Similarities and Difference between C3 and C4 Plants – A Comparison Table


C3 vs C4 Plants Comparison

Similarities and Difference between C3 and C3 Plants
(C3 plants vs C4 plants – A Comparison Table)

Green plants are unique to possess the ability to fix light energy from sunlight through a process called photosynthesis. The photosynthesis essential involves the synthesis of carbohydrates with atmospheric carbon dioxide, water and energy obtained from the sunlight. The process of photosynthesis in plants is completed in two broad steps, a light dependent ‘Light Reaction’ and a light independent ‘Dark Reaction”. In the light reaction, the chlorophyll molecules in the plants absorb energy from sunlight and synthesize energy rich chemical molecules such as ATP and reduced coenzymes (NADPHH+). In the dark reaction, these energy rich molecules are used up for the synthesis of carbohydrates with carbon dioxide. There are essentially three different types of dark reaction pathways are operated in different plants on earth and they are named on the basis of the components of these pathways. They are C3 plants, C4 plants and CAM plants. The present post describes the similarities and differences between C3 plants and C4 Plants.

C3 Plants: Plants which uses C3 cycle (Calvin cycle) of dark reaction of photosynthesis. C3 cycle is the first described dark reaction pathway. Majority of the plants (~95%) on earth are C3 type. The first stable product formed in C3 cycle is a three carbon (3C) compound, hence the name. The photosynthetic efficiency of C3 plants is comparatively less due the high rate or photorespiration. For a considerable period of time, the C3 cycle was thought to be the only dark reaction pathway in plants.

C4 Plants: These plants in addition to C3 cycle, uses an additional dark reaction pathway called C4 cycle. Very few plants (~5%) on earth are C4 type. The first stable product formed in C4 cycle is a four carbon (4C) compound, hence the name. The photosynthetic efficiency of C4 plants is very high due to the absence of photorespiration. 

Similarities between C3 and C4 Plants

@. Both C3 and C4 are types of dark reactions of photosynthesis.

@. Both C3 and C4 plants fix energy from sunlight.

@. Both C3 and C4 plants synthesize carbohydrates.

@. The general equation of photosynthesis (6CO2 + 12H2O → 6C6H12O6 + 6O2 + 6H2O) is similar in both C3 and C4 plants.

@. Both C3 and C4 plants require 6 molecules of CO2 and 12 molecules of water to synthesis one molecule of glucose.

@. The carbohydrate product of both C3 and C4 cycle is a three-carbon sugar phosphate molecules called Glyceraldehyde 3 phosphate (G3P).

@. Both C3 and C4 plants requires chloroplasts for doing photosynthesis.

@. The light reaction of photosynthesis is similar in both C3 and C4 plants.

@. RuBP can accept CO2 in both C3 and C4 plants.

Difference between C3 and C4 Plants

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Difference between C3 and C4 Cycles of Photosynthesis in Plants


C3 vs C4 Cycles of Photosynthesis

Similarities and Differences between C3 and C4 Cycles: A Comparison Table
(Calvin Cycles Vs Hatch and Slack Cycle)

Photosynthesis is one of the vital events in the earth in which the green plants fix the energy from the sunlight and synthesis nutrients with carbon dioxide and water. Almost all living things on earth, either directly or indirectly, depend on photosynthesis for energy. The process of photosynthesis in plants is completed in two major pathways, a light dependent ‘Light Reaction’ and a light independent ‘Dark Reaction’. In the light reaction, the chlorophyll molecules in the plants absorb energy from sunlight and synthesize energy rich chemical molecules such as ATP and reduced coenzymes (NADPHH+). In the dark reaction, this energy rich molecules are used up for the synthesis of carbohydrates from carbon dioxide. The first describe dark reaction pathway, better known as Calvin cycle (Melvin Calvin who discovered this pathway), is called C3 cycle. For a considerable period of time, the Calvin cycle (C3 cycle) was thought to be the only dark reaction pathway in plants. Later, a new pathway of dark reaction called Hatch and Slack pathway or C4 cycle was described in some plants. Both these cycles (C3 and C4 cycles) show many similarities and differences. The present post describes the similarities and differences between C3 cycle and C4 cycle of the dark reaction of photosynthesis.

