Download Energy of Life

Energy of Life
Energy
• the ability to do work
• Where does your energy come from?
– Autotrophs - use energy from the sun to
produce food.
– Heterotroph - get energy from the food
they eat
• Forms of Energy
– light
– heat
– electricity
Energy Compounds
• Adenosine Triphosphate or ATP
• 3 Phosphate Groups
• Energy powers active transport,
protein synthesis, & muscle
contractions
Storing Energy
• ATP = ADP + 1 Phosphate
– fully charged battery
Releasing Energy
• break off a phosphate,
energy is released
Photosynthesis Introduction
Photosynthesis Introduction
• Jan van Helmont - measured plant’s
water intake
– plants gain most of their mass from
water
Photosynthesis Introduction
• Priestley : took a candle and placed a
glass jar over it
– watched the flame gradually die out
– something in the air was necessary to
keep the candle burning: oxygen
Photosynthesis Introduction
• Priestly’s Second Experiment
– placed a live spring of mint under the jar
and allowed a few days to pass
– the candle would remain lite a while.
– Why? mint plant produced oxygen.
Photosynthesis Introduction
• Jan Ingenhousz - aquatic plants
produce oxygen bubbles in the light,
but not in the dark
– plants need sunlight to produce oxygen.
Photosynthesis
• plants use energy of sunlight to covert
water and carbon dioxide into
– high-energy carbohydrates: sugar &
starches
– oxygen: waste product
Photosynthesis Equation
• 6CO2 + 6H20 + (light)  C6H12O6 + 6O2
• carbon dioxide + water + (light) 
sugars + oxygen
Light and Pigments
Light Energy
• Energy travels to the Earth in the
form of light.
• White light: mixture of different
wavelengths/colors
Plants gather the sun’s energy with
light absorbing molecule called pigments
• Principle Pigment: chlorophyll
– which is in the chloroplast
– chlorophyll a & chlorophyll b
• Chlorophyll absorbs light well:
– blue-violet, chlorophyll b
– red region, chlorophyll a
– green light is reflected by leaves
Secondary Pigment: Carotene
• absorbs light in the red & orange
region
• leaves turn red, yellow, and orange in
the fall
Light  Energy
• When chlorophyll absorbs light, it
absorbs energy
• Energy is transferred to the electrons
in the chlorophyll molecule
• Allows photosynthesis to work
Reactions of Photosynthesis
Chloroplast
• In the chloroplast, thylakoids are in
stacks called grana
• Thylakoid organize chlorophyll and
other pigments into photosystem.
• Photosystems: light collecting units
of the chloroplast
•
Photosynthesis
• Light dependent reaction
• Thylakoid membrane
• Light independent reaction or Calvin
Cycle
• Stroma: region outside of the
thylakoid membrane
Electron Carriers
• electrons gain energy when excited by
sunlight
• high-energy electrons are transported by
electron carriers
• electron carriers are called the Electron
Transport Chain
Electron Carriers
• NADP+ - carrier that holds 2 high-energy
electrons and H+ ion
– NADP+  NADPH
• NADPH carries the high-energy electrons
throughout the cell
• High energy electrons are used to build
carbohydrates, like glucose
Electron Transport
Light-Dependent Reaction
•
•
•
•
•
Occurs in the thylakoid membrane
uses energy from light
ADP  ATP
NADP+  NADPH
produces O2 gas
Calvin Cycle
• Occurs in the stroma: region outside
the thylakoid membrane
• Uses ATP and NADPH to build high
energy sugars
• long term energy storage
• does not require light
Factors Affecting Photosynthesis
• Water shortage: slows photosynthesis
– Plants in dry conditions have waxy coating to
reduce water loss
• Temperature: 0-35ºC
– Above or below damages enzymes and
photosynthesis slows
• Light: rate increases with intensity
– Maximum exists