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MICRO 231
study for final test
| Question | Answer |
|---|---|
| Define microbiology. | A specialized area of biology that deals with living things ordinarily too small to be seen without magnification. |
| How small is the average bacterium? | 1 um diameter for cocci; 1 x 3 um for bacilli |
| Who pioneered the use of the microscope? | Van Leeuwenhoek |
| Know the basic metric units. | For weight: grams; for length: meters: for volume: liters All based on units of 10. Example Meters: 1/10 of meter is decimeter; 1/100 of meter is centimeter: 1/1000 of meter is millimeter; 1/1000000 of meter is u (micrometer); |
| What is the theory that life arose from inanimate objects? | biogenesis |
| Who disproved this theory? | Louis Pasteur with those specialized flasks |
| Who developed a series of “Postulates” to prove the etiology of an infectious disease? | Robert Koch--Koch's Postulates--take a look at the 4 Koch's postulates |
| When did the first bacteria appear and how do we know? | Bacteria fossils discovered in rocks date from at least the Devonian Period and there are convincing arguments that bacteria have been present since early Precambrian time, about 3.5 billion years ago. |
| What is the difference between a prokaryote and a eukaryote? | Eukaryotic cells contain membrane-bound organelles, such as the nucleus, while prokaryotic cells do not. Eukaryotes are larger and more complex. |
| Who is Carl Woese and what important discovery did he make? | Woese is famous for defining the Archaea (a new domain or kingdom of life) in 1977 by phylogenetic taxonomy of 16S ribosomal RNA, a technique pioneered by Woese which revolutionized the discipline of microbiology. |
| What are the three domains of life? | Bacteria (prokaryotes), Archaea (prokaryotes), and Eukaryotes |
| What are the 3 main bacterial morphologies? | Cocci, bacilli, and spirals |
| What is the function of a cell membrane? | The plasma membrane acts as a permeability barrier for most molecules and serving as the location for the transport of molecules into the cell. |
| Describe a cell membrane in detail. | Phospholipid bilayer |
| Which parts are hydrophobic? Which are hydrophilic? | Two layer--the fatty acid chains in each layer pointing towards the center of the membrane. The nonpolar regions of the molecules (hydrophobic) face the interior of the bilayer. The polar regions of the molecules (hydrophilic) face outward. |
| Name cell structures unique to Eukarya. | Nucleus; Endoplasmic reticulum; Mitochondria; Golgi body |
| What is the function of a mitochondria? | powerplant of the cell |
| What is the endosymbiotic theory and what evidence supports it? | Symbiogenesis, or endosymbiotic theory, is an evolutionary theory which explains the origin of eukaryotic cells from prokaryotes. It states that several key organelles of eukaryotes originated as symbiosis between separate single-celled organisms. |
| Evidence of endosymbiosis? | Most important evidence are the many striking similarities between prokaryotes (like bacteria) and mitochondria. |
| What are the differences between a Gram positive and Gram negative bacteria? | The cell wall is different. Gram-positive bacteria have a thick mesh-like cell wall made of peptidoglycan whereas gram-negative bacteria have a thinner layer. |
| What color is a gram positive? gram negative? | Gram positives are purple; gram negatives stain red |
| What is the outer membrane and its importance? | Only gram negatives have an outer membrane--it is made of LPS (lipopolysaccharide) and is toxic to the patient if the cell is destroyed (endotoxic shock). |
| What is the purpose of flagella? | Movement |
| What is chemotaxis? | is the movement of an organism in response to a chemical stimulus. |
| What is the difference between pili and fimbrae? | -Pili can serve in DNA exchange. Pili and fimbriae are often involved in attachment to surfaces and are important for biofilm formation. |
| What is an endospore and its function? | a dormant, tough, non-reproductive structure produced by a small number of bacteria from the Firmicute family. The primary function of most endospores is to ensure the survival of a bacterium through periods of environmental stress. |
