PHOTOSYNTHESIS and CELL RESPIRATION

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PHOTOSYNTHESIS and CELL RESPIRATION
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Part 1 Photosynthesis

• Photosynthesis is the process by which green
  plants ( autotrophs ) use carbon dioxide CO2
  and water H2O in the presence of light energy
  from the sun and make sugar ( glucose ).
• Autotrophs organisms that can make their own
  food.
• Heterotrophs organisms that cannot make their
  own food and must obtain their food from eating
  other organisms.

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WHO carries out Photosynthesis ?

• 1. green plants
• 2. some algae
• 3. photosynthetic bacteria

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Photosynthesis

• Producers or autotrophs ( plants that contain
  chlorophyll) use the light energy from sunlight
  to make sugars
• (glucose) from carbon dioxide (CO2) and water
  (H2O) through a process called photosynthesis.
• This food (glucose) can be used
• immediately, stored for later use,or used by
  other organisms such as plants and animals.

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Energy

• The energy for life comes primarily from the sun.

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Energy

• Photosynthesis is the connection between energy
  that is releases from the sun ( solar energy )
  and energy available for food ( glucose sugars
  ) chemical energy.

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Energy

• All plants, algae and many single-celled
  organisms use solar energy ( from the sun) to
  convert carbon dioxide and water into energy-rich
  sugars ( glucose ).

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Energy

• Organic Molecules
• substances that contain carbon
• found in living organisms
• Examples nucleic acids ( DNA and RNA )
• carbohydrates, lipids, proteins.
• Inorganic Molecules
• substances that do NOT contain carbon
• found in non-living things.
• Exceptions CO ( carbon monoxide) and CO2
  ( carbon dioxide ) are inorganic molecules.

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Organic Molecules vs. Inorganic Molecules
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Photosynthesis

• Photosynthesis is a synthesis reaction because it
  combines simple molecules into more complex
  molecules
• Photosynthesis is a Carbon dioxide (CO2)
  requiring process that uses light energy
  (photons) and water (H2O) to produce glucose
  molecules.
• 6CO2 6H2O ? C6H12O6 6O2

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Materials Used REACTANTS of Photosynthesis

• Carbon dioxide gas and water are used during
  photosynthesis.
• Both of these inorganic molecules come from the
  environment.

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Materials Produced PRODUCTS

• One organic compound that is produced during
  photosynthesis is the sugar glucose.
• Glucose is a simple carbohydrate or simple sugar.
• During photosynthesis carbon dioxide
  and water from the environment are combined to
  make glucose ( sugar ).

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Materials Produced

• Oxygen gas is also formed during photosynthesis.
• The oxygen that is produced is then released into
  the environment.

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Photosynthesis Equation
6 CO2 6 H2O light energy -----gt C6H12O6 6
O2 carbon water sunlight
glucose oxygen dioxide
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WHEN does Photosynthesis happen ?

• Photosynthesis occurs in autotrophs when sunlight
  is available.
• Generally this is during the daytime.

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WHERE does Photosynthesis happen ?

• Photosynthesis occurs in the leaves of plants.
• Photosynthesis occurs in the chloroplasts of
  plant cells when they are exposed to light.
• Chloroplasts are organelles that contain
  chlorophyll (the pigment molecule that absorbs
  sunlight energy) in green plants
• Chloroplasts are the location of the process of
  photosynthesis.

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WHY is Photosynthesis Important ?

• Plant cells use the glucose produced from
  photosynthesis in 2 ways
• 1. Glucose ( sugar ) is used to generate ENERGY
  during cell respiration where the glucose is
  broken down in the mitochondria to release its
  stored energy.
• All organisms use organic food compounds
  ( glucose, sugars) to supply the ATP energy
  they need to live.

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WHY is Photosynthesis Important ?

