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Homozygosis  Genetics  ]
Adjective: Homozygotic
Noun: Homozygosity
Synonym: Truebreeding -  purebred

Dictionary of botanic terminology
index of names

     
Homozygosis: The union of gametes identical for one or more pairs of genes, resulting in the formation of a homozygote.  
Homozygote: An organism with two or more identical alleles on homologous chromosomes.  
Homozygous: The state of having two identical alleles of a particular gene gene for a particular trait (eg AA, aa) at the same locus on both members of a pair of homologous chromosomes.  
     

An homozygote or hemizygote is an individual organism who has the same alleles (gene copies containing identical information) at a given genetic locus, one on each chromosome of a pair. An individual can be homozygous for the normal copies of the gene or can be homozygous for the mutated copies of the gene. it is therefore pure for any given trait. Individuals who are homozygous for a trait are referred to as homozygotes.

vs. heterozygous: since each individual carries two of these alleles, they can either be identical (homozygous) or different (heterozygous) "Homo" means "same" while "hetero" means "different"

 


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Holdfast roots  [ Botany  ]

Dictionary of botanic terminology - index of names

 
     
  Some species of climbing plants develop holdfast roots which help to support the vines on trees, walls, and rocks. By forcing their way into minute pores and crevices, they hold the plant firmly in place.  
     
Climbing plants, like the poison ivy (Toxicodendron radicans), Boston ivy (Parthenocissus tricuspidata), and trumpet creeper (Campsis radicans),  develop holdfast roots which help to support the vines on trees, walls, and rocks. By forcing their way into minute pores and crevices, they hold the plant firmly in place. Usually the Holdfast roots die at the end of the first season, but in some species they are perennial. In the tropics some of the large climbing plants have hold-fast roots by which they attach themselves, and long, cord-like roots that extend downward through the air and may lengthen and branch for several years until they strike the soil and become absorbent roots.

Major references and further lectures:
1) E. N. Transeau “General Botany” Discovery Publishing House, 1994
     

 

 

 

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