PHOTOSYNTHESIS &
CELLULAR RESPIRATION
•
ENERGY IN A
CELL!!
• Your body requires energy in order to
function…from your heart beating to
intense workouts.
• Energy is essential to LIFE!!
• Your body stores energy in a molecule
called ATP’s (adenosine triphosphate)
• This is a quick source of energy for any
organelle in the cell that needs it.
• The energy inside an ATP molecule is
released when it loses a phosphate and
becomes ADP (adenosine diphosphate)
• ADP is like a partially charged battery
while ATP is a fully charged battery.
PHOTOSYNTHESIS
• Photosynthesis
is a process in
which solar
energy in the
form of light is
converted into
chemical
energy within
carbohydrate
molecules.
EQUATION FOR
PHOTOSYNTHESIS
•
6 CO2 + 6 H2O + light ---> C6H12O6 + 6 O2
PHOTOSYNTHESIS
• Photosynthesis
occurs in
organelles,
present in
green plants
and certain
algae, called
Chloroplasts.
Chloroplast
Chloroplast
CHLORPLAST
• A chloroplast is filled with stacks of
membrane sacs called thylakoids.
• Thylakoids are stacked in columns of
grana.
Chloroplast
• A chloroplast usually
has dozens of
granum.
• They are suspended
in a fluid matrix
called the stroma.
• Chlorophyll molecules
are embedded in the
thylakoid membranes.
This is a close up version of a
chloroplast in a leaf.
Chloroplast
• These
chloroplasts
contain the
green
pigment
called
chlorophyll.
CHLOROPHYLL
Chlorophyll- pigment found
in plants it will absorb red,
blue, and violet better than
other colors.
• Green light is primarily
reflected so most leaves
appear green to us.
• There are two types of
chlorophyll a and b
•
CHLOROPHYLL
• Notice how Chlorophyll a absorbs light mostly in the
blue-violet and red regions.
• Chlorphyll b absorbs light in the blue and red regions
more.
CHLOROPHYLL
• Because light is a form of energy, any
compound that absorbs light also absorbs
the energy in that light.
• When chlorophyll absorbs light much of the
energy is transferred directly to electrons in
the chlorophyll molecule, raising the energy
available in these electrons.
CHLOROPHYLL
• Electrons carriers are seen throughout the
Photosynthesis concept.
• They are compounds that can accept highenergy electrons and transfer them along
with most of their energy to another
molecule.
– NADP+
– ADP
NADPH
ATP
2 REACTIONS OF
PHOTOSYNTHESIS
• Photosynthesis involves 2
reactions:
1. Light Reaction.
2. Calvin Cycle.
(Also called Light Independent
Reaction and Dark Reaction.)
STOMATA
• The stomata are
important for the
exchange of gases
by diffusion
between the
outside air and
intercellular spaces
for respiration and
also for the
evaporation of
water by
transpiration.
• Notice how the equation for photosynthesis
relates to the reactions shown in the
diagram below.
6CO2 + 6H2O + Energy
•
C6H12O6 + 6O2
Melvin Calvin (1911 –1997)
• Again, this is also
known as the
Calvin Cycle
• Named after the
American scientist
Melvin Calvin, who
worked out the
details of this cycle
in 1948
• Won Nobel Prize in
chemistry in 1961
http://www.brainpop.com/science/plantsandanim
als/photosynthesis/index.weml?&tried_cookie=t
rue
CELLULAR
RESPIRATION
C6H12O6 + 6O2 ---> 6 CO2 + 6 H2O + Energy
CELLULAR RESPIRATION
• The process by which living
organisms obtain energy from
the bonds of food.
• There are two important ways
the cells can harvest energy
from food….cellular respiration
and fermentation
AEROBIC RESP.
• Aerobic respiration occurs
when oxygen is present.
• Aerobic respiration produces
a relatively large amount of
energy (ATP)
ANAEROBIC RESP.
• Anaerobic respiration occurs
when oxygen is not present.
• Produces few ATP’s
• Anaerobic respiration may
also be called fermentation.
WHAT IS ATP?
• (adenosine triphosphate)
compound that contains 3
high energy phosphate bonds
and is an important source of
energy for cells
ATP
Cellular Respiration
• Takes place in the cytoplasm
and mitochondria
• 3 Main steps
– Glycolysis – occurs in the
cytoplasm
• Makes 2 ATP
– Krebs Cycle – occurs in the
mitochondria
– Electron Transport Chain –
occurs in the mitochondria
• Makes 34 ATP
CELLULAR RESPIRATION
• Cellular Respiration
consists of 3 major
stages:
• Glycolysis
• Krebs Cycle
• Electron Transport
Chain..(ETC)
GLYCOLYSIS
• They (CR and Fermentation) both
start with the Glycolysis
• The 1st stage of cellular
respiration.
