Major Groups of Microorganisms
Bacteria, Virus, Fungi, Protozoa, Algae, & Helminth
Microorganisms also termed "Microbes"
Microbes are ubiquitous, meaning "being or seeming to be everywhere at the same time". They are found in all natural habitats and most of those have been created by humans. They require a microscope to be observed or studied.
Specialized area of biology that deals with tiny life forms that are not readily obeserved without magnification, called "Microorganisms."
Small single-celled prokaryotic organisms.
This process involves the introduction of microbes into the environment to restore stability or to clean up toxic polutants. It is required to control the massive levels of pollution that result from human activities.
Microbes that cause harm. Almost all microbes can be pathogens, depending on environment.
Disease that is derived from animals.
Antonie Van Leeuwenhoek
Discovered the microscope. Single-lens microscope was hand-fashioned by Leeuwenhoek.
He invented pasteurization and completed some of the first studies showing that human disease could arise from infection. Discovered the germ theory.
Established Koch's postulates, a series of proofs that verified the germ theory and could establish whether an organism was pathogenic and which disease it caused.
Dr. Ignaz Semmelweis
Showed quite clearly that women became infected in the maternity ward after examinations by physicians coming directly from the autopsy room.
Dr. Joseph Lister
Took notice of Dr. Semmelweis' observations and became the first to introduce the aseptic techniques, which were aimed at reducing microbes in a medical setting and preventing wound infections.
Dr. Rudolph Virchow
Didn't think that microbes caused disease. He stated that most disease occurred from changes in the cell...Developed the "Cell Theory."
System for organizing, classifying, and naming living things.
Cocci (circular)...Bacillus (rods)...Coccobacillus (a short, plump rod)...Vibrio (gently curved coccobacillus)...Spirillum (spiral-shaped cylinder)...Spirochetes (more flexible - looks like a spring)...Pleomorphism (variation in cell wall structures)
Worms...Bigger concern in places other than U.S. but are found here. They are transmitted microscopically.
Eukaryotic Cells (true nucleus)
Found in animals, plants, fungi, and protists. They contain a number of complex internal parts called organelles that perform useful functions for the cell.
Prokaryotic Cells (pre nucleus)
Found only in bacteria and archaea. They have no nucleus and no organelles.
Prokaryotic...Most primitive of all life forms...Extremophiles (organisms capable of living in harsh environments, such as heat or cold).
Structures of Prokaryotes
Most have cell walls...Have no nucleus and no organelles...DNA aggregated in nucleoid (means of reprouction)...Contains Ribosomes (RNA and proteins)...Can store nutrients as "inclusions"
Structures of Eukaryotes
Plants, microscopic algae and fungi have cell walls...No cell walls in animals or protozoa...Has nucleus which contains the DNA of the cell...Has Organelles (Golgi apparatus, endoplasmic reticulum, vacuoles, and mitochondria)
Reproduction of Prokaryotes
Binary fission (asexual reproduction)
Reproduction of Eukaryotes
Metabolism of Prokaryotes
Use cell membrane to generate energy
Metabolism of Eukaryotes
Generates energy by chemical reactions in mitochondria. Chloroplasts are organelles found in algae and plan cells capable of converting sunlight into chemical energy through photosynthesis.
Movement of Prokaryotes
Have no cilia or pseudopods...Move by unusual flagella (tails) unique to bacteria or special fibrils that produce a bliding form of motility.
Movement of Eukaryotes
Move by locomotor organelles (cilia, flagella, pseudopods)
Control center of cell; directs all activities
Contains ribosomes which synthesize protein (cell is making its own protein)
Assists in sorting and packaging molecules for transport and removal from cell...Receives the proteins that are made, packages and sends it out
Energy generators...sends energy to the endoplasmic reticulum
Contains particles to be digested, excreted or stored
Have cell membranes...Only certain types of cells have cell walls...Cell wall is always on the outside of the cell membrane
Characteristics of Life
Heredity and reproduction...growth and development...Metabolism (energy)...Movement or irritability...Cell support (protection)...The capacity to transport substances into and out of the cell
How do we check for motility of bacteria?
