GENERAL BIOLOGY 1

• Cell


  Structural and functional unit of the organism, smallest unit of a living thing
• A living thing, whether made of one cell (like bacteria) or many cells (like a human), is called an organism
• Cells in multicellular organisms are often specialized
• All cells come from previous cells
• Anton Van Leeuwenhoek


  Discovered bacteria and protozoa in 1670, advances in lenses, microscope construction, and staining techniques enabled other scientists to see some components inside cells
• Robert Hooke


  Coined the term "cell" for the bow-like structures he observed when viewing cork tissue through a lens
• Matthias Schleiden and Theodor Schwann

  In the late 1830s, proposed the unified cell theory
• Expanded Cell Theory


  • Energy flow occurs within cells
  • All cells have the same basic chemical composition
  • Hereditary information contained the DNA is passed from cell to cell
• Smaller cells


  More efficient than larger cells due to lesser effort of maintaining the contents of the cell
• 4 Components of All Cells

  • Plasma Membrane
  • Cytoplasm
  • DNA
  • Ribosomes

  
• Prokaryotic Cells


  Predominantly single-celled organisms of the domains Bacteria and Archaea, no membrane-bound nucleus, have either peptidoglycan cell wall or polysaccharide capsule

  
• Prokaryotic Cell Structures


  • Cell Wall
  • Capsule
  • Flagella
  • Pili
  • Fimbriae

  
• Eukaryotic Cells


  Have a membrane-bound nucleus, have membrane-bound organelles such as the endoplasmic reticulum, Golgi apparatus, chloroplast, mitochondria, and others, multi-cellular organisms, significantly larger than prokaryotes
• Cell Size

  Prokaryotic cells measure 0.1 to 5.0 µm in diameter, Eukaryotic cells range from 10 to 100 µm, size affects diffusion to and from the cell, as cell grows it becomes less efficient due to decreasing surface area-to-volume ratio
• Animal Cell Characteristics


  • Membrane-bound nucleus
  • Numerous membrane-bound organelles
  • Rod-shaped chromosomes

  
• Animal Cell Structure


  • Cell Membrane
  • Nucleus
  • Cytoplasm
  • Cell Organelles
• Cell Membrane


  Boundary of the cell, surrounds the cytoplasm, organelles, and the nucleus, selectively permeable, controls the passage of organic molecules, ions, water, and oxygen in and out of the cell

  
• Fluid Mosaic Model


  Phospholipids are the most abundant, permit lipid-soluble materials easily enter or leave the cell by diffusion, cholesterol decreases fluidity of the membrane, proteins are embedded in the membrane
• Phospholipid Layer


  • Thin layer membrane made of two layers of lipid molecules, phospholipid is amphipathic with hydrophilic "water-loving" region and hydrophobic "water-fearing" region
• Functions of Proteins


  • Provide structural support
  • Act as carriers transporting water-soluble substances across the membrane
  • Allow active transport across the membrane by forming ion channels
  • Form recognition sites by identifying cells
  • Help cells adhere together
  • Act as receptors

  
• Types of Proteins


  • Extrinsic or Peripheral - on the surface of the bilayer or only partly embedded in it
  • Intrinsic or Integral - completely span the entire bilayer

  
• ATP is commonly referred to as the "energy currency" of the cell
• Microvili are finger-like membranes, the primary surface of nutrient absorption in the gastrointestinal tract
• Lipids are fatty acids
• Enzymes are proteins that act as biological catalysts by accelerating chemical reactions
• Cell shape is defined by proteins in the cytoskeleton

  
• Nucleus


  Most prominent feature of a eukaryotic cell, usually spherical, between 10 and 20 micrometers in diameter, contains most of the organism's hereditary material, controls the cell's activities
• Endosymbiotic Theory


  States that the mitochondria and chloroplasts in today's eukaryotic cells were once separate prokaryotic microbes
• Nuclear Envelope


  A double membrane that surrounds the nucleus, its outer membrane is continuous with the endoplasmic reticulum and often has ribosomes in its surface, controls the entry and exit of materials in and out of the nucleus and contains the reactions taking place within it
• Nuclear Pores


  Around 3000 pores per nucleus, each are 40 - 1000 nm in diameter, allows the passage of large molecules, such messenger RNA, out of the nucleus
• Nucleoplasm


  The granular, jelly-like material that makes up the bulk of the nucleus
• Chromatin


  The DNA found within the nucleoplasm, diffuse form that chromosomes take up when the cell is not dividing
• Nucleolus


  A small spherical body within the nucleoplasm, manufactures ribosomal RNA and assembles the ribosomes
• Cytoplasm


  Watery solution of minerals, gases, organic molecules, and cell organelles that is found between the cell membrane and the nucleus, cytosol is the water portion of cytoplasm and many chemical reactions take place within it
• Organelles


  Intracellular structures, often bounded by their own membrane, that have specific functions in cellular metabolism, allow different functions to be compartmentalized in different parts of the cell
• Endoplasmic Reticulum (ER)


  An elaborate 3D system of sheet-like membranes, spreading through the surface of the cytoplasm, continuous with the outer nuclear membrane

  
• Types of ER


  • Rough ER - has ribosomes present on the outer surfaces of the membranes, provides a large surface area for the synthesis of proteins and glycoproteins, provides a pathway for the transport of proteins throughout the cell
  • Smooth ER - lacks ribosomes on its surface and is often tubular in appearance, synthesize, store, and transport lipids and carbohydrates
• Ribosomes


  Small cytoplasmic granules found in all cells, may occur in the cytoplasm (free ribosomes) or be associated with the rough ER, can be 80s type (found in eukaryotic cells, around 25 nm) or 70s type (found in prokaryotic cells, slightly smaller)
• Proteasome


  A barrel shaped organelle made of enzymes that cut protein molecules apart (protease enzyme), particularly important during cell division and during embryonic development
• Golgi Apparatus


  More compact than the smooth ER, consists of cisternae (flattened sacs), with vesicles (small rounded hollow structure), adds carbohydrates to proteins to form glycoproteins, produce secretory enzymes and carbohydrates, transport, modify, and store lipids form lysosomes