2010 Lecture 2

From CellBiology

Life - Eukaryotes and Prokaryotes

Cells.jpg
Bacteria - Escherichia coli

Introduction

This lecture introduces the cell as the unit of life. Firstly, by the methods we use to see cells and biological structures and what we consider to be "alive". Then by looking at major differences between cell types and their organisation as unicellular or multicellular organisms. Finally, the presence or absence of a nucleus which is the definition of the major 2 classes of cells.

Lecture Audio

The University has a system for automated recording of lectures called Lectopia. Lectopia requires login using your student number and unipass. I will be adding the link to each iLecture Audio following the Lecture. Due to the automated recording method, most lectures begin 4-5 minutes into MP3 recordings and occasionally stop before the end of the lecture. 2010 All Audio Files


iLecture Lecture 02 - 10 Mar 2010 - 3:00pm

Archive

--M.hill 03:56, 25 February 2010 (UTC) note that content listed below will not match exactly current lecture structure but has been selected as having similar content.

Objectives

  • Introduction to biological molecules
  • Understand the dimensions cells
  • Understand differences between prokaryotes and eukaryotes
  • Understand differences between unicellular and multicellular organisms
  • Brief understanding of viruses and prions

About Human Body

Human Cells

  • 210+ cell types in body
  • total number of estimated cells in the body - 1013 (American Ten trillion/British Ten billion)

Flora

  • bacteria, fungi and archaea
  • found on all surfaces exposed to the environment
    • skin and eyes, in the mouth, nose, small intestine
  • most bacteria live in the large intestine
  • 500 to 1000 species of bacteria live in the human gut
  • total number of estimated flora ten times as many bacteria 1014 (American One hundred trillion/British One hundred billion)

Cell Sizes

Salamander egg (oocyte)
  • frog or fish egg are the largest individual cells easily visible, approx 1+ mm diameter
  • human or sea urchin egg, approx 100 micron (µm) diameter
  • typical somatic cell, approx 20 micron diameter
  • plant cells are larger, approx 30 x 20 micron
  • bacteria are smaller, approx 2 x 1 micron

Divisions of Life

Prokaryotic

Eukaryotic

File:Leukocyte phagocytosis of yeast
  • plants
  • animals
  • fungi
  • protists

MBoC -Divisions of Life

Unicellular and Multicellular

  • Unicellular
    • All prokaryotes and some eukaryotes
      • Yeast + budding, non-budding
      • Protozoa + classified by means of locomotion: flagellates, amoeboids, sporozoans, ciliates + often "feed" on bacteria
  • Multicellular
    • Eukaryotes
    • Plants and Animals
    • Allowed development of specialized cells
    • functions and tissues

Prokaryote

Escherichia coli
Micrococcus luteus bacteria
File:Bacteria_morphology
Prokaryote cell cartoon
Bacterial morphologies
  • evolutionarily arose first (3.5 billion years ago) Evolution of Cells
  • bacteria are smaller, approx 2 x 1 micron (1x10-6 m)
  • not all bacteria are dangerous or disease causing

(MH - the adult human in addition bacteria to the skin surface and lining of the respiratory/digestive tract, also has intestines contains trillions of bacteria made up from hundreds of species and thousands of subspecies)

   Greek, Karyose = kernel, as in a kernel of grain

Prokaryotes Cell Wall

  • Bacterial Shape - Bacterial shapes and cell-surface structures
  • Bacterial Membranes - A small section of the double membrane of an E. coli bacterium
    • Bacterial outer membranes - outer membrane contains porins
  • Bacterial cell walls - Bacterial cell walls
    • Gram-negative bacteria surrounded by a thin cell wall beneath the outer membrane
    • Gram-positive bacteria lack outer membranes and have thick cell walls

(MH - note that some unicellular eukaryotes can also have a cell wall)

  • Antibiotics - inhibit either bacterial protein synthesis or bacterial cell wall synthesis Antibiotic targets Gram-positive and Gram-negative bacteria
  • Bacterial Replication - DNA replication and cell division in a prokaryote MCB - DNA replication and cell division in a prokaryote

File:Bacterial cell division.mov

Bacterial Growth Movie

Prokaryote Mycoplasmas

  • smallest self-replicating organisms
  • smallest genomes (approx 500 to 1000 genes)
  • spherical to filamentous cells
  • no cell walls
  • surface parasites of the human respiratory and urogenital tracts
    • Mycoplasma pneumoniae infect the upper and lower respiratory tract
    • Mycoplasma genitalium a prevalent sexually transmitted infection
    • Mycoplasma hyorhinis found in patients with AIDS

Prokaryotic and Eukaryotic Cells

The following links describe the major differences between prokaryotic and eukaryotic cells, the way they divide and the way in which antibiotics have their action on prokaryotic cells.

