The document discusses photosynthesis and the structures involved in carrying out this process in plants. It describes how chloroplasts, which contain thylakoids, are where photosynthesis occurs within plant cells. Chloroplasts absorb light energy and use it to convert carbon dioxide and water into oxygen and glucose through two stages - the light-dependent reactions in the thylakoids and the light-independent reactions in the chloroplast stroma. The chloroplasts and thylakoids play a key role in harvesting sunlight and producing chemical energy to fuel plant growth and provide food and oxygen.

1. By: Roselle Altar

2. BASIC CONCEPT
LEAF AS
PHOTOSYNTHETIC SYSTEM
CHLOROPLAST
LIGHT AND CHLOROPLAST

3. BASIC CONCEPT
Most life on Earth depends on photosynthesis. The
process is carried out by plants, algae, and some types
of bacteria, which capture energy from sunlight to
produce oxygen (O2) and chemical energy stored in
glucose (a sugar).
(a) Mosses, ferns, and
flowering plants
(b) Kelp (c) Euglena
(d) Cyanobacteria

4. BASIC CONCEPT
• Herbivores then
obtain this energy
by eating plants,
and carnivores
obtain it by eating
herbivores.
• Energy can be
transformed from
one form to
another

5. Photosynthesis
• Photosynthesis is the process by which autotrophic
organisms use light energy to make sugar and oxygen
gas from carbon dioxide and water
Photosynthesis has 3 major events:
1. Sunlight is converted into chemical energy
2. Water (H2O) is split into oxygen (O2)
3. Carbon dioxide (CO2) is fixed into sugars (C6H12O6)
Carbon
dioxide
Water
Glucose
Oxygen
gas
PHOTOSYNTHESIS

6. PROCESS • During photosynthesis,
plants take in carbon
dioxide (CO2) and water
(H2O) from the air and
soil. Within the plant cell,
the water is oxidized,
meaning it loses
electrons, while the
carbon dioxide is
reduced, meaning it gains
electrons. This
transforms the water into
oxygen and the carbon
dioxide into glucose. The
plant then releases the
oxygen back into the air,
and stores energy within
the glucose molecules.
Video:https://www.youtube.com/w
atch?v=ucH2Q8wKmwQ

7. LEAF AS A
PHOTOSYNTHETIC SYSTEM
Video:https://www.youtu
be.com/watch?v=pwym
X2LxnQs

8. LEAF AS A
PHOTOSYNTHETIC SYSTEM
Oxygen — the oxygen that we breathe — is just a
waste product of what reaction?
Every split second that
sunlight hits that
leaf, photosynthesis is
initiated, bringing energy into
the ecosystem. It could be
said that this is one of the
most important - if not the
absolutely most important -
biochemical reactions. And it
all starts with the leaf.

9. FACTORIES FOR
PHOTOSYNTHESIS
A factory has specialized machines to
produce a product. It’s also connected to a
transportation system that supplies it with
raw materials and carries away the
finished product. In all these ways, a leaf
resembles a factory.
A leaf consists of several different kinds of
specialized tissues that work together to
make food by photosynthesis. The major tissues are
mesophyll, veins, and epidermis.
•Mesophyll -This is where
photosynthesis occurs. Mesophyll
consists mainly of parenchyma
with chloroplasts.
•Veins are made primarily
of xylem and phloem. They transport
water and minerals to the cells of
leaves and carry away dissolved
sugar.
•The epidermis of the leaf consists
of a single layer of tightly-packed
dermal cells. They secrete
waxy cuticle to
prevent evaporation of water from
the leaf.

10. The epidermis has tiny pores
called stomata (singular, stoma)
that control transpiration and
gas exchange with the air. For
photosynthesis, stomata must
control the transpiration of
water vapor and the exchange
of carbon dioxide and oxygen.
Stomata are flanked by guard
cells that swell or shrink by
taking in or losing water
through osmosis. When they do,
they open or close the stomata

11. CHLOROPLAST

12. CHLOROPLAST
Through evolution, plant cells, certain bacteria and
some algae have acquired chloroplasts to help
carry out the photosynthetic reaction.
Chloroplasts are a plastid or plant cell organelle.
Both pictures are
of chloroplasts in
plant cells at
different
magnifications.
Chloroplasts are full of round flattened discs called
thylakoids.
A stack of thylakoids is
called a granum.
Stroma is the
space inside
chloroplasts
Chloroplasts are where
photosynthesis occurs.

13. FUNCTION
Thylakoid System: internal membrane system
consisting of flattened sac-like membrane
structures called thylakoids where light energy
is converted into chemical energy. Thylakoids
contain the light-harvesting complex, including
the electron transport chains used in
photosynthesis and pigments like chlorophyll
and carotenoids.
Chlorophyll is a green pigment and
is the most abundant.
Granum: densely layered stacks of
thylakoids (10 to 20) that are the sites
of conversion of light energy to
chemical energy.
Chlorophyll absorbs all wavelength
colors except green, which is
reflected off giving plants their
green appearance

14. FUNCTION OF CHLOROPLAST
Chloroplasts are essential for the survival and growth of plants and
photosynthetic protists. They are responsible to carry out photosynthesis, the
process of conversion of light energy into sugar and other organic molecules
that are used by plants or algae as food. They also produce amino acids and lipid
components that are necessary for chloroplast membrane production.
Photosynthesis has two stages:
(i) The 1st stage: the light-dependent reactions occur. Sunlight is captured
through chlorophyll and carotenoids and converted into adenosine triphosphate
(ATP, the molecular unit of currency of intracellular energy transfer) and
nicotinamide adenine dinucleotide phosphate (NADPH), which carries electrons.
(ii) The 2nd stage: the light-independent reactions, also known as the Calvin
cycle, occur. The electrons carried by NADPH convert carbon dioxide to
carbohydrate, a process known as CO2 fixation. Hence, carbohydrates and other
organic molecules can be stored and used for energy.

15. LIGHT AND
CHLOROPLAST
Video:
https://www.youtube.com/
watch?v=Ry4J3aQpVX4

16. Different wavelengths of visible light are seen
by the human eye as different colors.
Gamma
rays
X-rays UV
Infrared &
Microwaves
Radio waves
Visible light
Wavelength (nm)

17. 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.

18. Chloroplasts absorb
light energy and
convert it to chemical
energy
Light
Reflected
light
Absorbed
light
Transmitted
light
Chloroplast
THE COLOR OF LIGHT SEEN IS THE COLOR NOT
ABSORBED

19. The light and dark reactions in the chloroplast
The chloroplast is involved in both
stages of photosynthesis. The light
reaction takes place in the
thylakoid discs. There, water (H20)
is oxidized, and oxygen (O2) is
released. The electrons freed up
from water are transfered to ATP
and NADPH. The dark reaction
occurs outside of the thylakoids. In
this reaction, the energy from ATP
and NADPH are used to fix carbon
dioxide (CO2).
The products of this reaction are sugar molecules and other organic molecules
necessary for cell function and metabolism. Note that the dark reaction takes
place in the stroma (aqueous fluid surrounding the stacks of thylakoids) and the
cytoplasm.
Video: https://www.youtube.com/watch?v=ua-4JmSa7Ik

20. THANK
YOU