Microbiology: Test 2 Microbiology Chapters 5, 7, 8, 20 Flashcards

A- adenine

G-guanine

T- thymine

C- cytosine

enzyme that produces primary transcript RNA. In cells, RNAP is necessary for constructing RNA chains using DNA genes as templates, a process called transcription.

Ribonucleic acid o

deoxyribose nucleic acid

(i) ribosomal RNA (rRNA),

(ii) messenger RNA (mRNA)

(iii) transfer RNA (tRNA).

these three types of molecules originate as complementary copies of one of the two strands of a DNA segment that constitutes a gene

structural component of ribosomes, the sites where translation occurs during protein synthesis (machinery of protein synthesis)

responsible to carry the genetic message from DNA to the ribosome. Their length and sequence vary depending upon the gene which is being transcribed into m RNA

the smallest of the three types. It carries amino acids to the ribosomes (protein) during translation.

A-

G -

C-

U - uracil

RNA

U

C

A

G

at the replication fork

two replication forks in bacteria

opposite directions

bi-directional

5'- 3'

leading strand

lagging strand 3'- 5'

okazaki fragments

primers

DNA ligase

study of genes

segment of DNA that encodes a functional product usuall a protein

DNA

RNA

Protein

expression of gene (protein that can be seen)

describes the mechanism by which DNA is replicated

1 strand of old and one strand of new DNA

transcription

translation

RNA polymerase

double helix (double strand)

mono strand

a sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule

triplets of bases in mRNA

a specific amino acid

genetic code

61

3

UCAG left (top to bottom), UCAG top (left to right), UCAG, UCAG, UCAG (right top to bottom 4x's) 4 columns

3 bases

no, only time there is a concern is if there is mutation in base 1 or 2

A U G

UAA, UAG, UGA

disenfectants normally effect PROTEINS in bacteria which prevents metabolism

there are 3 stages in translation

1. initation
2. elongation
3. termination

enzymes and proteins

1. codon recognition
2. peptide bond formation
3. translocation

mutation occurs in DNA

a change in genetic material (beneficial, netural, harmful)

ex. beneficial mutation- evolution

harmful mutation- cancer

netural mutation- no effect

mutagen

a gene that causes a mutation

a sequence of DNA that results in a premature stop codon, or a nonsense codon in the transcribed mRNA

insertion or deletion of one or more nucleotide pairs

*shorten or extend frame of DNA, RNA

x-rays and gamma rays that cause the formation of ions that can react with nucleotides and DNA phosphate backbone

thymine dimers

A pair of abnormally chemically bonded adjacent thymine bases in DNA, resulting from damage by ultra-violet irradiation. The cellular processes that repair this lesion often make errors that create mutations. (cancer)

naked dna from environment transfers to another bacteria

transfer of genetic material (plasmid) between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells...... through pilli (gram negative)

virus

jumping gene

the process by which DNA is transferred from one bacterium to another by a virus

completely destroys all forms of microbial life

• destroys VEGETATIVE cells on SURFACE
• reduces # of viable organisms in material

the chemical disinfection of living tissue, such as skin or

mucous membrane

• removal of pathogens from living tissue

physical removal(mechanical cleansing) of microbes via alcohol, swab, soap

ex. cleaning the skin with alcohol prior to injection

the absence of significant contamination

kill ALL bacterial

halt (inhibit) the growth of bacteria for as long as the inhibitory substance is present, NO DUPLICATION

ex. freezing food method

once inhibitor is removed, growth begins

ex. removing food from freezer

the TIME at a given temperature in which all the micoorganisms in a liquid culture will be killed

• time is the variable (it changes)
• temp is the constant (remains the same)
• ex. temp is 50 degrees celcius but bacteria may not die at 5, 10 or 15 mins but may die at 30 mins

the lowest temperature at which all microorganisms in a liquid suspension are killed in 10 mins

• temperature is the varaiable (it changes)
• time is the constant (it remains the same)

heat (below boiling) for short period of time to kill pathogens and reduce bacteria count, does not kill all bacteria- some useless ones survive

high heat at a short period of time

method used to destroy spores

consists of heating the substance to boiling point and holding it there for 15 minutes, three days in succession. After each heating, the resting period will allow spores that have survived to germinate into bacterial cells; these cells will be killed by the next day's heating. During the resting periods the substance being sterilized is kept in a moist environment at a warm room temperature, conducive to germination of the spores (favorable environment for bacteria). When the environment is favourable for bacteria, it is conducive to the germination of cells from spores, and spores do not form from cells in this environment

a pressure chamber used to sterilize equipment and supplies by subjecting them to high pressure saturated steam at 121 °C (249°F) for around 15–20 minutes

