OH NO! What’s THAT Mean?

by Addi Pittman

Those confusing terms…

  • allele – one of the inherited forms of a particular gene or stretch of DNA. An animal carries two alleles for each gene, one from each parent. AA, Aa, aa, etc.
  • autosomal – refers to chromosomes other than the sex chromosome.
  • chromosomes – discrete collections of DNA that contain the information that is passed from one generation to the next. Each animal species has a characteristic number of chromosomes.
  • crossover – a process that occurs during the creation of eggs and sperm in which chromosomes exchange segments of DNA, enhancing the possible variability in offspring.
  • epistasis – the process in which one gene cause another(other than its allele)is not to be expressed.
  • genes – stretches of DNA within a chromosome that contain specific information needed by the cell to make the proteins that control the growth,development, and function of the organism.
  • genome – the set of DNA molecules that specify the inherited characteristics of an animal. With a few minor exceptions, every cell in an animal’s body carries the entire genome within its nucleus.
  • genotype – the genetic makeup of an organism.
  • genotyping – the process of identifying which alleles an organism carries for a specific trait or traits.
  • linkage map – a map that describes the location of genes relative to other genes rather than as points on specific parts of specific chromosomes.
  • locus (loci) – the location of a particular DNA segment on a chromosome.
  • marker – a portion of DNA that appears in more than one form in a population, the variations of which can be detected in the laboratory and so used to identify patterns of heredity.
  • microsatellite – a stretch of DNA that contains a repeating nucleotide pattern, the length of which is polymorphic. Microsatellites are used as markers.
  • mutation – a change in genetic material.
  • phenotype – the expressed characteristics of an organism. Not all genes of the genotype affect the phenotype.
  • polygenic trait – traits controlled by many genes. There are likely to be degrees of a problem rather than all – or – nothing features.
  • polymerase chain reaction(PCR) – a biochemical technique that allows laboratory workers to produce millions of copies of a relatively short (100 – 300 nucleotide) sequence of DNA. PCR is an invaluable technique for distinguishing which allele of a microsatellite marker is present in a blood or tissue sample.
  • polymorphism – one of the various forms of a gene.
  • quantitative trait loci (QTL) – genes that contribute to the expression of a trait that is expressed on a continuum (e.g., weight gain).
  • recessive genes – genes that are not expressed in a particular organism. Even though these genes are silent for the time being, they can be passed along to – and expressed in – successive generations.
  • variance – ranges in phenotype that result from genetic and environmental parameters.
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