Transcript Energy and Photosynthesis

Energy and Photosynthesis/Cell Resp
S. Dickinson
Biology
HHS
Energy in Living Things
 Two Groups of Living Organisms in the
Way they meet their Energy needs:
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Autotrophs: plants and other living things that
build organic molecules from inorganic
substances internally (auto-by themselves)
Heterotrophs: organisms that do not make their
own food but depend on autotrophs for their
food directly or indirectly (hetero – different)
How do autotrophs make their
own food?
Photosynthesis
 Almost all of the Energy on the Earth
comes from the Sun and it drives the
chemical reactions that creates all other
forms of energy in life.
 Therefore, most all autotrophs get their
food directly or indirectly from the sun.
Photosynthesis
 The Sun’s energy is trapped in the
organelles of a plant cell called the
CHLOROPLAST, which is a type of
PLASTID.
 It uses the suns energy with the help of
chlorophyll,CO2, AND H2O to produce
glucose and O2 .
Photosynthesis
 Is the process of breaking that Glucose
molecule down and releasing that
stored energy and Oxygen.
 Overall-Photosynthesis-Allows Plants
to take in Light and Carbon dioxideturn it in to Sugar and release Oxygen
into the atmosphere---Yipee.
ATP
 USABLE Energy is stored in a molecule
called ATP.
 ADENOSINE TRI PHOSPHATE
ATP
 THREE PARTS:
Adenine
 Ribose
 3 Phosphate groups
 Its written as A-P-P-P the energy is
between the P’s. When the P bonds
are broken energy is released.

Photosynthesis-Chemical
Reactions
 Phostosynthesis:
 Sun Energy+6CO2+6H20 C6H12O6+6O2
 This chemical reaction takes place in
basically two steps: Light and Dark
reactions
Photosynthesis-Chemical
Reactions
 The light reactions-which require light
to form ATP and the Hydrogen carrier
molecule
 The dark reactions- which require no
light to use ATP and Carbon dioxide to
form sugar
The Chloroplast
 Both the Light and Dark reactions take
place in the Chloroplast.
 Organelle
 A number of Chloroplasts in Plant Cells
 Plant cell only
Plant cell and chloroplast
Chlorophyll
 Primary pigment of plants
 Job is to capture sun’s rays
 When sun’s rays…blue and red only
are captured, the green rays are
reflected and thus plants are seen as
green.
Chlorophyll
 When Chlorophyll absorb those waves
their molecules are excited and
electrons jump off ..which is necessary
for photosynthesis.
Light Reactions
 PAY ATTENTION OR YOU WILL GET
LOST….
 Sunlight hits chlorophyll
 Chlorophyll’s electrons get excited and one
escapes….this happens more than once during
photosynthesis
 Two molecules of water are split. Two
hydrogens form ions H+. Then the two
Oxygen ions come together to form Oxygen
gas and are released into the atmosphere.
Two more Molecules
 Let me give you the overall equation for
Photosynthesis and you can see just how much we
have covered:
 Energy from Sun+6CO2+6H20
C6H12O6
+6O2
 So what have we used so far?
Dark Reactions or the CALVIN
CYCLE
 These are called the Dark reactions because they
do not require sunlight to occur. BUT they do
require the ATP and NADPH from the light dep.
Reactions to occur.
 This time CO2 enters the plant and mixes with the
ATP and NADPH to form a 6 carbon sugar called
GLUCOSE.
 This cycle has to happen 6 times just to get 1
molecule of glucose.
IN REVIEW
 Glucose is the product of Photosynthesis as well as
Oxygen…However, plants store the glucose and release
the oxygen.
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So to review
Photosynthesis happens in the chloroplasts.
Light dep. Reactions
Light indep. reactions
Light dep. Uses light to form ATP, NADPH, split water
and make oxygen gas
 Light indep. Brings in carbon dioxide plus all of the stuff
from light dep. Reactions to make six turns of the
CALVIN cycle to produce glucose.
Cellular Respiration
 If animals and other life forms use a process
that is directly reversed from the
plants…what would its equation look like?
 Energy from Sun+6CO2+6H20 C6H12O6 +6O2
 Or ATP
 CELLULAR RESPIRATION??????
Respiration
 Before food can be used to perform work its
energy must be released in the process of
respiration.
 There are two forms of respiration:
 Aerobic
 Anerobic
Aerobic Respiration
 Basically, how do humans use sugar or food as
chemical energy?
 Please look at the following formula:
 C6H12O6 +6O2
 REACTANTS
6CO2+6H20 + 38 ATP
PRODUCTS
Basically
 Sugar and Oxygen break down and give off
water, Carbon Dioxide, and 38 molecules of
Energy.
 This happens in 3 STAGES
 GLYCOLYSIS
 KREB’s CYCLE
ELECTRON TRANSPORT CHAIN
Review
 Glycolysis which occurs without oxygen and
turns glucose into Pyruvic Acid ( which is a
3-carbon molecule)…takes place in the
cytoplasm of the cell.
 KREB’s CYCLE occurs in the
MITOCHONDRIA and turns pyruvic acid
into citric acid and ATP and Carbon
dioxide.
 And the electron transport chain helps take
the NADH and combine it with O2 to make
water.
The Formation of ATP
 The Electron Transport Chain….
 In the inner membrane of the mitochondria ..it
acts like a giant magnet… the positive parts
of the magnet are the H+ molecules of the
NADH+H and the FADH and H+
molecules…as they move through the
membrane they attract electrons which are
negative particles of the magnet.
The formation of Water and ATP
At the end of this magnet…
 oxygen picks up some Hydrogens and makes a
water molecule.
 Now did you know that the word “electricity”
comes from the movement of electrons…so, as our
electrons in this inner membrane of the
mitochondria are moving with the Hydrogens as a
magnet, they are creating enough energy to help
that enzyme ATP synthetase to create molecules of
ATP and that is why ATP is found in the
mitochondria.
Anerobic Respiration
 Anerobic respiration is the breakdown of
food into energy without the use of oxygen.
 So, if you are not breathing properly, you
will undergo glycolysis-break down of
glucose into pyruvic acid- but the acid will
turn into either ALCOHOL or LACTIC
ACID…which one do animals do?
Fermentation-anerobic respiration
 The breakdown of Pyruvic Acid without the
use of oxygen to form LACTIC ACID or
ALCOHOL
 Fermentation occurs in two forms:
 Lactic Acid –when pyruvic acid is turned into
lactic acid-which pierces muscle cells in
animals
 Alcoholic Fermentation – occurs in some plant
and yeast cells as pyruvic acid is converted into
ethyl alcohol without the use of oxygen
Aerobic Respiration
 Pathways of cellular respiration
require oxygen
 Cellular respiration releases energy by
breaking down glucose and other food
molecules in the presence of oxygen!