(1) Stab solid media with bacterial growth and check for growth (2) Look at "hanging drop" under microscope and look at motility
Flagellated bacteria can detect and move in response to chemical signals (can be positive toward the signal or negative away from the signal)
Fimbria and Pilus (Prokaryotes)
Appendages not used for movement...cause bacteria to "stick" to surfaces (5-second rule)
Outermost boundary that comes into direct contact with the environment. Usually composed of polysaccharides and appears as a network of fibers (a slime layer) or a capsule much like the glycocalyx of prokaryotes. Develops as a coating to protect the cell; Can help in formation of biofilms
Gram-positive and gram-negative organisms differ in their cell wall formations and the chemical composition of the cell wall.
Gram Positive Cell Wall
Like an open-faced sandwich which has one layer so it is able to "take up" the first stain presented in a gram stain and not release it.
Gram Negative Cell Wall
Like a closed sandwich (2 layers) so it does not "hold onto" the first stain. It is only able to "take up" a stain after the alcohol dissolves the lipids in the cell walls and allows the stain to get into the cell.
Antibiotics and the cell wall...
The differences in the cell walls allow certain antibiotics to disrupt the chemicals in the cell wall "killing" the bacteria. This is how penicillins and cephalosporins work. The cell walls (or its individual components such as lipids, proteins, etc) can contribute to disease.
Bacterial arrangements of Cocci
Singles...Pairs (diplococci)...Tetrads (groups of 4)...Clusters (staphylococci, micrococcus)...Chains (streptococci)...Sarcina (cubical packet of 8, 16, or more)
Bacterial arrangements of Bacilli
Singles...Pairs (diplobacilli)...Chains (streptobacilli)...Palisades (looks like "jackknifed train cars" or picket fences
Medically significant bacteria (unusual)
Rickettsias (obligate intracellular parasite - must live inside host cell; Very tiny Gram negative organisms that can cause Rocky Mountain Spotted Fever or typhus)...Chlamydia (require host cells forgrowth and metabolism; Chlamydia trachomatis can cause blindness or can be a sexually transmitted disease)
Cannot live alone and are not Prokaryotes or Eukaryotes. They depend on the host cell for everything.
Bacteria are also grouped according to:
Aerobic and anerobic growth requirements.
Can withstand hostile conditions and have very long survival rates. They differ from fungal spores!
Fungi (Kingdom Eumyota)
Eukaryote...100,000 known species...Hard to classify...Can be dimorphic (budding or thread-like), sexual and asexual...Identified with special media (SabDex, Cornmeal, blood)...Many fungal infections are "OPPORTUNISTS," meaning they are able to infect immunocompromised patients...Macroscopic (mushrooms, puff balls, gill fungi)...Microscopic (molds and yeasts)
Protists (Kingdom Protist)
Any Eukaryote that is not a plant, animal, or fungus (algae and protozoas)...65,000 species of protozoas...Algae are photosynthetic (consists of seaweeds, kept and help to make up plankton - produce most of the earth's O2)...Protozoa are non-photosynthetic (main limiting factor is availability of moisture)...Form can either be trophozoite or cysts...Very adaptable...Simple reproductive methods (asexual - eukaryotes are most often sexual)...Hard to classify...Algae are rarely infectious to humans...Protozoan infections include amebic dysentery, cryptosporidium and trypanosomes
Helminths (Kingdom Animals)
Worms...50 species...Consists of flatworms (cestodes, trematodes, and nematodes)...Highly developed reproduction (larval development occurs in intermediate host [secondary] Adulthood and mating occur in definitive [final] host)...Billions of infections/year (50 million in North America)
Essential Nutrients for All Organisms
C, H, O, P, K, N, S, Ca, Fe, Na, Cl, Mg
From atmosphere...Used in protein synthesis
From atmosphere...Structural and enzymatic function
From H2O, salts and gases...Maintains pH and accepts O
From Phospate (PO4) in rocks and minerals...Synthesis of nucleic acids and essential for genetics of organisms
From minerals, rocks, etc...Used in vitamins and disulfide bonds in proteins
Other nutrients such as mineral ions, amino acids, vitamins, etc. (growth factors)
These are found in food...For enzymatic reactions
A growth factor is an organic compound that cannot be synthesized by an organism and must be provided as a nutrient.
