Genetics

• Cell


  Functional unit of life in which all of the chemical reactions necessary for the maintenance and reproduction of life take place
• How cells are discovered

  1. Robert Hooke examined thin slices of cork and saw a network of tiny boxlike compartments

  2. Micrographia - "cells"

  3. "Cellula - little room
• Matthias Schleiden


  All plant tissues are composed of cells, and an embryonic plant always arises from a single cell
• Theodore Schwann


  • All organisms consist of one or more cells
  • The cell is the basic unit of structure
• Cell Theory principles


  • All organisms consist of one or more cells
  • Cell is the smallest unit of life of all living organisms
  • All cells arise only by division of a pre-existing cell
• Scientists who contributed to cell theory

  • Anton Van Leeuwenhoek (1674) - observed living cell
  • Felix Dujardin (1835) - discovered fluid content of cell
  • Robert Brown (1883) - discovered nucleus
  • JE Purkinje (1839) - named fluid content of cell as protoplasm
• Protoplasm


  • The living substance of the cell
  • 2 compartments: cytoplasm & karyoplasm
• Types of cells


  • UNICELLULAR - made of only ONE CELL (Euglena, paramecium, yeast)
  • MULTICELLULAR - made of 2 or more cells (Plants, animals, fungi)
• Prokaryote


  • Lacks nucleus and membrane-bound organelles
  • 1-10 micrometers
  • 2 kinds: bacteria and archaea
• Eukaryote


  • Has nucleus and membrane-bound organelles
  • 10-100 micrometers
  • Unicellular (protozoa) or multicellular (plants, animals)
• Protozoa


  Single-celled eukaryotes (Paramecium, euglena, amoeba, giardia)
• 3 Basic Parts of Eukaryotic Cell

  • Plasma membrane - outer boundary
  • Nucleus - control center
  • Cytoplasm - has cytosol and organelles
• Components of Cell Membrane

  • Phospholipids - Amphiphilic (hydrophilic head, hydrophobic tail)
  • Carbohydrates - Glycoproteins, glycolipids
  • Protein - Peripheral, integral
  • Cholesterol - Regulates the fluidity of the membrane
• Plasma Membrane


  A semi-permeable membrane that forms the boundary between a cell's contents and the outside of the cell
• Functions of Plasma Membrane

  • Transfer of nutrients and metabolites
  • Attachment of the cell to adjacent walls
  • Communication with the external environment
• Nuclear Envelope


  Double-layered membrane with tiny holes and nuclear lamina, disintegrates during cell division
• Nucleoplasm


  Contains round shaped nucleolus and network of chromatin fibers
• Nucleolus


  A membrane-less organelle within the nucleus that manufactures ribosomes
• Chromatin


  Chromatin fibers take on different forms inside the nucleus, condenses to form chromosomes
• Functions of Nucleus


  • Control all the cell activities
  • Nucleolus synthesizes ribosomes
  • Store hereditary information in genes
• Summary Structure of the Cell

  • Plasma membrane
  • Nucleus
  • Cytoplasm - cytosol and organelles
• Endoplasmic Reticulum


  Network of flattened sacs and branching tubules, connected to the nuclear envelope, provides a pipeline between the nucleus and cytoplasm
• Smooth ER


  Synthesis of lipid substances, in liver cells it detoxifies drugs and poisons
• Rough ER


  Composed of ribosomes involved in the synthesis of protein
• Golgi Apparatus


  Comprised of flattened sacs, cisternae, transports, modifies and packages proteins and lipids and prepares them for export
• Mitochondria


  Rod-shaped organelles that synthesize ATP, contain their own DNA, have 2 lipid bilayer protein membranes with cristae (infoldings of the inner membrane) and a matrix containing dissolved enzymes necessary for extracting energy
• Higher animals cannot exist without mitochondria
• Interphase


  1. Centrioles are duplicated

  2. Centrosome divides and pairs are split up

  
• Cytoskeleton


  Gives structure and shape to a cell, includes microtubules (serve as conveyor belts moving other organelles, component of cilia and flagella), microfilaments (help to generate forces used in cellular contraction and basic cell movements), and intermediate filaments (tension-bearing elements to help maintain cell shape and rigidity)
• Ribosomes


  Assemble amino acids to form proteins that are essential to carry out cellular functions, made up of ribosomal proteins and rRNA, each is composed of 2 subunits (larger and smaller)
• Chloroplast


  Double membrane-bound organelles mainly in plant cells, have 2 distinct regions: grana (stacks of thylakoids containing chlorophyll) and stroma (colorless dense fluid), convert light energy into chemical energy in the form of food, provide green color to leaves, stems, vegetables
• Chromoplasts


  Plastids that produce and store pigments, responsible for different colors found in leaves, fruits, flowers, vegetables
• Vacuole


  Single membrane sac filled with liquid or sap (water, sugar, ions), larger in plants than animal cells, store various substances (waste products), maintain osmotic pressure of cell, provide turgidity & rigidity to plant cells
• Cell Wall


  Non-living and outermost covering of a cell, made up of cellulose, hemicellulose, and pectin, provides definite shape, strength, and rigidity, prevents drying up (desiccation), helps in controlling cell expansion, protects cell from external pathogens
• Stem Cell


  Body's raw materials - cells from which all other cells with specialized functions are generated, divide to form more cells (daughter cells) that become either new stem cells or specialized cells
• Importance of Stem Cells

  • Increase understanding of how diseases occur
  • Generate healthy cells to replace cells affected by disease (regenerative medicine)
  • Test new drugs for safety and effectiveness
• Embryonic Stem Cells


  From 3-5 days old embryo, pluripotent - have unlimited capacity to divide, self-renew and differentiate into cells of early primary germ cell layers, except for extraembryonic cells

  
• Types of Stem Cells

  • Totipotent - can differentiate into any body cell, even extraembryonic cells (placenta)
  • Pluripotent - have unlimited capacity to divide, self-renew and differentiate into cells of early primary germ cell layers, except for extraembryonic cells
  • Multipotent - can differentiate into a specific type of cells (e.g. blood stem cells can differentiate to form platelets/red/white blood cells)
  • Adult Stem Cells - found in adult tissues (bone marrow/fat), have a more limited ability to give rise to various cells of the body
  • Adult cells altered to have properties of embryonic stem cells - regular adult cells are transformed into stem cells using genetic reprogramming
  • Perinatal Stem Cells - stem cells in amniotic fluid including umbilical cord blood

  
• Embryonic stem cells are obtained from early-stage embryos - a group of cells that forms when eggs are fertilized with sperm at an in vitro fertilization clinic
• Haploid Cell


  1 set of chromosomes (e.g. gametes)