You have been sent the first samples of a newly discovered Martian microorganism for analysis of its chromatin. The cells resemble Earthly eukaryotes and are composed of similar molecules, including DNA, which is located within a nucleus-like structure in the cell. One member of your team has identified two basic histone-like proteins associated with the DNA in roughly an equal mass ratio with the DNA. You isolate nuclei from the cells and treat them with micrococcal nuclease for various times. You then extract the DNA and run it on an agarose gel alongside DNA from rat-liver nuclei that had been briefly digested with micrococcal nuclease. As shown in Figure 4–9, the digest of rat-liver nuclei gives a standard ladder of nucleosomes, but the digest of the Martian organism gives a smear of products with a nuclease-resistant limit of about 300 nucleotides. As a control, you isolate the Martian DNA free of all protein and digest it with micrococcal nuclease: it is completely susceptible, giving predominantly mono- and dinucleotides. Do these results suggest that the Martian organism has nucleosome like structures in its chromatin? If so, what can you deduce about their spacing along the DNA?
Molecular Techniques
Molecular techniques are methods employed in molecular biology, genetics, biochemistry, and biophysics to manipulate and analyze nucleic acids (deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)), protein, and lipids. Techniques in molecular biology are employed to investigate the molecular basis for biological activity. These techniques are used to analyze cellular properties, structures, and chemical reactions, with a focus on how certain molecules regulate cellular reactions and growth.
DNA Fingerprinting and Gel Electrophoresis
The genetic makeup of living organisms is shown by a technique known as DNA fingerprinting. The difference is the satellite region of DNA is shown by this process. Alex Jeffreys has invented the process of DNA fingerprinting in 1985. Any biological samples such as blood, hair, saliva, semen can be used for DNA fingerprinting. DNA fingerprinting is also known as DNA profiling or molecular fingerprinting.
Molecular Markers
A known DNA sequence or gene sequence is present on a chromosome, and it is associated with a specific trait or character. It is mainly used as a genetic marker of the molecular marker. The first genetic map was done in a fruit fly, using genes as the first marker. In two categories, molecular markers are classified, classical marker and a DNA marker. A molecular marker is also known as a genetic marker.
DNA Sequencing
The most important feature of DNA (deoxyribonucleic acid) molecules are nucleotide sequences and the identification of genes and their activities. This the reason why scientists have been working to determine the sequences of pieces of DNA covered under the genomic field. The primary objective of the Human Genome Project was to determine the nucleotide sequence of the entire human nuclear genome. DNA sequencing selectively eliminates the introns leading to only exome sequencing that allows proteins coding.
4–44 You have been sent the first samples of a newly discovered Martian microorganism for analysis of its chromatin. The cells resemble Earthly eukaryotes and are composed of similar molecules, including DNA, which is located within a nucleus-like structure in the cell. One member of your team has identified two basic histone-like proteins associated with the DNA in roughly an equal mass ratio with the DNA. You isolate nuclei from the cells and treat them with micrococcal nuclease for various times. You then extract the DNA and run it on an agarose gel alongside DNA from rat-liver nuclei that had been briefly digested with micrococcal nuclease. As shown in Figure 4–9, the digest of rat-liver nuclei gives a standard ladder of nucleosomes, but the digest of the Martian organism gives a smear of products with a nuclease-resistant limit of about 300
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