Essential amino acids
Must be obtained from food.
70% of Cell is H2O
Carbon and Energy
The main determinants of a microbe's nutritional type.
Heterotroph (Organisms defines by their Carbon sources)
An organism that must obtain organic carbon from other life forms; thus they are dependent on other life forms for their survival (Takes in O2 and produces CO2)
Autotroph Phototroph (Organism defined by their energy sources)
An organism that uses inorganic carbon (C02) as its carbon source; autotrophs are not dependent on other life forms for organic carbon (Takes in CO2 as source and produces O2)
Phototroph (Organisms defined by their Energy sources)
Microbes that perform photosynthesis; form the basis for most food webs as primary producers of organic matter.
Chemotroph (Organisms defined by their Energy sources)
Microbes that gain energy from chemical compounds.
Chemoheterotroph...Photoheterotroph (sunlight)...Saprobes (parasites)
Chemoautotroph (lithoautotroph...don't require Light or organic Nutrients)...Photoautotroph (uses sunlight-photosynthesis)...Methanogens (produce swamp gas)
Unable to grow outside of a living host; can be intracellular (Malaria rickettsia, Chlamydia)
Free-living microorganisms that feed primarily on organic detritus from dead organisms
Derive nutrients from the cells or tissues of host
The net movement of molecules down their concentration gradient by random thermal motion
Diffusion of water through a selectively permeable membrane (isotonic, hypotonic, hypertonic)
Environment equal inside and outside cell; no net change in cell volume.
Solute concentration of external environment is lower than cell's internal environment; water moves into cell, causing it to sweel and sometimes burst
Solute concentration of external environment is higher than cell's internal environment; water moves out of cell causing plasmolysis, which shrinks cell membrane away from cell wall
A carrier protein in the membrane of a cell facilitates the movement of a specific substance down its concentration gradient. (the binding and transport of only a single type of molecule)
Requires energy and specific membrane proteins to move nutrients against their concentration gradients.
Method by which large substances are transported into cells [phagocytosis (cells or large solid matter) & pinocytosis (oils or liquids]
Range of temperatures for microbial growth [Minimal temperature, Maximum temperature, Optimum temperature]
Lowest temp at which growth and metabolism can proceed.
Highest temperature at which growth and metabolism can proceed.
Promotes the fastest rate of growth and metabolism; between minimum and maximum.
Grouping of Organisms
Organisms can be grouped based on whether they grow in cold (psychrophile), moderate (mesophile), or hot temperatures (thermophiles).
Gas requirements of Microbes
Aerobes--uses O2 in its metabolism (Obligate aerobe...can't grow without O2)...Anaerobes--lacks the metabolic enzyme systems for using oxygen gas in respiration...Capnophiles (grow best at higher CO2 concentrations) Doesn't like O2.
will use oxygen when it is available but can function in the absence of it.
Doesn't grow at normal atmospheric concentrations but requires a small amount of O2 in metabolism (1-15%).
Strict or Oobligate Anaerobe
Cannot tolerate any O2 and will die if exposed to it
Do not use O2 but can survive and grow in its presence.
Grow best at higher CO2 concentrations
Acidophiles & Alkalinophiles
Halophiles (a microbe that requires a high concentration of salt)...Osmotolerant (not resistant to salt even though they don't require it for growth)
Survives in increased hydrostatic pressure
A situation in which 2 organisms live together in a close partnership.
