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256 Cards in this Set
- Front
- Back
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Bacteria
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Prokaryotes. have a cell wall. contains peptidoglycan cell walls
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Archaea
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-prokaryotic -lacks peptidoglycan -lives in extreme environments -not known to cause disease in humans
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fungi
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-eukaryotes -chitin cell walls
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protozoa
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- unicellular eukaryotes, no distinct shapes, parasites, ingest organic compounds
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algae
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photosynthetic eukaryotes, cellulose cell walls, produce molecular oxygen
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virus
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a-cellular, consist of either dna or rna, but not both, viruses are only replicated in a living host cell. They are neither prokaryotic or eukaryotic.
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core of virus
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dna or rna - is surrounded by a protein coat, coat may be in a lipid envelope
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Major Benefits of microbes
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ecological - maintain balance between the environment by recycling chemicals
Industrial - production of foods and chemicals Health- led to aseptic techniques |
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How are microbes named?
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Genus (Upper case) and specific epithet (lower case)
are italicized or underlined. Staphylococcus aureus (clustered) - staphylo (spherical)- cocci (gold colored)- aureus |
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What are three domains of classification?
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-Bacteria
-Archaea -Eukarya |
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What is the difference between prokaryotic and eukaryotic?
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Prokaryotic - no nucleus, have cell wall contains peptidoglycan cell walls
Eukaryotic - have a nucleus |
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How are microorganisms classified?
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Cell wall composition, energy source.
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What was Pasteur's major contribution to microbiology?
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1861 Pasteur demonstrated that microorganisms are present in the air.
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Why was his discovery important?
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Applying Pasteur's work - Joseph Lister showed that microorganisms are in the air, they can spoil food, and cause animal diseases. He created a chemical disinfectant to prevent wound infections. - Aseptic techniques.
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What are three major events which followed Pasteur’s discovery?
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Germ Theory of Disease
Vaccination Synthetic Drugs and Antibiotic |
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What is the difference between synthetic drugs and antibiotics?
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Antibiotics are chemicals produced by bacteria and fungi that inhibit or kill
synthetic drugs - created in lab |
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Give an example of an antibiotic and a synthetic drug.
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Penicillin - antibiotic
Synthetic bathsalts |
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Bacteriology
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study of bacteria
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mycology
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study of fungi
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virology
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study of viruses
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parisitology
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study of parasites
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immunology
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study of all immune responses
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What are the major 6 branches of microbiology?
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Bacteriology
Mycology Virology Parasitology Immunology Recombinant DNA Technology |
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Recombinant DNA Technology
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biotech - genetically modified products
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Microbe benefits for ecology
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Microbial ecology: Bacteria recycle carbon, nutrients, sulfur, and phosphorus that can be used by plants and animals
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Industrial benefits of microbes
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bacteria degrade organic matter in sewage or detoxify pollutants such as oil and mercury
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health benefits of microbes
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prevent food spoilage
Prevent disease occurrence Led to aseptic techniques to prevent contamination in medicine and in microbiology laboratories |
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What is meant by normal flora?
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Microbes normally present in and on the human body are called normal microbiota
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What is the main function normal flora serves in protecting us from potential pathogens?
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Normal flora prevents growth of potential pathogens by “taking the place” of the pathogens, not giving them a place to “grab on to”.
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What is an example of a benefit that normal flora provides?
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Normal microbiota produce growth factors, such as folic acid and vitamin K
Resistance is the ability of the body to ward off disease Resistance factors include skin, stomach acid, and antimicrobial chemicals |
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How can normal flora cause disease?
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If they get in a spot where they’re not supposed to be.
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If a pathogen gains access, what are the resistance factors it will face?
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1st defense - skin
2nd defense - acid, lysosyme: chemicals 3rd defense- adaptive immune system, cell-mediated |
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What are biofilms?
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complex aggregation of microbes that attach to solid objects, like a catheter
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Why are biofilms hard to treat?
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The aggregation of microbes means that they all support each other. In order to destroy the microbe, you are essentially trying to destroy a whole colony.
