Basic Branches of Life More than 200 years ago, Linnaeus began with only the Plant and Animal Kingdoms. Later Kingdoms Protista, Fungi, and Monera were added. Recently the Kingdom Monera was divided into two kingdoms (Archae and Eubacteria),
According to scientific theory, the earth is approximately 4.5 billion years old. According to fossil records, bacteria has been on the earth for 3.5 billion years – it is the oldest known organism.
Prokaryotic Cells Where did the FIRST cell come from? No one was present to observe this event, so we really don’t know; what we do know is nobody has ever created a cell from scratch in the chemistry lab.
Kingdom Archaebacteria (Archae) Tiny prokaryotic cells, less than 2 micrometers in size All live without oxygen; they obtain energy from inorganic molecules or light Live in extreme environments and include Methanogens – methane producing, live in marshes, swamps and guts of animals Halophiles – salt loving – live in salt pools and seas Thermophiles – live in hot springs and volcanoes Acidophiles – acid loving – live in volcanoes
StructureFunction Cell WallProtects and gives shape Outer MembraneProtects against antibodies (Gram Neg. Only) Cell Membrane Regulates movement of materials, contains enzymes important to cellular respiration CytoplasmContains DNA, ribosomes, essential compounds Chromo-someCarries genetic information PlasmidContains some genes obtained through recombination Capsule & Slime Layer Protects the cell and assist in attaching cell to other surfaces EndosporeProtects cell against harsh environments PilusAssists the cell in attaching to other surfaces FlagellumMoves the cell
Anatomy of a Bacterial Cell 1. Cell envelope (the glycocalyx, cell wall and cell membrane) a. Glycocalyx Substance secreted on the surface Outside cell wall Usually sticky not found in all bacteria loosely attached types are called slime layer mucoid, sticky types firmly bonded to the cell are called a capsule both types of glycocalyx can also be antigenic and stimulate the production of antibodies needed for the body to eliminate bacteria with these structures from the body
Glycocalyx Both types of glycocalyx can benefit bacteria by: allowing better attachment to various surfaces, even when smooth biofilms on medical devices like pacemakers, catheters, IUDs, also on industrial filters and pipes, plaque helping to prevent the dehydration of the bacterium helping to prevent the attachment of bacteriophages serving as a storage depot of nutrients inhibiting phagocytosis by white blood cells this increases the pathogenicity (bacteria with capsules are usually noted to be more pathogenic than the same species without capsules)
Figure 4.11 Fimbriae Fimbriae short non-locomotor appendages used to attach bacteria to various surfaces