The study of nucleic acids began with the discovery of DNA, progressed to the study of genes and small fragments, and has now exploded to the field of genomics. Genomics is the study of entire genomes, including the complete set of genes, their nucleotide sequence and organization, and their interactions within a species and with […]
A functioning immune system is essential for survival, but even the sophisticated cellular and molecular defenses of the mammalian immune response can be defeated by pathogens at virtually every step. In the competition between immune protection and pathogen evasion, pathogens have the advantage of more rapid evolution because of their shorter generation time, large population
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Immunological Memory The adaptive immune system has a memory component that allows for a rapid and large response upon reinvasion of the same pathogen. During the adaptive immune response to a pathogen that has not been encountered before, known as the primary immune response, plasma cells secreting antibodies and differentiated T cells increase, then plateau
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The adaptive, or acquired, immune response takes days or even weeks to become established – much longer than the innate response; however, adaptive immunity is more specific to an invading pathogen. Adaptive immunity is an immunity that occurs after exposure to an antigen either from a pathogen or a vaccination. An antigen is a molecule
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Internal defense mechanisms Inflammation If pathogens manage to breach the barriers protecting the body, one of the first active responses of the innate immune system kicks in. This response is inflammation. The main function of inflammation is to establish a physical barrier against the spread of infection. It also eliminates the initial cause of cell
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Introduction The vertebrate, including human, immune system is a complex multilayered system for defending against external and internal threats to the integrity of the body. The human immune system is a host defense system, i.e. is able to keep most potential pathogens out of the body or quickly destroy them if they do manage to
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No one knows exactly when viruses emerged or from where they came, since viruses do not leave historical footprints such as fossils. The current school of thought considers that modern viruses are a mosaic of bits and pieces of nucleic acids picked up from various sources along their respective evolutionary paths. Viruses are acellular, parasitic
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Each somatic cell in the body generally contains the same DNA. A few exceptions include red blood cells, which contain no DNA in their mature state, and some immune system cells, which rearrange their DNA while producing antibodies. In general, however, the genes that determine whether you have green eyes, brown hair, or how fast
The heterocatalytic function is how DNA controls the development of the body, that is how it decodes the genetic information and transforms it into specific proteins by transcription and translation.
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The autocatalytic function is how DNA reproduces itself, that is the process of replication by semiconservative mechanism with duplication of genetic information.
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The nucleic acids DNA and RNA are key macromolecules in the continuity of life. They carry the genetic blueprint of a cell and carry instructions for the functioning of the cell. DNA is the genetic material passed from parent to offspring for all life on Earth. With the exception of identical twins, each person’s DNA
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The individual sexually reproducing organism – including humans – begins life as a fertilized egg, or zygote. Trillions of cell divisions subsequently occur in a controlled manner to produce a complex, multicellular organism like, for instance, the human organism. Hence, that original single cell is the ancestor of every other cell in the body. Once
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