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Provides animations of key biological processes, cell function overview and its anatomy, concept of gene expression as well as principle of evolution.
Because of the tendency of atoms to complete their outer energy shells with the stable number of electrons for each shell, atoms with incomplete shells have a tendency to gain electrons, lose electrons or share electrons. Atoms that have gained or lost electrons become ions. Oppositely charged ions form ionic bonds. Atoms that share electrons form covalent bonds. A much weaker, but very important bond in biological systems is the hydrogen bond.
Living cells are divided into two types - procaryotic and
eucaryotic (sometimes spelled prokaryotic and eukaryotic). This division
is based on internal complexity. The following pages can provide graphic
roadmaps to the organization of both of these cell types.
You've probably seen this table before it kind of looks like a mess of random letters and numbers, right? Well it's actually one of the most important tools for understanding chemistry!
All new cells come
from previously existing cells. New cells are formed by the process of
cell division which involves replication of DNA and division of the
cells nucleus (karyokinesis) and division of the cytoplasm (cytokinesis).
There are two types of nuclear division: mitosis and meiosis.
A class of nucleic acids characterized by the presence of
the sugar ribose and the organic base uracil. By contrast, DNA contains
deoxyribose and thymine, respectively. Most RNA molecules, including
messenger RNA and transfer RNA, act as cellular intermediaries; that is,
they convert the genetic information stored in DNA into the proteins
that provide cells with structure and enable them to carry out
Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)
are both polynucleotides, polymers of molecules called nucleotides.
Nucleotides are composed of three components.
DNA (deoxyribonucleic acid) is usually composed of two
very long helical polymers of nucleotides. The nucleotides are composed
of a sugar (deoxyribose), phosphate, and one of 4 nitrogenous bases,
adenine (A), cytosine (C), guanine (G), or thymine (T). The two polymers
are linked to each other by hydrogen bonds to form a double helix.
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