Download Ch. 6and7_Notes

Biology 20
Photosynthesis,
Cellular Respiration
ATP
• WHAT IS ATP?
•
•
•
•
•
Universal Energy Molecule
Energy in a form the cell can use
Makes energy readily available
Continuously being remade
Stands for Adenosine Triphosphate
Adenosine
P
P
+
P
ATP
• WHAT IS ATP?
•
•
•
•
Universal Energy Molecule
Makes energy readily available
Continuously being remade
Stands for Adenosine Triphosphate
Adenosine
P
P
Adenosine
P
P
+
P
P
High Energy Bond
ATP
• What is ATP used for?
1.Motion
2. Transport of ions and molecules.
3. Building molecules
4. Switching reactions on or off
Electron Transfer
• The transfer of electrons is important in
ATP production.
• Electron carriers
– strip a hydrogen proton and its electron
from a number of organic compounds
• Respiration
– NAD+
(becomes NADH)
• Photosynthesis
– NADP+ (becomes NADPH)
Biology 20
Photosynthesis
Introduction
• Photosynthesis is…
– the process by which plants and some
bacteria use chlorophyll, a green pigment,
to trap sunlight energy.
– The energy is used to synthesize
carbohydrates
Chlorophyll
• A green chemical
which traps sunlight
energy
• Located in the
chloroplast
Chloroplast Parts
• Thylakoid
– Disk
– Granum = stack of
disks
– Grana = many stacks
– site of light dependent
reaction
• Stroma
– gel surrounding the
thylakoids
– site of light independent
reaction
Thylakoid
Location
Leaves in the fall
• Why do leaves
change colors in
the fall?
Pigments
• White light is composed of all colors
– red, orange, yellow, green, blue, indigo,
violet
• Chlorophyll
– reflects green light
– absorbs blue and red ends of the spectrum
• chlorophyll a -- blue green
• chlorophyll b -- green
• Other pigments absorb light energy
from other parts of the spectrum.
Leaves in the fall
• Because of light.
• A decrease in light intensity and length.
• Causes the chlorophyll molecule to break down,
exposing the other pigments
General Equation
• There are two steps in photosynthesis
– Light Dependent Reaction
– Light Independent Reaction (no light required)
General Outline
Light
Dependent
Reaction
Light
Independent
Reaction
Cellular Respiration
-Explain how glucose is oxidized during Glycolysis
and the Krebs Cycle to produce reducing power in
NADH and FADH
-Describe where in the cell this takes place
-Explain how chemiosmosis converts the reducing
power of NADH and FADH to store chemical
potential energy as ATP
-Describe where in the mitochondrion this takes
place
Cellular Respiration
• Photosynthesis – stores energy
• Cell Respiration – releases energy
Sunlight
Energy
+6
CO2
+6
H2O
=
Photosynthesis
Glucose
+6
O2
Cellular Respiration
• Photosynthesis – stores energy
• Cell Respiration – releases energy
Sunlight
Energy
+6
CO2
+6
H2O

Glucose
+6
O2
Photosynthesis
Glucose
+6
O2

6 CO2
+6
H2O
Cellular Respiration!
+
Chemical
Energy
 Notice that the wastes from
photosynthesis are used as raw materials
in cellular respiration
 Atmospheric CO2 and water are used in
photosynthesis, while Oxygen is released.
 Atmospheric oxygen is used during
Cellular respiration, while CO2 and water
is released.
General Information
• Cellular respiration the process by
which cells break down glucose into
carbon dioxide and water, releasing
energy
• You can think of respiration as the
combustion of gasses in a car’s engine.
Car’s Engine
• MAIN ENGINE = Mitochondrion – The site
of the majority of ATP synthesis
• MAIN FUEL = Glucose – fats and proteins
may also be used in some instances
• MAIN EXHAUST = CO2 and H2O.
The 4 Steps of Cellular Respiration
1. Glycolysis
2. Pyruvate Oxidation
3. Krebs Cycle
4. Electron Transport Chain
1. Glycolysis
(in cytoplasm)
Mitochondria
•mitochondrial
matrix the fluid that
fills the interior
space of the
mitochondrion
2. Pyruvate Oxidation
• After glycolysis, if there is oxygen
available, the pyruvate molecules are
changed so the Krebs cycle can use them.
• CO2 portion is removed and released as
waste product
• An electron is released to NAD+  NADH
• Pyruvate Acetyl-CoA
3. Krebs Cycle
• Discovered by Sir Hans Kreb in 1937
• The Krebs cycle is an eight-step process
• Key features of the Krebs Cycle
– During one complete cycle a total of three NAD+ and
one FAD are reduced to form three NADH and one
FADH
– During one complete cycle one ATP is formed
– During one complete cycle three CO2 molecules are
produced
– However since glycolysis provides 2 pyruvate
molecules, we double all our numbers!
Krebs Cycle
4. Electron Transport Chain
• Electron Transport Chain
– Occurs on the inner membrane of the
mitochondrion
– Involves a group of molecules built into the inner
membrane of the mitochondrion
– Electrons pulled off of food by Glycolysis and
Krebs are passed between these molecules.
• This will ultimately result in the production of ATP
– Oxygen is required for this step.
– Lots of ATP is made (32)
Mitochondria
Electron Transport Chain
For each NADH that enters
the Electron Transport Chain,
how many ATP are produced?
For Each NADH Entering the
ETC, 3 ATP Are Produced!
But What About FADH?
• chemiosmosis a process for synthesizing
ATP using the energy of an
electrochemical gradient and the ATP
synthase enzyme
What’s Up With Oxygen?
• Oxygen is the final electron acceptor.
• If there is no oxygen, the electron transport
chain gets “backed up” as there is no where
for the electrons to go.
NADH
NAD+
– As a result, Krebs stops due to lack of
NAD+
• Lack of NAD+ also causes [H+] to
increase
– The body’s pH begins to fall inhibiting
normal enzyme activity.
Review
-Explain how glucose is oxidized during Glycolysis
and the Krebs Cycle to produce reducing power in
NADH and FADH
-Describe where in the cell this takes place
-Explain how chemiosmosis converts the reducing
power of NADH and FADH to store chemical
potential energy as ATP
-Describe where in the mitochondrion this takes
place
Let’s revisit Glycolysis!
• Glycolysis created two molecules of
pyruvate
• Oxygen available  aerobic respiration
occurs (Krebs, ETC)
• No oxygen  anaerobic respiration
Anaerobic Respiration
• Since pyruvic acid is poisonous, it must be
converted into a safer form.
– In animals (muscles!) -- LACTIC ACID
• causes muscle cramps
• process is called Lactic Acid
Fermentation
Anaerobic Respiration
– In bacteria and yeast -- ETHYL
ALCOHOL & CO2
• process is called Alcohol
Fermentation
Both only Yield 2 ATP! Very
inefficient!
Comparison of Photosynthesis and
Respiration
Photosynthesis
Respiration
Energy required
Oxygen released
CO2 and H20 required
Glucose produced
Energy Produced
Oxygen required
CO2 and H20 produced
Glucose required