Darwin's period saw virtually entirely morphological biology. Physiology and biochemistry were not yet recognized disciplines. Biologists now believe that all morphological features result from instantaneous gene expression in proteins. The biochemical come in between. Pathways govern physiological processes. As a result, the evidence presented by these domains in support of evolution is essential.
There is clear, complete consistency when the chemical base of living beings is examined. The ingredients uniquely connected with life are identical across the whole evolutionary range. Likewise, the 'building blocks' of biological stuff, such as amino acids, vitamins, and fatty acids, are the same. In addition, there is consistency in the fundamental mechanisms by which organisms might obtain energy for biological processes.
All of this suggests that speciation occurred following Darwin's postulated method. The study of physiological functions from unicellular to multicellular organisms, such as breathing, digestion, excretion, and reproduction, reveals that they have increasingly varied and, in many cases, increased in complexity in conjunction with species divergence and evolution. However, the essential principles of these processes remain consistent, lending credence to the idea of evolution.
Biochemistry is another family of chemicals that play an essential role in the physiology of higher plants and animals. Trypsin is an enzyme that breaks down proteins into smaller peptide units in all mammals. Hormones are another family of chemicals that play an essential role in the physiology of higher plants and animals. The thyroid hormone is present in all vertebrates and is interchangeable.
The study of diverse physiological processes from unicellular to multicellular organisms reveals that they have increasingly varied and, in many cases, increased in complexity in conjunction with species divergence and evolution. However, the essential principles of these processes remain consistent, lending credence to the idea of evolution.
Comparative biochemistry has revealed that many synthetic and degradative processes are shared by most species, whether closely or distantly related. For energy, all organisms rely primarily on carbs and lipids and, to a lesser extent, on proteins. When tracing the processes leading to energy generation, the glycolytic cycle, TCA cycle, and electron transport chain are usually found as common pathways in most species.
Another area that gives evidence for evolution is comparative serology. This research is based on the idea that an animal would develop antibodies to complicated molecules, such as proteins that are alien to the animal's body. An antigen is a material that causes the production of antibodies. When a small quantity of any animal's serum is injected into another test animal, the foreign serum functions as an antigen, causing the test animal to produce circulating antibodies.
A precipitate will occur if we create such an antiserum and add a few drops of the original antigenic serum. The immunological mechanism refers to this sort of antibody formation method. In other words, the test animal has been immunized against the type of serum administered. Precipitating antibodies are antibodies that react with antigens to generate a precipitate, and the test is known as a precipitin test. Consider the case of a rabbit that has been injected with human serum. The rabbit will be immunized against human serum and develop antibodies.
Antiserum made from rabbit blood with antibodies to human serum is currently used as a test fluid and is separated into four test tubes. In test tube 1, antiserum is combined with human serum, and a soft white precipitate will develop due to the antigen-antibody response. In test tube 2, antiserum is combined with chimp serum and reduced precipitation is generated, suggesting that chimp serum is similar to human serum.
In test tube 3, antiserum is mixed with baboon serum, and reduced precipitation is generated, suggesting that baboon serum is not sufficiently comparable to human serum proteins. In test tube 4, no precipitation is seen, suggesting that the proteins in dog serum are sufficiently dissimilar to those in human serum and do not react at all with antihuman serum antibodies. The amino acid sequences of common proteins are identified for distinct species to identify their relatedness.
For example, the respiratory pigment cytochrome C is a single polypeptide chain comprising 104 amino acids, and the amino acid sequence of cytochrome C has been established for over 67 plant and animal species, ranging from yeast. The phylogeny of cytochrome C has revealed that sequence changes between species occur only between amino acids whose substitution does not affect their activity.
Closely related species have fewer amino acid residues in common than distantly related species, suggesting a common ancestor. The evolutionary categorization of organisms based on cytochrome C structural similarities and differences is similar to the morphological phylogenetic categorization.
Nucleic acid hybridization is another approach used in biological research to track molecular lineage. This approach takes DNA from a test species, such as a human volunteer. Heating then separates the double-stranded molecule into single strands. These isolated strands are then locked in gel blocks, preventing complimentary chains from joining after cooling.
Similarly, radioactive phosphorus-labelled DNA from another species B is acquired, transformed into single-stranded DNA, and passed through the gel blocks holding the strands from species A. The complementary sections of species A and B strands will combine to produce double strands.
Once the double strands have formed on the gel, the uncombined portion and the double-stranded DNA may be recovered individually. These can then be calculated quantitatively. The fraction of double-stranded DNA recovered from the gel increases with the closeness of the relationship between the species from which the DNA sample was collected. This will once again allow us to construct a phylogenic tree.
The evidence presented by comparative physiology and biochemistry supports the idea of evolution, as there is consistency in the chemical base of living beings and the fundamental mechanisms by which organisms obtain energy for biological processes. Comparative biochemistry and comparative serology provide evidence for evolution, based on the idea that animals develop antibodies to complicated molecules.
Precipitating antibodies are antibodies that react with antigens to generate a precipitate. The amino acid sequences of common proteins are identified for distinct species to identify their relatedness. Cytochrome C sequence changes between species occur only between amino acids, suggesting a common ancestor. Nucleic acid hybridization is used to track molecular lineage.
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