Photosynthesis

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Photosynthesis

• By
• Dr. Huq

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What Is Photosynthesis?
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Photosynthesis

• Photosynthesis concept. The process by which
  autotrophs convert sunlight to a usable form of
  energy is photosynthesis

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What is the equation for the chemical reaction of
photosynthesis?
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What is the equation for the chemical reaction of
photosynthesis?
Six molecules of carbon dioxide react with six
molecules of water to form 1 molecule of glucose
and six molecules of oxygen.
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Why is this important to us?

• We cannot make our own food (glucose, energy), we
  must get our food from plants.
• Plants are the first step in the food chain.

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Why is this important to us?

• The oxygen released during photosynthesis is
  necessary for all living things.

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Photosynthesis

• AUTOTROPH. An organism that produces its own food
  from inorganic (carbon dioxide) compounds and
  sunlight.

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What Parts Of The Plants Are Involved In The
Process Of Photosynthesis?
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Chloroplast

• Chloroplast--A plastid that contains chlorophyll
  and is the site where photosynthesis and starch
  formation occur.

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Photosynthetic pigments

• Most of the pigments in green plants are bound to
  the trimeric light-harvesting complex II (LHCII).
  It is located at several positions in photosystem
  II, but also at other locations. It is very
  important for the organization of the thylakoid
  membranes in chloroplasts and for the separation
  of photosystems I and II.

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Photosynthetic Pigments

• Certain pigments in autotrophs are essential for
  photosynthesis. The most common and important of
  these photosynthetic pigments is called
  chlorophyll.

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Photosynthetic Pigments

• Chlorophyll a is the major pigment. However
  chlorophyll b Beta carotene are two accessory
  pigments for photosynthesis.

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What color of light is not needed?green
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What color of light is needed?
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What Color Of Light Is Needed?
chlorophyll which absorbs red and blue light (and
appears green) and carotenoids which absorb in
the blue (and appear yellow).
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What Organelle Does This Job?
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Organelles of photosynthesis
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Where these reactions take place?
Reactions occur in different areas of the
thylakoid called photosystem I photosystem II
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What are photosystems?
Inside the Thylakoids, hundreds of chlorophyll
molecules other pigments are organized into
units called photosystems. These are light
collecting units of chloroplast.
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Besides light and the organelle, what else is
used in this process?
H2O And CO2
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What is Light reaction?
PhotosystemII uses sunlight to split water into
H, energized electrons and O2. Most of the
Oxygen diffuses out into the air. The electrons
enter the electron transport chain
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Electron transport Systems
ATP Adenosin triphosphateADP ATP
NADPH Nicotinamide Adenine Dinucleotide
phosphate NADP NADPH
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Then what Happens in Light Reaction?

• Electron transport Energized electrons are
  shuttled from Photosystem II by carrier
  molecules. The carrier molecules use the
  electrons energy to actively transport H from
  the stroma into the thylakoid space

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What is next in Light Reaction ?

• Photosystem I. Using suns energy the
• energy- depleted electrons are reenergized in
  Photosystem I. The energized electrons are used
  to produce NADPH, (Nicotinamide Adenine
  Dinucleotide phosphate) a molecule that will
  later be used to make glucose.

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What next in light Reaction ?

• ATP synthesis The high H concentration in the
  thylakoid space creates a concentration
  gradient. H difuses back into the stroma
  through an enzyme, ATP synthase. The energy
  released by the flow of H converts ADP to ATP

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What is Dark reaction?

• The Calvin cycle follows light-dependent
  reaction. It takes place in the stroma. It uses
  NADPH ,ATP (Adenosin triphosphate) and H. It
  needs CO2 to make sugar. 6 molecules of CO2 is
  used to make one molecule of Sugar. However one
  molecule of CO2 is processed at a time

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What is Step 1 of Dark Reaction?

• Carbon Fixation For each glucose molecule , 6
  molecules of CO2 reacts with6 molecules of five
  carbon sugar RuBP (Ribulose 1,5 phosphate). The
  result is 12 molecules of 3 carbon
  PGA(3-Phosphoglyceric Acid). Only one CO2 goes
  through the Calvin cycle at a time.

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What happens in Step 2?

• Production of G3P Each molecule of PGA is
  converted to G3P, using energy from ATP and
  hydrogen from NADPH. Two G3P molecules can be
  combined to form glucose in other cellular
  process.

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And in Step 3 of Calvin Cycle?

• Restoring RuBP The other ten G3P molecules are
  recycled back to RuBP. This requires energy from
  6 ATP. RuBP is used in the next turn of the
  Calvin cycle.

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What are the products of this process?
What is the Chemical reaction?
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Chemical reaction6CO2 6H2O light enegry
chlorophyll C6H12O6 O2
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Name of the scientist
Melvin Calvin