anaphy lab

• Cytology

  A branch of biology dealing with the structure, function, multiplication, pathology, and life history of cells
• Cell

  Basic structural and functional unit of an organism
• Robert Hooke in 1665 published Micrographia, that includes his examination on a thin slice of cork where he observed box-shaped structures, which he called "cells"
• Classical/Unified Cell Theory

  • All organisms are made up of cells
  • The cell is the basic unit of structure and function in organisms
  • Cells arise from pre-existing cells
• Modern (expanded version) Cell Theory

  • DNA is passed between cells during cell division
  • Cells of all organisms within a similar species are mostly the same, both structurally and chemically
  • Energy flow occurs within cells

  
• Metabolism

  Set of chemical reactions occurring in living organisms to maintain life; involves metabolic pathways
• Divisions of Metabolism

  • Anabolism (constructive metabolic process; stages: production of precursors, activation into reactive forms, assembly of precursors into complex molecules)
  • Catabolism (breaks down complex molecules; provides energy and components needed by anabolic reactions)

  
• Three Essential Characteristics of Cells

  • Metabolism
  • Growth
  • Reproduction
• Growth

  Process by which cells accumulate mass and increase in physical size; occurs when the overall rate of cellular biosynthesis is greater than the overall rate of cellular degradation
• Reproduction

  Process by which cells duplicate their contents and then divide to yield multiple cells with similar, if not duplicate, contents

  
• Structures Present in All Cells

  • Genetic Material
  • Protoplasm
  • Plasma Membrane
• Nucleus

  Repository of genetic information, control center of the cell
• Chromosome Organization

  • Chromosome territories – discrete regions within the nucleus
  • Interchromosomal domain – separates chromosome territories; localization of RNA transcription
• Major Nuclear Structures

  • Nuclear Envelope
  • Nuclear Pore Complexes
  • Nuclear Lamina
• Nuclear Lamina

  Fibrous meshwork that provides structural support to the nucleus; lamins are a class of intermediate filament proteins

  
• Major Subnuclear Structures

  • Nucleoli
  • Cajal Bodies
  • PML Bodies
  • Speckles

  
• Nucleoli

  Sites of rRNA transcription and processing, and preribosomal assembly; play an important role in helping organize the genome during interphase, as well as in regulating the stability of p53, particularly when DNA damage occurs
• Cajal Bodies

  Compact structures that contain the human autoantigen p80-coilin and survival of motor neurons (SMN) protein; involved in small nuclear ribonucleoprotein (snRNP) and small nucleolar ribonucleoprotein (snoRNP) assembly and in maturation of telomerase
• Promyelocytic Leukemia (PML) Bodies

  Also known as PML Oncogenic Domains (PODs) or Nuclear Domain 10 (ND10); PML is an important regulator of cell growth and genome stability; thought to enhance gene repression by serving as assembly sites for certain transcriptional corepresser complexes
• Speckles


  Concentrations of components involved in RNA processing; may serve as storage depots of splicing factors, or may play a more active role in splicing factor modification and/or assembly
• Alterations in nuclear morphology leads to human diseases such as Laminopathies - genetic disorders arising from mutations in the genes encoding lamins
• Mitochondria


  Double-walled membranous organelles present in eukaryotes; houses Electron Transport Chain (ETC) and are sites of oxidative phosphorylation; have their own genes in the form of mitochondrial DNA (mtDNA)
• Mitochondrial Genome


  37 genes that encode for 13 proteins, 22 tRNAs, and 2 rRNAs; a cell typically has thousands of mitochondria, each of which has many copies of its "minichromosome"
• Heteroplasmy


  A state in which a particular mutation happens in some mitochondrial chromosomes but not in other mitochondria within the same cell; accounts for variable expression of diseases among siblings
• About 1 in 200 people has a mutation in a mitochondrial gene that may cause an illness; mitochondrial diseases are very rare as a result of weeding out process during egg formation
• Unique Features of mtDNA

  • No crossing over
  • No DNA repair
  • Maternally inherited
  • Many copies per mitochondrion per cell
  • High exposure to oxygen free radical
  • No histones
  • No introns

  
• mtDNA analysis was critical in analyzing evidence from the September 11, 2001 terrorist attacks
• Plasma Membrane


  Phospholipid bilayer; Fluid Mosaic Model; Selectively Permeable

  
• Six Major Functions Performed by Proteins of Plasma Membrane

  • Transport
  • Enzymatic Activity
  • Signal Transduction
  • Cell-Cell Recognition
  • Intercellular Joining
  • Attachment to the Cytoskeleton and ECM
• Synthesis of membrane components and their orientation in the membrane

  
• Golgi Apparatus


  Structure: Stacks of flattened membranous sacs; has polarity (cis and trans faces)

  Functions: Modification of proteins, carbohydrates on proteins, and phospholipids; Synthesis of many polysaccharides; Sorting of Golgi products, which are then released in vesicles

  
• Ribosomes


  Structure: Complexes (two subunits) made of ribosomal RNA and proteins; can be free in cytosol or bound to ER

  Function: Protein synthesis
• Endoplasmic Reticulum


  Structure: Extensive network of membrane-bounded tubules and sacs; membrane separates lumen from cytosol; continuous with nuclear envelope

  Functions: Smooth ER - synthesis of lipids, metabolism of carbohydrates, calcium storage, detoxification; Rough ER - aids in synthesis of secretory and other proteins from bound ribosomes, adds carbohydrates to proteins to make glycoproteins, produces new membrane
• Vacuole


  Structure: Large membrane-bounded vesicles derived from the ER and Golgi Apparatus; solution inside a vacuole differs in composition from cytosol

  Functions: Digestion, storage, waste disposal, water balance, cell growth, and protection
• Lysosome


  Structure: Membranous sac of hydrolytic enzymes

  Function: Breakdown of ingested substances, cell macromolecules, and damaged organelles for recycling
• Peroxisome


  Structure: Specialized metabolic compartment bounded by a single membrane

  Function: Contains enzymes that transfer hydrogen atoms from substrates to oxygen, producing hydrogen peroxide (H2O2) as a by-product, which in turn is converted to water by another enzyme
• Cytoskeleton


  Structure: Network of fibers extending throughout the cytoplasm, composed of microtubules, microfilaments, and intermediate filaments

  Functions: Plays a major role in organizing the structures and activities of the cell, gives mechanical support to the cell and maintain its shape, provides anchorage for many organelles and cytosolic enzymes
• Centrosome & Centrioles


  Centrosome - region near the nucleus where the cell's microtubules are initiated ("microtubule-organizing center") which function as compression-resisting girders of the cytoskeleton

  Centrioles - located within the centrosome; a pair composed of nine sets of triplet microtubules arranged in a ring; helps determine location of nucleus and other organelles within the cell
• Microvilli


  Minute projections / extensions from the cell's surface; each microvillus has a dense bundle of cross-linked actin filaments, which serves as its structural core

  Functions: Increase the cell's surface area, facilitate absorption of ingested food and water molecules

  
• Cilia & Flagella


  Structure: Shares a common structure having a group of microtubules sheathed in an extension of the plasma membrane; cilia - usually occur in large numbers on the cell surface, about 0.25 μm in diameter and 2-20 μm long; flagella - usually limited to just one or a few per cell, same diameter but longer (10-20 μm long)

  Functions: Acts as locomotor appendages – unicellular eukaryotes are propelled through water through cilia and flagella