Photosynthesis & Respiration
Intro Video:
http://www.neok12.com/php/watch.php?v=zX787d585f475a015b5c7c06&t=Photosynthesis
Cell Energy
(Photosynthesis and Respiration)
Energy:
•Energy for living things comes from food. Originally, the
energy in food comes from the sun.
• Organisms that use light energy from the sun to
produce food—autotrophs (auto = self)
Ex: plants and some microorganisms (some bacteria
and protists)
• Organisms that CANNOT use the sun’s energy to make
food—heterotrophs - must eat their food
Ex: animals and most microorganisms
Cell Energy:
•Cells usable source of energy is called ATP
•ATP stands for adenosine triphosphate
Adenine
Ribose
3 Phosphate groups
• ADP stands for adenosine diphosphate
Adenine
Ribose
2 Phosphate groups
• All energy is stored in the bonds of compounds—
breaking the bond releases the energy
• When the cell has energy available it can store this
energy by adding a phosphate group to ADP, producing
ATP
• ATP is converted into ADP by breaking the bond between
the second and third phosphate groups and releasing
energy for cellular processes.
Photosynthesis:
•Photosynthesis is the process by which the energy of
sunlight is converted into the chemical energy of glucose
• Photosynthesis occurs in the chloroplasts of plants
• Light absorbing compound is a pigment
• pigments absorb some wavelengths of light and reflect
others
• the color our eyes see is the color that the pigment
reflects
• Chlorophyll is the pigment inside the chloroplast the
absorbs light for photosynthesis
As the chlorophyll in leaves decays
in the autumn, the green color fades
and is replaced by the oranges and
reds of carotenoids.
•General formula for photosynthesis
:
sunlight
carbon dioxide + water
—>
glucose + oxygen
sunlight
6CO2
+ 6H2O
—>
C6H12O6 + 6O2
Reactants
•Diagram
Light
H2O
CO2
NADP
ADP + P
Light
Dependent
Reaction
Chloroplast
O2
Calvin
Cycle
ATP
NADPH
Products
C6H12O6
Glucose
Light Reaction
Takes place in the thylakoid membrane (contains chlorophyll)
Reactants needed for the light reaction:
Water, Light, ADP, NADP
Products made from light reaction and USED in dark reaction:
ATP energy to make sugar
NADPH supplies e- and H to make C6H12O6
Oxygen is released into the air
Dark Reaction - Calvin Cycle
Takes place in the stroma
Reactants needed for the dark reaction:
CO2, ATP, NADPH
Products made from the dark reaction used in light reaction are:
ADP returned to the light reaction to make more ATP
NADPreturns to the light reaction to pick up more electrons
and Hydrogens
Glucose is made in the dark reaction for use throughout the
organism.
Summary:
• Light Reaction—H2O is broken
down and light energy is stored
temporarily in ATP and NADPH.
Oxygen released.
• Calvin Cycle—energy is
transferred from ATP and
NADPH to the organic
compound glucose
Location
Light
Reaction
thylakoid
Reactants
H2 O
Light
Products
ATP – energy to
make sugar
NADPH – electrons
and Hydrogen to
make glucose
ADP and NADP
from dark
reaction
CO2
Dark
Reaction –
Calvin Cycle
stroma
ATP and NADPH
from light
reaction
ADP and NADP
back to light
reaction
GLUCOSE
Release
O2 to the air
Video - photosynthesis
http://www.goldiesroom.org/Multime
dia/Movie_Clips/05%20Nutrition/Pho
tosynthesis%20Review.wmv
Cellular Respiration
•Process where energy of glucose is released in the cell to
be used for life processes (movement, breathing, blood
circulation, etc…)
• Respiration occurs in ALL cells
• Takes place in the mitochondria
• Can take place either with or without oxygen present.
Glucose
Glycolysis
ATP
No
Oxygen
Pyruvic Acid
Oxygen
Fermentation
(anaerobic)
Lactic Acid
Aerobic
Respiration
Ethyl
Alcohol
ATP
Aerobic Respiration: Makes 38 ATP
-requires oxygen
-- makes 38 ATP
•Formula
C6H12O6 + 6O2
glucose + oxygen
Human cells contain a
specialized structure – the
mitochondrion – that
generates energy.
6 CO2 + 6H2O + 38 ATP
carbon dioxide + water + energy
Intro video - respiration
http://www.goldiesroom.org/Multimedia/M
ovie_Clips/07%20Respiration/Aerobic%2
0Review.wmv
STEP 1: Glycolysis
-First pathway of respiration - ALL organisms perform this
-Takes place in the cytoplasm on enzymes
-Splits glucose in half to form pyruvic acid or pyrates
-Gives off enough energy to make 2 ATP
STEP 2: Krebs Cycle
-pyruvic acid is broken down into carbon dioxide
-Occurs in matrix of mitochondria
STEP 3: Electron Transport Chain
-electrons from Krebs Cycle converts ADP into ATP
-Occurs along inner membrane of mitochondria
• Diagram - Cellular Respiration
Electrons carried in NADH
Mitochondria
electrons
carried in
NADH
In Cytoplasm
Glucose
Krebs
Cycle
Glycolysis
2
2
Electron
Transport Chain
34
Video on aerobic respiration:
http://videos.howstuffworks.com/discover
y/29543-assignment-discovery-cellularrespiration-video.htm
Anaerobic Respiration or Fermentation:
- pathway organisms use when no oxygen is available to the cel
- Mostly unicellular organisms (low energy requirement)
-Goes through glycolysis and makes 2 ATP (in cytoplasm)
- 2 kinds: Alcoholic and Lactic Acid
Lactic Acid Fermentation
pyruvic acid
lactic acid+carbon dioxide
•Performed by muscle cells
Lactic acid is produced in the muscles during rapid
exercise when the body cannot supply enough oxygen to
the tissues—causes burning sensation in muscles
Lactic Acid Fermentation
Alcohol fermentation
Pyruvic
acid
ethyl alcohol+carbon dioxide
-occurs in bacteria and yeast
-Process used by baking and brewing industry
-yeast produces CO2 gas during fermentation to make
dough rise and gives bread its holes
Photosynthesis and Respiration
Products of one
reaction are the
reactants of the other
(and vice versa)
Energy Flow: Producers
photosynthesize and provide glucose
for consumers
Carbon Cycle: Producers remove
CO2 from atmosphere while consumer
replaces CO2 during respiration
Water Cycle: Producers take water
out of ecosystem and consumers
produce water during respiration (also
O2 removed by producer and returned
by consumer)
Importance of ATP!
1. ALL organisms release ATP from break down of glucose during
cellular respiration
2. ATP powers the activities of the cell and allows living things to
do work
3. ATP/ADP is cycle that releases/stores energy for cell processes
4. ATP is used to actively transport material across the cell
membrane
• Cells require a constant source of energy for life processes but
keep only a small amount of ATP on hand.
• Cells can regenerate ATP as needed by using the energy stored
in foods like glucose.
• The energy stored in glucose by photosynthesis is released by
cellular respiration and repackaged into the energy of ATP.