Download Photosynthesis

Notes on Photosynthesis
What is Metabolism?
• Metabolism - All of the chemical
reactions that occur within an
organism.
There are 2 types of metabolic
reactions:
1. Catabolic
2. Anabolic
Catabolic - releases energy by
breaking down larger molecules
into smaller molecules.
Breaking Down!
Example of Catabolic Reaction:
Cellular Respiration - Catabolic
pathway in which organic
molecules are broken down to
release energy for use by the cell
C6H12O6 + O2  CO2 + H2O + ATP
Glucose
Oxygen
Carbon
Dioxide
Water
Energy
Anabolic - uses energy released by
catabolic pathways to build larger
molecules from smaller molecules
• Ever hear about “Anabolic
Steroids” in the news?
Building up
Example of Anabolic Reaction:
Photosynthesis - two-phase
anabolic pathway in which the
sun’s light energy is converted to
chemical energy for use by the
cell.
CO2 + H2O  C6H12O6 + O2
Carbon
Dioxide
Water
Sun
Light
Glucose
Oxygen
What is Metabolism?
The relationship of anabolic and
catabolic pathways results in the
continual flow of energy within
organisms.
Energy and Life:
All living organisms require energy
Living organisms are divided into 2
groups according to the way they
get food:
1. autotrophs
• auto = self
troph = feeder
a. Photosynthesis – green plants
and algae
b. Chemosynthesis – uses energy
from inorganic chemical
reactions
ex. some bacteria
2. heterotrophs
• hetero = other
troph = feeder
• animals either herbivores or
carnivores
• fungi (non-green; plant-like)
• parasites – lives off host
• saprophytes – lives on dead or
nonliving organic matter
• most bacteria
Energy Transfer Compounds:
ATP (adenosine triphosphate) –
main chemical compound
that living things use to
store energy
Why is ATP needed?
1. Light enters too rapidly for the
cell to store it all in glucose
2. Energy is released in
respiration too rapidly to be
used
ATP is made up of a nitrogencontaining compound called
adenine, a 5-carbon sugar
called ribose, and 3 phosphate
groups
Adenine
Phosphate groups
Ribose
≈ high energy bond
adenine
nitrogen
base
–
ribose
5-carbon
sugar
–
P≈P≈P
phosphate
groups
ATP Structure
ATP = Adenosine TriPhosphate
Adenine
Ribose
Adenosine
3 Phosphate groups
High
Energy
Bonds
ATP
ADP – adenosine diphosphate
AMP – adenosine monophosphate
Energy stored in ATP is released
when ATP is converted into ADP + a
phosphate group
ATP-ADP Cycle
ADP
ATP
Energy
Adenosine diphosphate + phosphate
Partially
charged
battery
Energy
Adenosine triphosphate
Fully
charged
battery
ATP is holding the ENERGY in
the last phosphate….
Pop off the last one!
When the last phosphate is POPPED off, it
releases energy for the cell to use…
& turns into ADP
ATP Cycle
ATP
A-P≈P≈P
photosynthesis
respiration
nerve conduction
active transport
ADP
A-P≈P
Most cells only have enough ATP to
last for a short-lived activity
• ATP can not be stored for long
periods of time
Whenever a cell needs energy it can
change ADP in glucose to ATP
Where does ATP come from?
Mitochondria (in plants & animals)
break down food (glucose)
to make ATP (ENERGY).
An animal (consumer) must EAT a
plant to get the food (glucose).
Where does the food (glucose) come
from? Photosynthesis in plants
ADP and ATP Video
Energy Flow Chart
active transport
Muscle
DNA synthesis
contraction
Protein
synthesis
Cell
division
ALL OF LIFE’s
PROCESSES!!!
