Short Notes on Microbodies, DNA and RNA


MICROBODIES (GLYOXYSOMES AND PEROXYSOMES)
In plant cell they are of following two types:
(1) Peroxysome: They are single membrane bounded microbodies that contain enzymes for transferring hydrogen atom to oxygen forming hydrogen peroxide (H2O2), a toxic molecule that is immediately broken down t water by the enzyme catalase. Peroxysome are abundant in cells that are metabolizing alcohol. Peroxysome are believed to help in detoxification of alcohol.

(2) Glyoxysome: They are another type of microbodes. Each glyoxysome has single layered bounding membrane enclosing fine granular stroma. Glyoxysome contain enzymes that can metabolize some of the molecules involved in Photosynthesis process and respiration through oxidation of fatty acid.

DNA (DEOXYRIBO NUCLEIC ACID):
They are important constituents of cell. They occur in nuclear reticulum (chromosome). DNA has deoxyribose with one less oxygen atom in ints molecule. DNA is double strended molecule Biologists view that all secrets of life are embodied in DNA. It is the chemical basis of life. DNA is the controlling centre of all vital activities of the cell. DNA is sole genetic (hereditary) material migrating intact from generation to generation through the reproductive units or gametes and is responsible for the development of specific characters of a plant. It also controls biosynthetic process of cell including Protein synthesis. In 1953 Watson and Crick gave the model of DNA.
Each pair is made of two distinct nitrogenous bases Purines and Pyramidines. Altogether there are two Purnes adnine and guanine and two Pyrimidines thyamine and cytosine. It is a rule that a specific purine always pairs with a specific pyrimidine.

RNA (RIBONUCLEIC ACID):
RNA occurs in Nucleoli, chromosomes and cytoplasm (about 90% of the cells RNA occurs in the cytoplasm). RNA chemically consists of 5 carbon ribose sugar. RNA is single stranded molecule/ RNA is chemical messenger and plays a key role in the process of Protein synthesis,

RNA consists of sugars, bases and Phosphoric acid. Sugar is ribose against Deoxyribose in DNA. In RNA the bases are adenine, guanine, uracil and cytosine i.e. they mine of DNA is replaced by uracil. Various types of RNA are found in plant cells. These are (a) messenger RNA (mRNA) which carries the information contained in DNA (b) transfer RNA (t RNA) also known as soluble RNA which work as adaptor molecules for carrying amino acids to the site of Protein synthesis (c) ribosomal RNA (r RNA) which is associated with ribosome. All these three types are monogenetic RNA.

Comments

Post a Comment

Popular posts from this blog

What is the Dynamic Theory of Profit

Image
Clark's Dynamic Theory of Profit And Its Criticism The Dynamic Theory of Profit is associated with the name of an American Economist, J. B. Clark. In the world of reality, according to J. B. Clark, profit arises only in a dynamic economy. An economy is said to be dynamic when there is a change in population growth or change in the method of production or a change in the consumer’s wants, etc. A society which is without these changes is called a static society. In a static society, only monopoly profits continue to exist. All other economic profits are gradually eliminated by competition. In a dynamic society, an entrepreneur is always confronted with continuous unpredictable changes in demand for his product. The variation in demand may take place due to changes in fashions, tastes, the standard of living, distribution of income, population, new inventions, international repercussions, technological advances, etc. A prudent entrepreneur will always keep an eye on future demand
Read more

Compare the anatomy of Bifacial and Isobilateral leaves

BIFACIAL LEAF: It is also called dorsiventral leaf. This leaf is more strongly illuminated on upper surface than on lower surface. This unequal illumination induces a difference in the internal structure between upper and lower sides. Its internal structure shows: (1)        Upper Epidermis This is single layer of cells with thick cuticle which checks excessive evaporation of water from the surface. It does not contains chloroplasts, stomata are also absent. (2)        Lower Epidermis This is also single layer but with a thin cuticle. It bears many stomata, two guard cells of which contain some chloroplast, none are present in the epidermal cells. Internal to each stomata is large cavity called respiratory cavity. Lower epidermis of leaf is meant for exchange of gases (oxygen and carbon dioxide) between the atmosphere and the plant body. Excess water also evaporates from lower epidermis. (3)        Mesophyll The ground tissue lying between upper epidermis and th
Read more

osmoregulation in terrestrial and aquatic animals

Mechanism of osmoregulation is very important for all groups of animals whether inhibting land or water. Unlike plant cells, animal cells when placed in hypotonic solution burst due to the continuous absorption of water. On the contrary they would shrink and die if constantly placed in hypertonic solution. Normally uptake and loss of water are in balance for proper survival of cell. (1)        Osmoregulation in terrestrial animals: Terrestrial animals are more likely to loose water by evaporation through their permeable surfaces exposed to amsophere. Among various animal groups only Arthropods and vertebrates became the most successful land dwellers. They have developed number of strategies to maintain osmoregulation of their body fluid. (a) Water proof external coverings: To prevent water loss through external surfaces, vertebrates like reptiles, birds and mammals have water proof keratinized epidermis. Similarly the insects have developed external water proof layer called
Read more