plant pigments and their role

TERM PAPER PRESENTATION

BTY 105: PRINCIPLES OF BIOCHEMISTRYTOPIC: PLANT PIGMENTS AND THEIR ROLE

Submitted to:

Dr. Kuldip Chandra Verma

Deptt. Of Biotechnology

Lovely Professional University

Submitted by:

Vir Sapan Pratap Anand

11202530

Section : B1205

Roll No. : A07

INTRODUCTION: WHAT ARE PIGMENTS ?

Pigments are “molecules that absorb specific wavelength (energies) of light and reflect all others.”

Pigments are coloured. The colour we see is the net effect of all the

light reflecting back at us…! They are the substances produced by living

organisms that have a colour resulting from selective colour absorption.

WHAT DO I MEAN BY “ABSORB” ?

Electrons exist at specific levels Normally exist at lowest specific levels However, if enough energy comes to boost

them into the next level, they can ABSORB that energy…!!! And occupy that higher level.

WHAT DO I MEAN BY “ABSORB” ? (CONT…)

The light they absorb contains just the right amount of energy to push them into the next level.

Light not having enough energy or having too much energy is reflected back…!!!

Electron does not want to stay at higher level It wants to return because it is unstable there. Inorder to do this it has to release energy that has put

it into higher level.

WAYS TO RELEASE ENERGY ??

By heat: Conversion in molecular motion By fluorescence: Losing e- by light By Resonance: The energy but not the e-

itself can be passed on to another molecule. By transferring the electron to another

molecule - - - - - - - - - - - - - - - - - - - - - Plant pigments usually utilize the last two of

these reactions to convert the sun’s energy into their own.

BIOLOGICAL PIGMENTS

Produced by living organisms. Have a colour resulting from selective colour

absorption. Include “Plant pigments” and “Flower pigments.” Biological structures such as

Skin Eyes Fur HairContain “melanin” pigment in specialized cells

called “chromatophores”.

PIGMENT COLOUR V/S STRUCTURAL COLOUR

Pigments colour differs from structural colour.

Pigment colour: “Same for all viewing angles”.

Structural colour: “ Result of selective reflection or iridescence, usually because of multilayer structure.

For example butterfly wings typically contain structural colour, although many butterflies have cells that contain pigment as well.

TYPES OF BIOLOGICAL PIGMENTS

1. Heme/Porphyrin based: Chlorophyll, bilirubin, hemoglobin, myoglobin.

2. Light Emitting: Luciferin3. Carotenoids: i) Hematochromes : Algal pigments, mixes of

carotenoids and their derivatives.ii) Carotenes: alpha and beta Caroteneiii) Xanthophylls: Oxidised Carotenes (Eg.

Canthaxanthin)4. Proteinaceous : Phytochrome5. Polyene enolates: A class of red pigments unique

to parrots6. Other: Melanin, Urochrome, flavanoids

PIGMENTS IN PLANTS-:

The Principal pigments in plants are-:1. Chlorophyll2. Carotenoids3. Xanthophylls4. Anthocyanins5. Betalins

PRIMARY FUNCTION OF PIGMENTS IN PLANTS:-

Primary Function : Photosynthesis Uses green pigment chlorophyll along with

several red and yellow pigments. Help to capture as much light as possible. Other functions include attracting insects to

flowers to encourage pollination.

CHLOROPHYLL Primary pigment in plant. Chlorin absorbs yellow and blue

wavelengths. Reflecting green. All land plants and green algae have two

types of chlorophyll. Chlorophyll a and Chlorophyll b. Kelps and photosynthetic heterokonts containChlorophyll c. Chlorophyll serve as fuel to photosynthesis.

STRUCTURE OF CHLOROPHYLL

MORE ABOUT CHLOROPHYLL-:

Name derived from greek words Chloros means “green” and phyllon means

“leaf”. Synthesized from succinyl-CoA and Glycine. Immediate precursor to Chlorophyll A and B

is protochlorophyllide. Contains hydrophobic phytol chain

embedded in lipid membrane. Rest structure is tetrapyrrolic ring. It is the part of pigment that absorbs the

energy from light.

CHLOROPHYLL AND PHOTOSYNTHESIS

Autotrophic Process: Plants and plant-like organisms make their energy (glucose) from sunlight.

Stored as carbohydrate in their bodies. 6CO2 + 6H2O + sunlight C6H12O6 + 6O2

Makes organic molecules (glucose) out of inorganic materials (carbon dioxide and water).

It begins all food chains/webs. Thus all life is supported by this process.

It also makes oxygen gas!!

WHY ONLY GREEN AND NOT BLACK ??

Black Colour is the best absorber of light. Then why couldn’t plants evolve this

change ? Plants except some red algae appear brown

or green but not black. Why ? If plants had pigments that absorbed UV and

X-Rays, this would mean that electrons could be knocked off their orbitals and the molecule destroyed.

If plants absorbed IR and Radio waves, there would not be enough energy for electron transfer, just enough to warm up the molecule.

CAROTENOIDS:

Red, orange or yellow pigments. Function as accessory pigments in plants. Absorb wavelength not readily absorbed by

chlotophyll. Ex: Carotene ( Found in Carrots) Lutein ( Yellow pigment found in fruits and

vegetables). Lycopene ( Red pigment in tomatoes)

ROLE OF CAROTENOIDS

Attract pollinators and seed dispersers Accessory photosynthetic Pigment in periods

of low light, Absorbs excess light energy, Anti oxidant roles, Substrate for hormones

CAROTENOIDS:

Carotenoids are Present in: Carrot, Sweet potato, Winter squash, Pumpkin, Green leafy vegetables, Cantaloupe, Apricot

ANTHOCYANINS:

Literally “Flower blue” Water soluble flavanoid pigments Colour appear as red to blue, acc to pH. Occur in all tissues of higher plants but

colour not noticeable. Have purple colur and are present in: vegetables (onions, cabbage, potatoes), red, blue &

purple berries, black beans

ROLE OF ANTHOCYANINS:

attract pollinators and seed dispersers repel predators, protect cells from

damage by excess light, improve plant tolerance to stress such

as drought, U V-B, improve night vision and other vision disorders, protect against heart

disease,

BETALINS

Red or yellow pigments. Water soluble. Synthesized from tyrosine. Never co-occur in plants having

anthocyanins. Occur in: beets (red and yellow ), chard, spinach, fruit

of prickly-pear cactus.

ROLE OF BETALINS Anti oxidant, May protect against heart disease, various cancers, ulcers, liver damage

XANTHOPHYLLS

Fourth common class of pigmentsEssentially oxidized carotenesUsually red and yellowDo not absorb energy as well as

carotenoids.

CONCLUSION:

Life would be nothing without Plants… And Plants would be nothing without

colours… Green plants having chlorophyll have a vital

role in photosynthesis, a process neccessary for life on earth.

Red and yellow plants and flowers having carotenoids or Betalins provide fresh fruits, and help in pollination.

Blue plants and flowers having Anthocyanins are strong anti-oxidants.

ANY QUERIES ??