Photosynthesis
Law Of Conservation of Matter and Energy
• Matter and energy can neither be created of
destroyed, only transformed.
• Total amount of energy in the universe is
constant-it’s stored in the bonds of matter.
• Potential energy =stored energy
• Kinetic energy= released(bonds broken)energy.
• (Released energy is NOT lost energy, it’s just
transformed)
Chemical Reactions
Chemical reactions
A chemical reaction is a process that changes one set of
chemicals into another set of chemicals by
creating/breaking bonds
Reactants
{
{
2Fe + 3H2O- 2FeO3 + 3H2
Products
http://www.youtube.com/watch?v=jRm-otFKWLI
http://www.youtube.com/watch?v=El6El4iapO4
Carbon Bonding
• Organic molecules are made mostly of
carbon atoms. Most matter in living
organisms is made of organic molecules.
• Use pg. 51-52 to answer the following
• QUESTION: How do carbon’s bonding
properties contribute to the existence of a
wide variety of biological molecules?
Carbon
ANSWER: One of the most important
elements found in living things
Has 4 valence electrons which means it
can form 4 bonds with other carbon
atoms or other elements such as
hydrogen (H), oxygen (O),
phosphorous (P)
Redox Reactions
An oxidation reduction(redox) is a reaction
where electrons are transferred from one
reactant to another
OIL= Oxidation is loss(of electrons)
RIG= Reduction is gain (of electrons)
Oxidation- an atom
loses an electron
Reduction- an atom
gains an electron
Compare/Contrast-the energy storing molecules
Question-Name all the
different molecules carbon
is attached to in BOTH
pictures!!
Energy Currency
• Life/cellular processes need constant
energy. ATP (adenosine triphosphate) has
energy stored in covalent bonds between
phosphates.
What is Photosynthesis?
Photosynthesis is when autotrophs
make their own food/glucose.
Photosynthesis takes light energy,
water, and breaks apart carbon
dioxide and converts it into stored
energy in glucose.
What is Photosynthesis?
• http://www.mhhe.com/biosci/bio_animation
s/02_MH_Photosynthesis_Web/
Where does Photosynthesis
happen? (read)
It happens inside the
CHLOROPLAST, with dozens in
the cells of each leaf.
What are the Parts of the Chloroplast?
• #1. Thylakoids—saclike photosynthetic membranes
-Arranged in stacks called= #2. Granum.
• solution surrounding them= #3. Stroma.
Single
thylakoid
Stroma
Granum
Chloroplast
A
B
C
D
A
Why are Most Plants Green?
Light travels in waves.
In order to capture the
energy in light, plants
use a main pigment
called chlorophyll.
This pigment reflects
green light making
plants look green.
Visible Light Spectrum
The suns energy travels in waves
The distance between waves = wavelength
Different wavelengths of light are visible as different
colors
ROY G BIV
Longest wavelength = Least amount of energy
Shortest wavelength = larger amount of energy
What colors do chlorophyll a,b absorb best? Worst?
What colors do caretenoids absorb best? Worst
• -Chlorophyll does not absorb light well in the green region
of the spectrum. (absorbs blue/violet best)
•
-Green light is reflected by leaves, which is why
plants look green.
Why Do Leaves Change Color in the Fall
The chlorophyll breaks down, leaving
only carotenoid pigments that reflect
orange, red, and yellow..
8-1
Why do plants look Green?
There is much more chlorophyll than the
other pigments (the other colors are
masked).
In the Fall, chlorophyll is broken down and
the accessory pigment colors are shown.
Why do trees lose leaves in the winter?
It’s difficult to absorb H2O from frozen
ground so leaves drop off to save water.
Reactants of photosynthesis?
LIGHT
Carbon
Dioxide
GLUCOSE
Water
Carbon Dioxide + Water
Products of photosynthesis?
LIGHT
Oxygen
GLUCOSE
Oxygen & Glucose
Glucose
The GOAL of photosynthesis?
LIGHT
WASTE PRODUCT
GLUCOSE
GOAL
-Oxygen is a waste productGLUCOSE is the goal!
The Equation!
Word Form:
Light Energy
Carbon Dioxide +Water
Glucose + Oxygen
Balanced Chemical Equation:
Light Energy
6CO2 + 6H2O
C6H12O6 + 6O2
6
What are the Reactions?
