Intro to Micro Flashcards

Question

BACTERIAL REPLICATION

Answer 1

Duplication of chromosomal DNA for insertion into a daughter cell * Begins at specific positions in chromosomes called “origins” where initiator proteins bind to DNA to start the process * At origin point, two replication forks form and enzymes move in opposite directions to reform two identical double strands of DNA. One for the original and one for the daughter cell daughter cells are genetically identical to parent - bacteria divides by binary fission

Answer 2

changes in the original nucleotide sequence of an organism’s genotype * Can occur spontaneously * Can be due to an error during replication * Can be due to chemical factors in the environment * Or by introduction of foreign DNA into the cell by mutagens such as plasmids, transposons or bacteriophages * May not cause any detectible changes * May provide a survival advantage like toxin production or resistance to antibiotics * May kill the cell

Answer 3

MUTAGEN Smaller circular double stranded DNA outside the chromosome but still in the cytoplasm – not essential for cell survival * Bacteria can have 1 – 100’s of plasmids * Can replicate independently of chromosome thru conjugationhorizontal transfer from one bacterial species to another * Or replicate with the chromosome and be passed on to a daughter cell * Contain genes encoding for: Antibiotic resistance, toxin production virulence factors, and proteins for transfer of plasmid to other bacteria

Answer 4

MUTAGEN jumping genes Moveable genetic elements of DNA segments * Often causes spontaneous mutations, can encode resistance to antibiotics * Can only replicate with the chromosome or piggy-backed on a plasmid do not replicate independently like plasmids

Answer 5

A virus that infects and replicates within bacteria by injecting their genome into the bacteria’s cytoplasm

Answer 6

Lytic cycle Lysogenic cycle

Answer 7

* Virulent viral bacteriophage-host cell is lysed * Lysis releases newly replicated packages of viral DNA that can infect other bacteria

Answer 8

Temperate (not continuing to replicate) viral bacteriophage - host cell is not lysed * Phage DNA combines with the bacterial chromosome, creating the prophage * Prophage is replicated along with the host chromosomes * Lysogenic cycle can continue indefinitely - Or become lytic

Answer 9

Vertical Transfer * Normal replication of chromosome -binary fission - mother to daughter * Organism replicates it genome and provides exact copies to descendants Horizontal Transfer * Donor contributes part of genome to recipient that are not descendants – usually through plasmids, bacteriophages, or incorporation of free naked DNA * Recipient will have a different genes than other descendants * Acquired DNA is incorporated into the chromosome or plasmid by Genetic Recombination Conjugation - Both plasmid and chromosomal genes can be transferred. Need a fertility gene F+ resulting in two cells with double stranded DNA Transduction - Transfer of bacterial genes by a bacteriophage

Answer 10

Autotrophs and heterotrophs

Answer 11

Don’t need preformed organic compounds for energy * Get energy photosynthetically or by oxidation of inorganic compounds * Do not need organic carbon. * Example of an inorganic carbon source = Carbon dioxide

Answer 12

Require organic carbon for growth * Obtain carbon from preformed carbon and nitrogen containing compounds or glucose * Acquire energy by oxidizing or fermenting organic substances * Often the same substance (like glucose) can be used as both the carbon & energy source All bacteria that inhabit the human body are Heterotrophs

Answer 13

Water - transport solutes across the cell , needed to move things in and out of the cell energy source - ATP nitrogen source - make proteins amino acids =nucleic acids carbon source - make cellular constituents Phosphate - nucleic acids sulfur - protein synthesis metal/ions - enzymatic activities WENCPMS

Answer 14

psychrophiles - 10-20 mesophiles - 20-50 (pathogens, opportunists because they are closest to body temperature) thermophiles - 50-80 extreme thermophiles - over 80

Answer 15

our air is 21% O2 and 1% CO2 bacteria can be obligate aerobes obligate anaerobes aerotolerant anaerobes faculative anaerobes microaerophilic capnophilic

Answer 16

is a toxic by-product of bacterial metabolism that happens in oxygen - causes cell damage and death * Organisms exposed to oxygen need enzyme superoxide dismutase * Enzyme converts superoxide and hydrogen to hydrogen peroxide and oxygen →less toxic * If organism also produces catalase enzyme→ hydrogen peroxide will be converted to water and oxygen * Or if organism produces peroxidase enzyme→ hydrogen peroxide will be converted to water and a hydroxide compound

