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How do we create energy?
List as many sources of energy you
can think of!
1.
2.
3.
The activities of all living things require
energy. Swimming, flying, growing,
reproducing, and even the flashing of a
firefly use energy.
Energy for cells is stored in the
chemical bonds of organic molecules.
Cell Energy (Photosynthesis and Respiration) Notes
I. Energy – ability to do work; forms of energy: heat, light,
chemical, electrical, mechanical, kinetic, potential
A. Energy for living things comes from - food
Originally the energy in food comes from - sun
B. Uses light energy from the sun to produce food –
autotrophs
Examples: plants + some microorganisms
(bacteria and protists)
C. Cannot use the sun’s energy to make food –
heterotrophs; obtain energy from food they consume
Examples: animals, fungi, most microorganisms
II. Cell Energy – needed for active transport, making
proteins and nucleic acids, chemical signals (fireflies’
light)
A. Cells usable source of energy – ATP
1. ATP stands for adenosine triphosphate
ATP
3 Phosphate groups
adenine
ribose
2. ADP stands for – adenosine diphosphate
ADP
2 phosphate groups
adenine
ribose
B. All energy is stored in the bonds of the compound
Breaking the bond releases energy
C. When cell has energy available it can store this
energy by adding a phosphate group to ADP,
producing ATP
D. Example:
ATP
ADP + P + E from breaking bond
ADP + Energy + P
ATP
http://www.youtube.com/
watch?v=bbtqF9q_pFw&NR
=1
Photosynthesis:
• List at least three things you know about
photosynthesis.
• 1.
• 2.
• 3.
PHOTOSYNTHESIS IN ACTION
III. Photosynthesis – energy of sunlight is converted to
energy of glucose
A. General Formula:
H2O + CO2 + light
water + carbon dioxide + light
C6H12O6 + O2
glucose + oxygen
B. 2 parts of photosynthesis:
1. light reaction – forms ATP and NADPH – contain
chemical E, but are unstable
2. Calvin cycle (dark reaction) – uses E from ATP
and NADPH to produce glucose
C. Photosynthesis occurs in the organelle –
chloroplast
D. Light absorbing (and reflecting) compounds – pigments
Most common photosynthetic compound –
chlorophyll (a + b)
Absorbs light energy needed for photosynthesis to work
Absorption of Light by
Chlorophyll a and Chlorophyll b
F. Sun’s energy is stored in – glucose
light energy
chemical energy
CO2 + H2O + light
Light Dep. Reactions:
•Trap E of sun in
chemical form
•Produces O2,
ATP, NADPH
Light
high E cmpds.
C6H12O6 + O2
Chloroplast
H2O
Calvin Cycle:
•Uses E from Light
Dep. Reactions and
CO2 to make glucose
CO2
NADP+
ADP+P+
Light
Dependent
Reactions
Calvin
Cycle
ATP
NADPH
Light Dep.
Reactions occur
in thylakoid
stroma—Calvin
Cycle occurs here
O2
released
C6H12O6
produced
CALVIN CYCLE
LIGHT RXN
SUN
ATP
NADPH
THYLAKOID
O2
STROMA
GLUCOSE
Take Ten…
• With a neighbor, quietly work on the next
page in your notes.
IV. Cellular Respiration – process by which E of glucose
is released in the cell to be used for life processes
(movement, breathing, blood circulation, etc…)
CELLULAR RESPIRATION IN ACTION
A. General Formula:
C6H12O6 + O2
CO2 + H2O + 36 ATP
B. Cellular respiration occurs in all cells of all organisms –
plants, animals, bacteria
C. Energy stored by photosynthesis in glucose is
converted into the energy of – ATP
Cellular Respiration
Basic Concept…
• Cells break down
GLUCOSE (sugar) through
a series of chemical
reactions
• That stored energy of
glucose is used to attach
phosphate groups to ADP
molecules to form ATP
molecules, the cell’s energy
currency.
Defining…
• Respiration =
the process by which
food molecules are
BROKEN DOWN to
release energy
E. Respiration requiring oxygen – aerobic respiration
C6H12O6 + O2
CO2 + H2O + 36 ATP
1. organelle occurring in – mitochondria
Human cells contain a
specialized structure – the
mitochondrion – that
generates energy.