KILLS SPORES

NO PENETRATION (ex. sound waves, visiable light)

PENETRATION (ex. gamma rays, Xrays, electron beams)

the passage of a liquid or gas (air) through a filter with pores small enough to remain microbes

pore size .45 or .2 micron

used with heat liable samples

light reactions

cyclic (mostly found in bacteria, used by cyanobacteria)

non-cycllic (found in green plants and cyanobacteria)

the cycle of reactions (the Calvin cycle) that occurs in the second phase of photosynthesis and does not require the presence of light

It involves the fixation of carbon dioxide

produces oxygen

carbon dioxide + water + light energy → carbohydrate + oxygen.

process where light energy is captured and converted to ATP, without the production of oxygen

water is not the electorn donor

light energy transformed into chemical energy

2 parts.....

• light reactions (require light)
• dark reactions (no light required)

lowest temperature where growth can occur

temperature where species grows the best

highest temperature where growth can occur

ph, osmotic pressure, food

cold-loving, grow at 0 to 20 degrees celsius,

• (optimum cold-loving temp 15 degrees Celsius)

middle temperature loving, human body temp, 20 degrees to 45 degrees celsius,

• (optimum middle-loving temp 20 - 37 degrees celsius) PATHOGEN

heat loving, grow at 37 to 65 degrees celsius

A psychrotroph can survive at a similar, but larger range than a psychrophile. It can survive from 0 - 35 degrees celsius but (optimally at 20 - 30 degrees celsius) These organisms can be found in refrigerated spoiled food.

6.5- 7.5

5 & 6

• grow in acidic enviroments such as: digestive tracts, dairy foods (yogurt), vagina
• considered probiotic Lactobacillus acidophilus (L. acidophilus) lactic acid bacteria

basic loving grown in intestines

optimum pH 8.5

due to their own waste products may be toxic due to pH change

bacterial metabolism

80-90%

water will move INTO cell (can cause cell to BURST)

water will move OUT of the cell (can cause cell to SHRINK)

salt loving

organism that can grow at high salt concentrations but DO NOT require high salt concentrartons

REQUIRES high salt concentration for growth

carbon, hydrogen, oxygen, nitrogen, phosphorus

inorganic elements required in small amounts (usually enzyme co-factors)

organisms produce more energy when growing in oxygen but toxic byproducts can be fatal to cells

superoxide radical (superoxide dismutase)

hydrogen peroxide (catalase, peroxidase)

oxygen

grow with or without oxygen

can NOT survive in oxygen environments

require SMALL (micro) or low amounts of oxygen

• superoxide dismutase
• catalase
• peroxidase

REQUIRE oxygen

can grow with or without oxygen

can NOT live with oxygen

tolerate oxygen

medium made of KNOWN amounts of chemicals

some ingredients are of unknown composition or amounts (extracts of plants, yeast, or meat) ex. nutrient broth tryptic soy broth

encourages the growth of certain organisms while discouraging the growth of others

• (ex. crystal violet, or basic dyes selective for Gram- against Gram+ (2 groups)
• MacConkey

distinguishes between different groups of bacteria. medium contains constituents which cause an OBSERVABLE change (color or pH change)

• ex: MacConkey contains lactose and netural red, lactose fermenters appear pink

the time required for cells to divide (and double the population) can be a short as 20 mins or longer than a day

5 generations

lag phase

log phase

log phase

1. plate counts
2. filtration
3. most probable number (statistical method)
4. direct microscopic count

cloudy (turbid) broth indicates greater bacterial population; estimate number of bacteria by analyzing turbidity with spectrophotometer (measures the amount of light passing through a culture); transmission of light is inversely proportional to population size of bacteria

does not distinguish between living and dead cells

estimates number of cells in a culture by measuring changes in metabolic processes (e.g., nutrient utilization, waste production, pH) ......ADD GLUCOSE

involves filtering mo's from culture medium, drying and then weighing; suitable for broth cultures, useful when there is an abundance of mo's; growth cannot be followed over time b/c mo's are killed in the process

more than half from Streptomyces and Bacillus and molds (fungi)

an antibiotic that acts against a wide range of disease-causing bacteria. A broad-spectrum antibiotic acts against both Gram-positive and Gram-negative bacteria.