• 2. Glucose is used as a material for building
  more complex molecules (
  macromolecules )that the plant needs.
• Macromolecules include
• Proteins
• Carbohydrates
• Lipids
• Nucleic Acids

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Plants

• Plants are autotrophs they produce their own
  food molecules (glucose)
• Living organisms that do not make their own food
  are called heterotrophs
• This process is called photosynthesis
• Photosynthesis occurs mainly in the leaves of
  plants

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Cross Section of a Leaf
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Stomata (stoma)

• Stomata are pores found on the underside of
  leaves through which gases (CO2 and O2) and water
  vapor are exchanged between the plant and the
  atmosphere.

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Stomata (stoma)

• Water vapor

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Mesophyll Cell of a Leaf
Photosynthesis occurs primarily in mesophyll
cells.
mesophyll cell
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Chloroplast

• Organelle in plant cells where photosynthesis
  takes place.

Thylakoid stacks are connected together
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The Chloroplast

• The chloroplast is made up of three types of
  membrane
• A smooth outer membrane that is freely permeable
  to molecules
• A smooth inner membrane which contains many
  special proteins that regulate movement of
  materials in and out of the chloroplast
• A system of thylakoid membranes
• Thylakoids are surrounded by a thick fluid called
  stroma.

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Thylakoids
Grana are stacks of thylakoids

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Question

• Why are plants green?

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Chlorophyll Molecules

• Located on the thylakoid membranes
• Chlorophyll pigments harvest light energy
  (photons) by absorbing certain wavelengths (blue-
  violet - and red- are most important)
• Plants are green because the green wavelengths of
  light are reflected, not absorbed.

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Wavelength of Light (nm)

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Absorption of Light by Chlorophyll
Absorption
wavelength
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Question

• During the fall, what causes the leaves to change
  colors?

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Fall Colors

• In addition to the chlorophyll pigments, there
  are other pigments present
• During the fall, the green chlorophyll pigments
  are greatly reduced revealing the other pigments
• Carotenoids are pigments that are either red or
  orange .
• Xanthophylls are pigments that are yellow.

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Relationship to Cell Respiration

• The energy stored in glucose during
  photosynthesis is transferred to the chemical
  bonds of ATP during cell respiration.
• Living organisms run on the energy released
  from ATP.

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Part 2 Cell Respiration

• Cell Respiration is the process by which food (
  glucose ) is metabolized ( broken down ) in the
  mitochondria of cells in the presence of oxygen
  and energy is released in the form of ATP.
• Cell Respiration involves the exchange of gases
  between the organism and the environment.

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Gas Exchange

• In many organisms, cell respiration requires
  oxygen, which is brought into an organism from
  the environment.
• Obtaining oxygen from the environment and
  releasing carbon dioxide is called cell
  respiration.

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Energy

• Through the process of cell respiration , glucose
  is broken down by an organism to produce energy
  which will be used for maintaining LIFE.
• All living things require energy in order to live
  !

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Materials Used in Cell Respiration

• The materials used during cell respiration
  include
• Glucose ( sugars ) which is made during
  photosynthesis in plants and obtained by feeding
  in animals.
• Oxygen which is obtained through gas exchange
  with the enironment.

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Materials Produced in Cell Respiration

• The materials produced during
• cell respiration include
• Energy in the form of ATP
• Two waste products
• 1. Carbon dioxide
• ( released into the environment
• as part of gas exchange )
• 2. Water

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WHEN does Cell Respiration happen ?

• Cellular Respiration occurs in cells when the
  organism needs a supply of energy.

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WHERE does Cell Respiration happen ?

• Cellular respiration occurs in organelles called
  mitochondria.
• Glucose ( sugars ) and oxygen enter the organelle
  and carbon dioxide and water are released.
• The energy released in now transferred to ATP
  molecules.

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WHY is Cell Respiration Important ?

• All cells run on the ATP that is released from
  mitochondria.
• Organisms can use ATP for
• Membrane Transport ( Active Transport )
• Growth and Repair
• Reproduction
• Movement