Chromosome mutation II
Change in Number One of the major type o chromosome mutation is change in chromosome number. There are two types of numerical changes (1) Euploidy and (2)Aneuploidy 1. Euploidy: (eu = true, ploidy = set of chromosomes) The number of chromosomes in a basic set is called the monoploid number (x). Organisms with multiples of […]
Comparison between rhizome and corm
Rhizome Corm 1. It is a prostrate, thickened underground stem 2. It is usually branched and rarely unbranched. 3. It is elongated in shape. 4. It contains a less amount of food material. 5. They are generally perennial and live for several years. 6. Growth is continuous so that succession of rhizome is not produced. […]
Difference between spine and thorn
Comparison between thorn and spine Spine Thorn Spines are modifications of leaves or parts of leaves. Their function is protection and also prevent excessive water loss. Does not deeply seated and not connected to vascular bundle Exogenous in origin Thorns are modifications of branches Protection as well as climbing organ of plant Deeply […]
Difference between leaf and leafy shoot
Compound Leaf Leafy Branch 1. Compound leaf never bears are terminal bud 2. Compound leaf, like a simple leaf, always bears and axillary Bud in the axil of leaf, but itself does not arise in the axil of another leaf. 3. The leaflets of compound leaf have no axillary buds. 4. The rachis of compound […]
Attenuation
Like regulation by the trp repressor, attenuation is a mechanism for reducing expression of the trp operon when levels of tryptophan are high. However, rather than blocking initiation of transcription, attenuation prevents completion of transcription. When levels of tryptophan are high, attenuation causes RNA polymerase to stop prematurely when it’s transcribing the trp operon. Only a short, stubby mRNA is made, one that does not […]
Tryptophan Operon
Operon: When a single promoter controls a number of genes. If tryptophan is present in the environment, then E. coli bacteria don’t need to synthesize it, so transcription of the genes in the trp operon is switched “off.” When tryptophan availability is low, on the other hand, the operon is switched “on,” the genes are transcribed, biosynthetic enzymes […]
Translation (Protein synthesis)
The process of protein synthesis. Charging of tRNA: Each amino acid is attached to a tRNA molecule, specific to that amino acid by a high-energy bond derived from ATP. The process is catalyzed by a specific enzyme called a synthetase (the tRNA is called charged when amino acid is attached) AA1 + tRNA1 + […]
Genetic Code
If genes are segments of DNA and if a strand DNA is just a string of nucleotides, then the sequence of nucleotides must somehow dictate the sequence of amino acids in proteins. How does the DNA sequence dictate the protein sequence? A combination of 3 nucleotides in DNA/mRNA, which specify a particular amino acid during […]
RNA splicing, the removal of introns
The vast majority of eukaryotic genes contain introns, segments of unknown function that do not code for polypeptides. Introns are present not only in protein-coding genes but also in some rRNA and even tRNA genes. Introns are removed from the primary transcript while RNA is still being synthesized and after the cap has been added, […]
Ecosystem
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