What work sheet? I'm great in Biology!
Answer:
A. The chromatin near cis-regulatory sequences will be more closed and there will be less transcription.
Explanation:
In the presence of histones, the cis-regulatory sequences of DNA like promoter, enhancers etc. are not exposed. The function of the histone acetyltransferases (HATS) is to cause chromosome decondensation i.e. removal of histones from the DNA so that transcription of the DNA could occur. Histone acetyltransferases (HATS) cause acetylation of lysine amino acid of the histone proteins. Acetyl group is negatively charged so the acetylation of histone proteins leads to the removal of their positive charge which ultimately leads to the decrease in the interaction between N terminal of histones and negatively charged phosphate group of the DNA molecule. As soon as histones are removed from the DNA where cis-regulatory sequences are located, the DNA becomes accessible for transcription.
But here a drug has been added which blocks the activity of histone acetyltransferases (HATS) in cancer cells. So it is quite evident that in these cells, histones will not get removed from the cis-regulatory sequences of DNA so the DNA will be more closer or tightly packed as a result of which less transcription will occur.
Answer:
A. Yes, because the %A approximately equals the %T and the %G approximately equals the %C in both species.
Explanation:
According to Chargaff's rule, in all cellular DNAs, the number of adenosine residues (A) is equal to the number of thymidine residues (T). And the number of guanosine residues (G) is equal to the number of cytidine residues (C). Therefore, the sum of the purine residues equals the sum of the pyrimidine residues (A+ G= C+ T). It is based on the fact that a purine base always pairs with a pyrimidine base in a double helix DNA.
Chargaff’s rule is followed in all the double-helical DNA molecules irrespective of the species. In DNAs of sea urchin and salmon, the percentage of adenine is equal to that of the thymine and the percentage of guanine is equal to that of the cytosine. Therefore, Chargaff's rule is followed.
Answer:
The correct option is <em>B) ultraviolet region, especially below a wavelength of 320 nm.</em>
Explanation:
Ultraviolet light carries an enormous amount of energy in it. It is invisible to the human eye. When UV light with enormous energy and wavelength lesser than 320nm, hits the DNA, it causes changes in the structure of the DNA. Mostly, it affects the thymine nitrogenous base regions and forms pyrimidine dimers. The structure of the DNA changes on all the sites where dimers form and hence, they cannot be properly transcribed.
Answer:
Most plant can't grow in darkness because they need energy from light to carry out photosynthesis
