BIOLOGY IAL UNIT 4
CHAPTER 5
ATP: Energy source for the cell
Making chemical bonds need an input of energy. Chemical bonds are constantly
being broken in the cells of any living organism. Energy has to be constantly available
in an accessible form, ready to use instantly in a multitude of different reactions. This
remarkable compound is called ATP.
When energy is needed, the third phosphate bond can be broken by a hydrolysis
reaction. This is catalysed by the enzyme ATPase. The result of this hydrolysis is ADP,
a free inorganic phosphate group (Pi) and energy.
, The breakdown of ATP into ADP and phosphate is a reversible reaction. ATP can
be synthesized from ADP and a phosphate group. This synthesis reaction is also
catalysed by ATP synthase and it requires an input of energy. The energy needed to
drive the synthesis of ATP usually comes from catabolic (breakdown) reactions or
reduction/oxidation reactions (redox).
PHOTOSYNTHESIS
Sunlight breaks down the strong oh bonds in water molecules via
photolysis.
Photosynthesis is the process used by living organisms particularly
plants, to capture the energy from the sun using chlorophyll and then
used to convert carbon dioxide and water into simple sugars.
The energy from light is used to break the strong OH bonds in water
molecules (photolysis). The hydrogen which is released is then
combined with CO2 to form a fuel for the cells (glucose). Oxygen is
released into the atmosphere as a waste product of this process.
, STRUCTURE OF CHLOROPLAST
o Light Dependent Reaction stage produces ATP and reduced NADP/NADPH +
H+
o Light Independent Reaction stage produces CO2 + ATP + Reduced NADP
Glucose
THE STRUCTURE AND IMPORTANCE OF
CHLOROPLAST
, Chloroplasts are relatively large organelles found in the cells of the
green parts of plants
Each chloroplast is surrounded by an outer and and an inner
membrane with a space between the two known as the chloroplast
envelope.
Inside the chloroplast is a system of membranes that are arranged in
layers called grana. A single granum is made up of layers of
membrane discs known as thylakoids. This is where the green pigment
chlorophyll is found. Thylakoids provide a large surface area for light
absorption and the chlorophyll molecules are grouped together to form
photosystems which are embedded in the membrane along with the
electron carriers. Folds in the thylakoid allow photosystems and
electron carriers to be close together.
Thylakoid spaces collect H+ ions for chemiosmosis so that the low
volume enables H+ gradient to be generated rapidly. H+ ions flow back
to the stroma down the gradient through ATPsynthase channels to
produce ATP.
The grana are joined together by lamellae. These lamellae connect two
or more grana. The lamellae act as a skeleton inside the chloroplast,
maintaining a distance between the grana so that they receive the
maximum amount of light and function as efficiently as possible.
CHAPTER 5
ATP: Energy source for the cell
Making chemical bonds need an input of energy. Chemical bonds are constantly
being broken in the cells of any living organism. Energy has to be constantly available
in an accessible form, ready to use instantly in a multitude of different reactions. This
remarkable compound is called ATP.
When energy is needed, the third phosphate bond can be broken by a hydrolysis
reaction. This is catalysed by the enzyme ATPase. The result of this hydrolysis is ADP,
a free inorganic phosphate group (Pi) and energy.
, The breakdown of ATP into ADP and phosphate is a reversible reaction. ATP can
be synthesized from ADP and a phosphate group. This synthesis reaction is also
catalysed by ATP synthase and it requires an input of energy. The energy needed to
drive the synthesis of ATP usually comes from catabolic (breakdown) reactions or
reduction/oxidation reactions (redox).
PHOTOSYNTHESIS
Sunlight breaks down the strong oh bonds in water molecules via
photolysis.
Photosynthesis is the process used by living organisms particularly
plants, to capture the energy from the sun using chlorophyll and then
used to convert carbon dioxide and water into simple sugars.
The energy from light is used to break the strong OH bonds in water
molecules (photolysis). The hydrogen which is released is then
combined with CO2 to form a fuel for the cells (glucose). Oxygen is
released into the atmosphere as a waste product of this process.
, STRUCTURE OF CHLOROPLAST
o Light Dependent Reaction stage produces ATP and reduced NADP/NADPH +
H+
o Light Independent Reaction stage produces CO2 + ATP + Reduced NADP
Glucose
THE STRUCTURE AND IMPORTANCE OF
CHLOROPLAST
, Chloroplasts are relatively large organelles found in the cells of the
green parts of plants
Each chloroplast is surrounded by an outer and and an inner
membrane with a space between the two known as the chloroplast
envelope.
Inside the chloroplast is a system of membranes that are arranged in
layers called grana. A single granum is made up of layers of
membrane discs known as thylakoids. This is where the green pigment
chlorophyll is found. Thylakoids provide a large surface area for light
absorption and the chlorophyll molecules are grouped together to form
photosystems which are embedded in the membrane along with the
electron carriers. Folds in the thylakoid allow photosystems and
electron carriers to be close together.
Thylakoid spaces collect H+ ions for chemiosmosis so that the low
volume enables H+ gradient to be generated rapidly. H+ ions flow back
to the stroma down the gradient through ATPsynthase channels to
produce ATP.
The grana are joined together by lamellae. These lamellae connect two
or more grana. The lamellae act as a skeleton inside the chloroplast,
maintaining a distance between the grana so that they receive the
maximum amount of light and function as efficiently as possible.
