Why species is called the basic unit of systematic biology

  • DNA= A self-replicating material that is a carrier of genetic information for most organisms
  • Chromosome= A structure found inside the nucleus of a cell.
    A chromosome is made up of proteins and DNA organized into genes. Each cell normally contains 23 pairs of chromosomes.
  • Gene= The basic unit of heredity passed from parent to child. Genes are made up of sequences of DNA and are arranged, one after another, at specific locations on chromosomes in the nucleus of cells.
  • Allele= each of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.
  • Dominant trait= Refers to a trait that appears more frequently than another trait, resulting from interactions between gene alleles.
  • Recessive trait= Refers to a trait that is expressed only when genotype is homozygous; a trait that tends to be masked by other inherited traits yet persists in a population among heterozygous genotypes.
  • Genotype= Encyclopedic Entry Vocabulary. In one sense, the term “genotype”—like the term “genome”—refers to the entire set of genes in the cells of an organism.
    In a narrower sense, however, it can refer to different alleles, or variant forms of a gene, for traits, or characteristics.
  • Phenotype-The observable characteristics in an individual resulting from the expression of genes; the clinical presentation of an individual with a particular genotype.
  • An amino acid is an organic molecule that is made up of a basic amino group (−NH 2), an acidic carboxyl group (−COOH), and an organic R group (or side chain) that is unique to each amino acid. The term amino acid is short for α-amino [alpha-amino] carboxylic acid.
  • A codon, in biology, is the basic genetic unit of life that acts as the template for the amino acid synthesis required for protein expression. All the information required for life is stored in the genes and protein expression is the modality through which information encoded on the genes is expressed.
  • Mutation-In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA.
  • Hybrid-hybrid, offspring of parents that differ in genetically determined traits. The parents may be of different species, genera, or (rarely) families.
  • Homozygous-The presence of two identical alleles at a particular gene locus. A homozygous genotype may include two normal alleles or two alleles that have the same variant.
  • Heterozygous-The presence of two different alleles at a particular gene locus. A heterozygous genotype may include one normal allele and one mutated allele or two different mutated alleles (compound heterozygote).
  • Inheritance-inheritance or biological inheritance is the passing on of traits from parents to their offspring; either through asexual reproduction or sexual reproduction, the offspring cells or organisms acquire the genetic information of their parents.
  • Zygote: zygote, fertilized egg cell that results from the union of a female gamete (egg, or ovum) with a male gamete (sperm). In the embryonic development of humans and other animals, the zygote stage is brief and is followed by cleavage, when the single cell becomes subdivided into smaller cells.
  • Fertilization: Fertilization is the fusion of the male and female gamete. The process involves the fusion of an oocyte with a sperm, creating a single diploid cell, the zygote, from which a new individual organism will develop.
  • Diploid: Diploid is a term that refers to the presence of two complete sets of chromosomes in an organism’s cells, with each parent contributing a chromosome to each pair. Humans are diploid, and most of the body’s cells contain 23 chromosomes pairs.
  • Haploid: Haploid refers to the presence of a single set of chromosomes in an organism’s cells. Sexually reproducing organisms are diploid (having two sets of chromosomes, one from each parent). In humans, only the egg and sperm cells are haploid.
  • Gamete: A gamete is a reproductive cell of an animal or plant. In animals, female gametes are called ova or egg cells, and male gametes are called sperm.

  • Mitosis: A type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth.
  • Meiosis: A type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores. “the sporophytes of green algae form spores only by meiosis”
  • Translation: translation is the process in which ribosomes in the cytoplasm or endoplasmic reticulum synthesize proteins after the process of transcription of DNA to RNA in the cell’s nucleus. The entire process is called gene expression.
  • Transcription: Transcription is the process of copying out the DNA sequence of a gene in the similar alphabet of RNA.
    Transcription is the first step in gene expression, in which information from a gene is used to construct a functional