] This powerpoint presentation has been adapted from Life 4e-Lewis, Gaffin, Hoefnagels and Parker. Publishers-McGraw-Hill 1998 and Principles of Anatomy and Physiology,Tortora and Grabowski. Publishers- John Wiley & sons, Inc. 2000

photoautotroph AUTOTROPHY Obtaining energy from a non-living world chemoautotroph

] Photoautotrophs F Convert CO 2 and H 2 O to sugars utilizing light E (blue and red) F Examples: plants, algae, some bacteria ] Chemoautotrophs F Some convert CO 2 and H 2 S to sugars utilizing chemicals(energy) such as H 2 S. F Examples: some bacteria (hydrothermal vents) Two types of Autotrophs

] Autotrophy is the energy basis for all life on this planet. F Directly keeps the autotroph alive (can make its own sugar) F Indirectly keeps all of the heterotrophs alive(get eaten!)

] Autotrophy produces glucose ] Glucose will be used for: F Cellular respiration F Modified with minerals/other molecules to become: Nucleotides, amino acids, lipids, other carbohydrates

Energy Flow Energy flows in one direction through an ecosystem. Route of energy flow is determined by an ecosystem’s trophic structure. photo- or chemoautotrophs animals that eat producers ( primary consumers) animals that eat herbivores ( Secondary consumers) animals that eat carnivores (tertiary consumers)

Food web - several species function at more than one trophic level.

I strongly suggest you view and use what is appropriate from the following link:

PHOTOSYNTHESIS ] 6CO H 2 O  C 6 H 12 O 6 + 6O 2 + 6H 2 O ] Several consequences to this evolutionary advance/mutation. F Oxygen gas (O 2 ) slowly built up in atmosphere- v Aerobic respiration now a possibility UV v Ozone forms (3 O 2 2 O 3 ) ª Life can now leave the safety of the water and colonize land

Light (see page 103) Visible light makes up only a small portion of the electromagnetic spectrum.

Characteristics of Visible Light: ] is a spectrum of colors/wavelengths ranging from violet to red ] consists of packets of energy called photons ] photons travel in waves, having a measurable wavelength ( ) measured in nanometers (nm)10 -9

A photon’s energy is inversely related to its wavelength ( )......the shorter the ( )..., the greater the energy it possesses. Which of the following photons possess the greatest amount of energy? Green photons = 530nm Red photons = 660nm Blue photons = 450nm

What happens to light when it strikes an object? ] reflected (bounces off) Only absorbed wavelengths of light function in photosynthesis. ] transmitted (passes through) ] absorbed

Photosynthetic Pigments Molecules that capture photon energy by absorbing certain wavelengths of light. Primary pigments F Chlorophylls a & b - bluish green pigments found in plants, green algae & some bacteria.

See page 105 Chlorophyll a is the dominant pigment in plant photosynthesis.

Accessory Pigments F Carotenoids - orange, yellow pigments found in plants, algae, bacteria. F Anthocyanins - reds and purples Each pigment absorbs a particular range of wavelengths.

See page 105

Leaf- See page 728 Chloroplasts- See page 104 Sites of photosynthesis in plants & algae. Concentrated in the palisade mesophyll cells of most plants.

Chloroplast structure: See page 104 ] Stroma - gelatinous matrix; contains ribosomes, DNA & various enzymes. ] Thylakoid - flattened membranous sac; embedded with photosynthetic pigments.

Chloroplast

Photosynthesis. CO 2 from atmosphere, H 2 O from soil 6CO H 2 O  C 6 H 12 O 6 + 6O 2 + 6H 2 O Requires correct enzymes and pigments plus sunlight (red and blue,) ATP, NADPH to convert the reactants into the products

F Stomata/Stoma - pores extending through the leaf epidermis Stomata regulate gas (CO 2,O 2 and H 2 O) exchange with the environment. Usually based on their different concentration gradients, CO 2 will diffuse into the leaf; H 2 O and O 2 will diffuse out of the leaf.

Photosynthesis occurs in two biochemical pathways: ] Light reactions - harvest photon energy to synthesize ATP & NADPH. Splits H 2 0 ] Calvin cycle reactions - use ATP and NADPH from light reactions to reduce (add hydrogen/electrons) to CO 2 forming carbohydrates.

Overview of Photosynthesis

Light Reactions F require light F occur in thylakoids of chloroplasts F involve photosystems II & I (light harvesting systems). Photosystems contain antenna complex that captures photon energy & passes it to a reaction center.

