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Bio. Ch. 8 Photosynthesis
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Photosynthesis definition:
Process which energy of sunlight is used to fix/redue CO2 into organic compounds
Ability to make food using sunlight
Function
: Produce sugars
Photoautotrophs/half in ocean
Equation for photosynthesis:
6CO2+12H20 ---> C6H12O6 + 6H20 + 6O2
CO2's reduced
Overal procedure of Photosythesis:
1.) cpature suns energy
2.) makes ATP and NADPH (electron carrier like NADH)
3.) uses ATP and NADPH to make sugar
Where is photosyntheis occuring:
(green parts) Chloroplasts
Structure of a leaf:
CO2 leaves from Stoma
Stoma is made of guard cells that open and close (prevent H20 from escaping)
Parenchyma- generalized cell typ
eq
: spongy parenchyma/palisade parenchyma
Chloroplasts Figure:
inside thylakoids
: photosystem...
Photosystem:
Energy bounces around until it hits the reaction center
SENDS OUT ENERGY
C.B. Van Niel's Work
1930's purple sulfur bacteria
using CO2 + 2H(S) ---light---> CH2O + H2O + 2(S)
S-sulfur
he predicted then maybe the general equation for photosyntheis is:
CO2 + 2H(some element)---> CH2O + H2O + 2(some element)
so by emplementing oxygen we get:
CO2+2HO--->CH2O+H2O+O2
carbon fixation:
the generated H+ ions and electrons by splitting water were used to convert CO2 into organic matter
2-stage process (photosynthesis)
a) light dependent reactions
: uses suns energy to make ATP and NADH
b) light independent reactions
: (non dependent on light)
-Calvin cycle
-uses ATP and NADH
Radiant energy
light from sun (waves/packets)
waves = photons
Length of light wave: (electromagnetic spectrum)
longe wave
: little energy
short wave
: higher energy
gamma rays (short/blue)----visible light---- radio waves (long/red)
photosynthetic pigments:
absorb light and use it for photosynthesis
Chloryphyll
(green) reflects green light and absorbs other colors
-main pigment in plants
-in thylakoid membranes
Types of chlorophyll:
chlorophyll a - main kind
chlorophyll b - accessory pigments- help out
chlorophyll c - " "
caratanoids - yellow,orange/accessory pigments
phycobiloproteins - red and blue (red algae)
Absorption spectrum of a pigment:
Action spectrum vs absorption spectrum
action is sum of all pigments (rate of photosynthesis)
absorbstion is single pigment
NADPH
another electron carrier like NADH
light dependent reactions:
H2O+NADP+ADP+P ----light---> NADPH + O2 + ATP
Pigments organized into:
Photosystems:
Photosystem I - reaction center
Photosystem II -
Z scheme
Non cyclic (begin and ends) photophosphorulation = made ATP
Calvin Cycle
makes sugar using ATP and NADPH (in stoma)
Steps:
1) Carbon fixation
2) Reduction
3) Regeneraton of RuBP
For every 3 molecules of CO2 that enter= 1 molecule of G3P (sugar)
Enzyme carries out reaction that incorporates CO2 into organic form:
Rubisco is the enzyme that helps the carbon fixation reaction (very slow 3 substrates/sec)
Photorespiration
RuBP (rubisco) combines w/ O2 instead of CO2 = sugar is lost if CO2 is low or temp is high.
@25degrees C 20% of photosynthetically fixed carbon is lost.
Stoma is closed (hot environments)
C3, C4, and CAM plants
C3- plants use calvin cycle
C4- more efficient to capture CO2
no photoresperation
Stoma can be closed more
4C sugars involved
C4 pathway and calvin cycle
(corn,grabgrass)
making of sugar w/o lots of CO2
CAM plants: C4 and C3 pathways. two pathways in same cell but seperated in time. C4 at night.
Author
tjtolman
ID
137737
Card Set
Bio. Ch. 8 Photosynthesis
Description
Chapter 8 Bio
Updated
2/27/2012, 1:16:10 AM
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