29 Questions
What is a key focus of Food Microbiologists?
Studying the impact of microbes on food supply
What distinguishes Prokaryotes from Eukaryotes in terms of cellular structure?
Prokaryotes lack nuclei and membrane-bound organelles
What are viruses composed of?
A nucleic acid and protein
What is the process of converting carbon dioxide to organic material with the help of light called?
Photosynthesis
What is a characteristic of parasites among microorganisms?
They damage the host they live on or in
Which branch of microbiology is concerned with microbial diversity?
Microbial Diversity
What is the composition of the gamma (γ) band in electrophoresis of globulin?
Primarily IgG
What type of cells are involved in the primary response to an antigen?
Plasma cells
What is the main characteristic of monoclonal antibodies?
They have a single specificity for antigen
Which type of T cell is involved in destroying foreign or abnormal cells?
Cytotoxic T cells
What happens during the secondary response to an antigen?
Gradual increase in antibody titer with production of IgG
What is the primary function of T helper cells?
Regulating immune reaction to antigens
What is the primary location where natural killer cells circulate?
Spleen
Cell-mediated immunity requires direct involvement of which type of lymphocytes?
T lymphocytes
What do T cells secrete that act on other cells in cell-mediated immunity?
Cytokines
Which type of T cells proliferate into long-lasting memory T cells upon sensitization?
Memory T cells
What drastic consequences can occur as a result of T cell reaction to superantigens?
Toxic shock
What is the function of selective media in microbiology?
Inhibits the growth of some microbes and encourages the growth of desired microbes
What is the main difference between solid and liquid media?
Solid media provides a firm surface for colony formation while liquid media does not
What is the role of differential media in microbiology?
Allows growth of several types of microbes with visible differences among them
Which type of media contains agents that inhibit the growth of some microbes?
Selective media
What is the purpose of enriched media in microbiology?
To supply special growth factors required by fastidious microbes
Which type of media can be both selective and differential?
Nutrient agar
What is the mechanism of action of penicillins and cephalosporins on bacterial cells?
Causing the cell wall to lyse
How do aminoglycosides (streptomycin, gentamycin) affect bacterial cells?
Cause misreading of mRNA
Which antimicrobial drugs affect metabolic pathways by blocking enzymes needed for tetrahydrofolate synthesis?
Sulfonamides and trimethoprim
What is the target of aminoglycosides as antibacterial drugs?
Ribosomes
Which drugs are active on young, growing bacterial cells by blocking peptidoglycan synthesis?
Penicillins and cephalosporins
What is the effect of a combination of antibiotics that exhibit a 'synergistic effect'?
'Synergistic effect' is greater than the sum of individual effects
Study Notes
Food and Drug Administration
- Collect soil samples to detect animal pathogens
- Food Microbiologists focus on the impact of microbes on the food supply, including food spoilage, food-borne diseases, and production
Branches of Microbiology
- Microbial Diversity: 6 types of microbes
- Origins of Microorganisms: bacteria-like organisms have existed on Earth for about 3.5 billion years
Microbial Structure
- Prokaryotes: simple cells, lack nuclei and membrane-bound organelles
- Eukaryotes: complex cells, have a true nucleus and membrane-bound organelles
- Viruses: acellular, parasitic particles composed of nucleic acid and protein
Microbes in Energy & Nutrient Flow
- Photosynthesis: light-fueled conversion of carbon dioxide to organic material
- Decomposition: breakdown of dead matter and wastes into simple compounds
Human Use of Microorganisms
- Biotechnology: production of foods, drugs, and vaccines using living organisms
- Genetic engineering: manipulating the genes of organisms to make new products
- Bioremediation: using living organisms to remedy an environmental problem
Lifestyles of Microorganisms
- Majority live a free existence, are relatively harmless and often beneficial
- Some microorganisms have close associations with other organisms
- Parasites live on or in the body of another organism and damage the host
Isolation Techniques
- Cell and colony morphology or staining characteristics
- DNA sequence
- Biochemical tests to determine an organism's chemical and metabolic characteristics
- Immunological tests
Media
- Can be classified according to three properties:
- Physical state (liquid, semisolid, solid)
- Chemical composition (synthetic, complex)
- Functional type (general purpose, enriched, selective, differential, anaerobic, transport, assay, enumeration)
- Selective media: contains one or more agents that inhibit the growth of some microbes and encourage growth of the desired microbes
- Differential media: allows growth of several types of microbes and displays visible differences among those microbes
- General-purpose medium: grows a broad range of microbes, usually nonsynthetic
- Enriched media: contains complex organic substances required by fastidious microbes
Miscellaneous Media
- Carbohydrate fermentation medium: contains sugars that can be fermented, converted to acids, and a pH indicator
- Antibodies in Serum: globulin separates into 4 bands (α1, α2, β, and γ) via electrophoresis
Immunity
- Primary response: production of IgM and a gradual increase in Ab titer after first exposure to an Ag
- Secondary response: rapid, stronger response due to memory cells after second contact with the same Ag
- Monoclonal Antibodies: originate from a single clone, have a single specificity for antigen, and are used in diagnosis of disease, identification of microbes, and therapy
T-Cell Activation and Differentiation
- T helper cells (CD4 or TH): regulate immune reaction to antigens, including other T and B cells
- Cytotoxic T cells (CD8 or TC): destroy foreign or abnormal cells by secreting perforins that lyse cells
- Natural killer cells: lack specificity, circulate through the spleen, blood, and lungs
- T cells act directly against Ag and foreign cells when presented in association with an MHC carrier
Test your knowledge on the separation of globulin bands (Alpha-1, Alpha-2, Beta, Gamma) in serum electrophoresis and the composition of different immunoglobulins. Explore the primary and secondary immune responses to antigens and the production of IgM and IgG antibodies.
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