Photosynthesis is the process by which plants, algae, and certain bacteria use sunlight, carbon dioxide, and water to produce glucose and oxygen. It occurs in two stages: the light reactions absorb sunlight and produce ATP and NADPH using water, and the Calvin cycle uses ATP, NADPH, and carbon dioxide to produce glucose in the chloroplasts of plant cells. The overall equation for photosynthesis is: 6CO2 + 6H2O + sunlight → C6H12O6 + 6O2.

1. Photosynthesis
An Introduction & Overview

2. Our Big Fat Question
• What are some things plants
NEED in order to survive?

3. The plant cell

4. 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.
Chloroplasts are full of round flattened discs
called thylakoids.
A stack of thylakoids is called a granum.
Chloroplasts are where photosynthesis occurs.
Both pictures are of
chloroplasts in plant
cells at different
magnifications.
Chloroplast
Stroma is the
space inside
chloroplasts

5. Photosynthesis
• Photosynthesis is a process
plants use to convert the light
energy from the sun into
chemical energy that they can
use
• The chemical energy is a
molecule of sugar called
glucose
• Plants and animals use this for
food

6. Photosynthesis is carried out by:
plants
cyanobacteria
certain bacteria
most algae phytoplankton
These organisms are known
as photoautotrophs or
producers meaning they
make their own food and
energy from the sun.
Consumers such as herbivores and
carnivores depend on the products
of photosynthesis that producers
make to live.

7. Glucose
During photosynthesis, plants
produce glucose molecules when they
convert light energy into chemical
energy. The chemical energy is
stored in the bonds of glucose.
Glucose (C6H12O6) is a
sugar and its molecular
structure looks like this.
When animals
digest plants, they
are breaking down
the glucose bonds
to release stored
energy to power
their bodies.
Plants produce sugars as a source of food.
However, they produce way more than they
need to survive. This is a great benefit for all
the species that depend on glucose for energy.
Plants also use the
glucose they produce for
energy. When plants
produce excess glucose
they store it in their
leaves.
All biological energy comes from glucose.

8. Glucose in Plants
Why do plants make glucose?
What is it plants do with glucose?
Plant Chef
Glucose
“My masterpiece!”
Glucose molecules can be broken
apart for energy to power reactions.
Plants can also make glucose into carbohydrate
chains called polysaccharides.
poly = many saccharide = carbohydrate
There are 2 polysaccharide chains in plants:
Cellulose Starch
Cellulose is the structural
component of cell walls.
Starch is a long term energy store that
the plant can use later.
O O
O O O O
O O
Glucose is a monosaccharide.
mono = one saccharide
Glucose
Glucose is a simple sugar
because it is one of the smallest
units of carbohydrates.

9. Photosynthesis in plants happens in the chloroplasts.
Chloroplasts are full of thylakoids stacked in granum.
The thylakoid membranes are
lined by pigments such as
chlorophyll and cartenoids.
These pigments harvest
light energy packets or
photons when they
absorb sunlight.
Chlorophyll is a green pigment
and is the most abundant.
Chlorophyll absorbs all wavelength colors
except green, which is reflected off
giving plants their green appearance.

10. Photosynthesis
• Plants need 3 things to do
photosynthesis:
1. Water
1. Taken in through roots or
surroundings
2. Carbon dioxide (CO2)
1. Taken in from air or water
3. Light energy from the sun

11. Photosynthesis
• We can show the overall process of
photosynthesis in a chemical equation
• Water = H2O
• Carbon dioxide = CO2
• Light energy
• Glucose = C6H12O6
• Oxygen = O2

12. Rinse and Repeat
•What is the chemical symbol for carbon
dioxide?
•What is the chemical symbol for glucose?
•What is the chemical symbol for oxygen?

13. Equation
REACTANTS – what goes into a
chemical process
They react during photosynthesis
to make something new
Water + Carbon
dioxide + Light energy
Write this part of the equation on your
whiteboard in SYMBOLS

14. Photosynthesis
equation
• PRODUCTS: what comes out of a chemical
process
• Glucose - C6H12O6
• Oxygen – O2
Water + Carbon
dioxide + Light energy Glucose + Oxygen
Write the entire equation for photosynthesis on
your whiteboards using SYMBOLS

15. Quick Check with
Popsicle Sticks
• What is the chemical symbol for water?
• What is the chemical symbol for oxygen?
• What is the chemical symbol for carbon
dioxide?
• What is the chemical symbol for glucose?
• What are the reactants of photosynthesis?
• What are the products of photosynthesis?

16. Balance the equation
6H2O + 6CO2 Light energy C6H12O6 + O
6
2

17. On your whiteboards
• What type of energy goes
into a plant during
photosynthesis?
• How do plants store this
energy?

18. 2 stages of
photosynthesis
• Stage 1 – the Light
Reactions
▪ Reactants: Light and
water
▪ Products: oxygen
(O2), energy
molecules ATP and
NADPH
▪ Location: thylakoid
membranes inside
the chloroplast

19. 2 Stages of Photosynthesis
• Stage 2 – the Calvin
Cycle (or light-
independent reactions)
▪ Reactants: carbon
dioxide (CO2)
▪ Products: glucose,
ADP, NADP+
▪ Location: stroma
inside the chloroplast

21. Objective
1. Write the overall equation for
photosynthesis in both symbols
and words
2. Identify the reactants and
products for the 2 stages of
photosynthesis