• Occurs in the cytoplasm of the
cell.
• Occurs in both aerobic and
anaerobic conditions.
• BUT Does NOT require oxygen
GLYCOLSIS
• This metabolic pathway breaks
down glucose (produced in
photosynthesis) to 2 molecules
of pyruvate
• There is a net gain of 2 ATP
molecules.
KREBS CYCLE
• Also known as citric acid
cycle
• 2nd phase of aerobic
respiration
• Occurs in the Mitochondria
Kreb Cycle
• The process of Kreb Cycle is
essentially removing carbon
dioxide, getting out energy in the
form of ATP, NADH and
FADH2, and lastly regenerating
the cycle.
Kreb Cycle
• The Kreb Cycle has a by-product of
CO2
• Energy is carried to the ETC by two
electron carriers….NADH and
FADH2
• A total of two ATP’s are produces
through the Kreb Cycle
Hans Krebs (1900 – 1981)
• Krebs cycle named after
Hans Krebs, biochemist
who demonstrated its
existence
• Born in Germany, son of
Jewish physician, forced to
leave Nazi Germany in
1933
• Spent rest of life in Great
Britain
• Discoveries were initially
rejected
• Won Nobel Prize in 1953 in
medicine & physiology
ELECTRON TRANSPORT
CHAIN (ETC)
• Last stage of cellular respiration
• Series of Reactions in which an
electron is passed from one
molecule to another to produce
energy for synthesis of ATP
ETC
• The electrons move down the
chain along the inner
membrane of the
mitochondria
• They are carried by NADH
and FADH2 (carrier
molecules)
ETC
• As hydrogen ions move across the
channels in the membrane to the
matrix, they release energy that is
used by an enzyme to make ATP
• Oxygen is the final electron acceptor.
• Water is formed in this process..it is
a by-product
ETC
• Results in ETC  the electron
transport chain produces 32
molecules of ATP
• With H2O being a by-product
• O2 enters the ETC
Cellular Respiration
• TOTAL ATP PRODUCTION IN
CELLULAR RESPIRATION 
o
Glycolysis, 2 ATPs
o
Krebs, 2 ATPs +
o
ETC, 32 ATPs
o
= 36 ATPs TOTAL
OVERVIEW
• Glycolysis is anaerobic
• When oxygen is present, then the
previously discussed pathway
(Krebs cycle, ETC) is taken
• When oxygen is NOT present, a
different pathway is taken,
fermentation
Comparing energy flow
Cellular Respiration Photosynthesis
Occurs in what
organelle
Cytoplasm
Mitochondria
Chloroplast
Reactants
C6H12O6 and O2
CO2 and H2O
Products
CO2 and H2O
C6H12O6 and O2
CELLULAR RESPIRATION
• A car and our
bodies are similar
in the fact that the
mitochondria is our
bodies engine that
burns sugar for
fuel. The exhaust
would be H2O and
CO2
FERMENTATION
• Fermentation releases energy
from food molecules in the
absence of oxygen.
The Process of Fermentation
• Glucose is broken down into
pyruvate during glycolysis
• Pyruvate is then broken down
into ethyl alcohol or lactic acid
• Only results in 2 ATP
molecules (vs. 36 from aerobic)
ALCOHOLIC
FERMENTATION
• Most common type of fermentation is
yeast cells converting pyruvate into
ethyl alcohol
• Fermentation by itself is able to
produce liquids that are about 15%
alcohol
• The same process enables yeast cells
to convert the sugar in dough to ethyl
alcohol & carbon dioxide
FERMENTATION
• Bakers use
alcoholic
fermentation of
yeast to make
breads
• As yeast ferments,
it causes dough to
rise & create the
bubbles that are
present in bread
FERMENTATION
• As the dough
bakes, yeast cells
die and the alcohol
they have made
evaporates
FERMENTATION
• Also used to
make wine,
beer, and
ethanol
added to
gasoline
LACTIC ACID
FERMENTATION
• Occurs in muscle
cells when they use
up all the available
oxygen
• Muscle cells feel
fatigued and sore b/c
lactic acid forms
when oxygen is NOT
present
LACTIC ACID
• Most lactic acid made in muscles
diffuses into bloodstream, then to
liver, where it is converted back to
pyruvate, which enters the aerobic
respiration process
• Yogurt, cheeses, rye bread, pickles,
sauerkraut, and olives are lactic acid
products
LACTIC ACID
• Yogurt, cheeses,
rye bread,
pickles,
sauerkraut, and
olives are lactic
acid products