Particulate inheritance: Difference between revisions

Revision as of 15:44, 6 February 2013

Revision as of 20:39, 12 March 2014

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[[File:Mendel.png|right|thumb|[[Gregor Mendel]], the Father of Genetics]]

'''Particulate inheritance''' is a pattern of inheritance discovered by [[Mendelian]] theorists (or by [[Gregor Mendel]] himself) showing that characteristics can be passed from generation to generation through "discrete particles" (now known as [[genes]]). These particles can keep their ability to be expressed while not always appearing in a descending generation.<ref>[http://www.webref.org/anthropology/p/particulate_theory_of_inheritanc.htm "Particulate theory of inheritance"], WebRef</ref>

== Scientific developments leading up to the theory ==

Early in the 19th century, scientists had already recognized that Earth has been inhabited by living creatures for a very long time. On the other hand, they did not understand what mechanisms actually drove [[Biodiversity|biological diversity]]. They also did not understand how [[Trait (biology)|physical traits]] are inherited from one generation to the next. [[Blending inheritance]] was the common ideal at the time, but was later discredited by the experiments of Gregor Mendel. Mendel proposed the theory of '''particulate inheritance''' by using [[pea]] plants (''Pisum sativum'') to explain how variation can be inherited and maintained over time.

=== Blending Model vs. Particulate Model ===

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** Offspring are a blend of both parents (i.e. in modern terms, alleles would blend together to form a completely new allele)

** The characteristics of the blended offspring are passed on to the next generation

** Variation is washed out over time<ref name=bioed>[http://www.bioedonline.org/slides/slide01.cfm?q=particulate+model+of+inheritance&dpg=2 Particulate Model of Inheritance], ''BioEd Online''</ref>

* '''Particulate Model:'''

** Offspring are a combinations of both parents

** The characteristics of both parents are passed on to the next generation as separate entities

** Variation is maintained over time<ref>[http://www.bioedonline.org/slides/slide01.cfm?q name=particulate+model+of+inheritance&dpg=2 Ibid.]<bioed/ref>

== Mendel's Methods ==

=== Mendel's Laws ===

Since Mendel used experimental methods to devise his particulate inheritance theory, he developed three basic laws of inheritance: the [[Law of Segregation]], the [[Law of Independent Assortment]], and the [[Law of Dominance]]:<ref>[http://www.bioedonline.org/slides/slide01.cfm?q name=particulate+model+of+inheritance&dpg=2 Ibid.]<bioed/ref>

==== Law of Segregation ====

Mendel's experiment with tall and short pea plants demonstrates how each individual plant has two particles called [[alleles]]. When a pea plant produces [[gametes]] (reproductive cells), it segregates one allele to each one.

==== Law of Independent Assortment ====

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==== Law of Dominance ====

In the pea plants, Mendel observed that the "T" allele ([[dominance (genetics)|dominant]]) masked the effects of the "t" allele ([[recessive]]). The terms "dominant" and "recessive" are used for the masking and the covered allele, respectively. All offspring from this cross are [[heterozygotes]] in terms of their [[genotypes]]. They also are tall (because the allele for tall masks the allele for short) in terms of their "[[phenotype]]".<ref>[http://www.bioedonline.org/slides/slide01.cfm?q=%22law+of+dominance%22&dpg=6 Ibid.Particulate Model of Inheritance], ''BioEd Online'']</ref>

== See also ==