Molecular Biology Tutorials

Single Stranded DNA (ssDNA) vs Double Stranded DNA (dsDNA): Similarities and Differences


single stranded and double stranded DNA

ssDNA vs dsDNA – A Comparison Table

The DNA molecules are not always double stranded helical structures, sometimes they occur in single stranded form called ssDNA. In 1959 Robert Sinsheimer discovered a unique bacteriophage called φX 174 (which infect Escherichia coli) with single stranded DNA as its genetic material. Even though the chemical composition of single stranded and double stranded DNA are the same, they also show some characteristic differences. The present post describes the similarities and differences between dsDNA and ssDNA.s

Similarities between dsDNA and ssDNA

Ø  Both dsDNA and ssDNA can acts as genetic material

Ø  Both are polymers of nucleic acids

Ø  The sugar molecule in both the case is deoxyribose

Ø  Both contain purines and pyramidines

Ø  Both ssDNA and dsDNA contain the nitrogen bases A, G, T and C

Ø  Both can absorb UV light

Difference between dsDNA vs  ssDNA

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Molecular Biology Tutorials

Similarities and Difference between RNA and DNA- A Comparison Table


difference-between-rna-and-dna

Similarities & Differences between DNA and RNA – A Comparison Table

We wish to suggest a structure for the salt of deoxyribose nucleic acid (DNA).
This structure has novel features which are of considerable biological interest.
Watson & Crick, 1953

DNA and RNA are the two types of nucleic acids (a class of macromolecules in the cells) present in all prokaryotic and eukaryotic organisms. Both are essentially the polymers of nucleotides and have immense role in the storage and expression of genetic information in an organism. DNA and RNA allow the storage of genetic information for long period of time without any changes in the genetic constitution of the organism. The presence of two categories of nucleotides also allows the decoding of genetic information during protein synthesis by the process of transcription and translation. The current post describes the similarities and differences between DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

Similarities between DNA and RNA

Ø  Both DNA and RNA can acts as genetic material.

Ø  Both are polymers of nucleotides.

Ø  Both DNA and RNA are linear structures with secondary and super-secondary arrangements.

Ø  Both contain purines and pyrimidines.

Ø  Both DNA and RNA contain pentose sugar.

Ø  In DNA and RNA the adjacent nucleotides are connected by 3’-5’ phosphodiester bonds.

Ø  Both DNA and RNA absorb UV light at 260 nm.

Ø Both DNA and RNA contain hydrogen bonds

Difference between DNA and RNA

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Molecular Biology Tutorials

Difference between Necrosis and Apoptosis: A Comparison Table


necrosis vs apoptosis

Apoptosis vs Necrosis
(Similarities and Differences)

Apoptosis and Necrosis are two types of cell death occur in organisms. The cells undergo death when the cell death becomes necessary as a part of developmental process or they fail to adapt to injuries. Both these types of cell deaths differ in their initial cause and progression of the cell death pathway.

Apoptosis definition (programmed cell death): a physiological process by which unwanted or useless cells are eliminated during the development and other normal biological processes. Often found during tissue homeostasis, embryogenesis, immunological reactions and development of nervous systems. During apoptotic cell death, the cells undergo some characteristic events such as chromatin condensation, nuclear and cytoplasmic aggregation and partitions of cytoplasm and nucleus into membrane bound vesicles called apoptotic bodies containing ribosomes and mitochondria. Apoptotic bodies are recognized and phagocytized by either by macrophages or adjacent cells and thus no inflammatory response are elicited during apoptotic cell death.

Necrosis definition: (accidental cell death) a pathological process occurs when the cells are exposed to serious physical or chemical insults. Occur during pathological infections such as bacterial and fungal infections, hypothermia and hypoxia conditions. The cell and cellular organelles swell and ruptures to release the entire cell content including lysosomal enzymes into the extracellular fluid.  Due to this, necrotic cell deaths are always associated with severe inflammatory response in the surrounding tissues.

The current post describes the similarities and difference between apoptotic and necrotic cell death with a comparison table.

Similarities between Apoptosis and Necrosis

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Molecular Biology Tutorials

Nucleosome Model of Chromosomes in Eukaryotes (Short Notes)


structure of nucleosome short notes

image source: scitable

Nucleosome Model of Chromosome

Does the DNA really need to FOLD inside the nucleus?

A diploid human cell contains approximately 6.4 billion base pairs. These 6.4 billion base pairs are distributed in our 23 pairs (2n = 46) of chromosomes. We know that each chromosome contain a single linear segment of DNA.

According to Watson and Crick model, the distance between each base pair in a DNA double helix is 0.34 nm. Thus, the 6.4 billion base pair will constitute a total length of about 2.2 m DNA strand. The total length of DNA of a single human cell is approximately 2.2 meters long (when all 46 DNA strands are joined end to end).

The size of the nucleus in which the chromatin situated is about 10 µm in diameter. Thus, it is evident that the 2.2 m long DNA should fold several times to fit in the nucleus of 10 µm diameter. The exact nature and pattern of folding of DNA strands in the nucleus disclose the organization of genetic material in the cells.

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Botany lecture notes

Gamma Gardens for Mutation Breeding and Crop Improvement (Advantages and Disadvantages)


atomic garden

Satellite Map of a Gamma Garden at Institute of Radiation Breeding, Hitachiohmiya, Japan

Gamma Gardens (Atomic Gardens)

What are Gamma Gardens or Atomic Gardens?

Gamma garden or Atomic garden is a concept popularized after the Word War 2 for the peaceful use of atomic energy (atoms for peace) for the crop improvement. Gamma gardens or atomic gardens are a type of induced mutation breeding where radioactive sources particularly gamma rays from cobalt -60 or Caesium-137 are used to induce desirable mutations in crop plants. 

Salient features of Gamma Garden

Ø  Gamma gardens are “area subjected to gamma irradiation of crop plants”.

Ø  They are giant structures, enclosed by thick high wall to protect the plants and animals outside.

Ø  The purpose of a gamma garden is to irradiate the whole plants during different stages of development and of varying duration.

Ø  The source of radiation used is Cobalt-60.

Ø  Rarely Caesium-137 is also used as the source of radiation.

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