Transcript 4.1 Energy PS Honors

5.1 Energy &
Photosynthesis
Chapter 9
Energy:
 All

organisms require energy for survival
All energy in food ultimately comes from
the sun
Energy: How do we get it?
 Make


it! Autotrophs
Organisms that make their own food
(glucose) using energy from the sun
Examples: plants, algae & some bacteria
Energy: How do we get it?
 Eat


it! Heterotrophs
Organisms that eat plants or animals to get
energy
Examples: animals & fungi
Energy: What’s it all for?
 Why

To move, breathe & reproduce
 Why

do organisms need energy?
do cells need energy?
Active transport, cell division & make
biomolecules
 Where

does energy come from?
Food: Carbs – quick energy; Lipids – long
term energy
Energy Molecules:
ATP
ADP
Energy Molecules: ATP
 ATP



(adenosine triphosphate)
1 ribose (sugar) molecule
3 phosphate groups
Adenine (nitrogenous base)
Energy Molecules: ADP
 ADP




(adenosine diphosphate)
1 ribose (sugar) molecule
2 phosphate groups
Adenine (nitrogenous base)
Created when ATP loses energy & a
phosphate
Energy Molecules
So what happens?
 ATP


ADP
Bond between 2nd & 3rd phosphate is
broken
Energy is released
 Energy
can be used by the cell
So what happens?
 ADP

ATP
Energy is stored when 3rd phosphate adds
to ADP
How do cells get ATP?
 Break

down carbohydrates & lipids
Creates energy – energy used to make ATP
 Where
do animals get carbohydrates &
lipids from?

Their FOOD
 That
food is produced by autotrophs in
the process of photosynthesis
Photosynthesis
 Ability
to capture
light energy from
the sun and
change it into
chemical bond
energy while
making oxygen
Photosynthesis Equation
6CO2 + 6H2O + Light energy
C6H12O6 + 6O2
Photosynthesis Questions:
 Where
does it occur in plants?
 What are the reactants?
 How do the reactants get into the plant?
 What are the products?
 What happens to the products?
Location?
 In
the chloroplast of plant cells
Where does it occur?
 Chloroplast
structure:
Thylakoids:
Sacs of membrane with
pigment molecules
Grana:
Stacks of thylakoids
Stroma:
Liquid surrounding
thylakoids
Contains enzymes for PS
Photosynthesis Pigments
Photosynthesis Pigments
 Pigments
in the plant chloroplast &
vacuole absorb light energy
 Chlorophyll is the main pigment found in
plant cell chloroplasts

Reflect green light
Photosynthesis process
 Occur

in two steps:
Light-dependent reactions
 Purpose:
Make energy for light-independent
reactions

Light-independent reactions
 Also
called Calvin cycle
 Purpose: Use energy from light reactions to make
glucose
Lightdependent
Reactions
Lightindependent
Reactions
thylakoid
Glucose
Photosynthesis process:
light-dependent reactions
Location: Thylakoids
1. Light energy is absorbed by chlorophyll
1.
2.
3.
Chlorophyll electrons gain lots of energy
NADPH carries high-energy electrons to
the Calvin Cycle
Light Energy used to make ATP for Calvin
Cycle
NADP+
NADPH
NADP+
Photosynthesis process:
light-dependent reactions
Water is split to produce oxygen and
hydrogen atoms
4.
2H2O + Light


2H2 + O2
Oxygen is released as a product; released
through the stomata of leaves.
Photosynthesis process:
light-dependent reactions
Used:
 Light
Made:
energy
 ATP
 NADPH
 H 2O
 Oxygen
Light-independent
rxns
(product)
Photosynthesis process:
light-independent reactions
 Called
 No
Calvin cycle
light required!
 Location:
Stroma of chloroplast
Photosynthesis process:
light-independent reactions
ATP broken apart to release energy
1.

ATP
ADP + P + energy
Energy used to bond electrons from NADPH
with CO2 to make glucose
2.
1.
Equation: CO2 + electrons
C6H12O6
ADP goes back to light reactions to get
recharged
3.

Turned back into ATP
Photosynthesis process:
light-independent reactions
Used:
Made:
 CO2
 ATP (from light rxns)
 NADPH (from light rxns)
 GLUCOSE
!!!
Photosynthesis review:
 Where
 How
did the CO2 come from?
did water enter the plant?
 What
 What
absorbed the sunlight?
reactant is used in the lightindependent reactions?
Photosynthesis questions:
 What
is made in the light-dependent
reactions that is used in the lightindependent reactions?
 What
reactant is responsible for making
oxygen?
Photosynthesis questions
 Where
do the light-dependent reactions
take place?
 Where
do the light-independent reactions
take place?
 What
is the final product of the lightindependent reactions?
H2O
O2
Light
ATP
CO2
Glucose
H
NADPH
ADP
Factors that influence PS Rates
 Lack

of water
Example/Adaptation:
 Desert
plants/conifers (pines): waxy coating
and “needle” leaves to reduce water loss
Factors that influence PS Rates
 Temperature:
influences enzymes involved
in the PS reactions

What is the best temperature?
Factors that Influence PS rates
 Intensity

of light (varies by plant)
Excess UV rays/sunlight can decrease PS