| What is a capsule and its function? | a slimy gluelike layer that encloses bacterium; protects bacteria against drying, environmental fluctuations and the IMMUNE system--resists phagocytosis |
| Describe a bacterial chromosome. | a circular DNA molecule. Unlike the linear DNA of vertebrates, typical bacterial chromosomes contain circular DNA.--not enclosed in a membrane |
| What is an organic compound? | any member of a large class of chemical compounds whose molecules contain carbon. |
| What is the composition of a carbohydrate? | Carbohydrates consist of the elements carbon (C), hydrogen (H) and oxygen (O) with a ratio of hydrogen twice that of carbon and oxygen. Carbohydrates include sugars, starches, cellulose. |
| What is the composition of a lipid? | Lipids are fatty acids and their derivatives, composed of C and H. |
| What is the composition of a protein? | C, H, O, N |
| What is the composition of a nucleic acid? | C, H, O, N, P |
| What do enzymes do and what are they made of? | biological catalysts made of protein; make reactions go |
| Define catabolism and anabolism. | Catabolism: break down reactions Anabolism: building up reactions |
| What is the energy currency of the cell? | ATP |
| What is the purpose of glycolysis? | Glycolysis does not require an oxygen source. Its production of ATP allows the cell to generate at least a small amount of energy even without oxygen. 2 ATP produced |
| What are the steps in aerobic respiration? How many ATP are produced? | Cells break down food in the mitochondria in a long, multistep process that produces roughly 36-38 ATP. The first step in is glycolysis, the second is the citric acid cycle and the third is the electron transport system. |
| What is DNA? What is the basic structure of DNA? What sugar is DNA made of? | Deoxyribonucleic acid; double helix; deoxyribose |
| What does it mean to say that DNA strands are antiparallel, and complementary, and form a double helix? | The two strands of DNA run in opposite directions to each other and are therefore anti-parallel.Complimentary--the bases only bind to the complimentary base (A with T; G with C) |
| What are the monomers of DNA and how are the arranged in the cell? | Nucleotide has 3 basic parts, all connected together into a single molecule. The 3 parts are a phosphate, a sugar and a base. |
| What is a nucleotide? Draw a picture of the three major components of a nucleotide. | Each nucleotide has the same deoxyribose (a five carbon sugar) and a phosphate group (PO4). There are 4 different bases: Adenine (A), Cytosine (C), Guanine (G), and Thymidine (T). |
| Name the DNA bases/nucleotides and their abbreviations. | A--adenine; T- thymine; G- guanine; C- cytosine |
| How are DNA, genes, chromosomes and genomes related? | All genes are DNA, but not all DNA is a gene. Chromosomes are made of DNA and proteins. Genes are stretches of DNA that contain code to make proteins. Genome--the entire genetic material in organism |
| What is the central dogma? | DNA goes to RNA goes to protein |
| Describe conjugation. | A form of genetic information transfer between bacteria utilizing a sex pilus (we called it bacterial sex--even though it isn't sex). |
| What is a plasmid? | Extrachromosomal DNA-often containing antibiotic resistance genes--usually what is transfered in conjugation. |
| What are the differences between RNA and DNA? | Different sugars (DNA has deoxyribose; RNA has ribose); different bases (DNA has ATCG; RNA has AUCG); and different no. strands--DNA is double stranded; RNA is single stranded |
| What is transcription? Translation? | Transcription is making RNA from DNA. Translation is making the protein from RNA. |
| What RNAs are involved in translation and what are their roles? | mRNA--messenger RNA gets the code from the DNA and takes it to the Ribosome: rRNA--part of the ribosome; tRNA--transfer RNA brings the amino acid to the ribosome |
| Describe the steps in translation. | Initiation, elongation, termination |
| Define growth. | Growth of bacterial cultures is defined as an increase in the number of bacteria in a population rather than in the size of individual cells. |
| How do bacteria reproduce? | occurs through binary fission. |
| Diagram a typical bacterial growth curve. What happens at each phase? | Review the diagram--Lag phase, log phase, stationary phase, death phase |
