Presentation photosynthesis
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Transcript of Presentation photosynthesis
By Ganyaza Z
Review
What is photosynthesis? Process by which energy from sunlight is used
to convert water and carbon dioxide into high-energy carbohydrates (sugars and starches) and oxygen as a waste product
Who uses photosynthesis? Plants and other producers
Jan van Helmont 1643 Belgian physician Do plants grow by taking material out of the
soil? Mass of soil Mass of seed Watered regularly @ end of 5 yrs, tree was 75 g, soil the same Conclusion: Mass came from water Accounts to the “hydrate” portion of
carbohydrate produced but what made the “carbo-” portion
Joseph Priestly
1771 English minister Bell jar, candle, plant Jar over candle flame
died out Jar over candle with live
sprig of mint flame didn’t die
Conclusion: Plant releases oxygen
Jan Ingenhousz
1779 Dutch scientist Aquatic plants produce
bubbles only when light is present
Conclusion: Plants need sunlight to produce oxygen
Julius Robert Mayer
1845 German scientist Proposed that plants
convert light into energy into chemical energy
The experiments performed by van Helmont, Priestly, and Ingenhousz led to work by other scientists who finally discovered that in the presence of light, plants transform carbon dioxide and water into carbohydrates, and they also release oxygen
Hill, R. (May 1999). "Oxygen Produced by Isolated Chloroplasts". Proceedings of the Royal Society of London. Series B, Biological Sciences 127 (847): 192–210
Review Sunlight White light
ROYGBIV Combo of all colors
Pigments Chemicals that absorb electromagnetic radiation
(visible light) Light absorbing molecules
Electromagnetic spectrum Electrons=energy
Structures and molecules
Chloroplast
Chlorophyll
Thylakoids
Chloroplast (found in cells in leaves)
Concentrated in the cells of the mesophyll (inner layer of tissue) in leaf
Stomata Tiny pores on surface of leaf Allows carbon dioxide and
oxygen in and out of the leaf Veins
Carry water and nutrients from roots to leaves
Deliver organic molecules produced in leaves to other parts of the plant
Chloroplast
Cellular organelle where photosynthesis takes place Double membrane Outer membrane Stroma (fluid filled space) Inner membrane Thylakoids Granum Intermembrane space
Contain chemical compound called Chlorophyll This molecule gives
chloroplast its green color
Structure of Chloroplast
Structures organize the many reactions that take place in photosynthesis
Stroma Thick fluid enclosed by the inner
membrane
Thylakoids Disc-like sacs suspended in the
stroma
Has membrane that surrounds inner thylakoid space
Grana (sing. Granum) Stacks of thylakoids
Chlorophyll Plants principle pigment 2 types
Chlorophyll a Absorbs light in the blue-violet and red regions of visible spectrum
Chlorophyll b Absorbs light in the blue and red regions of the visible spectrum
Chlorophyll does NOT absorb light well in the green portion of the visible spectrum
Green light reflected by leaves This is why plants look green…they reflect green light
Carotene Secondary plant pigment Red and orange pigments Absorb light in other regions of the spectrum other than red and
orange
2 main stages Light Dependent Rxn Light-Independent or Calvin Cycle
Photosynthesis Overview
#1 “Light-Dependent” reactions Convert the E in sunlight to chemical energy
Rxns depend on molecules made in membranes of thylakoids
Chlorophyll in membr. captures light E
Chloroplast use E to remove e- from water
Splits water into oxygen (waste) and hydrgen ions
e- taken are used to make high-E molecule NADPH (similar to NADH)
Chloroplast also use captured E to make ATP
Overall Product: convert light E into chemical energy stored in compounds ATP and NADPH
Photosynthesis Overview# 2 “Light- Independent” Reactions aka
The Calvin Cycle Makes sugar from atoms of CO2 and H+ ions and High-E e- carried by NADPH
Enzymes for these reactions are dissolved in the stroma (outside thylakoid)
ATP made by light Rxns provides E to make sugar (glucose)
Called light independent, b/c unlike unlike the light reactions, these do NOT require light tp begin
However, this cycle does require two things made by the light reactions: ATP and NADPH
This means that the calvin cycle cannot necessarily continue in the dark
List of references
^ "photosynthesis". Online Etymology Dictionary.
(http://bioenergy.asu.edu/photosyn/study.html).
REFERENCES
Bryant DA, Frigaard NU (November 2006). "Prokaryotic photosynthesis and phototrophy illuminated". Trends Microbiol. 14 (11): 488–96]
Buick R (August 2008). "When did oxygenic photosynthesis evolve?". Philos. Trans. R. Soc. Lond., B, Biol. Sci. 363 Olson JM (May 2006). "Photosynthesis in the Archean era". Photosyn. Res. 88 (2): 109–17.
Online Sources
http://bioenergy.asu.edu/photosyn/stuy.html
http://hdgc.epp.cmu.edu/teachersguide/teachersguide.htm