Spontaneous in Biological Definition

Abiogenesis

... proven to be incorrect. These early concepts of spontaneous generation (referred to here as "Aristotelian ... Aristotelian abiogenesis , also known as spontaneous generation , (and, in older texts, Generatio ... of all the higher and readily visible organisms, spontaneous generation did not occur, but that omne vivum ex ...

Louis Pasteur

... , and that the growth of microorganisms in nutrient broths is not due to spontaneous generation . He exposed boiled broths to air in vessels that contained ... within the broth. Thus, Pasteur dealt the death blow to the theory of spontaneous generation and supported germ theory. While Louis Pasteur did not ...

Diffusion

... This article is about the physical mechanism of diffusion. For alternative meanings, see diffusion (disambiguation) . Diffusion is the spontaneous spreading of something such as particles , heat , or momentum . The phenomenon is readily observed when a drop of colored water is added to clear ...

Enzyme

... pathway with higher net energy, or vice versa. An enzyme can, however, run a normally non-spontaneous reaction 'backwards' by coupling it to a spontaneous one , as long as the net free energy from the total of both reactions is negative. Enzymes are necessary within biological cells to control ...

Cell membrane

... or facilitated diffusion of polar and ionic molecules, which relies on a transport protein to provide a channel or bind to specific molecules. This spontaneous process decreases free energy, and increases entropy in a system. Unlike active transport, this process does not involve chemical energy ( ATP ). ...

Gene

... the meaning of life?" may be "the survival and perpetuation of ribonucleic acids and their associated proteins". Types of genes Due to rare, spontaneous errors (e.g. in DNA replication ) mutations in the sequence of a gene may arise. Once propagated to the next generation, this mutation may lead to ...

Homeobox

... Mutations in any one of these genes can lead to the growth of extra, typically non-functional body parts in invertebrates , but usually results in spontaneous abortion in vertebrates . Pit-1 homeobox-containing protein bound to DNA The homeobox genes were first found in the fruit fly ...

Insulin

... She also was awarded a Nobel Prize. 1. Preproinsulin ( L eader, B chain, C chain, A chain); proinsulin consists of BCA, without L 2. spontaneous folding 3. A and B chains linked by sulphide bonds 4. Leader and C chain are cut off 5. Insulin molecule remains Structure and production ...

Jean-Baptiste Lamarck

... arise, provided that the acquired modifications are common to both sexes, or at least to the individuals which produce the young. Lamarck saw spontaneous generation as being ongoing, with the simple organisms thus created being transmuted over time (by his mechanism) becoming more complex and closer ...

Lipid

... the entropy (state of disorder) of the polar molecules in the liquid increases. This is essentially a form of phase separation, similar to the spontaneous separation of oil and water into two separate phases when one puts them together. Figure 2: Self-organization of lipids. A lipid ...

Molecular evolution

... a selective advantage or disadvantage to the individual that inherits them. Answering such questions is an aim of population genetics . Rare spontaneous errors in DNA replication cause the mutations that drive molecular evolution. The molecular clock technique, which researchers use to date when ...

Neutral theory of molecular evolution

... theory is that most evolutionary change is the result of genetic drift acting on neutral alleles . A new allele arises typically through the spontaneous mutation of a single nucleotide within the sequence of a gene. In single-celled organisms, such an event immediately contributes a new allele to ...

Origin of life

... pre-existing life these molecules may have accumulated and provided a rich environment for chemical evolution ("soup theory"). On the other hand, spontaneous formation of complex polymers from abiotically generated monomers under these conditions is not at all a straightforward process. And there is ...

Cell membrane

... or facilitated diffusion of polar and ionic molecules, which relies on a transport protein to provide a channel or bind to specific molecules. This spontaneous process decreases free energy, and increases entropy in a system. Unlike active transport, this process does not involve chemical energy ( ATP ). ...