| What is the doubling time (generation time) of E. coli? | 20 minutes |
| How do you measure bacterial growth? | turbidity (spectrophotometer), viable plate count, lab equipment |
| What factors affect bacterial growth? | nutrients, atmospheric requirements, moisture, pH, temperature, osmotic pressure |
| Define the following terms: psychrophile, mesophile, thermophile, hyperthermophile, acidophile, neutrophile, alkaliphile, halophile. halotolerant, barophile. | Psychrophile--cold temps; mesophile--body temps; thermophile--hot temps, hypertermophile--really hot; acidophile--acid pH, neutrophile--neutral pH, alkaliphile--basic pH, halophile--like salt; halotolerant--tolerates salt; barophile--high barometric pres |
| What terms would you use to describe the various microbial lifestyles (where do they get their energy, electrons and carbon)? (autotrophs, heterotrophs, chemotrophs, lithotrophs, etc.) | Chemotrophs--get energy through chemical reactions; Phototrophs--get energy through light; Autotrophs--get carbon from CO2; Heterotrophs--get carbon from organic compounds; lithotrophs--use inorganic compounds for energy |
| What methods are used to inhibit or kill bacteria? | disinfectants (alcohols, bleach, etc.); steriliants (autoclave, incineration), antibiotics |
| Define sterilize, sanitize, disinfect and antiseptic. | Sterilize--to remove all life (including viruses); sanitize--to remove most life; disinfect-- like sanitize; antiseptic--what you do to remove most life on skin |
| What are antibiotics? | Antibiotics, also known as antibacterials, are types of medications that destroy or slow down the growth of bacteria. |
| What do bacteriostatic and bacteriocidal mean? | Bacteriostatic--prevent GROWTH of bacteria (but not kill) Bacteriocidal--Kill bacteria |
| What are the various modes of action of antibiotics? | Inhibition of Cell Wall Synthesis (most common mechanism) Inhibition of Protein Synthesis (Translation) (second largest class) Alteration of Cell Membranes. Inhibition of Nucleic Acid Synthesis. Antimetabolite Activity. |
| How do bacteria acquire resistance to antibiotics? | Usually from another bacteria through: conjugation, transformation, transduction, or lysogenic conversion or a mutation |
| What is causing increased antibiotic resistance? | Every time a person takes antibiotics, sensitive bacteria are killed, but resistant germs may be left to grow and multiply. Improper uses of antibiotics are primary causes of the increase in drug-resistant bacteria. |
| What class of antibiotic does penicillin belong to? How does it work and what type of bacteria is it most effective against (which ones have thick cell walls) | beta-lactams; targets production of bacterial cell wall; gram positives |
| How many bacterial species are estimated to be present in the human mouth? | More than 700 bacterial species or phylotypes, of which over 50% have not been cultivated, have been detected in the oral cavity. |
| What areas of the body are colonized? Which are not colonized? | Areas colonized: gut (intestines), upper respiratory tract; skin; ear; mouth; distal end of urethra--Areas not colonized: blood, most of urinary tract; spinal fluid and central nervous system; internal organs |
| What phyla of bacteria are associated with human skin? | Staphylococcus (especially epidermidis) |
| How many estimated bacterial species in the human intestine? | The microbial community of the human gut is believed to be composed of at least 1013 microorganisms, including more than 800 species of bacteria (most of which have not yet been successfully cultured in the laboratory). |
| What is another (more proper) name for the normal flora? | Indigenous microflora |
| What bacterial species can be found in the human stomach and causes ulcers? | Helicobacter pylori |
| What roles do the normal flora play in human health? | The normal flora synthesize and excrete vitamins, they prevent colonization by pathogens through competition, they produce substances that kill other bacteria ,they stimulate the development of certain tissues and the production of natural antibodies. |
