Answer:
a. resolve the branching patterns (evolutionary history) of the Lophotrochozoa
b. (the same, it is repeated)
Explanation:
Nemertios (ribbon worms) and foronids (horseshoe worms) are closely related groups of lofotrocozoa. Lofotrocozoans, or simply trocozoans (= tribomastic celomados with trocophoric larva) are a group of animals that includes annelids, molluscs, endoprocts, brachiopods and other invertebrates. They represent a crucial superphylum for our understanding of the evolution of bilateral symmetry animals. However, given the inconsistency between molecular and morphological data for these groups, their origins were not entirely clear. In the work linked above, the first records of genomes of the Nemertine worm Notospermus geniculatus and the foronid Phoronis australis are presented, along with transcriptomes along the adult bodies. Our phylogenetic analyzes based on the genome place Nemertinos as the sister group of the taxon that contains Phoronidea and Brachiopoda. It is shown that lofotrocozoans share many families of genes with deuterotomes, suggesting that these two groups retain a common genetic repertoire of bilaterals that do not possess ecdisozoans (arthropods, nematodes) or platizoos (platelets, sydermats). Comparative transcriptomics demonstrates that foronid and brachiopod lofophores are similar not only morphologically, but also at the molecular level. Although the lofophore and vertebrates show very different cephalic structures, the lofophorees express the vertebrate head genes and neuronal marker genes. This finding suggests a common origin of the bilaterial pattern of the head, although different types of head will evolve independently in each lineage. In addition, we recorded innate immunity expansions of lineage-specific and toxin-related genes in both lofotrocozoa and deuterostomes. Together, this study reveals a dual nature of lofotrocozoans, in which the conserved and specific characteristics of the lineage shape their evolution.
Answer: The DNA on the paternal copy of the chromosome will be methylated at the imprinting center, while the DNA on the maternal copy of the chromosome will not be methylated in this region.
Explanation:
Chromosomes are DNA structures associated with proteins such as histones. They are found in the nucleus of cells and contain genetic information for the development and functioning of an organism. Human beings are diploid, meaning that they possess two copies of each of the 23 chromosomes (a total of 46).
Gametes, which are sex cells such as the sperm (produced by the male) and the egg (produced by the female) that are haploid. This means that they possess only one chromosome of each pair. During fertilization, a male gamete fuses with a female gamete to generate a zygote, which will give rise to a new human being. <u>This new individual will possess half of the genetic material from its father and half from its mother. Thus having a total of 46 chromosomes, 23 from each parent</u>.
Genetic imprinting modulates gene expression by chemical modification of DNA and/or modification of chromatin structure. Often, genetic imprinting causes a gene to be expressed only on the chromosome inherited from one of the parents. One example of imprinting is DNA methylation, which is a process by which methyl groups are added to DNA. <u>Methylation modifies DNA function when found in the promoter gene, repressing gene transcription. This means that a methylated gene will not be expressed</u>, that is, it will not produce a protein encoded by that gene. So, if a region of DNA is imprinted in the sperm cell, the paternal chromosome inherited from this sperm will be methylated in the genes of the offspring. And the offspring will only express the maternal copy inherited, which will not be methylated.
Semen is the thick fluid that contains the sperm that is basic in nature, thus protecting it from the acidic nature of the vagina.
The evolution of molecular biology has made possible to establish a new classification of all organisms according to their DNA, and it's called phylogenetic classification. This classification group living beings according to their kinship it is established according to anatomical, and especially genetic, based on the similarity of genes between species.
This made it possible to discover kinship ties between species of which there is no suspicion of any morphological link between them, something which the old classification (the traditional classification) was incapable of doing (and this proves the importance of the DNA and genes in organisms classification.
