Unit 2 - AOS 1

• DNA 


  A double stranded nucleic acid chain made up of nucleotides. DNA carries the instructions for proteins which are required for cell and organism survival.
• Gene


  Length of DNA that contains the coded instructions for building a gene product.
• Alleles


  And alternative form or versions of genes.
• Nucleic Acid


  The class of macromolecules that includes DNA and RNA. All nucleic acids are polymers made out of nucleotide monomers.
• Nucleotide


  The monomer unit of nucleic acids. Made up of nitrogen-containing base, a sugar molecule and phosphate group.
• Genome


  The complete set of DNA contained within an organisms chromosomes. All genetic information in a cell, species or individual.
• Phenotype


  Observable trait of individual
• Haploid


  Single Set of chromsomes
• Chromosome


  Structure made of protein and nucleic acids that carries genetic information. Molecule of DNA Coiled and recoiled around histones
• Histone Protein


  Highly basic proteins that associate with DNA inside the nucleous and help it condense into a chromosome allowing it to fit inside the nucleus.
• Somatic Cell


  Any cell that is not a reproductive cell
• Chromatid


  One half of a replicated chromosome
• Homologous Chromosome


  Pair of chromosome of similar length, gene position and centromere location.
• Karyotype 


  A visual representation of an individuals entire representation of an individuals entire genome organised into homologous pairs. Photograph of persons chromosomes lined up in order of size
• Autosome


  Any chromosome in humans that is not a sex chromosome.
• Sex chromosome 


  Chromosome responsible for determining the biological sex of an organism
• Polyploidy


  When an organism contains additional sets of chromosomes in it's genome
• Monosomy


  A genetic abnormality where one organism has missing chromosome
• Trisomy


  A genetic abnormality where an organism has one extra chromosome
• Tetrasomy


  A genetic abnormality where an orgnaisum has two extra chromosomes
• Mega-chromosome 


  more than 40 mega bases in length
• Micro-chromosome


  less than 20 mega bases in length
• Meiosis


  Type of cell division that takes place in germline cells; reproductive tissues in gonads.

  Purpose: Produce gametes in sexually reproducing organisms.
• Gametes


  Reproductive cells that arise from germline cells and contain half the genetic material of somatic cell. Gametes in animal are sperm and eggs.
• Zygote


  Diploid cell formed by combination of two haploid gamete cells
• Germline Cells


  Cells that are involved in the generation of the gametes in eukaryotes.
• Gonads


  The organs that produce gametes from germline cells. In humans these are the testes and ovaries.
• Homologous Pairs


  Humans have 46 chromosomes, 23 from mother and 23 from father. 44 of these form 22 matching pairs.
• Homologous chromosome


  Same size and length, same centromere position, same genes at soome gene loci.
• Locus (Loci)


  The fixed position on a chromosome, where particular gene is located
• Haploid


  Single set of chromosomes
• Diploid


  Cells of organisms that have two sets of chromosomes
• Homozygous


  having identical alleles for the same gene on homologous chromosomes
• Heterozygous


  having different alleles for the same gene on homologous chromosomes
• Dominent allele


  the variant of a gene that masks the effect of a recessive allele of the same gene on a homologous chromosome ( stronger )

  -Capital Letter
• Recessive allele


  the variant of a gene that is masked by a dominant allele on a homologous chromosome

  -Lower case letter
• Complete Dominence 


  a pattern of dominance where only the dominant allele from the genotype of a heterozygous individual is expressed in the phenotype of that organism
• Co-dominence 


  Situation in which to alleles are expressed in phenotype
• Phenotype


   the physical or biochemical characteristics of an organism that are the result of gene expression (or set of genes) and the environment
• Genotype


  e the genetic composition of an organism at one particular gene locus, as represented using letter symbols