Peroxisomes

The name peroxisome (Peroxi = Peroxide and Soma = body) has been given because this organelle is specifically involved in the formation and decomposition of hydrogen peroxide in the cell.

Discovery

These were isolated by De-Duve and his coworkers in 1965 from liver cells and other tissues, which were enriched with some oxidative enzymes, such as peroxidase, catalase, glycolic acid oxidase and some other enzymes.

Characteristics

These are single membrane enclosed cytoplasmic organelle found both in animal and plant cells.
They are characterized by containing H2O2producing oxidases and catalases.
They are approximately 0.5 μm in diameter.
They have also been found in protozoa, yeast and many cell types of higher plants.

Function

These are involved in the formation and decomposition of hydrogen peroxide in the cell, which is used in various metabolic reactions.

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Deoxyribonucleic acid (DNA)

Deoxyribonucleic acid (DNA) DNA is heredity material. It controls the properties and potential activities of a cell. Location in cell DNA occurs in chromosomes, in the nuclei of the cells and in much lesser amounts in mitochondria and chloroplast. Chemical composition of DNA DNA is made of four kinds of nucleotides; d-adenosine monophosphate (d-AMP) d-guanosine monophosphate (d-GMP) d-cytidine monophosphate (d-CMP) d-thymidine monophosphate (d-TMP) These nucleotides are united with one another through phosphodiester linkages in a specific sequence to form long chains. Two nucleotides join to form dinucleotide e.g nicotinamide adenine dinucleotide (NAD) which is important coenzyme in several oxidation-reduction reactions in the cell. Three nucleotides join to form trinucleotide . Ratio of Bases in DNA In 1951, Erwin Chargaff provided data about the ratios of different bases present in DNA. This data suggested that ade...

Mr chips important short questions.

Chapter#1 Question # 1:How does a person spend his time in old age after retirement? Answer : After retirement when a person becomes old, he has nothing to do. His time seems to pass like lazy cattle moving across a landscape(valley). Question # 2:Why did Chips keep on adjusting his timetable according to the school bells even after the retirement? Answer : After spending more than forty three(43) years at Brookfield, it was not possible for Chips to break his ties with school. He began to live across the road and Mrs. Wickets. That's why it was possible for Chips to keep on adjusting his timetable according to the school bells. Question # 3:How did Chips voice sound in old age? Answer : Although Chips had become old yet he did not loose the zeal and zeast for the life. So his voice remained resonant and lively even in his old age. Question # 4:What did Chips do before going to the bed? Answer : Chips was spending a pleasant and placid time at Mrs. Wickets after his retirem...

What are zymogens? How they are formed? What Is a Zymogen? A zymogen is like a wrapped candy bar. In order to get to the good stuff, you need to tear away what's keeping you from it. Zymogens , or proenzymes , are enzymes that aren't functioning yet because their action is infertile by a 'wrapper'. The 'wrapper' can be a link between two amino acids (the building blocks of proteins), like a piece of string keeping a box closed. Or it can be an further section of protein, like a jar lid. How they are formed? When cells make enzymes, especially proteases, they often make them as zymogen, an inactive form of the enzyme. This is so they don't go crazy and are only used when needed. Imagine your reaction if your blender suddenly hopped about on the counter, out of control, spewing half-chopped fruit everywhere. The counter would be a mess, and so would the cell. You can recognize most zymogens by their name. Enzymes that begin with ...

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