Download Photosynthesis

Photosynthesis
3.2 – Light Independent
reaction
Settling activity
• Using Fig 7 worksheet draw boxes
around the 3 sets of reactions in the
light dependent reaction
Learning outcomes
Success criteria
By the end of this lesson I will
know –
• The light-Independent
reaction in detail
• That carbon dioxide is
accepted by ribulose
bisphosphate (RuBP) to form
2 molecules of glycerate 3phosphate
• That ATP and reduced
NADP are required for the
reduction of GP to triose
phosphate
• That RuBP is regenerated in
the calvin cycle
• That triose phosphate is
converted to useful organic
substances
By the end of this lesson I can
–
• Construct a diagram of the
light independent reaction
• Answer exam questions on
the work covered so far
Starter
• Where does the light dependent reaction of
photosynthesis take place?
• Thylakoids (disc structures that are stacked
together in groups called grana)
• Name 2 ways chloroplasts structurally adapted
to their function of capturing sunlight and
carrying out the light dependent reaction.
• Thylakoid membranes have a large surface area
for the attachment of chlorophyll, electron
carriers and enzymes
• Proteins in the grana hold the chlorophyll to get
optimum light absorption
• Granal membranes have enzymes attached which
help make ATP
• Chloroplasts contain DNA and ribosomes so
they can quickly manufacture proteins needed
for the light dependent reaction
Light independent reaction
• What are the light dependent products?
• ATP and reduced NADP
• Where does the light independent reaction
take place?
• Stroma
• How is the stroma adapted for this reaction?
• Fluid contains enzymes that reduce carbon
dioxide
• Fluid surrounds grana so products of light
dependent can diffuse through
• Contains DNA and ribosomes so it can make
proteins
The Calvin cycle
1. Carbon dioxide diffuse through the stroma and
dissolves into mesophyll cell walls, the membrane,
cytoplasm, chloroplast membranes and stroma
2. Carbon dioxide is taken up by ribulose
bisphosphate (RuBP), a 5-carbon compound. This
gives an unstable 6-carbon compound, which
quickly breaks down into 2 x 3-carbon glycerate 3phosphate (GP)
3. This reaction is catalysed by the enzymes ribulose
bisphosphate carboxylase (rubisco).
4. Activated GP is reduced by (ATP and reduced
NADP) into triose phosphate (TP)
5. NADP is reduced further going back into the
light dependent reaction by accepting more H+
6. Most Triose phosphate (TP) is use to regenerate
RuBP using ATP
7. Some TP is converted to useful organic
substances such as glucose
The light-independent reactions of
photosynthesis: Calvin Cycle
CO2 (1C)
Rubisco
RuBP
Ribulose bisphosphate
Unstable intermediate
(6C)
GP
(5C)
2X Glycerate-3-phosphate
ADP
ATP
ATP
ADP + Pi
TP
(3C)
Reduced NADP
NADP
2X Triose phosphate Glucose (6C), amino
(3C)
acids and lipids
Tasks
1) Complete the cut and stick of the
calvin cycle using the information
from the lesson.
2) Complete the exam paper question
Homework – Complete exam questions
Plenary
Construct a simple overview of photosynthesis
Learning outcomes
Success criteria
By the end of this lesson I will
know –
• The light-Independent
reaction in detail
• That carbon dioxide is
accepted by ribulose
bisphosphate (RuBP) to form
2 molecules of glycerate 3phosphate
• That ATP and reduced
NADP are required for the
reduction of GP to triose
phosphate
• That RuBP is regenerated in
the calvin cycle
• That triose phosphate is
converted to useful organic
substances
By the end of this lesson I
can –
• Construct a diagram of the
light independent reaction
• Answer exam questions on
the work covered so far