chemistry

• Cell theory


  1. All living things are composed of cells
  2. Cells are the basic functional unit of life
  3. Cells arise only from pre-existing cells
  4. Cells carry genetic information in the form of DNA
• Prokaryotes


  Cells without a true nucleus, DNA is not protein-bound and is circular
• Eukaryotes


  Cells with a true nucleus bound by a membrane, organelles also bound by membranes, DNA is linear and protein-bound
• Examples of eukaryotes


  • Mammals including humans
• Cell


  • Has a nucleus, cytoplasm, and is surrounded by a plasma membrane

  Genetic material is DNA organized into chromosomes in the nucleus

  Contains organelles like mitochondria, lysosomes, endoplasmic reticulum, Golgi apparatus
• Plasma membrane


  Phospholipid bilayer, with hydrophilic heads facing outwards and hydrophobic tails facing inwards
• Cytosol


  Fluid within the cell with no organelles
• Cytoplasm


  Cytosol plus the organelles
• Protoplasm


  Cytoplasm plus the nucleus
• Nucleus


  Control center of the cell, contains DNA organized into chromosomes, has nuclear pores to allow entry and exit of molecules
• Each somatic cell in the human body has 46 chromosomes
• Central dogma of molecular biology

  1. DNA replication

  2. Transcription (DNA to RNA)

  3. Translation (RNA to proteins)
• Mitochondria


  The powerhouse of the cell, provides energy in the form of ATP, has its own DNA
• Lysosome


  Destroys foreign invaders and the cell's own damaged/senescent components using hydrolytic enzymes
• Endoplasmic reticulum


  Rough ER translates proteins, smooth ER synthesizes lipids and detoxifies
• Golgi apparatus


  Modifies, sorts and directs cellular products for delivery, works with ER
• Peroxisome


  Destroys fat through beta-oxidation, also helps kill foreign invaders
• Cytoskeleton


  • Protein network that provides structure, allows movement, and acts as tracks for transport

  Consists of microfilaments, microtubules, and intermediate filaments
• Cilia and flagella


  Microtubule-based structures for motility, have a 9+2 arrangement
• Centrioles


  Microtubule-based structures involved in cell division, have a 9+0 arrangement
• Types of tissues


  • Epithelial
  • Connective
  • Muscle
  • Nervous
• Cell cycle


  G0 (resting), G1 (growth), S (DNA synthesis), G2 (growth), M (mitosis or meiosis)
• Karyokinesis (nuclear division) and cytokinesis (cell division) occur during the M phase of the cell cycle
• Cell cycle


  1. Rest G0

  2. Growth phase 1

  3. DNA synthesis

  4. Growth phase 2

  5. Mitosis or meiosis M phase
• Somatic cells


  Cells that are not germ cells
• Germ cells


  Cells that give rise to gametes
• DNA replication


  Happens during the S phase of the cell cycle
• Transcription


  Taking the DNA into RNA
• Translation


  Taking the RNA to proteins
• Cell types


  • Permanent cells
  • Stable cells
  • Labile cells
• Permanent cells


  Do not divide under normal circumstances
• Stable cells


  Do not divide under normal circumstances, but can divide under certain conditions
• Labile cells


  Always dividing
• If cells are dividing like crazy with no check, this is cancer
• Chemotherapy


  Stops or arrests cell division, killing cancer cells but also some normal rapidly dividing cells (e.g. hair, GI)
• Cell cycle checkpoints


  • G1/S checkpoint
  • G2/M checkpoint
  • Metaphase checkpoint
• p53 and RB genes

  Tumor suppressor genes
• Defects in cell cycle checkpoints can lead to diseases
• Mitosis


  1. Prophase

  2. Metaphase

  3. Anaphase

  4. Telophase
• Meiosis


  1. Meiosis I

  2. Meiosis II