• binds 50s subunit, inhibits peptide bond formation

an antibiotic effective against specific families of bacteria.

(small range of pathogens they are effective against)

penicillin (affects Gram positive bacteria)

Yes, broad-spectrum antibiotics can destroy the normal microbial flora.

highly effective against the microbe but have minimal or no toxicity to humans (host).

Alexander Fleming 1928

Howard Florey and Ernst Chain 1940

Penicillum

mode of action and which pathogen it is effective against

destruction of normal microbial flora can lead to a superinfection in which a survivng organism overgrows

A superinfection is generally defined as a second infection superimposed on an earlier one, especially by a different microbial agent of exogenous or endogenous origin, that is resistant to the treatment used against the first infection. An example of this in bacteriology is the overgrowth of endogenous Clostridium difficile which occurs following treatment with a broad-spectrum antibiotic.

• Clostridium difficle (c-diff)
• Candida albicans (yeast)

1. selectively toxic
2. soluble
3. resists excretion (breakdown)
4. shelf life
5. does NOT lead to resistance
6. cost

Peptidoglycan is found only in bacterial cell walls (animals do not have PGC/cell walls).
-Penicillin prevents the synthesis of PGC, weakening the walls and the cell undergoes lysis.

b-lactum ring

enzymes produced by some bacteria that provide resistance to β-lactam antibiotics like penicillins

penicillin and cephalosporin

vancomyicin

yes penicilinase is resistant to penicillin

occurs when the effect of two drugs together is greater than the effect of either alone

occurs when the effect of two drugs together is less than the effect of either alone

ex. penicillin does not worl well with tetracycline because cells are not growing

1. using outdated (weakened) antibiotics
2. using antibiotics for common cold and other inappropiate conditions
3. using antibiotics in animal feed
4. faliure to complete subscribed regimen of antibiotics
5. using someone else's leftover prescription

occurs when bacteria change in some way that reduces or eliminates the effectiveness of drugs, chemicals, or other agents designed to cure or prevent infections. The bacteria survive and continue to multiply causing more harm

Bactericidal: kills the bacteria.
-Bacteriostatic: inhibits the growth of the bacteria.

90%

yes

synthetic nucleosides which interfere with DNA and RNA synthesis

inactivate reverse transcriptase

to make DNA from RNA viral genome

Kirby-Bauer

Broth dillution

is an antibiotic useful for the treatment of a number of bacterial infections.

effective mostly against gram-positive (cell wall) bacteria

test which uses antibiotic-impregnated wafers to test whether bacteria are affected by antibiotics. In this test, wafers containing antibiotics are placed on an agar plate where bacteria have been placed, and the plate is left to incubate. If an antibiotic stops the bacteria from growing or kills the bacteria, there will be an area around the wafer where the bacteria have not grown enough to be visible. This is called a zone of inhibition.

the lowest concentration of an antimicrobial that will inhibit the visible g rowth of a microorganism after overnight incubation.

the lowest concentration of an antibacterial agent required to kill a particular bacterium.

from both dilution

1. inhibition of cell wall synthesis
2. inhibition of protein synthesis
3. inhibition of nucleic acid synthesis
4. injury to plasma membrane
5. inhibit the synthesis of essential metabolites

• simple structure
• easily manufactured
• broad spectrum
• SERIOUS SIDE EFFECTS (used only as last resort)

contain macrocyclic lactone ring

ex. erythromycin (not able to penetrate most Gram negative cell walls

erythromycin (macrolides)

• auditory nerve damage
• kidney damage

streptomyces

supress normal flora (causing superinfection)

not advised to:

children-brownish teeth

pregnant women-liver damage

stop folic acid synthesis (broad spectrum)

stops DNA gyrase (urinary tract infections)

topical

combined with bacitracin and neomycin in O-T-C preparation

they stop cartilage development

Antibacterial & anti-fungal drugs.
Polymyxin B and bacitracin cause damage to plasma membranes.