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Examples of nucleophiles are anions such as Cl −, or a compound with a lone pair of electrons such as NH 3 and PR 3. [citation needed] In the example below, the oxygen of the hydroxide ion donates an electron pair to form a new chemical bond with the carbon at the end of the bromopropane molecule.
This is because α-nucleophiles showing the α-effect have smaller HOMO(nucleophile)-LUMO(substrate) gap, in other words, high HOMO energy level that allows more orbital interaction. Examples of α-nucleophiles with α-effects are shown in Figure 4. The α-nucleophiles have smaller HOMO lobes than the parent normal nucleophile. Figure 4.
Nucleoli are made of proteins, DNA and RNA, and form around specific chromosomal regions called nucleolar organizing regions. Malfunction of the Golgi apparatus means that nucleocid is the cause of several human conditions called "nucleolopathies" [ 3 ] [ 4 ] and the nucleolus is being investigated as a target for cancer chemotherapy .
In animals, the plasma membrane is the outer boundary of the cell, while in plants and prokaryotes it is usually covered by a cell wall. This membrane serves to separate and protect a cell from its surrounding environment and is made mostly from a double layer of phospholipids , which are amphiphilic (partly hydrophobic and partly hydrophilic ).
The classification of living things into animals and plants is an ancient one. Aristotle (384–322 BC) classified animal species in his History of Animals, while his pupil Theophrastus (c. 371 –c. 287 BC) wrote a parallel work, the Historia Plantarum, on plants. [7]
A heterotroph (/ ˈ h ɛ t ər ə ˌ t r oʊ f,-ˌ t r ɒ f /; [1] [2] from Ancient Greek ἕτερος (héteros) 'other' and τροφή (trophḗ) 'nutrition') is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are ...
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. [22] A number of noncanonical bases are known to occur in DNA. [23] Most of these are modifications of the canonical bases plus uracil. Modified Adenine. N6-carbamoyl ...
For example, most plants are photolithoautotrophic, since they use light as an energy source, water as electron donor, and CO 2 as a carbon source. All animals and fungi are chemoorganoheterotrophic , since they use organic substances both as chemical energy sources and as electron/hydrogen donors and carbon sources.