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What is the major requirement a biofilm must have in order to form?
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solid object
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What is an EID? Emerging Infectious Disease?
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is an infectious disease whose incidence has increased in the past 35 years and could increase in the near future.
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What are the three ways EIDs arise?
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Evolutionary
Increased human exposure in undergoing ecological changes Antimicrobial resistance |
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Example of evolutionary EID arising
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genetics arises this way with respect to EID
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Example of Increased human exposure in undergoing ecological changes for EID arising
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Ebola hemmoragic fever arises this way with respect to EID
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Example of Antimicrobial resistance for EID arising
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MRSA arises this way with respect to EID
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What are the basic shapes for bacteria?
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Bacillus (rod-shaped)
Coccus (spherical) Spiral Spirillum Vibrio Spirochete |
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How are bacterial species differentiated beyond morphology?
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chemical composition - peptidoglycan layer - gram + or gram-
nutritional requirements biochemical activities source of energy |
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What factors can alter morphology?
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altering cell wall will alter shape, also altering nutritional requirements would alter the shape.
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What are the arrangements for bacterial cells?
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Pairs: diplococci, diplobacilli
Clusters: staphylococci Chains: streptococci, streptobacilli |
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Identify four structures that play a specific role in virulence?
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Capsule: bacterial virulence
Cell Wall or Flagella: bacterial identification Cell Wall: target for antimicrobial agents Plasmids: encode genes for production of toxins |
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What are the 5 external cell wall structures?
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Glycocalyx
Flagella Axial Filaments Fimbriae and Pili |
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What are the 6 internal cell wall structures?
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Plasma Membrane
Cytoplasm The Nucleoid Ribosomes Inclusions Endospores |
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What is the function of glycocalyx?
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Attachment, secretes a sticky sugar coating (glue)
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What is EPS? Extracellular polysaccharide
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allows cell to attach, chemical composition varies by species
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What is the difference between capsule and slime layer glycocalyx?
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Capsule - neatly packed together
Slime Layer - unorganized and broken capsule |
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Give an example of EPS.
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glycolax and target surface. and example would be Streptococcus pneumoniae
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What is the function of flagella?
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Propel the organism.
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What are the three basic parts of flagella and how do they differ?
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Three basic parts: outermost region (filament) globular protein , hook (different protein), basal body
Anchored to the cell wall and membrane by the basal body |
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Gram negative have this many pairs of basal bodies
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2
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Gram positive have this many pairs of basal bodies
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1
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What is meant by taxis?
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Move by itself toward a favorable environment.
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This is a major factor in the bacteria's virulence or ability to cause disease.
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capsule
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Bacterial identification is contained here
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cell wall or flagella
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This is the target for antimicrobial agents
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cell wall
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These encode genes for production of proteins
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plasmids
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Which type of bacteria contains axial filaments?
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spirochetes
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What is the function of axial filaments?
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the rotation moves the cell
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Give an example of a bacterium that has axial filaments.
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Treponema pallidum: syphilis
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What is the function of fimbriae?
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attachment
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what is the function of pili?
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DNA transfer
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What happens if fimbriae are absent in bacteria; via genetic mutation?
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no attachment, thus disease will not occur
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What is the major function of the cell wall?
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prevents osmotic lysis
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What are two other functions the cell wall provides?
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maintains shape
point of anchorage for basal bodies |
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What is the cell wall made of?
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peptidoglycan
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Thick Peptidoglycan - gram positive or gram negative
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gram-positive
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Purple Gram Stain - gram positive or gram negative
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gram-positive
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Disrupted by lysozyme - gram positive or gram negative
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gram-positive
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Penicillin sensitive - gram positive or gram negative
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gram-positive
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Exotoxins - gram positive or gram negative
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gram-positive
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teichoic acids -gram positive or gram negative
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gram-positive
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2-ring basal body -gram positive or gram negative
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gram-positive
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thin peptidoglycan layer
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gram-negative
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outer membrane
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gram-negative
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4-ring basal body
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gram-negative
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Thin Peptidoglycan
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gram-negative
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Red Gram Stain
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gram-negative
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Outer Membrane
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gram-negative
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Tetracycline sensitive
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gram-negative
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Exo and Endotoxins
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gram-negative
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Describe the cell wall of a gram negative. 4 pts
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Thin layer of peptidoglycan and an outer membrane
Lipopolysaccharides (LPS) LPS: evade phagocytosis and actions of immunity, provide barrier to certain antibiotics and enzymes Porins: proteins that form channels, selective permeability |
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What are the LPS and its components?