Answer 17

Grow ONLY in presence of oxygen * Produce superoxide dismutase ,catalase, peroxidase to protect them from toxic superoxide * These bacteria oxidize sugars * ATP made mostly from oxidative phosphorylation but some substrate level phosphorylation as well

Answer 18

Grow with or without oxygen – grow faster in O2 so colonies will often appear larger in an aerobic condition - has enzyme superoxide dismutase * Can shift between fermenting or oxidizing sugars depending on the presence of O2 * ATP made by both substrate level and oxidative phosphorylation

Answer 19

Can’t grow in oxygen- because they lack superoxide dismutase, catalase, & peroxidase * Ferment sugars * ATP made from substrate phosphorylation only * Must be grown in anaerobic jar with Gas pak added

Answer 20

Grow in reduced oxygen levels – specifically 5 % O2 * Killed by high oxygen levels * Require a Campy pak * Oxidize sugars

Answer 21

Grow best in 5 – 10% CO2 * Candle Jar * CO2 Incubator * Oxidize sugars

Answer 22

Grow with or without oxygen (not killed by 02) * Grow better without oxygen * Uses fermentative metabolism regardless of whether O2 is present or not

Answer 23

Bacteria adapt to growth conditions * Maturing and not yet able to divide * Synthesizing RNA, enzymes and other molecules best time to grow bacteria will take 18-24 hours time on x axis------ log number of bacteris on y axis

Answer 24

Active cell division – cell doubling * Best stage for biochemical testing * But can’t continue indefinitely due to depleted nutrients and buildup of wastes

Answer 25

Growth rate and death rate are equal * The number of new bacteria created is limited by the declining nutrients and increasing toxic byproducts * Result is a “smooth,” horizontal linear part of the curve during the stationary phase

Answer 26

Bacteria run out of nutrients and only toxic byproducts are present, so all bacteria die * The # of organisms dying > number produced

Answer 27

The time it takes for a single bacteria to divide or double in number - also called the doubling time Factors affecting growth rate: * Species and strain, whether nutritional requirements are in media, presence of inhibitors, radiation, detergents or toxins * Environmental factors: temperature, presence or absence of oxygen, osmotic pressure, pH

Answer 28

* To make energy in the form of ATP

Answer 29

Uses energy (ATP) to make cell components like proteins and nucleic acids

Answer 30

Makes energy (ATP) from breakdown of organic matter

Answer 31

Two mechanisms used to breakdown carbohydrates: Oxidation (also called Respiration) & Fermentation

Answer 32

* Aerobic metabolic process used by obligate aerobes, facultative anaerobes, microaerophiles & capnophiles Achieved through: * Glycolysis (also called the Embden–Meyerhof pathway) * Krebs Cycle (also called Citric Acid Cycle) * The Electron Transport Chain (ETC) Phosphorylation of ADP: * By substrate level in Glycolysis and Krebs * And oxidative phosphorylation in the Electron transport chain * More ATP (up to 38) & very little acid is produced by oxidative breakdown of glucose

Answer 33

Used in the absence of O2 or if organism can’t grow inO2 * In this case energy is made from glucose in one of two ways fermentation or anaerobic respiration

Answer 34

Non-oxygen requiring way to get energy from the breakdown of glucose or other sugars * Performed by strict anaerobe, facultative, aerotolerant bacteria & yeast * Glycolysis forms pyruvate then in the absence of O2 & depending on the enzymes available, is converted into acids, gases, or alcohols -no Krebs cycle or ETC * Purpose of fermentation reactions is to regenerate NAD+ so glucose continues to be broken down by glycolysis * Lots of acid but only 2 ATP produced in glycolysis – fermentation does not produce any extra ATP Lactate dehydrogenase converts pyruvate to lactate NADH reduced to NAD+ which can be reused in glycolysis

Answer 35

Considered an anaerobic process but facultative bacteria & yeast can choose to use it even when oxygen is present Not all sugars can be fermented by all bacteria – E. coli is a lactose fermenter, but other similar organisms can’t do this The end products are used as phenotypic markers & in bacterial ID schemes * Some biochemical test media used to ID bacteria have a carbohydrate & a pH indicator - Fermentation produces lots of acid and a color change in the pH indicator in the media

