TERMS USED IN GENETICS

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TERMS USED IN GENETICS
  1. 1.       Gene; This is a particle-like structure which is found on a small segment of a chromosome. It is the FUNDAMENTAL UNIT OF HEREDITY, i.e. it is the fundamental unit of structure that determines the hereditary traits in an organism. It can be defined as a segment of the DNA which carries enough information for the formation of a complete protein or RNA molecule including the promoter and the coding system or simply put it is a UNIT OF CHEMICAL INSTRUCTION which is passed down from the parent to the offspring during reproduction.
2.       Allele; This refers to a variation of a particular gene. Since genes usually occur in groups (usually pairs) which are variations of each other (alleles of each other). So the best illustration would be allele= a variation of a gene and alleles= variations of a gene. An allele is a member of a group of genes occupying the same locus on a homologous chromosome. 3.       Locus; This is the gene location on a chromosome i.e. the position where a gene is situated on a chromosome. 
4.       Genotype; This refers to the allelic constitution of an individual, usually emphasizing the gene studied or the sum total of gene variations that make up an individual, or the genetic constitution of an individual. This factor controls the total outward traits that would be expressed by the individual. 
5.       Phenotype; This refers to the traits expressed by an individual, usually emphasizing the traits controlled by the gene studied. This factor is determined by the genotype and refers to traits outwardly expressed. It could be seen in structural, behavioral or physiological features of the individual.
6.       Wild-type; This refers to a standard genotype against which other genotype are weighed in breeding experiments. This concept does  not apply for the human being because we do not have a standard genotype 
7.       Haploid; This refers to a cell with only one set of chromosomes (1n)
8.       Diploid; This refers to a cell with two sets of chromosomes (2n) 
9.       Homozygous; this refers to  a diploid cell containing two alleles that are alike  
  •   Heterozygous; This refers to a diploid cell containing two alleles that are different
  •    Dominant allele; This is an allele that expresses its traits in a heterozygous condition
  •  Recessive allele; This is an allele whose trait is not expressed (overshadowed by a dominant allele)in a heterozygous condition
  •    Incomplete dominance;  This occurs when parents with contrasting traits generate offspring of intermediate phenotype e.g. red plants crossed with white plants producing pink plants. It is a condition in which the offspring produced( heterozygote) gives phenotypic expressions that are in between (intermediate to) that expressed by the normal heterozygote or homozygote
  • 1  Incomplete penetrance; This occurs when mutant genotype does not produce phenotypic expressions that can be differentiated from the phenotypic expression of a normal genotype. This can be caused by genetic of environmental influences
  • 1 True breeding; This refers to a line of individuals who on crossing always produce offspring of the same phenotypic expression e.g. pure tall pea plants crossing with pure tall pea plants producing offspring that are pure and tall all through
  •  DNA; deoxyribonucleic acid. This is a nucleic acid made up of underlying layers of gene. The DNA and genes are then organized into chromosomes. The products of the genes control the cell’s activities, while the chromosomes are transmitters of genetic information. The DNA is a long ladder-like macromolecule that is twisted to form a double helix. Each strand of helix is a linear polymer made up of subunits called nucleotides
  •   Nucleotides; They form the rung of the ladder and are the repeating units in the DNA, they are the Adenine, Guanine, Thymine, or Cytosine. The sequential arrangement of these nucleotides is what carries information
  •  Chromosome; This is a long thread-like structure that carries the fundamental unit of structure that determines the hereditary traits (the gene) which is contained in the DNA. It contains a long strand of DNA which is packaged in a condensed form.
  •  Gene engineering; This is the process of changing an organism by adding or deleting genes
  •   Mutation; This is an event that changes the sequence of DNA in a gene.
PLEASE BE OPEN TO CORRECT ANYTHING YOU FEEL MIGHT BE WRONG BY SUGGESTING IN THE COPMMENT BOX AND I'LL REVIEW. THANKS!! 

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