| Describe what you know about E. coli O157:H7. What does each term of the strain designation mean? What disease(s) does it cause? | A strain of E. coli that produces a Shiga-toxin and is known to produce hemolytic uremic syndrome (HUS) starting as bloody diarrhea and progressing to kidney failure and anemia in Kids. O stands for the somatic (cell wall) antigen and H is the flagellar. |
| What is an opportunistic infection? What are the sources of an opportunistic infections. | An infection with a bacteria or other organism that normally would not produce a problem but the patient doesn't have an immune system or a depressed one. Sources could be environment or even the person's body flora. |
| Know the terms used to quantify the spread of disease – prevalence, incidence, | prevalence: The number or proportion of cases or events or conditions in a given population.; incidence rate: A measure of the frequency with which an event, such as a new case of illness, occurs in a population over a period of time. |
| Know the terms morbidity, mortality, | morbidity: number of sick people; mortality: number of dead people |
| Know the terms endemic, | endemic: The constant presence of a disease or infectious agent within a given geographic area or population group; |
| Know the terms epidemic, | epidemic: The occurrence of more cases of disease than expected in a given area or among a specific group of people over a particular period of time. |
| Know the terms pandemic. | pandemic: An epidemic occurring over a very wide area (several countries or continents) and usually affecting a large proportion of the population |
| What are the steps in the chain of Infection? | Infectious agent, reservoir, portal of exit, mode of transmission, portal of entry, susceptible host |
| What’s the difference between signs and symptoms? | signs-any indication of a medical condition that can be objectively observed, whereas a symptom is merely any manifestation of a condition that is apparent to the patient |
| What is a virulence factor? Give examples of virulence factors. | molecules produced by pathogens (bacteria, viruses, fungi and protozoa) and contribute to the pathogenicity of the organism; ex. capsules, toxins, enzymes, |
| How can a bacterium avoid the immune system? | changing their antigens, avoiding macrophages, killing macrophages, producing enzymes that help them move through the tissues, capsule inhibit phagocytosis |
| Why doesn’t exposure to a pathogen always result in disease? | sometimes the person is already immune, sometimes the pathogen can't attach to the host, sometimes the person's immune system takes care of the pathogen before disease results |
| Staphylococcus aureus is associated with what diseases? | almost any type of infection (boils, furuncles, styes, wound infections)--especially skin related, but can be septicemia or toxic shock; scalded skin |
| Several streptococcal species are associated with human disease. What diseases do they cause? | Streptococcus pyogenes--strep throat and sequelae of glomerulonephritis and rheumatic heart disease; scarlet fever, necrotizing fasciitis Streptococcus pneumonae--pneumonia, ear infections, meningitis |
| What distinguishes one influenza strain from another? | The H (hemagglutinin) and N (neuraminidase) |
| How would you classify the genome of influenza? | As either DNA or RNA (but not both) |
| Know examples of DNA and RNA viruses. | DNA: Herpes virus, Hepatitis B virus, Adenovirus, Parvovirus, Pox virus, Papomavirus RNA: polio, Hepatitis A and C, rubella, rabies, mumps, measles, influenza, Hanta, Ebola, Lassa fever, HIV, |
| What are the steps in the viral life cycle? | 1.) Attachment (Adsorption)2.) Penetration3.) Uncoating 4.) Targeting 5) Gene expression.6) Genome replication 7) Virion assembly/maturation 8) Release of new infectious virus |
| Include the latent cycle and the lytic cycle. | Latent cycle--viruses that just hang out in the host cell--with host cell reproducing the virus genome until later date when virus can cause disease/lytic cycle--when virus bursts out of host cell causing cell destruction |
| Identify the structural components of a virus | 1) a nucleic acid genome and 2) a protein capsid that covers the genome. Together this is called the nucleocapsid. |
| What are prions? | Infectious proteins |
| What are some diseases caused by prions? | Mad Cow disease, vCJD, Creutzfeld-Jakob disease, Kuru, scrapie, etc. |