Answer 36

Anaerobic or aerotolerant organisms use anaerobic respiration facultative can switch from aerobic to anaerobic respiration or fermentation depending on O2 or if it has enzymes to ferment. * Even though fermentation also happens without oxygen, it isn't the same as anaerobic respiration. * Anaerobic respiration starts with glycolysis it continues with acetyl CoA entering a modified cycle of Krebs. * Electrons formed in Krebs enter the ETC, but O2 is not the terminal electron acceptor - instead, other molecules like nitrate (NO3), sulfate or carbon dioxide are used as final electron acceptors * ATP in ETC by oxidative phosphorylation but in < #s max of 36

Answer 37

Media can include * Solid form -agar in plastic petri dishes * Fluid form - broths in tubes can be grown using a patient swab or by transferring colony from another sample - subculture - purity plate

Answer 38

Increased size or increased numbers -qualitative Direct plate estimation – semi qualitative * Estimate the number of viable bacteria present * Bacteria growth is described as light, moderate or heavy depending on which quadrant it grows up to on solid agar media - 4 quadrant plate estimate Direct plate count – quantitative *measure count * Grow known dilutions of broth culture * Count colony forming unit per milliliter (CFU/mL) - calibrated loop * Provides bacterial cell count of viable organisms Turbidometric-quantitative cfu/ml * Using photometer to measure turbidity it makes a broth photometer is used to compare the amount of light that goes through * Does not distinguish between live or dead organisms Radiometric, Colorimetric or Fluorescence - Measure CO2 produced by bacteria as they grow blood culture

Answer 39

35ºC – 37ºC aerobic (O2) * 35ºC – 37ºC with 5% CO2 * 42 ºC or 30 ºC aerobic (O2)

Answer 40

To create anaerobic conditions jar must include * GasPak™ EZ Container System Sachets - Envelope gas generator (Anaerobe Container System Sachets white) * Inorganic carbonate, activated carbon, ascorbic acid and water * produce an anaerobic atmosphere within 2.5 hours To monitor anaerobic conditions jar must include * Methylene blue oxidation- reduction indicator strip - Verifies that anaerobic conditions have been achieved - Changes from blue to white in anaerobic conditions

Answer 41

Campy Container System Sachets (are blue) * Produce a microaerophilic atmosphere within 2 hours * Does not have a chemical indicator * Must use a biological indicator that proper growth conditions were achieved * Include a known microaerophilic organism in the jar

Answer 42

5-7% CO2 * As flame burns, oxygen decreases and flame goes out * CO2 increases due to the flame * Use of white unscented candle(scented inhibitory to certain bacteria) * Humidity provided by the moisture evaporating from the media within the jar

Answer 43

A human fetus is in a sterile environment in the womb * At delivery it is exposed to microorganisms on their mother’s body & in the environment * Each organism finds the area of the baby’s body where it can colonize and become the predominant organism

Answer 44

is the growth of microbiota in or on a body site without the production of damage or notable symptoms

Answer 45

Any association of two or more organisms living together * If both organisms benefit from the relationship = mutualism * If the organisms benefit but there is no benefit or harm to the host = commensalism * If the organisms benefits at the expense of the host = parasitism

Answer 46

Bacteria produce vitamins that the human body can’t like B12 & K. * Help digest food * Helps prevent infection by out-competing invaders for nutrients & production of antibiotics that kill other organisms * Helps develop our immune system – induce production of natural antibodies & stimulate low levels of circulating antibodies to enhance immunity * Induce growth of lymphatic tissue and the wall of the Caecum in the GI tract

Answer 47

Microorganisms that colonize an area for months or years

Answer 48

Microorganisms that are present at a site temporarily. * Come to “visit” but don’t stay because they are eliminated by the host immune system or competing resident biota

Answer 49

Resident microorganisms can cause disease when their habitat is altered or the host’s immune system is compromised like yeast that can lead to yeast infection if left unchecked * Compromised due to immunosuppressive drugs, chemotherapy and radiation * Or due to diseases that cause immune disorders

Answer 50

True pathogens are organisms that cause disease in a healthy immunocompetent individual a high percentage of the time (in nearly all situations) * Opportunistic pathogens are organisms that are usually normal flora and under usual conditions do not cause disease but can cause infections if changes occur in the host immune system or habitat alteration

