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.
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.
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