Transcript Cell energy

Cell energy
Ch.9
• All living organisms must be
able to produce energy, store
the energy for future use and
use energy.
Cell processes that require energy
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Active transport
Movement
Cell division
Production and storage of
proteins
• Cells use energy to maintain
homeostasis
ATP
• Molecule in your cells that is a
quick source of energy for any
organelle in the cell that needs it.
• This energy is stored in the
chemical bonds of
the molecule ATP
• Adenosine Triphosphate is
composed of an adenosine
molecule with 3 phosphate
groups attached.
• AMP - adenosine monophosphate small amount of energy
• ADP - adenosine diphosphate - more
substantial amount of energy
• ATP - When bond is broken, a great
amount of energy is released & the
cell can use the energy for activities.
ADP can then reform ATP by bonding
with another phosphate group
Photosynthesis
• The process plants use to trap the
sun’s energy and build
carbohydrates, called glucose, that
store energy.
• Occurs in 2 phases
1. Light-dependent reactions
2. Light-independent reactions
• 6CO2 + 6H2O
C6H12O6 + 6O2
Light-dependent reactions
• Convert light energy into
chemical energy
• ATP produced in LDR are used
to fuel LIR that produce glucose
Chloroplasts
• Cell organelle where photosynthesis
occurs
• Within chloroplasts, thylakoid discs
contain pigments
• Most common pigment is chlorophyll
• Light-dependent reactions take place
in the thylakoid discs
Chlorophyll
• Absorbs most
wavelengths of light
except green which it
reflects, giving leaves a
green appearance
Light-dependent reactions
• Requires sunlight
• Sunlight strikes molecules in
thylakoid membrane & light
energy is transferred to electrons
• These electrons are passed to an
electron transport chain
Electron transport chain
• A series of proteins embedded in
the thylakoid membrane
• Each protein passes energized
electrons along from protein to
protein
• At each step the electron loses
energy
• ETC allows small amounts of
energy to be released at time
• This energy can be used to form
ATP
• This energy is not wasted, the
electron is transferred to the
stroma of the chloroplast
• NADP+ is used & becomes
NADPH
Photolysis
• Electrons must be restored to
chlorophyll because many leave with
NADPH
• To replace the lost electrons,
molecules of water are split through a
process called photolysis
Light-independent reactions
• Does not require light
• Calvin cycle
• Series of reactions that use
carbon dioxide & ATP from Lightdependent Reactions to form
carbohydrates
• Takes place in the stroma of the
chloroplast
• We know that plants use sunlight energy to split water
(H2O) into hydrogen and oxygen.
• The hydrogen is added to the carbon dioxide to make
CARBOHYDRATES such as glucose.
• The oxygen produced from this splitting of water is
released into our atmosphere.
• We summarise this using a chemical equation:
6 CO2
+ 6 H20
------------ C6H12O6 + 6 O2
carbon
water
glucose
oxygen
dioxide
Cellular Respiration
• The process by which
mitochondria break down food
molecules to produce ATP
3 Stages
1. Glycolysis (anaerobic)
2. Citric acid cycle (aerobic)
3. Electron Transport Chain
(aerobic)
• Anaerobic – no oxygen
required
• Aerobic – oxygen required
Glycolysis
• A series of chemical reactions in the
cytoplasm of a cell that break down
glucose into 2 molecules of pyruvic acid
• Uses 2 molecules of ATP to start & only
produces 2 molecules of ATP per glucose
broken down
• Not very efficient but can occur in the
absence of oxygen
• Uses an electron carrier called NAD+
• NAD forms NADH when it is carrying an
electron
• Following glycolysis, the pyruvic acid
molecules move to the mitochondria
Citric Acid Cycle
• Occurs in mitochondria
• One molecule of ATP is produced for
every turn of the cycle
• 2 electron carriers are used
– NAD+
– FAD
• Electron carriers pass energized electrons
along to the electron transport chain in the
inner membrane of the mitochondrion.
Electron Transport Chain
• NADH & FADH2 pass energized electrons from
protein to protein within the membrane slowly
releasing small amounts of the energy contained
within the electron
• Some energy is used to form ATP & some is
used to pump H+ ions into the center of the
mitochondrion.
• Mitochondrion inner membrane becomes
positively charged because of the high
concentration of positively charged hydrogen
ions.
• Exterior of membrane is negatively
charged which further attracts hydrogen
ions
• Inner membrane of the mitochondrion
forms ATP from this electrochemical
gradient of H+ ions across the membrane.
• Overall ETC produce 32 ATP molecules
Fermentation
• When your cells are without oxygen
for a short period of time, an
anaerobic process called
fermentation follows glycolysis.
• Two major types
– Lactic acid fermentation
– Alcoholic fermentation