversely proportionate)

 The electromagnetic spectrum  The entire range of electromagnetic energy, or radiation Gamma rays X-raysUVInfrared Micro- waves Radio waves 10 –5 nm 10 –3 nm 1 nm 10 3 nm 10 6 nm 1 m 10 6 nm 10 3 m nm Visible light Shorter wavelength Higher energy Longer wavelength Lower energy

Color we SEE = color most reflected by pigment; other colors (wavelengths) are absorbed  BLACK  all colors are reflected Light Reflected Light Chloroplast Absorbed light Granum Transmitted light

How is Energy Absorbed by Plants?! Pigment molecules – PHOTONS = packets of light energy that are absorbed by pigments to energize electrons Chlorophyll – 2 types 1) Chlorophyll a 2) Chlorophyll b – Differ b/c they absorb different wavelengths (colors) 28

Primary vs. Accessory Pigments  Primary Pigment  Chlorophyll a (most abundant)  Accessory (Antennae) Pigments  Chlorophyll b  Anthocyanins  Xanthophylls  Cartenoids

Why are plants green? Whatever color wavelength is reflected is the color that the pigment appears to be GREEN – Plants do not absorb (aka reflect) green regions of visible spectrum  are therefore GREEN! Chlorophyll a and chlorophyll b redblue – Absorb red and blue (b est colors for PS!) – What would the worst color be…? GREEN!

Carotenoids Plant pigment Often appear orange and yellow Also found in green plants, too Can give flower petals their color! Carotenoids Plant pigment Often appear orange and yellow Also found in green plants, too Can give flower petals their color! Carotenoids 31

What happens to leaves in the fall? Days get shorter (less sunlight) Temperature drops Less chlorophyll is made, but is still broken down at the same rate Underlying red and orange pigments (which were always there) are now seen

The Two Stages of Photosynthesis: A Preview The Light reactions NEEDS LIGHT Light Dependent Reactions The Calvin cycle A.k.a- Dark Reactions or Light Independent Reactions DOES NOT NEED LIGHT

The Light Reactions  Occur in the grana (& thylakoids)  Convert solar energy to chemical energy  Chlorophyll absorbs solar energy  Splits water  release O 2 (a by-product)  produce ATP (chemical energy)

The Calvin Cycle  Occurs in the stroma  Forms SUGAR from carbon dioxide  Carbon fixation occurs (CO 2  fixed carbon from C 6 H 12 O 6 )  Uses ATP for energy and NADPH for reducing power

An overview of photosynthesis H2OH2O CO 2 Light LIGHT REACTIONS CALVIN CYCLE Chloroplast [CH 2 O] (sugar) NADPH NADP  ADP + P O2O2 ATP NADPH - Carries electrons that are needed to build molecules such as glucose.

Photosynthesis This is the equation you are used to seeing, but this is not the whole story… + water + energy  glucose + oxygen carbon dioxide 6CO 2 6H 2 O C 6 H 12 O 6 6O 2 light energy  +++