DNA & Chromosomes

• Gene


  The basic unit responsible for the process of inheritance from one generation to the next
• Chromosome


  Structures that pair together inside the nucleus of a cell to form homologous pairs

  
• Genome


  The haploid set of chromosomes within an organism, including all of its genes

  
• Gene


  A section of DNA that carries the code to make a protein

  
• Allele


  An alternative form of a gene
• We typically have two alleles – one from each parent – which are found at the same gene locus on corresponding chromosomes
• Polypeptide chain


  An individual chain created from the instructions of a gene

  
• Phenotype


  The physical expression of a genotype
• Genotype


  The combination of alleles
• DNA

  Deoxyribonucleic acid, formed by the continuous pairing of base pairs into a longer, double-stranded nucleic acid chain

  
• Nucleotide monomers


  Individual nucleic acid molecules that consist of a phosphate group, a deoxyribose sugar, and a nitrogen-containing base
• Nitrogen-containing bases

  • Adenine
  • Thymine
  • Guanine
  • Cytosine

  
• Telomeres


  A region of repetitive base sequences found at the end of every chromosome, used to protect the ends of chromosomes

  
• DNA Molecule


  Each chromosome is composed of a long DNA molecule coiled tightly around histone proteins

  
• Centromere


  A specialised sequence of DNA that holds together the two chromatids, important for meiosis

  
• Sister Chromatids


  The identical daughter strands of a replicated chromosome
• Short arm


  The section of the chromosome that is shorter in length, also known as the 'p arm'
• Long arm


  The section of the chromosome that is longer in length, also known as the 'q arm'
• Homologous Chromosomes

  Sets of 23 chromosomes within a human nucleus, one set inherited from each parent

  
• Criteria for homologous chromosomes

  • Same size and length
  • Same centromere position
  • Share the same genes at the same gene loci

  
• Karyotype


  A visual representation of an individual’s entire genome organised into homologous pairs