Similarities between C3 cycle and C4 cycle

Ø  Both C3 and C4 cycles are pathways of dark reaction of photosynthesis.

Ø  Both are light independent reactions.

Ø  Both C3 and C4 cycle requires energy from ATP or reduced coenzymes.

Ø  Both C3 and C4 plants accept carbon dioxide to perform dark reaction.

Ø  End products of C3 and C4 cycle are similar.

Ø  Both C3 and C4 cycle requires RuBP and RUBISCO to complete the pathway.

Difference between C3 cycle and C4 cycle:

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biological chemistry

Chemical Bonds Involved in Protein Structure and Conformation


bonds stabilizing protein structure

Bonds involved in Protein Structure
(Bonds Stabilizing the Primary, Secondary, Tertiary and Quaternary Structure of Proteins)

Proteins are the polymers of amino acids. Amino acids are joined together by a special type of covalent bond (peptide bond) to form linear structures called polypeptides. The polypeptides are then folded into specific structures to form the functional conformation of the protein. The folding of proteins into specific shapes and conformations are assisted and stabilized by many types of bonds in them. Some of these bonds are strong bonds whereas others are weak interactions. Important types of bonds involved in protein structure and conformation are Peptide bonds, Ionic bonds, Disulfide bonds, Hydrogen bonds and Hydrophobic Interactions. The current post describes the importance of each of these bonds and their role in the functional conformation of the protein.

What are the different types of bonds present in a protein?

Ø  Typically, proteins possess the following FIVE types of bonds.

(1).    Peptide bond

(2).   Ionic bond

(3).   Disulfide bond

(4).   Hydrogen bond

(5).   Hydrophobic Interactions

(1). Peptide Bond

Ø  Peptide bond definition: a covalent bond formed between the carboxylic group of one amino acid and the amino group of another amino acid.

Ø  Peptide bond is a strong covalent bond with high bond dissociation energy.

Ø  It is formed by the joining of two amino acid residues during protein synthesis.

Ø  The carboxylic group (- COOH) of one amino acid combine with the amino group (-NH2) of another amino acid to form the peptide bond.

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biological chemistry

Classification of Proteins Based on Structure and Function

protein classification

Classification of Proteins

Proteins are important macromolecules of the cells, formed by the polymerization of amino acids according to the sequence of genetic code in the mRNA. Proteins are the mode of expression of the genetic information. They perform a variety of duties in the cells such as they act as the structural components of cells, enzymes, hormones, pigments, storage proteins and some toxins in the cells. The proteins are classified into many categories based on different criterions.

Criterion for the classification of proteins:

Ø  Proteins are classified based on the following THREE criterions:

                             (I).     Classification based on STRUCTURE of Protein

                            (II).    Classification based on COMPOSITION of Protein

                           (III).    Classification based on FUNCTIONS of Proteins

(I). Classification of Proteins based on the Structure of Proteins

Ø  Based on the structure, proteins are classified into 3 groups.

(A).   Fibrous Proteins

(B).   Globular Proteins

(C).   Intermediate Proteins

(A). Fibrous Proteins

Ø  They are linear (long fibrous) in shape.

Ø  Secondary structure is the most important functional structure of fibrous proteins.

Ø  Usually, these proteins do not have tertiary structures.

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biological chemistry

Biological Importance of Water


biological functions of water

Biological Importance of Water

Water is the mother liquid of all forms of life. The essentiality of water for living systems is quite evident as without water, there is no life. No other substance on earth is abundant as water. All aspects of cell structure and functions are adapted to the physical and chemical properties of water. The following are the important biological significance or importance of water in the living system.

(1).  Water is a ‘universal solvent’.

(2).   Water can dissolve most of the biologically important molecules.

(3).  It is the solvent of life. The life originated in water and adapted to survive only in the presence of water.

(4).  About 70 to 90% of a cell occupies water.

(5).  Water acts as a medium for the diffusion of molecules in the cell.

(6).  Osmotic concentration of cell is maintained by water and dissolved solutes.

(7).  The turgidity of the cell is maintained by the water.

(8).  Translocation of inorganic and organic compounds in the living system takes place through the water.

(9).  Carbohydrates, the product of photosynthesis, in plants are transported through the water.

(10).  Water is the source of H+ ions for photosynthesis.

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