Photosynthesis and Chlorophyll

Biological Pigments or Biochromes

• chemical compounds that have an intense color

• used in the coloring of other materials

• insoluble in water

• appear as ground particles in solid form

• found in plants and animal

Plastid

• a double membrane organelle found in plants and algae

• responsible in manufacturing and storing food

Types of plastids

1. Chloroplasts - Chlorophyll

2. Chromoplasts - ageing chloroplasts, other pigments

3. Gerontoplasts - aged chromoplasts

4. Leucoplasts - found in roots and stems. Storage of starch, proteins, and lipids

Photosynthesis

• process that captures light energy and converts it into sugars

• begins with the absorption of light energy by a specialized form of organic pigments

Types of Pigment in Plants

1. Chlorophylls

2. Carotenoids

3. Betalains

4. Flavonoids

Chlorophyll

• plays a vital role in the biological process, photosynthesis. 

• Stimulates photosynthesis by reflecting green light and absorbed violet - blue and orange - red light.

Chlorophyll A

• Contains methyl group in the third position of its chlorin ring

• Principal pigment that captures sunlight for photosynthesis 

• Absorbs violet- blue and orange- red light from the spectrum

• Reflects blue- green in color

• Found in all plants, algae, and cyanobacteria 

  
  

Chlorophyll B

• Contains an aldehyde group in the third position of its chlorin ring

• Accessory pigments that collects sunlight and passes it into Chlorophyll a

• Absorbs orange- red light from the spectrum

• Reflects yellow- green in color

• Found in all plants and green algae

  
  

Chlorophyll c

found in certain photosynthetic Chromista and in some marine algae.

Chlorophyll d

found only in red algae.

Chlorophyll e

• very rare

• found in golden algae

Carotenoids

Common Types: Carotenes and xanthophylls (e.g. lycopene)

Where they are found: In chloroplast and chromoplast of green plants (masked by chlorophyll), vegetables like carrots, mangoes, etc.

Examples of typical colors: Oranges, reds, yellows, pinks

Benefits of carotenoids

• capture light energy and transfer it to the chlorophyll a

• protect the photosynthetic system from the damaging effects of ultraviolet light.

• Antioxidant

• Source of vitamin A.

• promote good eyesight in humans 

• regulates the growth and division of your cells

• helps your body produce white blood cells 

• plays a role in remodeling bone 

Flavonoids

Common types: Anthocyanins, aurones, chalcones, flavonols and proanthocyanidins

Where they are found: In the cell vacuole of common plants such as berries, eggplant, and citrus fruits. Present in certain teas, wine, and chocolate. 

Examples of typical colors: Yellow, red, blue, purple

Benefits of Flavanoid

• provide visual cues for animal pollinators and seed dispersers to locate their targets.

• play a role in the colors of ripening fruit

• antioxidant 

• help in lower cholesterol levels. 

• utilized as dyes

• use as dietary supplements in most of the food products.

Betalains

Common types: Betacyanins and betaxanthins

Where they are found: In the cell vacuole of Flowers and fungi

Typical colors: Red to violet, also yellow to orange

Benefits of Betalains

• play an important role in attracting animals to flowers and fruit.

• food colorants

NOTE

Over 600 naturally occurring carotenoid structures have been identified, as well as over 7,000 flavonoids, including over 500 anthocyanins.

Outer and Inner Membrane

• Outer and inner covering of the chloroplast. 

Stroma

• Space between the thylakoid and inner membrane

• Site of the Calvin cycle phase of photosynthesis

Stroma lamellae

• Skeleton of the chloroplast 

• Separate stacks of thylakoid

Granum

• Stacks of thylakoid

Thylakoid

• Contains the photosystem of the chloroplast

• Made up of pigments and proteins that absorb light energy

• Chlorophyll and carotenoids

• Site of the light dependent phase of photosynthesis

The Light Reaction Phase

Capture the energy in sunlight and convert it to chemical energy in the form of ATP and NADPH using photosystems, electron transport chains and chemiosmosis.