E. Respiration NOT requiring oxygen – anaerobic
respiration (an = without)
Also called – fermentation
1. Alcoholic Fermentation:
glucose
ethyl alcohol + CO2 + 2 ATP
a. organisms -- yeast, bacteria
b. industries – baking, brewing, wine-making
2. Lactic acid fermentation:
glucose
lactic acid + 2 ATP
a. lactic acid is produced in the muscles during rapid
exercise when the body cannot supply enough
oxygen to tissues (burning painful sensation)
3. occurs in – cytoplasm
ANAEROBIC
alcoholic fermentation = 2 ATP
glucose
2 pyruvic acid
lactic acid fermentation = 2 ATP
cytoplasm
mitochondria
AEROBIC
Krebs cycle
ETC = 36 ATP
First…GLYCOLYSIS
Glycolysis (glyco = sugar; lysis = breaking)
• A glucose molecule is broken down and changed
into Pyruvic acid
• Occurs with or without oxygen
• Occurs in the cytoplasm of the cell (so bacteria
can do this too!)
• Result:
• 2 molecules of ATP
• NADH (electron carriers to be helpful later)
• 2 Pyruvate
SECOND…The Kreb’s Cycle
(AKA the Citric Acid Cycle)
• Occurs in the mitochondria within the mitochondrial
matrix and requires oxygen.
• Pyruvic acid (made from Glycolysis) is broken down
into citric acid.
• Citric Acid is broken down and releases CO2 during
each step of the cycle.
• ATP is also created
• Also releases more high energy electrons
• Input = Pyruvic Acid, NAD+, FAD_ (another electron
carrier), and ADP
• Output = NADH, FADH2, and ATP
Third… THE ETC
Electron Transport Chain
• The ELECTRON Transport CHAIN (ETC)
• An electron transport chain is a series of molecules along which electrons
are transferred by carriers (input: NADH and FADH which were made
previously), releasing energy
• Molecules of the ETC are located on the inner membranes of the
mitochondria
• As the electrons are transferred, hydrogen ions build up and create a
chemical gradient.
• That gradient will cause hydrogen ions to diffuse to through the ATP
Synthase, which is an enzyme that puts phosphates on ADP to make ATP.
• Final electron acceptor in the transport chain is oxygen
• Oxygen combines with 2 hydrogen ions to form a molecule of water
• NADH and FADH are reduced to FAD+ and NAD+ and will be converted
back to NADH and FADH again by glycolysis and krebs
AEROBIC
C6H12O6 + O2
CO2 + H2O + 36 ATP
High E e- carried in NADH
O2
High E ecarried in
NADH and
FADH2
Pyruvic Acid
2 3-C molec.
Glucose
1 6-C molec.
Krebs
cycle
Glycolysis
CO2
released
Cytoplasm
2
Mitochondria
2
32
**E transferred from glucose to ATP
3 stages of aerobic respiration:
1. Glycolysis – cytoplasm, 2 ATP
2. Krebs cycle – mitochondria, 2 ATP
3. Electron Transport Chain – mitochondria, 32 ATP
36 ATP
total
E. T. C.
H2O
released
ANAEROBIC
Pyruvic Acid
2 3-C molec.
Glucose
1 6-C molec.
Glycolysis
Mitochondria
Cytoplasm
2
Yeast
Bacteria
Fermentation
Alcoholic
muscles
Lactic Acid
Lactic Acid Fermentation
Lactic acid is formed as an end product of glycolysis
When your muscles cells require energy at a faster rate
than it can be supplied by aerobic respiration, they begin
to carry out lactic acid fermentation
In lactic acid fermentation, cells do not have the oxygen
needed to do Krebs and ETC. Therefore, glycolysis is the
only step performed.
In lactic acid fermentation, cells must regenerate NAD+ so
that they can continue.
http://www.phschool.com/science/biology_place/biocoac
h/cellresp/review5a.html
Alcoholic Fermentation
This is when ethyl alcohol and carbon dioxide are the end
products of fermentation
Bacteria and yeast carry out alcoholic fermentation
Alcholic fermentation is done in the absence of oxygen so
Krebs and ETC cannot be performed.
Just like lactic acid fermentation, NADH must be returned
to its oxidized state (NAD+).
http://www.phschool.com/science/biology_place/biocoac
h/cellresp/review5b.html