DNA Packaging

• DNA: Double-stranded helical structure.
• Nucleosomes: Complex consists of DNA wrapped around histone proteins.
• Chromatosome: Complex consists of a nucleosome plus H1 histone.
• Chromatin Fiber: Consists of folded stacks of nucleosomes.
• Chromosome ( or chromatid ): Tightly coiled chromatin fibers.
• P arm: Short arm structure.
• Centromere: Constricted point of the chromosomes.
• Q arm: Long arm structure.
• Telomere: Region of repetitive DNA sequences at the end of a

  chromosome.
• Kinetochore; Protein structure in duplicated chromatids where

  the spindle fibers attach to.
• Autosomes - Any chromosome that is not a sex chromosome.
• Sex chromosome - Either of a pair of chromosomes that determine whether an individual is male or female.
• A human cell has 22 pairs of autosomes and 1 pair of sec chromosomes ( female , XX or male , XY ).
• Karyotype - Laboratory produced image of a person’s chromosomes isolated from an individual cell and arranged in numerical order.
• Based on Number of Centromeres:

  • A-centric

      -does not have a centromere

  • Monocentric

      -has only one centromere

  • Dicentric

      -has 2 centromeres

  • Polycentric

      -has 3 or more centromeres
• Based on Location:

  • Telocentric

       -not present in humans

  • Acrocentric

       -P arm is very short while the Q arm is very long

  • Submetacentric

       -Same as acrocentric

  • Metacentric

      -the arms are equal in length
• What are the Functions?

  • Genetic Code Storage
  • Sex Determination
  • Control of Cell Division
  • Protein Synthesis and Storage