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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Free Net Life Science Study Materials

CSIR JRF NET Life Sciences Model Question Paper for June 2017 Exam (Set 1/5)


Biosynthesis of purine & pyrimidine

CSIR JRF/NET Life Science Exam
June 2017 (I)
Model Question Paper 1/5
(Practice Questions with Answer Key)

(1). Action of topoisomerase leads to changes in

a.       Linking number of single-stranded linear DNA
b.      Lining number of double stranded linear DNA
c.       Linking number of closed circular single stranded DNA
d.      Linking number of closed circular double stranded DNA

(2). Sarcomas are cancers originating from:

a.       Spleen
b.      Lymph node
c.       Skin
d.      Connective tissue

(3). Receptor mediated endocytosis from plasma membrane requires which one of the following coat proteins

a.       Clathri
b.      Adaptin
c.       Arrestin
d.      Glycophorin

(4). Which of the following compound does not acts as ‘second messenger’ during signaling process?

a.       cAMP
b.      Calcium ions
c.       Inositol 3.4.5 triphosphate
d.      Triacylglycerol

(5). Which of the following peptide is not synthesized on ribosome?

a.       Cyclosporin
b.      Somatotropin
c.       Vasopressin
d.      Oxytocin

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Biotechnology Eligibility Test Preparation

DBT BET JRF Exam 2017 Original Solved Question Paper with Answer Key (Download PDF)


DBT JRF 2018 Exam Question Paper

Original (original) Previous Year (old) Solved Question Paper of DBT BET JRF 2017 Examination (Department of Biotechnology- Biotechnology Eligibility Test – Junior Research Fellowship) with Answer Key and Explanations as PDF. DBT BET JRF aspirants can download the question paper as single PDF file for your exam preparation. Please feel free to inform us for any mistakes in the answer key provided.

To download the question paper as single PDF file, please click on the download button below.

To download the question paper, click on the link below

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Molecular Biology Tutorials

Different Forms of DNA (A-DNA, B-DNA and Z-DNA) A Comparison Table with PPT


A-DNA, B-DNA and Z-DNA

Different Types of DNA Conformations
(A-DNA, B-DNA and Z-DNA: A Comparison Table)

DNA, the genetic information carrier molecule of the cell, is a long polymer of nucleotides and can adopt different types of structural conformations. The various types of conformations that the DNA can adopt depend on different factors such as:

1.      Hydration level
2.      Salt concentration
3.      DNA sequence
4.      Quantity and direction of super-coiling
5.      Presence of chemically modified bases
6.      Different types of metal ions and its concentrations
7.      Presence of polyamines in solution.

The most common types of structural conformations of DNA are named as:

(1).  A-DNA

(2).  B-DNA

(3).  Z-DNA

Among these three types, the most abundant type of DNA is B-DNA, commonly known as Watson-Crick Model of DNA double helix. The present post describes the structural features of A, B and Z forms of DNA in a comparative manner. We will also discuss the similarities and differences between A-DNA, B-DNA and Z-DNA.

(1). A-DNA

A-DNA is a rare type of structural conformation that a DNA can adopt under dehydrating conditions. A-DNA is a double stranded helical structure almost similar to B-DNA but with a shorter and more compact structural organization. A-DNA was discovered by Rosalind Franklin and the credit for the naming of A-DNA and B-DNA was also accounted to her. Important structural features of A-DNA are given below:

Ø  A-DNA is formed from B-DNA under dehydrating condition.

Ø  A-DNA is much wider and flatter than B-DNA.

Ø  Similar to B-DNA, the A-DNA is also a right handed helix.

Ø  The helix diameter of A-DNA is 26 Å.

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Botany lecture notes

Types of Stelar Systems and its Evolution in Pteridophytes and Higher Plants with PPT


types of steles in pteridophytes

Stelar Evolution in Vascular Plants
(Origin and Evolution of Stele in Pteridophytes and Higher Plants)

What is stele? What are the components of stele?

Ø  Stele is the central cylinder or core of vascular tissue in higher plants.

Ø  The stele consists of xylem, phloem, pericycle and medullary rays and pith if present.

Ø  The term ‘stele’ was for the first time used by Van Tieghem and Douliot in 1886 in their ‘Stelar Theory’.

What is ‘stellar theory’?

Ø  Proposed by Van Tieghem and Douliot in 1886.

Ø  Major highlights in stellar theory are:

$.  The stele is a real entity and present universally in all axis of higher plants.

$.  The primary components of stele are xylem and phloem.

$.  Tissues like pericycle, medullary rays and pith are also the components of stele.

$.  ‘Stelar theory’ also says that the cortex and the stele are the two fundamental parts of a shoot system.

$.  Both these components (stele and cortex) are separated by the endodermis.

$.  In higher vascular plants (Pteridophytes, Gymnosperms and Angiosperms), the leaf traces are large, and it appears that they play an important role in the vascular system of the axis.

$.  The whole set-up of leaf traces appears as a composite structure in these plants.

$.  Such composite structures do not remain within the limits of stellar theory of Van Tieghem and Douliot.

What are the different types of steles in plants (Pteridophytes and higher plants)?

Ø  On the basis of ontogeny and phylogeney, there are THREE broad categories of steles in vascular plants.

Ø  They are:

(1).  Protostele

(2).  Siphonostele

(3).  Solenostele

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