AIM: SWBAT explain the overall
reaction of photosynthesis and
describe the light reactions in detail
Please Do Now: Explain specifically
where in the cell chlorophyll is found
Agenda
 Do
Now
 Annotate article
 Begin notes on light reactions of
photosynthesis
Reminder
 Homeworks
are due today
 Please put them in the bucket on your
way out
Annotating
 In
this class, we will tackle the reading of
some upper level texts
 To make this process more useful, I have a
system of annotation I want you to follow
while you read
 This should allow you to better understand
the point of the article
How should I be annotating
text in this class?
 The
main scientific claim(s) of the article should be
boxed
 Any quantitative evidence to support the main
scientific claim should be underlined and tagged
with a pound sign (#)
 Any quantitative evidence to support the main
scientific claim should be underlined and tagged
with a star
 Vocabulary words that you are unfamiliar with
should be circled
 You should write at least two questions that you
have about the content in the margins of the page
Abbreviated version
 Main
point(s)
 # Quantitative evidence #
 Qualitative evidence
 Unknown vocabulary
 At least 2 questions should be going in the
margins
You try
 You
will practice this annotation with a
reading on the acidification of the Arctic
Ocean
 Then, as a group, we will go over the
article together to see how everybody did
What is photosynthesis?
 The
process of creating sugar using the
energy in sunlight
 The sun’s energy is stored in the chemical
bonds of the sugar
 Overall equation:
sunlight + CO2 (carbon dioxide) + water
(H2O)  (oxygen) O2 + glucose (C6H12O6)
How does sunlight turn into
chemical bonds during
photosynthesis?
 Photosynthesis

takes place in two steps:
Light Dependent Reactions
A
complex system of enzymes, membrane proteins,
and pigments make ATP from sunlight

Light Independent Reactions (Calvin Cylcle)
 The
ATP generated in the LDR is used by enzymes in
the Calvin Cycle to combine CO2 with a 5 carbon
compound to make glucose
H20
O2
CO2
Glucose
Step 1: Oxygen Evolving
Complex
A
complex sex
of enzymes in
the lumen splits
water apart,
freeing an
electron
Step 2: Light hits chlorophyll
 Chlorophyll,
embedded in the thylakoid,
catches sunlight
Step 3: Electron Transport Chain
 the
energy in the sunlight excites the electron to a
higher energy state, and it flows through an
“electron transport chain”
 ETC is actually a bunch of proteins in the thylakoid
membrane
 that generates ATP and NADPH and a proton
gradient inside the thylakoid
Step 4: protons flow
 the
protons flow through a membrane
proton (ATP synthase) like a water wheel,
generating more ATP
Light Reactions EVEN MORE BRIEFLY
Sunlight
ATP
out
in
Z scheme