| What is a mutation? | the change in structure of a gene |
| What are the 4 mechanisms of transfer of genetic material in bacteria? | conjugation, transformation, transduction, lysogenic conversion |
| What is an endotoxin? Exotoxin? | Exotoxins are toxic substances secreted by bacteria and released outside the cell. Whereas Endotoxins are bacterial toxins consisting of lipids that are located within a cell. |
| What is passive vs. active immunity? | In passive immunity--someone else produced the antibody (like mom, or another person). In active immunity--the person themselves produced the antibody. |
| What is natural vs. acquired immunity? | In natural immunity, it occurs via a natural process. In acquired immunity, it involves an injection of some type or is from mom to her baby. |
| What is hypersensitivity? | An overactive immune response--like anaphylactic shock or allergies |
| What is immunocompromised? | where the person has a depressed or absent immune system |
| What is autoimmune disease? | Where your own antibodies are attacking your body |
| What are nosocomial, health care acquired, infections? | Those acquired during hospitalization or up to 14 days after hospitalization. |
| Neisseria gonorrhoeae | bacteria that causes gonorrhea, sexually transmitted disease |
| Salmonella sp | bacteria that causes food poisoning; fecal-oral transmission and also associated with chickens (eggs) and turtle and snakes and lizards |
| E. coli | normal flora in the human gut and generally non-pathogenic but there are some nasty strains |
| E. coli O157:H7 | a nasty strain--can cause a type of food or water poisoning--resulting in bloody diarrhea and a disease called Hemolytic Uremic Syndrome (HUS) which can be life-threatening |
| Campylobacter | a bacteria that can cause diarrhea; generally acquired through food or water; associated with chickens and cattle |
| Bordetella pertussis | a bacteria that produces Whooping Cough; droplet transmission |
| Bacillus anthracis | a bacteria that causes anthrax; 3 forms cutaneous, gastrointestinal, and respiratory |
| Clostridium botulinum | a bacteria that causes botulism; generally a food borne illness however, there is infant botulism (comes from honey) and wound botulism. Botulinum toxin is one of the most deadly toxins. |
| Clostridium tetani | a bacteria that causes tetanus; generally get this from a contaminated wound, will cause lock jaw and death if untreated |
| Listeria monocytogenes | a bacteria that causes food poisoning; especially problematic in pregnant women. Can grow in refrigerator temperatures. |
| Treponema pallidum | a bacteria that causes syphilis. Primary, secondary, latent, and tertiary stages |
| Corynebacterium diphtheria | a bacteria that causes diphtheria. Pseudomembrane forms in the back of the throat. |
| Mycobacterium tuberculosis | a bacteria that causes tuberculosis. |
| What are the pathogens of hepatitis and their transmissions? | Hepatitis A--RNA virus; fecal-oral transmission Hepatitis B--DNA virus; blood borne Hepatitis C--RNA virus; blood borne Hepatitis D--RNA--can only get this if you have Hep. B too Hepatitis E--RNA- fecal/oral |
| What type of virus is HIV? | retrovirus |
| What is the cause of ringworm? | a fungus!! There are 3 dermatophytes (fungi) that each can cause a form of ringworm. |
| What is Candida albicans and that types of problems does it cause? | the most common yeast that causes infections like vaginal yeast infection or thrush |
| What is a dimorphic fungus? Give 4 examples. | a fungus that grows as a mold at room temperature and a yeast at body temperature. Sporothrix schenckii; Blastomyces dermatitids, Paracoccidioides brazeliensis, Coccidioides immitus |
| What is Giardia lamblia and what problem does it cause? | Protozoan parasite; causes diarrhea |
| What is Toxoplasma gondii and what problems does it cause? | Protozoan parasite, causes abortions or fetal defects in pregnant women |
| What is Enterobius vermicularis? | pinworm |
| How is total magnification determined? | the power of the ocular x the power of the objective |
| List some zoonoses. | diseases that are acquired from animals--like Brucellosis, Anthrax, Hanta virus, |
| What are some arthropod borne infections? | malaria, yellow fever, Trypanosomasis, |
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