photosynthesis chapter 8 (m). energy and life section 8.1
TRANSCRIPT
Photosynthesis
Chapter 8 (M)
Energy and Life
Section 8.1
Chemical Energy and ATP Energy ability to do work All life depends on the ability to obtain and
use energy Energy
Light Heat Chemical
Living organisms use the energy stored in chemical bonds of compounds
ATP Adenosine Tri-phosphate Provides Energy for Cellular Work
Energy Needed For
Muscle cells to contractMove ions & molecules across membranes
Heart to pump bloodMaking new molecules growth & repair
ATP Packs EnergyCarbohydrates, fats, proteins
from food do not drive work in cells directly
The chemical energy stored in these must be converted into a more usable form
ATP Energy Molecule
High EnergyFood Energy Released Stored in ATP
Low Energy Waste
ATP
ATP
ATP
Adenosine Tri PhosphateATP = Adenosine tri phosphateWhen phosphate bond is broken energy is released
ATP & Cellular WorkChemical Rxn Phosphate
bond in ATP is broken & transferred to another molecule
Work in a cellTransportMechanicalChemical
ATP converted to ADP ATP
recyclable Work consumes
ATP, ATP regenerated from ADP +P
Working muscle need 10 million ATP / second
Energy Flow in Ecosystems
Organisms require a constant source of energy to survive
Producers/Autotrophs
Producer: an organism that makes its own food
Producer = Autotroph (gets energy directly from the sun)Ex. Plants, Algae, some bacteria
Consumers/ Heterotrophs
Consumer: an organism that gets its energy by eating other organisms
Consumer = Heterotroph (gets energy indirectly from the sun)Ex. all other organisms except autotrophs
“I MUST BE A HETEROTROPH I CAN'T MAKE THESE !!"
LIFE depends on the SUN
The SUN provides light energy
Plants, algae, & some bacteria capture this energy and store it as food (Photosynthesis)
PhotosynthesisThe use of sunlight to make food
Takes place in the chloroplast of leaves
Chloroplasts
Special organelles that can capture the energy of the sun
Present in the mesophyll layer of leaves
Stomata tiny pores also present in leaves CO2 enters and O2 exits
Structure of Chloroplasts Stroma thick fluid in
the inner membrane Thylakoidsdisc
shaped sac suspended in the stroma
Grana stacks of thylakoids
Chlorophylls pigments that give the leaves color
Light Energy and Pigments
Sunlight is a form of electromagnetic energy
Electromagnetic energy travels in waves
Wavelength distance between two adjacent waves
Electromagnetic Spectrum Range very short (gamma) to
long (radio waves)
PigmentsAbsorb and reflect light resulting in the color of the leaves
Green wave length of light is not absorbed, it is reflected back hence leaf appears green
Why leaves are green: interaction of light with chloroplasts
Absorption Spectrum
Action & Absorption Spectra photosynthesis is greatest in the blue and red end
Pigments and Chromatography Paper chromatography technique used
to separate a mixture into its component molecules.
The molecules migrate, or move up the paper, at different rates because of differences in solubility, molecular mass, and hydrogen bonding with the paper
In paper chromatography the pigments are dissolved in a solvent that carries them up the paper.
Chromatography
Retention Factor
Rf = distance traveled by spot/ distance traveled by solvent
If the for an unknown is close to or same as that for a known compound, the two are most likely similar or identical
Sample origin
Solute front
Solvent Front
Plants take CO2 from the air
Veins carry water and nutrients from the plants roots to the leaves
6CO2 + 6H2O C6H12O6 + 6O2
Overview of Photosynthesis
PhotosynthesisStages:1. Light reaction takes
place in the thylakoid membrane
2. Calvin cycle takes place in the stroma
Light ReactionsPhotosystems present within
the thylakoid membrane, contain chlorophylls (a,b) and other pigments (carotenoids)
Pigments act as a light gathering panel
Light pigment absorbs energy energy transferred to Reaction center
Reaction CenterChlorophyll a traps energy
makes ATP & NADPHATP & NADPH used in Calvin
Cycle
Calvin Cycle Like a sugar factory Uses NADPH & ATP form the light
rxn to fix CO2
3 CO2 enters the cycle and joins with RuBP (ribulose bisphosphate)
G3P is formed that exits the cycle, RuBP is regenerated
G3P is used by the plant to make sugar
Calvin Cycle
Rubisco most abundant enzyme in the world Why?
Adds CO2 to RuBP to form a six carbon compound that breaks down into G3P
Calvin Cycle
Overview of Photosynthesis
Photosynthesis
Reactants 6CO2 + 6 H2OProducts C6H12O6 + 6O2
Factors Affecting Photosynthesis Temperature best between 0oC-
35oC Light Intensity high intensity
increase photosynthesis maximum is reached
Water raw material, shortage can slow down or stop photosynthesis
Photosynthesis Under Extreme Conditions Under hot dry, bright condition stomata
close, plant conserves water Decreases the photosynthetic output Certain species of plants have evolved
alternate modes of carbon fixation to minimize photorespiration
C4 Photosynthesis CAM Plants
C4 Plants
Have a specialized pathway to capture low levels of CO2 and pass it to the Calvin cycle
Rxn takes place that incorporates CO2 into 4C compounds
Occurs in corn, sugar cane, crabgrass, at least 19 plant families use this
CAM Plants
Crassulaceae Acid Metabolism Aloe , Jade , Cacti Keep in as much water as possible by
opening stomata only at night Store CO2 organic acids (in vacuoles) During the day these organic acids
release CO2 Calvin cycle takes place
C4 and CAM Plants