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Lipid A – functions as an endotoxin , responsible for symptoms associated with gram - infections
Core Polysaccharide – attached to Lipid A, provides stability O Polysaccharide – functions as an antigen, useful in identification |
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functions as an endotoxin , responsible for symptoms associated with gram - infections
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Lipid A
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attached to Lipid A, provides stability
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Core Polysaccharide
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functions as an antigen, useful in identification
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O Polysaccharide
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What function does the outer membrane in a gram negative cell provide?
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it is semi-permeable, therefore acts as a sieve. Small molecules can pass through porins.
prevents some toxins like penicillin G and lysozyme from entering. LPS adds strength |
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Chemicals that damage or interfere with bacterial cell walls do not harm the human host. Why?
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human hosts do not have cell walls
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How does lysozyme affect gram positive cell walls?
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Exposure to digestive enzyme lysozyme, destroys peptidoglycan
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What does the plasma membrane contain?
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enzymes for metabolic reactions
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What is the function of the plasma membrane?
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selective barrier
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passive diffusion
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moves from high concentration to low concentration
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active diffusion
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moves from low concentration to high concentration
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What does the cytoplasm contain?
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nucleoid, ribosomes, and inclusions
80% water and contains primarily proteins (enzymes), carbs, lipids, inorganic ions and many lower molecular weight compounds |
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What is a bacterial nucleoid?
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chromosome: cell’s genetic information
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What is the difference between a nucleoid and plasmid?
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Plasmids: not connected to main bacterial chromosome but have very important functions
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Describe three functions that plasmids can provide.
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Antibiotic resistance
Tolerance to toxic metals Production of toxins |
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What is the function of the ribosomes?
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Protein synthesis
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prokaryotic ribosomes
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70s
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eukaryotic ribosomes
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80s
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What are the two subunits of prokaryotic ribosomes?
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protein and type of RNA (rRNA)
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Located within cytoplasm
Some are common to a wide variety of bacteria May serve as a basis for identification Example: C. diphtheriae |
inclusions
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When are inclusions used?
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Reserve deposits: environment is deficient
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What are endospores?
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Resting cells: when essential nutrients are depleted
Resistant to desiccation, heat, chemicals Bacillus, Clostridium; Gram positive |
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When are endospores used?
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In absence of food, high heat, lots of chemicals
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Sporulation
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endospore formation
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Germination
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return to vegetative state
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What are the 5 chemical requirements for growth?
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Carbon
Nitrogen, Sulfur, phospohorus Trace elements Oxygen Organic growth factors |
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function of carbon
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Structural organic molecules, energy source
Chemoheterotrophs use organic sources of this Autotrophs use CO2 |
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Nitrogen
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In amino acids and proteins
Most bacteria decompose proteins Some bacteria use NH4+ or NO3– A few bacteria use N2 in nitrogen fixation |
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Phosphorus
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In DNA, RNA, ATP, and membranes
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Sulfur
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In amino acids, thiamine, and biotin
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Trace elements
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Inorganic elements required in small amounts
Usually as enzyme cofactors |
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Where are organic growth factors obtained?
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environment
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What are organic growth factors involved with?
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Vitamins, amino acids, purines, and pyrimidines
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Catabolic
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energy released
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anabolic
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needs energy
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What is a metabolic pathway?
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sequence of enzymatically catalyzed chemical reactions in a cell
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What are metabolic pathways determined by?
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enzymes
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What are enzymes?
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Proteins
Biological catalysts Produced by living cells Catalyze chemical reactions by lowering activation energy Speed up a chemical reaction without being permanently altered |
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What is the function of an enzyme?
