Abdul Archive
In most members of the Mucorales, numerous spores are contained in globose sporangia borne at the tips of aerial sporangiophores. Within the sporangium the spores may surround a central core or columella, although in some species the columella is greatly …
Taxonomy is the science of classification, i.e. the ‘assigning of objects to defined categories’. Classification has three main functions: it provides a framework of recognizable features by which an organism under examination can be identified; it is an attempt to …
In many ascomycetes, studies of the fine structure of asci during cleavage of the ascospores have shown that a system of double membranes continuous with the endoplasmic reticulum extends from the envelope of the diploid fusion nucleus. The double membrane …
In yeasts and related fungi, the ascus arises directly from a single cell, but in most other ascomycetes it develops from a specialized hypha, the ascogenous hypha, which in turn develops from an ascogonium. Ascogenous hypha The ascogenous hypha of …
Introduction: Sexual reproduction is the formation of offspring that are genetically distinct from their parents; most often, two parents contribute genes to their offspring. Among most eukaryotes, sexual reproduction consists of two processes that lead to an alternation of haploid …
A useful tool for analyzing genetic crosses is the testcross, in which one individual of unknown genotype is crossed with another individual with a homozygous recessive genotype for the trait in question. A testcross tests, or reveals, the genotype of the …
Mendel started with 34 varieties of peas and spent 2 years selecting those varieties that he would use in his experiments. He verified that each variety was genetically pure (homozygous for each of the traits that he chose to study) …
The cell cycle is the life story of a cell, the stages through which it passes from one division to the next. The cell cycle consists of interphase (a period of cell growth) and M phase (the period of nuclear and …
Like prokaryotic cell reproduction, eukaryotic cell reproduction requires the processes of DNA replication, copy separation, and division of the cytoplasm. However, the presence of multiple DNA molecules requires a more complex mechanism to ensure that one copy of each molecule …
The term gene was a word that Mendel never knew. It was not coined until 1909, when the Danish geneticist Wilhelm Johannsen first used it. The definition of a gene varies with the context of its use, and so its …