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A gene is a hereditary unit consisting of [[DNA|DNA]] made up of [[Nucleotides|nucelotides occupying]] a specific position (loci) on a [[Chromosome|chromosome]] that specifies for a specific characteristic within an organism<ref>The American Heritage® Dictionary of the English Language, Fourth Edition,2000(Updated in 2009) Published by Houghton Mifflin Company.</ref>. Genes are trancribed into [[MRNA|mRNA]]&nbsp;within the cell nucelus and then translated to create a [[Polypeptide|polypeptide]] chain of a specific sequence that go on to form a specific protein. [[Alleles|Alleles]] are&nbsp;different forms of a gene,&nbsp;and are&nbsp;present in a [[Diploid|diploid]] cell on both of the [[Homology|homologous]] chromosomes at the exact same [[Gene loci|loci]]. They are&nbsp;variants because of [[Mutations|mutations]];&nbsp;random&nbsp;[[Nitrogenous base|nitrogenous base&nbsp;sequence]] changes that lead to different [[Nucleotide|nucleotide sequences]]. A different base sequence can therefore code for a different [[Codon|codon]] on the [[MRNA|mRNA]]&nbsp;transcribing molecule, and therefore lead to the binding of a different [[Anticodon|anticodon]] on a [[TRNA|tRNA]] molecule, producing an alternate sequence of amino acids during the process of [[Translation|translation]] on the [[Ribosome|ribosome]]. This alternate sequence of amino acids may produce a different [[Proteins|protein]]&nbsp;to the non-mutated form of the gene. In this way, genes are vital coding units for the [[Proteins|proteins]] of the cell <ref>Bruce Alberts et al.(2002)'Molecular Biology of the Cell' -- 4th ed. New York, Garland Science.</ref>.  
A gene is a hereditary unit consisting of [[DNA|DNA]] made up of [[Nucleotide|nucleotides]], complementary to each other on opposite sides of the DNA molecule, occupying a specific position (loci) on a [[Chromosome|chromosome]] that specifies for a specific characteristic within an organism<ref>The American Heritage® Dictionary of the English Language, Fourth Edition,2000(Updated in 2009) Published by Houghton Mifflin Company.</ref>. Genes are transcribed into [[MRNA|mRNA]] within the cell [[Nucleus|nucleus]] and then [[Transcription|translated]] to create a [[Polypeptide|polypeptide]] chain of a specific sequence that go on to form a specific [[Protein|protein]]. [[Allele|Alleles]] are different forms of a gene, and are present in a diploid cell on both of the [[Homologous chromosome|homologous chromosomes]] at the exact same loci. They are variants because of [[Mutation|mutations]]; random [[Nitrogenous base|nitrogenous base]] sequence changes that lead to different nucleotide sequences. A different base sequence can therefore code for a different [[Codon|codon]] on the mRNA transcribing molecule, and therefore lead to the binding of a different [[Anticodon|anticodon]] on a [[TRNA|tRNA]] molecule, producing an alternate sequence of [[Amino acid|amino acids]] during the process of translation on the [[Ribosome|ribosome]]. This alternate sequence of amino acids may produce a different protein to the non-mutated form of the gene. In this way, genes are vital coding units for the proteins of the cell<ref>Bruce Alberts et al.(2002)'Molecular Biology of the Cell' -- 4th ed. New York, Garland Science</ref>.  


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=== References ===


A gene is a hereditary unit consisting of [[DNA|DNA]] made up of [[Nucleotide|nucleotides]] occupying a specific position (loci) on a [[Chromosome|chromosome]] that specifies for a specific characteristic within an organism[1]. Genes are transcribed into [[MRNA|mRNA]] within the cell [[Nucleus|nucleus]] and then [[Transcription|translated]] to create a [[Polypeptide|polypeptide]] chain of a specific sequence that go on to form a specific [[Protein|protein]]. [[Allele|Alleles]] are different forms of a gene, and are present in a diploid cell on both of the [[Homologous chromosome|homologous chromosomes]] at the exact same loci. They are variants because of [[Mutation|mutations]]; random [[Nitrogenous base|nitrogenous base]] sequence changes that lead to different nucleotide sequences. A different base sequence can therefore code for a different [[Codon|codon]] on the mRNA transcribing molecule, and therefore lead to the binding of a different [[Anticodon|anticodon]] on a [[TRNA|tRNA]] molecule, producing an alternate sequence of [[Amino acid|amino acids]] during the process of translation on the [[Ribosome|ribosome]]. This alternate sequence of amino acids may produce a different protein to the non-mutated form of the gene. In this way, genes are vital coding units for the proteins of the cell [2]. &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; [edit]
<references />
 
<references />&nbsp;Reference&nbsp;
 
↑ The American Heritage® Dictionary of the English Language, Fourth Edition,2000(Updated in 2009) Published by Houghton Mifflin Company.
 
↑ Bruce Alberts et al.(2002)'Molecular Biology of the Cell' -- 4th ed. New York, Garland Science.<references />

Latest revision as of 12:15, 16 November 2018

A gene is a hereditary unit consisting of DNA made up of nucleotides, complementary to each other on opposite sides of the DNA molecule, occupying a specific position (loci) on a chromosome that specifies for a specific characteristic within an organism[1]. Genes are transcribed into mRNA within the cell nucleus and then translated to create a polypeptide chain of a specific sequence that go on to form a specific protein. Alleles are different forms of a gene, and are present in a diploid cell on both of the homologous chromosomes at the exact same loci. They are variants because of mutations; random nitrogenous base sequence changes that lead to different nucleotide sequences. A different base sequence can therefore code for a different codon on the mRNA transcribing molecule, and therefore lead to the binding of a different anticodon on a tRNA molecule, producing an alternate sequence of amino acids during the process of translation on the ribosome. This alternate sequence of amino acids may produce a different protein to the non-mutated form of the gene. In this way, genes are vital coding units for the proteins of the cell[2].

References

  1. The American Heritage® Dictionary of the English Language, Fourth Edition,2000(Updated in 2009) Published by Houghton Mifflin Company.
  2. Bruce Alberts et al.(2002)'Molecular Biology of the Cell' -- 4th ed. New York, Garland Science