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speed up biochemical reactions at a temp which is compatible with a living, normal functioning cell
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What are an enzyme’s components?
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Are specific (active site) – act on specific substance (substrate)
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What factors influence enzymatic activity?
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Temperature
pH Substrate concentration Inhibitors |
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What is the function of inhibitors?
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control bacteria by control of enzymes
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competitive inhibitors
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compete with the normal substrate for the active site (sulfa drug), shape and chemical structure are similar to normal substrate
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non-competitive inhibitors
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interact with another part of the enzyme, changes shape = nonfunctional
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What is the effect of temperature and pH on enzymatic activity?
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denatures proteins
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obligate aerobe
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needs oxygen, thus is where the oxygen is
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facultative anaerobe
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can exist without o2, but exists better w/ o2
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obligate anaerobe
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does not survive w/ o2
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areotolerant anaerobes
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o2 has no effect
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What is meant by carbohydrate catabolism?
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The breakdown of carbohydrates to release energy
Glucose most commonly used carbohydrate |
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Glycolysis
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breaking down glucose to pyruvic acid
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What are the physical requirements for growth?
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temperature, pH, Osmotic Pressure
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What is the optimal temperature for pathogenic bacteria?
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60 - 130 degrees f
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Name the three primary groups of organisms in regards to temperature.
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Psychrophiles
Mesophiles Thermophiles |
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Psychrophiles
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cold loving
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mesophiles
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moderate loving
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thermophiles
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heat loving
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Which group is responsible for food spoilage?
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psychrophiles
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What is the optimal pH range for bacteria?
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6.5 to 7.5
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What are acidophiles?
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grow in acidic environments
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What is agar and why is it used?
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Complex polysaccharide
Used as solidifying agent for culture media in Petri plates, slants, and deeps Generally not metabolized by microbes |
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How can bacteria and yeast be identified?
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by biochemical tests- enzymes
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Why are fermentation tests used?
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trace metabolic pathways
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Chemically defined media
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Exact chemical composition is known
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Complex media
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composition is not known
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What is an example of a reducing media?
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thiofluid: heated to drive off 02
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Why is the streak plate method used?
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Streak plate method is used to isolate colonies
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Deep-freezing
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–50° to –95°C
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Lyophilization
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freeze drying. Frozen (–54° to –72°C) and dehydrated in a vacuum
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What are the indirect methods for measuring microbial growth? - 3
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Turbidity
Metabolic activity Dry weight |
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Define generation time.
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the time it takes for a cell to divide (and thus for its population to double)
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What variables can affect the generation time?
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GT varies according to the organism and environmental conditions
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What are the four phases of the bacterial growth curve
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lag, log, stationary, death
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little/no cell division, adjusting to new medium
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Lag
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exponential growth, appears as a straight line when plotted logarithmically
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log
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growth slows, new cells = dying cells
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stationary
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dying cells > new cells formed
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death
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elimination of ALL microbial life
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Sterilization
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use of heat to a level that does not destroy the food,
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Commercial sterilization
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commercial sterilization kills this organism
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Clostridium botulinum endospores (produce toxin)
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microbial contamination
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sepsis
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the absence of significant contamination
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asepsis
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destruction of vegetative pathogens
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disinfectant
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destruction of pathogens on living tissue
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antiseptics
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What are the three ways in which antimicrobial agents kill or inhibit the growth of microbes?
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alter membrane permeability, damage proteins, damage nucleic acids
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Alter membrane permeability
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Damage to membrane lipids or proteins → diminished cell growth
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Damage proteins
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Proteins can be denatured by heat & chemicals
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Damage nucleic acids
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Nucleic acids (DNA & RNA) damaged by heat, chemicals, or UV
Hinders replication and protein synthesis |
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How does heat destroy/inactivate microbes?
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denatures them
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Thermal death point (TDP) =
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lowest temp at which the microbes in a liquid suspension will be killed in 10 mins
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Thermal death time (TDT) =
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minimum length of time for all microbes in a liquid culture to be killed at a given temp
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Decimal reduction time (DRT, D-value) =
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time (mins) in which 90% of a bacterial population will be killed at a given temp
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What method(s) does an autoclave use to destroy microbes?
