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For example, a molecule can be viewed as a grouping of elements, and an atom can be further divided into subatomic particles (these levels are outside the scope of biological organisation). Each level can also be broken down into its own hierarchy, and specific types of these biological objects can have their own hierarchical scheme.
One ancient view of the origin of life, from Aristotle until the 19th century, is of spontaneous generation. [19] This held that "lower" animals such as insects were generated by decaying organic substances, and that life arose by chance. [20] [21] This was questioned from the 17th century, in works like Thomas Browne's Pseudodoxia Epidemica.
Molecular biology is the study of molecular underpinnings of the biological phenomena, focusing on molecular synthesis, modification, mechanisms and interactions. The central dogma of molecular biology , where genetic material is transcribed into RNA and then translated into protein , despite being oversimplified, still provides a good starting ...
Once dissolved in water, these solutes are more likely to come in contact with one another and therefore take part in chemical reactions that sustain life. [33] In terms of its molecular structure, water is a small polar molecule with a bent shape formed by the polar covalent bonds of two hydrogen (H) atoms to one oxygen (O) atom (H 2 O). [33]
Atomic, molecular, and optical physics (AMO) is the study of matter–matter and light–matter interactions, at the scale of one or a few atoms [1] and energy scales around several electron volts. [2]: 1356 [3] The three areas are closely interrelated. AMO theory includes classical, semi-classical and quantum treatments.
Carbon atoms bond readily to other carbon atoms; this allows the building of arbitrarily long macromolecules and polymers in a process known as catenation. [ 20 ] [ 21 ] [ 22 ] "What we normally think of as 'life' is based on chains of carbon atoms, with a few other atoms, such as nitrogen or phosphorus", per Stephen Hawking in a 2008 lecture ...
3' untranslated region (3'-UTR). Also three-prime untranslated region, 3' non-translated region (3'-NTR), and trailer sequence.. 3'-end. Also three-prime end.. One of two ends of a single linear strand of DNA or RNA, specifically the end at which the chain of nucleotides terminates at the third carbon atom in the furanose ring of deoxyribose or ribose (i.e. the terminus at which the 3' carbon ...
This enzyme system acts at least in part as a molecular immune system protecting bacteria from infection by viruses. [21] Modifications of the bases cytosine and adenine, the more common and modified DNA bases, play vital roles in the epigenetic control of gene expression in plants and animals.