Download Photosynthesis

DO NOW
You have 5min memorize
the amount of NADH,
FADH2, and ATP produced
by…
 Glycolysis
 Acetyl CoA Formation
 Citric Acid Cycle
 Electron T ransport Chain
ANABOLIC INTERCONVERSIONS: GLUCONEOGENESIS
Glycolysis: Glucose oxidized to form CO2
 Gluconeogenesis: CO2 reduced to form Glucose
“creation of new glucose”

KEEPING METABOLISM CONSTANT


1 Carbon atom from your hamburger can end up as
DNA, fat, or CO2
Metabolic Pool- the creation and number of
biochemical molecules is usually the same
Ex1. Traffic Patterns- if Rt 36 is closed, cars just move to Rt
35. But, Net # of the cars is the same on the roads.
 Ex2. High concentrations of products from a Signal
Transduction Pathway can stop the initial enzyme from
working

PHOTOSYNTHESIS
Done by: Plants, Bacteria, Algae
PHOTOSYNTHESIS

Anabolic (Endergonic)
6
CO2 + 6 H2O + Light  C6H12O6 + 6 O2
SUNLIGHT
H2O
CO2
SUGAR
O2
2 Pathways:
Light Reactions (Light + H2O Energy)
2. Calvin Cycle (Energy + CO2  Sugar)
1.
PHOTOCHEMISTRY
LIGHT
Electromagnetic Radiation
 Travels in waves
 The shorter the wavelength (λ, nm), the more energy
 Behaves like particles, called Photons (no mass)
 Plants have receptive molecules (pigments) that only
λ
receive certain photons

YOU ARE THE COLOR
YOU REFLECT
WHAT’S A PLANT’S
LEAST FAVORITE
COLOR?
GREEN!
“Visible Spectrum”
MOVEMENT OF PHOTONS
1.
2.
3.
Reflected/Scattered- bounces off
molecule
Transmitted- pass through molecule
Absorbed- into molecule, *adds energy
PHOTOBIOLOGY
PIGMENTS
PIGMENTS: molecules that absorb light in the visible
spectrum

White Light: contains all wavelengths of the visible
spectrum, pigments are designed to absorb only
some
Plant Pigments:
1. Chlorophyll a absorbs BLUE and RED, and we see
the reflected, GREEN light
2.
Chlorophyll b
Accessory Pigments:
1.
2.
Carotenoids (B-Carotene)- orange
Phycobilins
DO ANIMALS HAVE
PIGMENTS?
1. Melanin- brown protective pigment, in skin
2. Hemoglobin- red, oxygen carrying pigment in
blood
Absorption Spectrum
CHLOROPLAST
STROMA
-Calvin Cycle
Thylakoids
GRANUM
-stacks of Thylakoids
-Light Reactions
Inner and
Outer
Membranes
LIGHT
REACTIONS
Light

Energy
(ATP + NADPH)
-In Thylakoid
PHOTOSYSTEM
Thylakoids
In thylakoid membrane
 Many proteins that link together
 Electron Transport Chain that is very similar to cell
respiration
 Chlorophyll (Chl) absorbs light and gets excited
(Chl*) and loses/oxidizes electron (Chl+)

1. Photosystem 2: “P680 chlorophylls” absorb light at
680nm. Makes ATP and Oxygen.
2. Photosystem 1: “P700 chlorophylls” absorb light at
700nm. They pass an excited electron to NADP+
making NADPH
CYCLIC ELECTRON TRANSPORT
Uses Photosystem1, makes ATP not NADPH
 An exited electron is passed from 1 chlorophyll
to the next

CALVIN CYCLE
Energy + CO2  Sugar
-In Stroma
CALVIN CYCLE

The ATP & NADPH made in Light Reaction will “fix”
CO2 into Sugar
ATP + NADPH + RUBP + CO2 + RUBISCO ENZYME  G3P  Sugar
Energy

(5C)
(1C)
(3C)
Sugar Options: Glucose, Sucrose, Maltose
(6C)
PHOTORESPIRATION
… the bad one
PHOTORESPIRATION
In times of Low CO2
 Instead, O2 jumps into Calvin Cycle and ruins every thing
 Actually causes plant to Lose Energy

WHY?
 The Earth originally didn’t have oxygen
 The only time a plant doesn’t have CO2 is when stomata
close, AKA its REALLY HOT
TYPES OF
PHOTORESPIRATION
PLANTS
CAM PLANTS
Only open stomata at night
 NIGHT: CO2 comes in, stores CO2 as Malic Acid and
stores in vacuoles
 DAY: close stomata, use CO2 stored in Malic Acid to
use in Light Reaction

C4 PLANTS
Take CO2 and use enzymes to make 4C molecule
 4C molecule moves to Bundle of Sheath cells and
they make CO2