Light Reactions of Photosynthesis

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig Light Reactions 1.Light drives both photosystems (PS). 2.Water splits, O 2 formed & electron to PS II 3.excited electron enters ETC. ATP is made, similar to respiration. 4.electron replaces the one lost in PS I. 5.electron from PS I enters ETC. 6. This ETC produces NADPH

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig

ATP Production: See page 108

Go to Light Reaction animation Go to Calvin Cycle animation

Overview of Photosynthesis

Carbon Reactions (Calvin cycle; C 3 cycle)  occurs in stroma of chloroplasts F requires ATP & NADPH (from light reactions), and CO 2 from atmosphere. F Produces- H 2 O and 2 PGALs (glucose)

Calvin Cycle; see pg.111

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig

Overview of Photosynthesis

] PS II & PS I are both filled with chlorophyll molecules. (all contain e-) ] Light shines on PS II & PS I simultaneously. ] e- get excited & transfer energy to reaction center in both. ] e- is released from reaction center of both. ] e- need to be replaced on both, so where do they come from? Steps of Light Reaction

] Steps of Light Reaction ] In PS II, water is split, freeing e -, H + & O. F To be balanced, 2H 2 O --> 4H + + 4e - + O 2 ] E- travel along the electron transport chain. ] When they pass the hydrogen pump, they lose energy and a H + is transported across. ] The e- from PS II join PS I to replace the e- lost from there.

] Now the e- join a H+ to make a H atom. ] Then the H joins a molecule called NADP + to change it into NADPH. ] Well….. Now we’ve got a higher concentration gradient of H+ in the thylakoid disc. ] H+ moves from high to low through ATP synthetase (ATPsynthase/ATPase). ] As it moves through, ATP is made. PHEW! Steps of Light Reaction

] Calvin Cycle Steps ] CO 2 combines with the 5-carbon sugar RuBP ] This reaction is catalyzed by the enzyme RUBISCO ] The resulting unstable 6-carbon compound breaks down into 2 molecules of 3-carbon PGA ] The PGA molecules get energy from ATP and a H from NADPH to form PGAL. ] The PGAL gets rearranged and another ATP is used to recycle into RuBP.

] It takes 3 “turns” of the cycle to release one PGAL. ] It takes 2 PGALs to make a glucose. ] So… it takes 6 turns of the cycle to make a glucose. ] Each turn of the cycle is started by the entrance of one CO 2. ] So look back at the overall equation. It takes 6CO 2 to make one C 6 H 12 O 6. Calvin Cycle

Calvin Cycle; see pg.111

Plants that use only the Calvin cycle to fix carbon are called C 3 plants. Ex. cereals, peanuts, tobacco, spinach, sugar beets, soybeans, most trees & lawn grasses.

Calvin Cycle; see pg.111

Photorespiration: See page 118 Process that counters photosynthesis. Occurs when stomata close under hot, dry conditions: F O 2 levels in plant leaf increase F CO 2 levels in plant leaf decrease Under these conditions, rubisco attaches to O 2 (rather than to CO 2 ). Thus,less PGAL is produced (up to 50%). Photorespiration and Special Adaptations

] No known function of photorespiration ] Photosynthesis has produced all atmospheric O 2. So when photosynthesis and Rubisco are thought to have evolved there was little to no O 2 therefore photorespiration was not a problem.

C 3 because first stable molecule is a 3 Carbon sugar

C 4 and CAM Photosynthesis: See pages Adaptations that allow certain plants to conserve water and reduce photorespiration when exposed to higher temperatures. C 4 Photosynthesis C 4 plants reduce photorespiration by physically separating the light reactions and Calvin cycle.

Leaf anatomy of a C 4 plant vs. C 3 plant C 4 Photosynthesis: ] Light reactions occur in chloroplasts of mesophyll cells. ] Calvin cycle occurs in chloroplasts of bundle sheath cells.

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

CAM Photosynthesis CAM plants reduce photorespiration by acquiring CO 2 at night. Therefore don’t have to open stomata and dehydrate during hot days. Night: ] mesophyll cells fix CO 2 as malic acid ] malic acid is stored in vacuoles. Day: ] malic acid releases CO 2 which enters Calvin cycle. Malic acid

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig

Rate of photosynthesis ] Rate= activity per unit of time ] Light intensity,water conc., temperature, conc. of oxygen and carbon dioxide F All affect the rate of photosynthesis

Light- see page 115 increasing light= increasing rate of photosynthesis until light saturation point, then declines. Why? CO 2 - increasing CO 2 similar curve except no decline (reaches saturation)

] See page 116 ] Temperature F As temperature increases so does rate of photosynthesis, then it declines to zero. ª Why?

] See page 116 ] Limiting factors ] Light, temperature etc. all interact with each other. ] Factors in shortest supply have the greatest effect on the rate of photosynthesis. These are called limiting factors..

] Sugar made in the chloroplasts supplies the entire plant with chemical energy and carbon skeletons to synthesize all the major organic molecules of cells. F About 50% of the organic material is consumed as fuel for cellular respiration in plant mitochondria. F Carbohydrate in the form of the disaccharide sucrose travels via the veins to nonphotosynthetic cells. F There, it provides fuel for respiration and the raw materials for anabolic pathways including synthesis of proteins and lipids and building the extracellular polysaccharide cellulose. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings