Biology unit 2

• Repetitive DNA


  Many genes have only one copy, except some genes that are repeated hundreds of times
• Genes are responsible for histones and are needed by the cell in large amounts
• In Drosophila fly, A-G-A-A-G is repeated 100,000 times
• Types of DNA


  • Coding
  • Non-Coding
• Satellite DNA


  Found on the tips of chromosomes, keeps chromosomal structure
• Promoter


  Non-coding sequence found on DNA template, refers RNA polymerase to start mRNA transcription
• Amount of genome


  Does not represent complexity of life
• Salamander genome is 30x human genome, but most of it is non-coding
• Amount of protein produced by Salamander genome

  Is neglected compared to amount of protein produced by human genome
• Endocrine glands include the pituitary gland, thyroid gland, parathyroid glands, adrenal glands (including the adrenal medulla), pancreas, ovaries/testes, and pineal gland.
• SUB


  Abbreviation for subject
• DATE


  Abbreviation for date
• mn


  Abbreviation, meaning unknown
• Genome


  The complete set of genes or genetic material present in a cell or organism
• Total number of genes in a living cell
• Chromosomes


  Structures in the nucleus of a cell that contain the genetic material
• mRNA


  Messenger RNA, which carries the genetic instructions from the DNA to the ribosomes for protein synthesis
• Proteins


  Large biomolecules made up of one or more long chains of amino acid residues
• Chromatin


  The complex of DNA and proteins that makes up the contents of the nucleus of a eukaryotic cell
• tRNA


  Transfer RNA, which carries the specific amino acid to the ribosome during protein synthesis
• Ribosomes


  Organelles in the cytoplasm of cells where protein synthesis takes place
• Protein synthesis


  The process of creating proteins in cells
• Prokaryotic genome


  The genome of a prokaryotic organism, which is typically a single circular chromosome and has a high percentage of coding DNA
• Eukaryotic genome


  The genome of a eukaryotic organism, which is typically larger and more complex, with multiple linear chromosomes and a lower percentage of coding DNA
• Prokaryotic genomes have most of their genome as coding DNA, and can produce RNA and proteins
• Eukaryotic genomes have less than 70% coding DNA, and more than 30% non-coding DNA, and cannot produce RNA and proteins from all of their genome
• DNA packaging

  • 10 folds
  • Histones 100,000 times
• DNA packaging


  1. Nucleosomes

  2. Structural non-Histones

  3. Chromatin unwinding

  4. DNA replication
• DNA in the nucleus is packaged into chromatin
• Chromatin is made up of DNA and histone proteins
• Nucleosomes are the basic units of chromatin
• Non-histone proteins also play a role in DNA packaging
• DNA replication occurs during the interphase stage of the cell cycle
• The human cell nucleus contains 46 chromosomes
• The total length of DNA in the human genome is approximately 2 meters
• Histones


  Basic proteins that help package DNA into chromatin
• Non-histones


  Heterogeneous group of proteins that also play a role in DNA packaging
• Histones and non-histones help organize the DNA in the nucleus
• Histones contain a high proportion of basic amino acids like arginine and lysine
• Histones and non-histones help maintain the spatial organization of DNA in the nucleus