2. Cellular metabolism
• Metabolism is the sum total of all chemical
processes
• It takes place within a living system
• Catabolism – breaking down
• Anabolism – building up
3. ATP and cell energy
• ATP (adenosine triphosphate)
• The energy from sugar as carbohydrates must
be transformed into another molecule (ATP)
• Adenosine-substance made up of purine and
adenine plus a five - carbon ribose and a
triphosphate group
• The phosphates are connected by high energy
bonds
4. • Phosphoanhydride bonds – high energy bonds
because of a great deal of free energy is
liberated when these bonds are broken
5. Photosynthesis and cell energy
• energy transformation – activity that occurs at
the cellular and molecular levels
• In cells, there are two basic patterns:
• Autotrophic cells – light energy is transformed
into chemical energy that can be used by the cell
• Heterotrophic cells – cells that cannot transform
light energy but can break down organic
molecules that have been manufactured by the
autotrophs
6. • Photosynthesis process by which living plant
cells combine carbondioxide and water in the
process of chlorophyll and light energy :)
• Two raw materials used in photosynthesis are
water and carbon dioxide
• Xylem vessels are roots system and the
network of conducting cells
7. • Stomata – structures where carbon dioxide is
normally obtained by plants from the
atmosphere
8. Light reaction - photolysis
• Sunlight – mixture of different wavelengths of
light
• Each wavelength has a particular color and
amount of energy
• Light reaction in photosynthesis occurs in the
thylakoids found in chloroplasts.
9. • The process can be summarized as follows:
1. light energy strikes chlorophyll bodies, and
electrons are excited
2. Electrons are accepted by
NADP++(nicotinamide adenine dinucleotide
phosphate) in the electron transport train
3. Light hits a second chlorophyll molecule and
splits the water molecule into hydrogen and
oxygen. Oxygen is released into the
atmosphere and hydrogen ions are added
10. 4. More H+ is carried by the electron transport
chain
5. Energy is generated with the formation of ATP.
The light reaction results in the production of
a) ATP, a high-energy molecule, and NADPH++
for use in the dark-reaction phase; and
b) Oxygen, which is released into the
atmosphere
11. Dark Reaction- Carbon fixation
• ATP & NADPH- formed in the light reaction.
Sources to fix and reduce carbon dioxide.
• Dark reaction- second stage of photosynthesis.
• The Calvin cycle consists of four major steps:
1. Carbon dioxide enters the plant. It combines
with RuDP (ribulose diphosphate), a five-
carbon sugar molecule
• Carbon dioxide fixation-an enzyme, RuDP
carboxylase, catalyzes the fixation reaction
12. • RuDP- makes up about 25% of the total
protein on the chloroplast. Also the most
abundant protein on earth
• The resulting product from this fixation
process is an unstable six-carbon sugar
molecule that easily splits into 2 molecules of
phosphoglyceric acid (PGA), a three-carbon
molecule.
1. 2. PGAL (phosphoglyceraldehyde) is formed
from
13. • 1 PGA molecule combining with a phosphate
group supplied by ATP (from the light reaction);
and
• Another PGA molecule reacting with hydrogen
from a molecule of NADPH+ (also from the light
reaction)
3. Glucose is formed from two PGAL molecules
4. Most of the PGAL is used to regenerate more
RuDP, using the energy supplied by ATP. The RuDP
produced is reused in another cycle of CO2 fixation.
Also PGAL is converted to other products such as
fructose, sucrose, maltose, and starch