Names of the protein chain/electron chain

• Plastoquinone - Pq

• cytochrome complex - Cyt

• Plastocyanin - Pc

• Ferredoxin – Fd

Stages of Light Reaction

1.  Light absorption - A process by which light is absorbed by chlorophyll that will excite its electrons.

2. Oxygen production  - When water is split oxygen ,H ion, and electrons will be produced. 

3. Electron transport - The movement of excited electrons through a series of proteins/chains to build a proton/ H ion gradient. 

4. Chemiosmosis - The process that produces ATP by enzyme ATP synthase because of the difference in the electrochemical gradient across the thylakoid membrane.
   

Phases of Calvin Cycle

1. CARBON FIXATION

2. REDUCTION

3. REGENERATION OF RUBP

Carbon Fixation

• This is the process of assimilating carbon from a non-organic compound (CO2) and incorporating it into an organic compound (carbohydrates).

• In Carbon Fixation,  3 molecules of CO₂ (from the atmosphere) are joined to 3 molecules of RuBP (a 5-carbon sugar) by Rubisco (an enzyme also known as RuBP carboxylase)

Reduction

• In this phase the 3-PGA molecules created through carbon fixation are converted into molecules of simple sugar – glucose.

  1. The 6 – carbon molecules are reduced by gaining electrons from NADPH.

  2. Molecular rearranging with the use of ATP. The three 6-carbon molecules will split in half, forming six 3-carbon molecules.

  3. One of these “extra” 3-carbon G3P/PGAL molecules will exit the cycle and be used to form ½ a glucose molecule.

  4. Once the Calvin Cycle “turns” twice (well, actually 6 times), those 2 molecules of G3P (a 3-carbon carbohydrate) will combine to form 1 molecule of glucose (a 6-carbon carbohydrate molecule) OR another organic compound.

Regeneration of RuBP

The remaining 5 G3P molecules (3-carbons each!) get rearranged (using ATP) to form 3 RuBP molecules (5-carbons each).

Summary

• Calvin Cycle occurs in the stroma inside the chloroplasts (inside the cell.)

• In the Calvin Cycle, energy and electrons from the Light Reactions (in the form of ATP and NADPH) and carbon dioxide from the atmosphere are used to produce organic compounds.

• Carbon dioxide, ATP, and NADPH are required (reactants).

•  Glucose and G3P are produced (products).

6 H₂O

Split during the light reactions to replace electrons lost from Photosystem II 

6 CO₂

Provides the carbon to produce organic compounds during the Calvin Cycle

6 O₂

Produced as a byproduct of the splitting of water during the light reactions

 C₆H₁₂O₆

The organic compound ultimately produced during the Calvin Cycle

3-Phosphoglycerate Molecules (3-PGA)

This forms 3 molecule. 

Each have 6 carbons

Total = 18 Carbon

Rubisco

an enzyme also known as RuBP carboxylase

Metabolism

• sum of chemical reactions that take place within each cell of a living organism and that provide energy for vital processes and for synthesizing

2 types of metabolism

1. Catabolism

2. Anabolism

Catabolism

• bigger to smaller

• exocytosis

• makes and releases energy

• potential energy to kinetic energy

• required to perform different act

Anabolism

• smaller to bigger

• endocytosis

• uses energy

• kinetic to potential

• maintenance, growth, and storage of living entities

Oxidation

• molecule loses an electron

• LEO

• NADH to NAD+

Reduction

• gaining of electron

• GRR

• NAD+ to NADH

Respiration

• physical and chemical processes such as breathing and diffusion

• organism supplies its cells and tissues with the oxygen

3 steps of respiration

1. External - between the environment and lungs

2. Internal - lung and circulatory (blood and cells)

3. Cellular

Cellular Respiration

• break down nutrients to release energy

• conversion of food to energy

• organisms breakdown glucose from food to create energy

• occurs inside the living cells of all types of various vital activities

• energy is released when P is released

• muscle contractions requires energy to work

• muscle can only store 6-10 seconds muscular contraction worth of ATP

ex. strenuous activities