Galeopsis tetrahit G. pubescens G. speciosa (a) Chromosomal compostion of 3 Galeopsis specles Fertile Infertile Infertile G. tetrahit x G. tetrahit G. tetrahit x G. pubescens G. tetrahit x G. speciosa (b) Outcome of Intraspecles and Interspecles crosses FIGURE 29.4 A comparison of crosses bet ween three natural species of hemp nettle that vary in the number of chromosome sets. (a) Galeopsis tetrahit is an allotetraploid that is thought to be derived from Galeopsis pubescens and Galeopsis speciosa. (b) If G. tetrahit is crossed with either of the other two species, the F, hybrid offspring will be monoploid for one chromosome set and diploid for the other. The F, offspring are likely to be sterile, because they will produce highly aneuploid gametes.
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.
A technique called fluorescence in situ hybridization (FISH) is described. In this method, a labeled piece of DNA is hybridized to a set of chromosomes. Let’s suppose that you cloned a piece of DNA from G. pubescens and used it as a labeled probe for in situ hybridization. What would you expect to happen if this DNA probe were hybridized to the G. speciosa or G. tetrahit chromosomes? Describe the expected results.
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