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machine utilizing pressurized steam to produce even hotter temps than boiling/free-flow steam
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High-temperature short-time pasteurization (HTST) =
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heat (72oC) is applied to milk for 15 seconds as it flows past a heat exchanger
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Ultra high temperature (UHT) sterilization =
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can be used to sterilize milk for storage at room temperature by exposing it to 140oC for 4 seconds followed by rapid cooling and storage in an airtight container
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How does filtration work?
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passage of liquid/gas through a screen-like material with pores too small for microbes to pass
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When might filtration be used for microbial control?
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Used on heat-sensitive liquids , hepa air filters
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How can cold temperatures affect microbes?
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Inhibits microbial reproduction and toxin synthesis
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Psychrotrophs
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grow at slightly colder temperatures (like in the fridge) and alter taste & appearance of food
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Which is more effective in killing microbes: rapid (“flash”) freezing or slow freezing?
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slow freezing
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slow freezing
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ice crystals form in the cell and disrupt cell structure
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What effect does high pressure have on microbes
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Can inactivate bacterial cells by denaturing proteins within the cell
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when is high pressure useful in the control of microbial growth?
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useful in food - Preserves flavor, color and nutrient value
Commonly used to treat fruit juices |
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What is dessication
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absence of water
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What are some sources of radiation that can be used to kill microbes?
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gamma rays, xrays, uv rays
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gamma rays and x rays kill by
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Produce hydroxyl (-OH) radicals from the ionization of water that react with cell components like DNA
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uv light damages by
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Damages DNA by pyrimidine dimers → interfere with proper replication
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derivatives of phenol altered to reduce irritating qualities
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Phenolics
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derivatives of phenol containing two connected phenolic groups
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Bisphenols
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phenols and bisphenols work by
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disrupting plasma membrane lipids
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What is Chlorohexidine
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biguanide used on skin and mucous membranes
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what are some uses for Chlorohexidine
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Combined with detergent or alcohol for pre-op skin preparation and surgical hand scrubs
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an iodophor (combo of iodine and an organic molecule) that consists of iodine and povidone for the slow-release dispersion of iodine
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Betadine
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chlorine compound used in bleach for disinfection
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Sodium Hypochlorite (NaOCl)
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Chlorine in combination with ammonia; stable compounds for slow release of chlorine ; used for glassware and eating sanitation
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Chloramines
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examples of heavy metals that can denature microbial proteins
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Silver
Mercury Copper zinc |
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How do the soap and detergent surfactants act to control microbes?
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aka surface acting agents; decrease surface tension of molecules making up a liquid
Don’t kill or inhibit growth of microbes, mechanically remove them through scrubbing Breaks the film of oil, dead skin cells, sweat and microbes into droplets → emulsification Rinsing with water lifts and carries away the emulsified droplets |
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Sodium nitrite used in
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preserves meat like ham, bacon, hot dogs & sausage by preventing botulism endospore growth
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Inhibits iron-containing enzymes of C. botulinum
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sodium nitrite
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carcinogens thought to be produced by reaction of nitrates with amino acids
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Nitrosamines
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usually in the form of formalin, a 37% aqueous solution of formaldehyde gas
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formaldehyde
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less irritating and more effective; commonly in the form of a 2% aqueous solution (Cidex)
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Glutaraldehyde
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Name two chemicals that can be used as Chemosterilants
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Ethylene oxide, Chlorine dioxide
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Chlorine dioxide =
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used to fumigate enclosed areas contaminated with anthrax endospores
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Ethylene oxide
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replaces proteins’ hydrogen atoms with a chemical radical → denaturation
Applied in a closed chamber over several hours Toxic and explosive in pure form → usually mixed with a non-flammable gas such as CO2 |
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Why is hydrogen peroxide not very effective against aerobic microbes?
