Photosynthesis - DeRiemaker

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Transcript Photosynthesis - DeRiemaker

Photosynthesis

Energy & Life

Overview of Photosynthesis

Autotrophs Plants and some other types of organisms that contain chlorophyll are able to use sun food.

light energy from the to produce

Autotrophs

• Autotrophs

include organisms that make their own food

• Autotrophs can

use the sun’s energy directly Euglena protist

Heterotrophs

• Heterotrophs

are organisms that can NOT make their own food

• Heterotrophs

can NOT directly use the sun’s energy

Energy

• Energy Takes Many

Forms such as light, heat, electrical, chemical, mechanical

• Energy can be changed

from one form to another

• Energy can be stored in

chemical bonds & then released later Candles release energy as HEAT & LIGHT

ATP – Cellular Energy

• Adenosine Triphosphate • Contains two, high-energy phosphate

bonds

• Also contains the nitrogen base adenine

& a ribose sugar

ADP

• Adenosine Diphosphate • ATP releases

energy , a free phosphate, & ADP energy from ATP when cells take One phosphate bond has been removed

Releasing Energy From ATP

• Adding

A Phosphate Group To ADP stores Energy in ATP

• Removing

A Phosphate Group From ATP Releases Energy & forms ADP Gain Lose

More on ATP

• Cells Have Enough ATP To

Last For A Few Seconds

• ATP must

constantly be made

• ATP

Transfers Energy Very Well

• ATP Is

NOT Good At Energy Storage

Glucose

• Glucose is a

monosaccharide

• C

6 H 12 O Stores 6

• One Molecule of glucose

90 Times More Chemical Energy Than One Molecule of ATP

History of Photosynthesis & Plant Pigments

Photosynthesis

• Involves the Use Of light

Energy to convert Water (H 2 0) and Carbon Dioxide (CO Oxygen (O 2 ) Carbohydrates 2 ) into and High Energy (sugars, e.g. Glucose) & Starches

The Photosynthesis Equation

Pigments

• In addition to water,

carbon dioxide, and light energy, photosynthesis requires Pigments

• Chlorophyll

is the primary light-absorbing pigment in autotrophs

• Chlorophyll is found

inside chloroplasts

Light and Pigments

• Energy From The Sun

Enters Earth’s Biosphere As Photons

• Photon = Light Energy

Unit

• Light Contains A

Mixture Of Wavelengths

• Different Wavelengths

Have Different Colors

Light & Pigments

• Different pigments

absorb different wavelengths of light

• Photons of light

“excite” electrons in the plant’s pigments

• Excited electrons carry the

absorbed energy

• Excited electrons move to

HIGHER energy levels

Chlorophyll There are 2 main types of chlorophyll molecules: Chlorophyll a Chlorophyll b Magnesium atom at the center of chlorophyll

Chlorophyll a

•Found in all

plants, algae, & cyanobacteria

•Makes photosynthesis possible •Participates

directly in the Light Reactions

•Can

accept energy chlorophyll b from

Chlorophyll b

• Chlorophyll b is an

accessory pigment

• Chlorophyll b acts

and indirectly in photosynthesis by transferring the light it absorbs to chlorophyll a

• Like chlorophyll a, it

absorbs red & blue light REFLECTS GREEN

The Biochemical Reactions

It Begins with Sunlight!

Inside A Chloroplast

Structure of the Chloroplast

• Double membrane

organelle

• Outer membrane

smooth

• Inner membrane

stacks of connected sacs called granum thylakoids

• Thylakoid stack is called the

(grana-plural)

• Gel-like material around

grana called forms stroma

Thylakoid membranes

• Light Dependent

reactions occur here

• Photosystems are made up of

clusters of chlorophyll molecules

• Photosystems are

Photosystem I Photosystem II embedded in the thylakoid membranes

• The two photosystems are: 28

Function of the Stroma

• Light Independent

reactions occur here

• ATP used

to make carbohydrates like glucose

• Location of the

Calvin Cycle

Photosynthesis Overview

Energy Carriers

• Nicotinamide Adenine Dinucleotide

Phosphate (NADP + )

• NADP

+ = Reduced Form

• Picks Up • NADPH

2 high-energy electrons and H + from the Light Reaction to form NADPH carries energy to be passed on to another molecule

Light Dependent Reactions

• Occurs across the

thylakoid membranes

• Uses light energy • Produce

Oxygen from water

• Convert

ADP to ATP

• Also convert

NADP + the energy carrier NADPH into

Light Dependent Reaction

Photosynthesis Begins Photosystem II absorbs light energy Electrons are energized and passed to the Electron Transport Chain Lost electrons are replaced from the splitting of water into 2H +, free electrons, and Oxygen 2H + pumped across thylakoid membrane

Photosystem I High-energy electrons moved to Photosystem I through the Electron Transport Chain Energy is used to are transport H + from stroma to inner thylakoid membrane NADP+ converted to NADPH when it picks up 2 electrons & H+

Phosphorylation Enzyme in thylakoid membrane called ATP Synthase As H+ ions passed through thylakoid membrane, enzyme binds them to ADP Forms ATP

Light Reaction Summary Reactants:

• H

2 O

• Light Energy

Energy Products:

• ATP • NADPH 41

Light Independent Reaction

• ATP & NADPH

reactions used as energy

• Atmospheric

C0 from light 2 is used to make sugars like glucose and fructose

• Six-carbon Sugars made

during the Calvin Cycle

• Occurs in the

stroma

Melvin Calvin 1948

•First to trace the path

that carbon (CO 2 ) takes in forming Glucose

•Does

NOT require sunlight

•Called the

Calvin Cycle or Light Independent Reaction

•Also known as the

Dark Reaction

The Calvin Cycle

• Two turns • 3-CO

2 of the Calvin Cycle are required to make one molecule of glucose molecules enter the cycle intermediate compounds (PGA)

• A 3-carbon molecule called

Ribulose Biphosphate cycle (RuBP) is used to regenerate the Calvin

Factors Affecting the Rate of Photosynthesis

• Amount of

available water

• Temperature • Amount of

available light energy

•

Increasing levels of CO2 will also cause the rate of photosynthesis to increase then level off.