Answer 51

the ability of a microbe to produce disease in an individual

Answer 52

the invasion and multiplication of microorganisms in/on body tissues Damage to the infected cells or organs is called disease

Answer 53

Endogenous: source is from inside host (reactivation of a dormant virus or bacteria) - herpes causing cold sores or TB Exogenous: source is from outside the host Latrogenic: source acquired during a medical procedure Nosocomial: source acquired while in hospital Opportunistic Zoonotic: source acquired from an insect or animal

Answer 54

ability of a microbe to cause disease or the degree of pathogenicity * Measured by # of organisms needed to cause an infection * Organisms that cause infection with a low infective dose are more virulent than organisms that need a high dose

Answer 55

varied mechanisms that allow microbes to persist in a host and cause disease – can be coded in the genome of chromosome or acquired from plasmids, transposons or phage Ability to Resist Phagocytosis Ability to Evade Antibodies Adhesion to Host Cells & Tissues: Ability to Survive Intracellularly & Proliferate Bacterial Ability to Produce Toxins Exotoxins endotoxins

Answer 56

Host phagocytic cells ingest invading microbes * Organism’s with a capsule can hide cell surface structures (antigens) recognized by receptors on the surface of the phagocytic cell * Capsule & WBC are negatively charged therefore repel * Capsule may also inhibit the activation of complement by masking structures which bind to complement * Bacteria can release material in tissue that kill phagocytes * Examples: hemolysin (lyse red blood cells), leucocidins (kill leucocytes) * Organism with pili attach to target cell and resist phagocytes

Answer 57

* Some bacteria produce immunoglobulin protease –degrades Ab * Or can change their antigen structure so antibodies can’t bind * Protein A on bacteria, binds to FC portion of Ab & neutralizes it.

Answer 58

Most microbes must attach to host cells before infection occurs * Surface structures that cause attachment are called adhesins – host cells must have the corresponding receptors for the adhesins * Main adhesin in bacteria are capsules or pili (fimbriae) * But host can make antibodies to the adhesins to prevent attachment

Answer 59

* Some bacteria can live in phagocytic or tissue cell after being engulfed via a cell vacuole into the cell * Can make a substance that neutralizes the lysozyme enzyme made in the vacuole to kill it - or escape from the vacuole into the cell’s cytoplasm * Continue to replicate inside host cell & are protected from the host immune system * Some bacteria multiply and continue to penetrate other cells in the host tissue = invasion * Some spread to other distant organs or tissues = dissemination * Examples of enzymes made by bacteria that allow them to disseminate: hyaluronidase , collagenase or kinase

Answer 60

Poisonous substances that cause damage to host cells or tissues * Two main types Exotoxins & Endotoxins

Answer 61

Can be produced by gram negative and gram positive organisms * Gene for making toxin found on plasmid * Secreted by organism into the environment – or when the cell lyses * Can cause formation of antibodies or antitoxin by immune system * Damage to tissue and connective tissue helps organism spread * Are heat labile Types of Exotoxins: have a defined action to specific cells Cytotoxin: damage to host cells Neurotoxin: damage to nervous tissue Enterotoxin: specifically damage the intestinal mucosa

Answer 62

Chromosomally mediated * Heat stabile * Part of the cell wall (LPS –lipopolysaccharide portion)of gram negative bacteria * Released only when the bacteria is killed & cell wall breaks apart * Not specific in their activity on host cells * Not as potent * Stimulate inflammatory response in the host innate immune response * lowering blood pressure, bleeding, high fever, increase or decrease in different WBCs. Can sometimes become shock, organ failure & death

Answer 63

when labelling the plate label the bottom one around the edge - need to be able to see the growth if the slant growth label the other side Specimen number * Mailbox number * Date * Atmosphere of incubation if not O2 35oC

Answer 64

if you took too much sample it wont dry

Answer 65

turn left 30 go into the prior quadrant 2 times the fourth quad takes up the the edge and the middle

Answer 66

put the loop directly inside - shows motility

Answer 67

Plates are placed into a container * A special pouch is added to the container with the plates before it is closed. * A chemical reaction occurs in the pouch that removes all O2 from the container environment. * A special Methylene blue oxidation- reduction indicator strip is also added to ensure ANO2 conditions have been reached * The strip starts blue and turns white when ANO2 conditions have been reached

Answer 68

saline on the slide with organism and cover

Intro to Micro Flashcards

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