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it is broken down to water and oxygen by catalase in aerobic cells
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one of most effective liquid chemical sporicides; can be used as a sterilant
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Peracetic acid
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building blocks of DNA and RNA
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nucleotides
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Purines
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a, g
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Pyrimidines
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t, c, u
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T-A , C-G
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dna
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U-A, C-G
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rna
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What is the basic physical structure of DNA?
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Double stranded double helix
Backbone = alternating sugar and phosphate Bases form the “rungs” of ladder Complementary base pairing Antiparallel strands (opposite orientation |
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Is usually single-stranded
Contains ribose instead of deoxyribose Contains uracil instead of thymine |
rna
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three types of rna
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mRNA
rRNA tRNA |
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Transcription =
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synthesis of complementary RNA from DNA
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What is the name of the complementary strand that is generated from DNA during transcription?
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mRNA
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3 steps in transcription
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RNA polymerase binds the promoter
Synthesis continues until the terminator is reached mRNA can now be used in the translation process |
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synthesis of proteins through decoding of mRNA
(converts nucleic acid sequence into an amino acid chain) |
translation
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groups of 3 nucleotides that “code” for a particular amino acid
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codons
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initiates protein synthesis
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Start codon
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terminate protein synthesis
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stop codon
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The process of “reading” mRNA codons and generating the amino acid chain takes place
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ribosome
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molecules transport amino acids to the ribosome
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tRNA
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3 base sequence complementary to a codon
pairs to the complementary codon on mRNA carries the amino acid of the codon it recognizes |
Anticodon
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Ribosomal subunits assemble on mRNA strand
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step 1 Translation: MRNA to protein
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AUG of mRNA is matched to tRNA with proper anticodon
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step 2 Translation: MRNA to protein
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Another tRNA carrying the 2nd amino acid arrives
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step 3 Translation: MRNA to protein
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The second codon pairs with the anticodon of 2nd tRNA
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step 4 Translation: MRNA to protein
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A peptide bond forms between the amino acids
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step 5 Translation: MRNA to protein
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Ribosome moves, opening up space for another tRNA
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step 6 Translation: MRNA to protein
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The ribosome reaches a stop codon, releases polypeptide
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step 7 Translation: MRNA to protein
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Last tRNA is released; ribosome subunits dissociate; new protein!
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step 8 Translation: MRNA to protein
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not regulated so have constantly expressed protein products (~60-80% of genes)
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Constitutive genes
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Why is the expression of some genes regulated and the expression of other genes is not?
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control mechanisms
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What are two methods of regulating gene expression in bacteria?
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repression and induction
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•inhibits gene expression by action of a repressor
-Blocks RNA polymerase from initiating transcription •Usually a response to buildup of a product of a metabolic pathway à decreases synthesis of the enzyme producing the product |
repression:
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turns on transcription of a gene by an inducer
-Binds the repressor and keeps it from blocking transcription à ends repression on synthesis of the enzyme needed for metabolism of a particular substrate |
Induction
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A change in the base sequence of DNA
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mutation
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Agent that causes mutations
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mutagen
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Occur in the absence of a mutagen
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Spontaneous mutations
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What can cause mutations to occur?
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mutagens and spontaneous mutations
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Change in one base, replaced with a different base
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Base substitution (point mutation)
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Result in change in amino acid
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Missense
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A base substitution, which results in a stop codon
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nonsense
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Insertion or deletion of one or more nucleotide pairs
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frameshift
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segments of DNA that can move from one region of DNA to another
-Contain insertion sequences for cutting and resealing DNA complex versions of these carry other genes |
transposons
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transfer of genetic material from one bacterial cell to another in the form of a plasmid
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Conjugation
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circular piece of DNA that replicates independently from the chromosomes
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Plasmid
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projection from surface of donor cell that contacts surface of recipient cell to bring them into contact
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Sex pilus
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How can the emergence of antibiotic resistant bacteria be prevented?
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do not do the following:
•Misuse of antibiotics selects for resistance mutants -This can happen from: •Using outdated or weakened antibiotics •Using antibiotics for the common cold and other inappropriate conditions •Using antibiotics in animal feed •Failing to complete the prescribed regimen •Using someone else's leftover prescription |
