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Cellular Energy
Photosynthesis & Respiration
Energy Flow
• Sun  Glucose (photosynthesis)  ATP (Respiration)
Cell Energy
• Energy ~ The ability to do work.
• Main source of energy in living things: Glucose!
C6H12O6
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–
–
–
Glucose is a monosaccharide.
Glucose is made by photosynthesis for autotrophs.
Glucose is part of food eaten by heterotrophs.
Glucose is powerful – it must be turned into a gentler form
of energy called ATP to be used by a cell.
Glucose
C6H12O6
How do you get glucose?
• Autotroph ~ Organism that makes its own
food (glucose) by photosynthesis.
– Ex: plant
• Heterotroph ~ Organism that must eat food
(glucose) from an outside source.
– Ex: human
Energy Storing Compounds
• NADPH
• ATP
ATP
• Adenosine Triphosphate
• ATP is an energy storing compound made in
the mitochondria. It is made when glucose is
broken down.
ADENOSINE
ATP
• http://www.biologyinmotion.com/atp/index.h
tml
• Be sure to watch!
Cellular Organelles
• Chloroplasts: plant cells; energy from the sun
is converted into glucose
• Mitochondria: glucose is converted into ATP
Chloroplast Structure
• Outer and Inner membranes contain and protect the
inner parts
• Stroma: area where reactions occur and sugars are
created
• Thylakoids: have chlorophyll molecules on their surface
• Chlorophyll – pigment that uses sun’s energy to create glucose
• Stroma lamella: act like the skeleton of the chloroplast,
keeping all of the sacs a safe distance from each other
and maximizing the efficiency of the organelle.
Mitochondria
• Outer membrane
• Cristae: the folds
• Matrix: contains high number of enzymes;
several steps of cellular respiration are
performed here
• DNA
• Ribosomes
Photosynthesis
• A chemical reaction in which light energy is
converted into bond energy stored in a
glucose molecule.
Photosynthesis Reaction
6CO2  6 H 2O  Light C 6 H12O6  6O2
Chlorophyll
•
•
•
•
Requirements for
photosynthesis:
Carbon dioxide
(CO2)
Water (H2O)
Light
Chlorophyll
Products of
photosynthesis:
• Glucose (C6H12O6)
• Oxygen (O2)
Plant Pigments
•
•
•
•
Chlorophyll - green
Xanthophyll - yellow
Carotene - orange
Anthocyanins
*Plant Pigments absorb energy and pass on to
chlorophyll
Chlorophyll
• Chlorophyll is green in color, meaning that
green light is reflected, not absorbed.
• Chlorophyll absorbs primarily red and blue
light for photosynthesis.
What is happening?
Red Light:
Green Light:
Light Reactions
•
•
Starting molecules: CO2, H2O
Ending molecules: O2, NADPH,
ATP
e-
Dark Reactions (Calvin Cycle)
•
•
Starting molecules:
Ending molecules:
CO2
C6H12O6
C5
Cellular Respiration
• Chemical reactions that convert glucose into
ATP.
• May or may not use oxygen.
• Occurs in mitochondria.
Aerobic Respiration
Materials Needed:
– Oxygen
– Glucose
Materials Made:
– 36 ATP
– Water
– Carbon dioxide
C6 H12O6  6O2  6CO2  6H 2O  36 ATP
Anaerobic Respiration
•Breaks down glucose without using oxygen.
•Produces a poisonous waste product.
•Only produces 2 ATP molecules from one
glucose molecule.
•Two types of anaerobic respiration:
•Alcoholic fermentation
•Lactic acid fermentation
Lactic Acid Fermentation
• C6H12O6 CO2 + lactic acid + 2ATP
 Produces lactic acid as
a waste product.
 Carried out by bacteria.
 Causes milk to go sour.
 Carried out by human muscle cells (reason you are sore
after a workout)
 Used in industry to make cheese and yogurt.
Alcoholic Fermentation
• C6H12O6 CO2 + alcohol + 2ATP
• Yeasts and other microorganisms carry out
alcoholic fermentation
• Formation of ethyl alcohol and carbon dioxide
as wastes
• Causes bread dough to rise
Aerobic vs. Anaerobic Respiration
Aerobic
• Uses O2.
• Breaks down glucose.
• Produces 36 ATP.
• Carried out by plants and
animals.
Anaerobic
• Does not use O2.
• Breaks down glucose.
• Produces 2 ATP.
• Alcoholic fermentation is
carried out by yeast.
• Lactic acid fermentation is
carried out by bacteria.
Aerobic organisms
• An organism that requires oxygen
Anaerobic organisms
• An organism that does not require oxygen
Photosynthesis vs. Respiration
Photosynthesis
• Produces C6H12O6 (glucose).
• Occurs in the chloroplasts.
• Produces O2 (oxygen gas).
• Carried out by autotrophs.
Respiration
• Produces ATP.
• Occurs in the mitochondria.
• Produces CO2 (carbon
dioxide).
• Carried out by heterotrophs
and autotrophs.
• Aerobic respiration
produces 36 ATP, anaerobic
2 ATP.