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What is the composition of the peel of papaya and chiku peel not the pulp. I wanted to know the composition of peel or skin of the papaya and chiku. Hello Aamir, Although there are many studies on the growth, propagation, and ripening of Carica papaya papaya , Manilkara zapota chiku trees and fruits, there are few studies on the compositions of papaya and chiku peels.
These three studies have examined particular chemicals of interest rather than comprehensively measuring all of the components of papaya and chiku peels.
In one study, scientists measured the concentrations of benzylglucosinolates and benzylisothiocyanates in papaya peels, as well as in papaya pulp and seeds. These two chemicals have anti-oxidant and anti-cancer properties. In a second study, scientists investigated the radical scavenging potential of papaya peel extracts along with several other fruit peel extracts.
A third study measured the sugar composition of chiku peels using mass spectrometry and thin layer chromatography. Sunanda Nath Location: India. M N Location: United States. David Hockney Location: United States. Moatter G Location: United States. Send Message To user. Send Cancel. Post your genetics question. View All Questions. Lactose is a sugar molecule that these cells often use as a source of energy. When lactose is not present in a bacterium's environment, the protein products of these three genes aren't needed.
As a result, a repressor protein binds to the operator of the lac operon and blocks transcription of the three genes. In contrast, when lactose is present, a molecule of this sugar binds to the repressor protein and changes its shape. The shape change prevents the repressor from binding to the operator, thereby permitting transcription of the three genes in the lac operon to occur. In this case, lactose itself "turns on" the genes of the lac operon, which means that it acts as an inducer.
In prokaryotes, a similar system can also be used to turn genes off. Consider, for example, the E. This operon functions much like the lac operon except for one major difference — specifically, the repressor protein in this system only binds with the operator sequence when tryptophan is present.
Here, tryptophan binds with the repressor, thereby changing the repressor's shape such that it fits with the operator. This means that tryptophan acts as a co-repressor, because it helps turn the genes of the trp operon off. Gene expression is much more complicated in eukaryotic cells than it is in prokaryotic cells.
This is due, in large part, to the fact that eukaryotic cells must differentiate into different cell types, and they also contain a greater number of genes than prokaryotic cells. Furthermore, the transcription and translation sites of eukaryotic DNA are separated from one another by the nuclear membrane.
Given these complicating factors, eukaryotic cells employ a greater variety of control strategies than prokaryotic cells, and they do so at various steps in both transcription and translation. Nonetheless, each of these strategies begins at the level of DNA. In eukaryotes, control at the level of transcription is specific and efficient. Eukaryotic cells do not have operator sequences like prokaryotic cells do; rather, different kinds of regulator sequences occur upstream of eukaryotic promoters and serve as sites for the binding of RNA polymerase.
In some instances, enhancer sequences occur upstream of these regulator sequences and bind to activator proteins to further stimulate transcription. Silencer sequences that reduce transcription may also be present. These sequences bind to repressor proteins and turn transcription off by interfering with RNA polymerase binding. Sometimes, the stability of the mRNA molecule itself affects levels of eukaryotic gene expression.
Once created, mRNA does not last forever; stable mRNAs will last long enough to be translated many times thereby producing many protein molecules , but unstable mRNAs may not last long enough to be translated at all. The stability of an mRNA molecule depends upon its nucleotide sequence and the length of its poly-A tail, or the long sequence of adenines added to one end of the mRNA after transcription.
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