Photosynthesis is 2 reactions happening
simultaneously in the chloroplast!
-1st- Light Dependent Reaction.
2nd –Calvin Cycle a.k.a. Light Independent
reaction
The 2nd reaction can not happen without
the first.
Light Dependent
Reaction
Water molecule is split by water
splitting enzyme-Oxygen is
released and Hydrogen is sent to
Calvin cycle
Light
Light- dependent
reactions
Chloroplast
Calvin
Cycle
Light dependent reaction(Step 1)
a.)Occurs in the thylakoids of chloroplast
b.)Starts w/water (H2O) and sunlight light
absorbed by chlorophyll molecules
c.)Makes Oxygen (O2) ,ATP energy and
NADPH energy
**The ATP and NADPH will be used in reaction
2
Light Dependent
Reaction
H2O
CO2
Light
NADP+
ADP + P
Lightdependent
reactions
Calvin
Calvin
cycle
Cycle
Chloroplast
O2
Glucose
With your shoulder partner explain
when/what/where happens to each of the
following when they enter the thylakoids of
the Light Dependent Reaction:
1.Water
2.NADP+
3.ADP
Light- dependent Reactions
Light energy is absorbed by chlorophyll
molecules
This light energy excites electrons (excited
electrons supply energy) and boosts them
to higher energy levels.
The electrons “fall” to a lower energy state,
releasing energy that is harnessed to
make ATP
Energy Shuttling
ATP: superb molecule for shuttling
energy around within cells.
Other energy shuttles-coenzymes
(nucleotide based molecules): move
electrons and protons around within the
cell
NADP+, NADPH
FADH2
NAD+, NADP
FAD,
Silently and Independently
• Q: Explain why the splitting of water is important the
continuation of the calvin cycle and to our survival?
• Provides Hydrogen the Calvin Cycle requires to make glucose
and oxygen we need to breathe.
• Q: Explain how oxygen is generated in photosynthesis(p.117
Paragraph 5,6)
• Water is split in light dependent reaction, and the oxygen is
released as a waste product
The Calvin Cycle (light-independent)
(2nd Step)
Occcurs in the stroma of the chloroplast
Uses ATP from the light dependent reaction
and CO2 to produce high energy glucose
Calvin Cycle -aka-Light Independent Reaction
H2O
CO2
Light
NADP+
ADP + P
Lightdependent
reactions
Calvin
Calvin
cycle
Cycle
Chloroplast
O2
Glucose
STROMA
• Identify the reactants/products for BOTH the light
reactions and the calvin cycle.
• Light reaction reactants =sunlight, water, NADP+, ADP
• Light reaction products= Oxygen, ATP and NADPH
• Calvin Cycle Reactants= CO2,
• Calvin Cycle Products= NADP+, ADP, Glucose (orgaqnic
compunds)
• Calvin cycle energy used =ATP and NADPH
•
What might happen to photosynthesis if ATP were not produced in
the light reactions
• W/O ATP calvin cycle would stop, and so would photosynthesis
• Relate the rate of photosynthesis to carbon dioxide levels
• Increase CO2=increased photosynthesis rate
•
•
•
•
•
Which of the following is a reactant in the calvin cycle
A. 02 B. CO2 C. H2O D. C6H12O6
Oxygen is produced at what point in photosynthesis?
A. when CO2 is fixed B.when water is split C. When ATP is
converted to ADP D. when 3-GPA is converted to G3P
Glucose is used for what?
Glucose is:
1) Broken apart and used to make ATP energy(easy to
use) in cellular respiration-ATP is used for active
transport and protein synthesis.
2) Chained together to make the plants body-(cellulose
for cell walls)
3.) Stored as starch(another carbex.=potatoes) to be used later
Factors Affecting Photosynthesis
1) Light Intensity
in light = ____ in the rate of photosynthesis
2)Temperature –
best between 0 C and 35 C
If the temperature is too high/low,
this changes the shape of the
enzymes involved in photosynthesis.
3) Carbon Dioxide Levels
in CO2 = ____ in the rate of photosynthesis
Why does the RATE of photosynthesis plateau/peak
even though light intensity continues to increase?