Phenylketonuria (fee-null-keet-o-noo-ria), mercifully also known as “PKU” (pee – kay – you) is a disorder in which phenylalanine, an essential amino acid, is not broken down as it normally would be by an enzyme (phenylalanine hydroxylase) and thus accumulates (in the form of phenylpyruvic acid) in the body. Normally, Phenylalanine hydroxylase coverts phenylalanine into tyrosine, [...]
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…They are as black as the porous rocks over which they crawl & seek their prey as from the Sea. — Somebody calls them “imps of darkness”. — They assuredly well become the land they inhabit. — When on shore I proceeded to botanize & obtained 10 different flowers; but such insignificant, ugly little flowers, [...] Last Darwin Post I gave you the famous “Tangled Bank” quote, in which Darwin links the concept of selection to the concept of ecology and thus derives “grandeur in this view of life.” This is a theme of much of Darwin’s writing in The Origin, and in fact, the Phrase “Tangled Bank” shows up [...] The Avian Brood Parasites The Avian Brood Parasites Brood parasitic birds lay their eggs in the nests of other birds (the “hosts”) who then raise them as their own. Examples of parasitic birds includes the cuckoo, cow birds, widow (“whyda”) birds, honeyguides, and even the South American Black-headed Ducks. Brood parasitism is virtually a [...] Darwin was puzzled by exaggerated traits. (Aren’t we all, really?) For example, why would a widow bird male have a tail so long that he could scarcely fly away from predators? Indeed, speaking of birds: What a contrast is presented between the sexes by the polygamous peacock or pheasant, and the monogamous guinea-fowl or [...] Chimp, Australopith and Human Teeth Compared. The evolution of human diet followed a major zig (as in zig-zag) in a wholly unexpected direction, followed by the most significant biological innovation to ever occur among multi celled animals: The invention of cooking. I’m actually going to point you to two papers on this topic, and [...] There many ways of dividing up and categorizing Natural Selection. For example, there are the Natural Selection, Sexual Selection and Artificial Selection, and then there is the Modes of Selection (Stabilizing, Directional, and Disruptive) trichotomy. We sense that these are good because they are “threes” and “three” is a magic number. Here, I’m focusing [...] Natural Selection is the key creative force in evolution. Natural selection, together with specific histories of populations (species) and adaptations, is responsible for the design of organisms. Most people have some idea of what Natural Selection is. However, it is easy to make conceptual errors when thinking about this important force of nature. One way [...] I was recently looking at a practice AP biology test question on evolution, and sparing you the details, I found it interesting that two of the four parts dealt with genetic variation and speciation in such a way that it was difficult to tell them apart. As expected, students who answered these questions got confused [...] |
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