DNA : A Genetic Material

DNA: A Genetic Material

DNA provides genetic instructions for the biological production of all cell life types and several viruses. DNA functions as genetic material and is used to store genetic information of organic life-form. DNA encodes the sequence of amino acid residues in proteins using the genetic code, the triplet nucleotide code.

For all currently known living organisms, the genetic material is almost exclusively DNA, some viruses use RNA as their genetic material.

The first genetic material is commonly assumed to be RNA, initially expressed by self-replicating RNA molecules that float on water bodies. This hypothesis phase in cell life is called the world of RNAs.

However, as proteins that form enzymes came into being, a more stable molecule, DNA became the dominant genetic material, a condition continues today. This is focused on the capacity of the RNA, which can be both genetic material and catalysis, or ribosome.

The double-stranded existence of DNA not only enables the correction of mutation but also makes RNA unstable. In the form of messenger RNA, ribosomal RNA, and RNA transfer, modern ceils mainly use RNA to create protection from DNA instructions.

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Allele definition biology || NEET | AIIMS ||

Alleles Each gene may exist in alternative forms known as alleles, which code for different versions of a particular inherited character. We may also define alleles as genes occupying corresponding positions on homologous chromosomes and controlling the same characteristic (e.g. height of plant) but producing different effects (tall or short). The term homologous refers to chromosomes that carry the same set of genes in the same sequence, although they may not necessarily carry identical alleles of each gene. Wild-type Alleles Normal or Prevalent alleles in a population are called wild-type alleles. These alleles typically encode proteins that are made in the right amount and function normally. Mutant Alleles Alleles that are present at less than 1% in the population and have been altered by mutation are called mutant alleles ....

Examples of Multiple Allelism

Gene may has more than 2 alleles 😕.... Is it !!!!!!!! As we have studied that some genes may exist in three or more allelic forms which we called as multiple alleles . ⇦ Here are some examples of multiple allelism ABO Blood group in Humans. Skin Colour in Humans. Eye colour in Drosophila. Coat colour in Rabbit. 1. ABO Blood group in Humans. A classical example of multiple alleles is found in the ABO blood group system of humans. The RBC's of people with type A blood group contain A antigens, those with blood group B contain B antigens, those with type AB blood group have both A and B antigens and those with O blood group don't have any A or B antigens. The I A and I B alleles are responsible for production of A and B antigens. The alleles I A for the A antigen is codominant with the allele I B for the B antigens. Both I A and I B are completely dominant to allele i, which ...

Larval forms of Echinoderms……..

Larval forms of Echinoderms…….. A. Dipleurula Larva: 1. The dipleurula form is reached during development and is characterised by its bilaterally symmetrical, egg-shaped body. 2. The ventral concave side bears the mouth and is encircled by a circumoral ciliated band. 3. The digestive canal is differentiated into oesophagus, stomach and intestine while anus is disposed ventrally. 4. The pre-oral lobe which is situated at the anterior to mouth, bears an apical sensory plate and a tuft of cilia. 5. The ciliation on the surface of the body becomes reduced to a ciliard band. >>> This Dipleurula form is regarded by many as the hypothetical ancestral form of Echinoderm, as this form is universally present. The Dipleurula concept was first propounded by Bather (1900). The major changes involved in other Echinoderm larvae are due to differential disposition of the ciliated bands. ...

Basics of Biology

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