6th lesson
TRANSCRIPT
BIOLOGY
UNIVERSITY OF FOOD INDUSTRY- HOCHIMINH CITY
1
THE FOOD WEB
• trap radiant energy from sunlight and convert it into the energy of chemical bonds in large molecules, such as carbohydrates,
• estimated 99.9% of life on Earth relies on
photosynthesis for its energy needs
7.1 Photosynthesis and Life
7.2 An Overview of Photosynthesis
Sunlight minus absorbed
wavelengths or colors equals
the apparent color of an
object.
The feathers of male cardinals are
loaded with carotenoid pigments.
These pigments absorb some
wavelengths of light and reflect
others.
Why are plants green?
Transmitted light
WHY ARE PLANTS GREEN?
Plant Cells
have Green
Chloroplasts
The thylakoid
membrane of the
chloroplast is
impregnated with
photosynthetic
pigments (i.e.,
chlorophylls,
carotenoids).
• Chlorophyll: An important molecule in the process of harvesting sunlight,
• light energy is transformed to chemical-bond energy in the form of ATP,
7.2 An Overview of Photosynthesis
• Light-capturing events,
• Light-dependent reactions,
• Light-independent reactions
3 distinct events in the photosynthesis
• Chlorophyll consists of chlorophyll a and chlorophyll b,
• Chlorophyll capture light energy and become excited,
Light-Capturing Events:
• Chloroplasts contain several pigments
Chloroplast Pigments
– Chlorophyll a – Chlorophyll b – Carotenoids
Figure 7.7
Chlorophyll a & b
•Chl a has a methyl
group
•Chl b has a carbonyl
group
Porphyrin ring
delocalized e-
Phytol tail
Light-Dependent Reactions:
Water-splitting
photosystemNADPH-producing
photosystem
ATP
mill
• Two types of photosystems cooperate in the light reactions
• The O2 liberated by photosynthesis is made from the oxygen in water (H+
and e-)
Plants produce O2 gas by splitting H2O
Light-Independent Reactions
C3-C4 and CAM photosynthesis
7.4 Other Aspects of Plant Metabolism
7.5 Interrelationships BetweenAutotrophs and Heterotrophs
Be ready for next lesson!