Plant Cell

Plant Cell cartoon
Plant Plastid types
  • plant cells are larger than mammalian cells approx 30 x 20 micron
  • Additional Organelles
  • Central Vacuole
    • tonoplast maintains cell's turgor
    • storage (water, ions, and nutrients such as sucrose and amino acids, and waste products)
  • Plastids
    • organelles found in plants and algae
    • chloroplasts for photosynthesis
    • Amyloplasts for starch storage
    • Chromoplasts for pigment synthesis and storage
    • Leucoplasts - can differentiate into more specialized plastids (Amyloplasts - starch storage, Elaioplasts - storing fat, Proteinoplasts - storing and modifying protein)
    • (MH - plastids and mitochondria and have own DNA)
  • Cell Wall
    • Rigid structure outside cell membrane
    • No ability to move
    • Resist osmotic stresses
    • Structure - cellulose, hemicellulose, pectin
  • Specialized Adhesion Junctions
    • plasmodesmata
    • cell-cell communication pathways
    • allow cell membrane and endoplasmic reticulum of adjacent cells are continuous Plasmodesmata

Chloroplasts

  • disk-shaped and about 5-8 µm in diameter and 2-4 µm thick. A typical plant cell has 20-40 of them.
Plant organelles

Animal and Plant Cell

Plant Cell Structure.jpg

Virus

Dengue virus Herpes virus - CDC electron micrograph

  • not a cell Latin, virus = toxin or poison
  • not alive
  • infects living cells
  • unable to grow or reproduce outside a host cell
  • Infect different hosts (animal, plant and bacterial)
  • Classified
    • RNA or DNA viruses
    • double or single stranded

Virion

  • contains the genetic material, DNA or RNA
  • within a protective protein coat (capsid)

Bacteriophage

  • A virus that infects bacteria

Prion

VCJD brain
  • not alive
  • an infectious prion protein
  • misfolded normal protein (three-dimensional structure)
  • can form aggregates
  • Types
    • Creutzfeldt-Jacob disease (CJD) and Kuru a human neural prion disease
    • Bovine spongiform encephalopathyvery (BSE) in cattle, "mad cow disease"
    • Scrapie in sheep


Biological Levels

  • Whole cell
  • Organelles
    • nucleus, mitochondria,
  • Components
  • Biological polymers
    • chains of molecules
    • consisting of monomer subunits
    • DNA, RNA, Protein, sugars, cellulose
  • Organic molecules
    • monomer subunits
    • nucleotides, amino acids, carbohydrate

Eukaryotic Cell Organelles

  • Fundamental concept - all cells
    • Specialized exceptions
  • Organelle
  • specialized part of a cell that has its own particular function
  • Membrane bound (enclosed)
  • forms "compartments" within the cell


Next Lecture

  • Cell Compartments and Membranes
    • Metabolic and biochemical “specialization”
    • Localization of function
    • Import and export
    • Regulation of transport
    • Detection of signals
    • Cell-cell communication
    • Cell Identity
    • Cell membrane - plasma membrane, plasmalemma
    • Organelle membranes - basic structure similar

References

Textbooks

Search Online Textbooks

Books

  • CellsBenjamin Lewin, Lynne Cassimeris, Vishwanath R. Lingappa, M.D., George Plopper Jones & Bartlett Publishers, 2007
  • Plant Cell Vacuoles By Deepesh Narayan De, CSIRO (Australia)

Reviews

Articles

Internal Links

External Links


2010 Course Content

Lectures: Cell Biology Introduction | Cells Eukaryotes and Prokaryotes | Cell Membranes and Compartments | Cell Nucleus | Cell Export - Exocytosis | Cell Import - Endocytosis | Cell Mitochondria | Cell Junctions | Cytoskeleton Introduction | Cytoskeleton 1 Intermediate Filaments | Cytoskeleton 2 Microtubules | Cytoskeleton 3 Microfilaments | Extracellular Matrix 1 | Extracellular Matrix 2 | Cell Cycle | Cell Division | Cell Death 1 | Cell Death 2 | Signal 1 | Signal 2 | Stem Cells 1 | Stem Cells 2 | Development | Revision

Laboratories: Introduction to Lab | Microscopy Methods | Preparation/Fixation | Immunochemistry | Cell Knockout Methods | Cytoskeleton Exercise | Confocal Microscopy | Microarray Visit | Tissue Culture 1 | Tissue Culture 2 | Stem Cells Lab | Stem Cells Analysis

Dr Mark Hill 2015, UNSW Cell Biology - UNSW CRICOS Provider Code No. 00098G