Download Chapter 8: The Working Cell: Energy from Sunlight

Chapter 8: The Working Cell: Energy from Sunlight
Concept 8.1: Photosynthesis Uses Light Energy to Food
I. The Structure of Chloroplasts
A. Photosynthesis takes place in the chloroplast
B. Chloroplasts contain compounds called
pigments that give leaves their color (chlorophyll).
C. Leaves contain the most chloroplasts. (fig. 8-2)
D. Stoma are tiny pores that allow carbon dioxide to
enter and oxygen to leave the plant cell.
E. Veins (xylem) carry CO2 and H2O from the plants
roots to the leaves and deliver(phloem) organic
compounds to other parts of the plant.
F. The inner membrane of a chloroplast encloses a
thick fluid called stroma.
G. Suspended in the stroma are many disk shaped
sacs called thylakoids which are arranged in
stacks called grana.
H. These stacks organize the series of reactions that
make up photosynthesis.
II. Overview of Photosynthesis
A. In cellular respiration, electrons “fall” from glucose
to O2 to release energy.
B. In photosynthesis, electrons from water are
boosted “uphill” (potential) by the energy of sunlight.
C. These excited electrons, along with carbon dioxide
and hydrogen ions to produce C6H12O6 molecules
D. Photosynthesis occurs in two main steps: Light
and Calvin Cycle (Dark Reaction).
III. The Light Reactions
A. Light Reactions convert the energy in sunlight to
chemical energy.
B. Chloroplasts use captured light energy to remove
electrons from H2O, splitting it into oxygen and
hydrogen ions.
C. The electrons and hydrogen ions are used to make
NADPH, which is an electron carrier.
D. Chloroplasts also use the captured light energy to
generate ATP.
E. The overall result of the light reactions is the
conversion of light energy to chemical energy stored
in NADPH and ATP
IV. The Calvin Cycle
A. Calvin Cycle makes sugar from the atoms in
carbon dioxide plus the hydrogen ions and high
energy electrons carried in NADPH
B. The ATP made in the light reactions
provides the energy to make sugar.
C. The Calvin cycle is sometimes referred to as the
“light-independent reactions” because it does not
require light energy to begin.
Overview fig. 8-4