In the bonds of ATP
PLANTS BY
PHOTOSYNTHESIS
In the bonds of GLUCOSE
ALL ORGANISMS
BY CELL RESPIRATION
Photosynthesis
photo = light
synthesis = put together (make
complex from simple)
Photosynthesis – the process by
which green plants combine CO2
and H2O in the presence of
chlorophyll and light energy to
form glucose and release O2
Brief Photosynthesis Video
Equation for photosynthesis:
6CO2 + 6H2O
C6H12O6 + 6O2
reactants
products
Raw materials – CO2 and H2O
(both are inorganic)
Product – glucose, which is organic
Photosynthesis requires light and
chlorophyll
• Light (radiant) energy is changed
to the chemical bond (stored)
energy of glucose
• The light energy transferred to
the electrons in the chlorophyll
molecule raises the energy level
of the electrons providing the
energy for photosynthesis to
begin
• Chlorophyll acts as a catalyst
Photosynthesis takes place inside
the chloroplasts
• contain chlorophyll
• have a double layer of
phospholipids and proteins
• chloroplasts contain saclike
photosynthetic membrane called
thylakoids
• thylakoids are arranged in stacks
called grana
• solution inside chloroplast called
stroma
Photosynthesis is broken down into
2 stages:
1. Light-dependent reactions –
take place in thylakoid
membrane
2. Calvin Cycle – uses ATP and
NADPH from lightdependent reactions to
produce high energy
sugars (glucose)
Summary of light-dependent
reaction:
a. Chlorophyll traps energy
Kinetic (light) – stored as
potential (chemical)
b. Water splits  2H+ + O-2
c. ADP to ATP (stores energy)
d. O2 is released
Summary of Calvin Cycle:
a. Does not require light
b. “Fixing of a carbon in a
carbohydrate”
Photosynthesis: An Overview
Light
Water
Chloroplast
CO2
NADP+
ADP + P
Calvin
Cycle
LightDependent
Reactions
ATP
NADPH
O2
Sugars
Factors affecting photosynthesis
1. shortage of water
2. temperature (0º to 35º C)
3. intensity of light
Photosynthesis Concept Map
Write the complete chemical reaction here… reactants and products
6H2O + 6CO2 →
6O2 + C6H12O6
Photosynthesis
Includes two stages
Lightdependent
reactions
use
Energy from
sunlight
NADPH
NOTICE THIS…
takes place in
take place in
Thylakoid
membranes
to produce
ATP
Calvin cycle
Stroma
of
O2
goes into
the
atmosphere!
Chloroplasts
uses
ATP
NADPH
to produce
High-energy
sugar
goes into
plant roots,
for ex.
Detailed Photosynthesis Video
Respiration
Cellular Respiration – chemical
energy from glucose and other
food is released in a chemical
pathway to control the speed
and amount
• includes all the chemical
reactions in which energy is
released in support of cell life
Where does the energy come from?
the sun (stored in the chemical
bonds of glucose)
• photosynthesis is
energy storing
• respiration is energy
releasing
Equation for Respiration:
respiratory
C6H12O6 + 6O2
enzymes
6CO2 + 6H2O + 38 ATP
• Respiration is the opposite of
photosynthesis
• Respiration occurs in the
mitochondrion
There are 2 stages of Cellular
Respiration:
1. Glycolysis – (anaerobic) occurs
in the cytoplasm
• glycolysis produces 2
ATPs/glucose
2. Aerobic – (Krebs cycle and
electron transport
chain) occurs in
mitochondrion
• for every turn of the Krebs cycle
1 ATP is generated
Cellular Respiration: An Overview
Electrons carried in NADH
Pyruvic
acid
Glucose
Glycolysis
Krebs
Cycle
Electrons
carried in
NADH and
FADH2
Electron
Transport
Chain
Mitochondrion
Cytoplasm
2
2
34
Cell Respiration Concept Map
6O2 + C6H12O6 → 6H2O + 6CO2
Write the complete chemical reaction here… reactants and products
Cell Respiration
includes
Krebs, Electron
Transport Chain
glycolysis
uses
glucose
Cytoplasm
to produce
pyruvic acid
electrons
takes place in
take place in
Membranes
(cristae)
of
2 ATP
Mitochondrion
uses
pyruvic acid,
electrons
oxygen
to produce
Carbon dioxide,
water
36 ATP!
(total)
NOTICE THIS…
goes into
atmosphere
If after glycolysis, oxygen is still
absent – fermentation results
(anaerobic respiration)
2 forms of fermentation:
1. Lactic acid – occurs in animal
cells (bacteria)
• accumulates in tissues –
muscles, results in fatigue
Examples – yogurt, buttermilk,
sauerkraut, dill
pickles
2. Alcohol – occurs in plants such
as yeast
• end product – ethyl alcohol
Examples – brewing and
baking
In both forms of fermentation, the
energy of glucose remains in the
products: lactic acid and alcohol
Chemical Pathways for Cell Respiration
Glucose
With oxygen
Glycolysis
=reactants
= products
Krebs
cycle
Electron
transport
Without oxygen
Fermentation
Which pathway makes more ATP—with oxygen or without?
Why would a cell have the other option, then?
Alcoholic
or lactic
acid
ATP yield:
Glycolysis - 2
Krebs cycle - 2
Electron transport - 34
_____________________
Total = 38
ATP stored energy is used to:
1. Build starches, fats and oils,
nucleic acids, and proteins
2. Supports cell activities:
a. active transport
b. cell division
c. nerve transmission
d. biosynthesis (assimilation
and photosynthesis)
e. muscle contraction
f. bioluminescence