 Organisms get their energy through 2 methods:  Organisms that make their own food are…. Autotrophs  Organisms that get energy from the food they consume are…. Heterotrophs

Plants and some other organisms are able to use light energy from the sun to produce food

 Plants convert solar energy into chemical energy  Chemical Energy = stored in the bonds between atoms.  Breaking the bonds releases the energy  Examples: Eating & digesting food Burning a fuel (wood, gasoline, oil, etc…)

 Primary source of chemical energy in cells is ATP  Stands for adenosine triphosphate

 Each bond between phosphates contains energy (electrons)  Break the bond and “lose” a phosphate to release energy (ATP  ADP + P + E)  Add a phosphate to ADP to store energy (ADP + P + E  ATP)

 Making proteins and nucleic acids  Active Transport of material across cell membrane  Cell movement/response to stimuli (flagella)

Active Transport

 Remember how the cell theory was developed? Through a series of smaller discoveries. #1 Jan van Helmont (physician) #2 Joseph Priestley (minister) #3 Jan Ingenhousz (scientist)

Ques. “Do plants grow from materials in soil?”  Recorded mass of dry soil and seed  Grew for 5 years  Gained 75 kg  Mass of soil the same  Had to come from water (only thing he added) Also claimed to invent the term “gas” Had theories about digestion

 Lit candle lost flame when covered by glass jar  Something in air kept it lit, when used up the flame died  That substance was oxygen  Placed a mint leaf inside and candle could be lit again  Plant produced the oxygen to keep flame lit  Invented Pop/Soda Great Commercial

 What Priestly found only occurred when plant exposed to light  Together found that: Light necessary for plants to produce oxygen.  Friends with Benjamin Franklin

 Plants use solar energy to turn CO 2 and H 2 O into sugars and oxygen.  6 CO H 2 O + light  C 6 H 12 O O 2 Carbon dioxide + water + light  glucose + oxygen

 Water: uptake through roots  Sunlight: absorbed by chlorophyll in chloroplasts in leaves/stems  CO 2 : holes in leaves called stomata that allow CO 2 to be exchanged w/ O 2

 Chlorophyll pigment  Green light reflected, all other colors absorbed by chlorophyll  Reddish-Orange & Blue have best absorption (Remember ROYGBIV???)  If plant absorbed all light from the Sun what color would it be? Black  What problems would the plant have if its leaves were this color? Overheat and therefore lose A LOT of water.

 First, what is inside?  Thylakoids = photosynthetic membranes  stacked together to form Grana  light-dependent reactions occur here  Lumen = space inside Thylakoid  Stroma = the space chloroplast, between the grana

Divided into two reactions 1) Light dependent Reaction 2) Calvin Cycle (light independent) Ingredients for Light Dependent Reaction:  Inputs: Water (H 2 O) & Sunlight  Parts of Thylakoid Membrane: Photosystems I & II Electron Transport Chain ATP Synthase Channel  Parts in Stroma: NADP + (electron carrier) ADP & P

 Electrons in photosystems are energized by sunlight  High energy electrons are: very reactive, but unstable useful later in Calvin Cycle  Electron Carrier Molecules like NADPH transport the electrons while they are in their highly energized state

 Occurs in the thylakoid membrane: 1) Begins with a photon of light absorbed by photosystem II 2) This energy is used to energize electrons 2a) The electrons come from splitting water molecules: 2 H 2 O  4H + + O electrons 2b) Electrons passed down the electron transport chain to photosystem I 2c) Oxygen (O 2 ) is released from plant 2d) Hydrogen ions will build up inside thylakoid creating a high concentration of H + inside thylakoid

3) More light absorbed at photosystem I 4) This energy plus electrons from photosystem II is used to bind hydrogen ions to NADP to form NADPH (in stroma) 5) Hydrogen ions travel through ATPsynthase to stroma (ATP is made from ADP inthe process)

 Water + light go in, O 2 is released  In the process NADP becomes NADPH and ADP becomes ATP  The ATP and NADPH will go on to be used in the Calvin Cycle where glucose is made

photosynthesis (oversimplified) photosynthesis (complicated) photosynthesis complete

 Light Independent reactions occur in Stroma 1. cytoplasm of chloroplast

Let’s start with energy needed to run it… 1. ATP made from light dependent rxn. 2. NADPH supplies high energy electrons - needed to make bonds - NADPH full of e - ; NADP + empty

Now CO 2 is needed… 1. supplies carbon atoms to make glucose 2. The carbon atoms get rearranged a few times to form base units called PGAL or G3P 3. Every 3 CO 2 that enter the cycle makes 1 PGAL or G3P 4. 2 G3P’s can form 1 Glucose = the ultimate goal

G3P

 MANY glucose molecules bonded together to form sheets  Makes them difficult to digest

2 Reactions or stages Light Dependent:  Water & sunlight taken in  Oxygen given off  ATP and NADPH are generated for Calvin Cycle Light Independent (Calvin Cycle)  CO 2 taken in  ATP & NADPH used to form glucose from smaller carbon units  photosynthesis video review photosynthesis video review

 Moisture/Water less water = less photosynthesis  Plant adaptations to prevent water loss: Waxy coatings Thick or expandable leaves and stems = succulents

Temperature between 0 o C- 35 o C Proteins involved in photosynthesis require this temp range Warmer is best Light Intensity – the more the better Direct sunlight at the equator maximizes photosynthesis and plant growth Indirect sunlight at poles minimizes photosynthesis Trees in Temperate zones lose their leaves due to decrease in light intensity, lower temps and less water available

Cuticle – waxy coating to prevent water loss Epidermis – “skin” of leaf, holds it together Palisade Mesophyll – near top surface, densely packed, do photosynth. Spongy Mesophyll – near bottom surface spread out, do photosynth. Vein – contains vascular tissues (xylem & phloem) Xylem – moving water and nutrients into leaf Phloem – moving sugar out of leaf Stomata – openings for gas exchange (CO 2 in, O 2 out) Guard Cells – open and close stomata

2. Upper Epidermis 4. Mesophyll- cells containing chloroplasts 3. Lower epidermis Covers and protects see stoma –in lower epidermis only

Xylem-( blue ) carries water Phloem (thicker cell wall )- ( yellow ) carries food