A complex association that arises from microorganisms growing together and interacting on the surface of a habitat. Microbes in a biofilm can communicate with one another through quorum sensing. This is an activity among bacteria in a biofilm in which the members signal each other and coordinate their functions.
The division of a bacterial cells occurs through this.
Period of slow growth
Maximum rate of growth during this phase
Most cells unable to multiply
List the 4 Phases of Growth Curves of bacteria
List the methods of analyzing bacterial populations.
Turbidity (visual with naked eye)...Direct Cell Count (microscopic)...Automation (Coulter cell counter)...Flow Cytometry (requires flourescence)...Real-time PCR
Larger molecules are degraded or broken down into smaller molecules, usually with the release of energy.
Larger molecules are built from smaller ones, which results in the formation of cell structures; usually driven by energy derived from catabolism.
Chemicals that increase the rate of a chemical reaction without becoming part of the products or being consumed in the reaction; enzymes cause a substrate to bind to a particular site on a molecule causing a reaction to take place which yields a product.
Energy of Activation
The energy required to initiate a chemical reaction
Consist only of protein
Combination of proteins and cofactors (ex: metal ions and organic growth factors)
Enzymes are sensitive to...
Changes in temperature, pH, and osmotic pressure.
The activity of an enzyme can be inhibited by...
A competitive or noncompetitive inhibition.
A "mimic" molecule competes with the substrate for the binding site; reaction is blocked because competitive inhibitor is incapable of becoming a product (1 binding site)
Reaction is blocked because binding of regulatory molecule in regulatory site changes conformation of active site so that substrate cannot enter. (2 binding sites)
Enzymes can be controlled genetically by regulating...
A constant input of energy.
Cells manage energy...
In the form of chemical reactions that change molecules.
Release energy as they proceed
Require energy to proceed
A compound that loses electrons
A compound that receives electrons
Electron and proton carriers...
Accept and release electrons and hydrogen atoms
A process that adds an inorganic phosphate P to adenosine diphosphate (ADP), converting it to ATP and capturing potential energy.
Adenosine Triphosphate (ATP)
Contains unique energy storing properties, allowing it to serve as a connection between energy-yeilding catabolism and all other cellular activities. Starts the metabolic process.
ATP utilization and replenishment is a...
Constant cycle in active cells
To release the energy contained in glucose...
Aerobic heterotrophs perform aerobic respiration by 3 processes (Glycolytic pathway...Kreb's cycle...Electron transport system)
A series of enzyme-catalyzed reactions in which electrons are transferred from fuel molecules such as glucose to oxygen as a final electron acceptor.
Enzymatically converts glucose through several steps into pyruvic acid and provides a small amount of ATP
Converts acetyl coenzyme A into CO2 and H2O and generates NADH and FADH2
Electron Transport System
Receives electrons from NADH and FADH2, shuttles the electrons and gives off ATP; This is the MAIN POWERHOUSE cycle in the cell
Combining ATP synthesis with electron transport
Anaerobic respiration...The incomplete oxidation of glucose or other carbohydrates in the absence of oxygen...yeilds small amounts of ATP
Occurs in yeast or bacterial species that have metabolic pathways for converting pyruvic acid to ethanol
Converts pyruvic acid to lactic acid or a combination of acids by various pathways (ex: sour milk, cheese, etc.)
Microbes can be used to produce a variety of fermentation products by...
Varying the raw materials provided them
Waste not, Want not!!! The property of a system to integrate catabolic and anabolic pathways to improve cell efficiency; some compounds in the reactions serve in multiple functions
Made of building blocks that are either performed or synthesized by anabolic pathways.
Process occuring in plants, algae, and some bacteria that traps the sun's energy and converts it to ATP in the cell; used to fix CO2 into organic compounds.