Chapter 8 Miss Colabelli Biology CPA Photosynthesis Chapter 8 Miss Colabelli Biology CPA

Obtaining Energy Autotroph: energy (glucose) from sunlight. 6CO2 + 6H2O + sunlight  C6H12O6 + 6O2 Heterotroph: energy from food

Why is Photosynthesis important? Makes organic molecules out of inorganic materials It begins all food chains & webs All life is supported by this process It also makes oxygen gas! Organic molecules = glucose Inorganic = CO2 + water

Photosynthesis-starts ecological food webs!

Photo-synthesis = "putting together with light." Plants use sunlight to turn water and carbon dioxide into glucose Plants use glucose as food Autotrophs make glucose and heterotrophs are consumers of it

Overview of Photosynthesis Light Reactions Sunlight is absorbed and converted to chemical energy Chemical energy is temporarily stored in plants as ATP and NADPH Calvin Cycle CO2, ATP, and NADPH make organic compounds 6CO2 + 6H2O C6H12O6 + 6O2

Photosynthesis 6CO2 + 6H2O + energy  C6H12O6 + 6O2 sunlight Carbon dioxide + water glucose + oxygen absorbed by chlorophyll 6CO2 + 6H2O + energy  C6H12O6 + 6O2 As can be seen from the equation for photosynthesis, the wood, bark, and root came from water and carbon dioxide

Plants in Action

Capturing Light Energy During light reactions, the plant’s chloroplasts absorb the sunlight Chloroplasts have two membranes. In the inner membrane there are flat sacs called thylakoids. Thylakoids that are bunched together are called granum. The stroma is the space between the grana.

Elodea Same plant that we used for transport. The green circular organelles are the chloroplasts!

Elodea using photosynthesis What gas do you think is in the bubbles that the plant made?

Why are plants green? The light we see from the sun is white light, but its way more than white! Colors that we see are reflected from the object

Pigment in Plants Why do we see green? Green color from white light reflected NOT absorbed by the chlorophyll in the chloroplast

Visible light is only a small part of the electromagnetic spectrum (all forms of light).

Converting Light Energy to Chemical Energy Absorbing light energy to make chemical energy Pigments: Absorb different colors of white light (ROY G BIV) Main pigment: Chlorophyll a Accessory pigments: Chlorophyll b and Carotenoids These pigments absorb all wavelengths (light) EXCEPT green! http://www.youtube.com/watch?v=ljPU1nDVq-0 http://www.youtube.com/watch?v=-yrZpTHBEss

Light Reactions

Light Reactions Reactants used Products made Require sunlight in order to occur Light reactions take place in two parts Photosystems I and II Occurs in the thylakoid of the chloroplasts Reactants used Water Products made O2 NADPH (form of energy used in plants) Some ATP http://www.dnatube.com/video/2899/Photosynthesis-101-presented-by-Dr-Undergrad

H2O Sunlight Light Reactions O2 ATP NADPH

Making ATP! The thylakoid has its membrane and proteins throughout Facilitated Diffusion!! The thylakoid has its membrane and proteins throughout H+ ions are higher concentration in the cell ATP synthase: protein in membrane that transports H+ ions via facilitated diffusion This process make ATP

http://www.youtube.com/watch?v=AUPugYBkNJQ&list=PLB3AF0B8D290D071D http://www.stolaf.edu/people/giannini/flashanimat/metabolism/photosynthesis.swf

Calvin Cycle Named after American biochemist Melvin Calvin Most commonly used pathway by most plants Calvin cycle is used by plants that are called C3 because of the 3-Carbon molecules that are made

Calvin Cycle Light-independent reaction (Dark Reaction) Does not require light Occurs in stroma of chloroplast Reactants used CO2 Uses ATP and NADPH Products made Glucose sugar

Calvin Cycle Uses products from the light reactions + CO2 to make sugars and other compounds What are the products of the light reactions? Where does the CO2 come from?

O2 ATP NADPH Glucose ATP Calvin Cycle

Overview

Stoma This opening how plants exchange gases! Stoma Open Stoma Closed CO2 can increase O2 will decrease and leave cells Stoma Closed CO2 decrease O2 increases

C4 Pathway Plants that use this are called C4 plants and have stomata closed during hot part of day Enzyme fixes CO2 to a 4-carbon compound when CO2 is low and O2 is high Corn, sugar cane, & crab grass Usually tropical climates

CAM Pathway Water conserving pathway Hot dry climates Stoma closed during day & open at night Opposite of ordinary plants Pineapples & cacti

CAM Pathway During the day During the night Stoma are closed CO2 is released from compounds and enters Calvin cycle During the night Stoma are open Take in CO2 and fix into carbon compounds

PHOTOSYNTHESIS What affects photosynthesis? Light intensity: as light increases, rate of photosynthesis increases until it reaches a certain point

PHOTOSYNTHESIS Carbon Dioxide: As CO2 increases, rate of photosynthesis increases until it reaches a certain point

PHOTOSYNTHESIS Temperature: Temperature Low = Rate of photosynthesis low Temperature Increases = Rate of photosynthesis increases If temperature is too hot, rate drops