This media inhibits growth for some bacteria while selecting for growth for others
Selective Media
What type of bacteria is inhibited by dyes?
Gram (+)
Most gi infections are caused by what type of bacteria?
Gram (-)
These two types of agar are commonly known for inhibiting bacteria by the use of dye.
Brilliant Green Agar
EMB (Eosin Methylene Blue)
When using this type of selective media, E.Coli will give off a green metallic color.
EMB (Eosin Methylene Blue)
What does EMB stand for?
Eosin Methylene Blue
This type of media differentiates between different organisms growing on the same plate.
Differential Media
This type of differential media is used to differentiate between different types of streptococci.
Blood Agar Plate
What is a blood agar plate?
TSA with 5% sheep blood
Using a blood agar plate, this leaves a incomplete lysis of RBC leaving a yellow-green zone.
Alpha hemolysis Streptococci
Using a blood agar plate, this leaves a lysis of RBC leaving a clear zone.
Beta Hemolytic Streptococci
What is the most common type of streptococci found on a blood agar plate?
Beta hemolytic streptococci
Using a blood agar plate, this leaves no lysis of RBC leaving no zones.
Gamma hemolytic streptococci
What does MRSA stand for?
Methicillin Resistant Staphylococcus aureus
This type of media is used to identify Staphylococcus aureus.
Mannitol Salt Agar
How does Mannitol Salt Agar inhibit bacteria?
High salt concentrations (7.5%)
How does Mannitol Salt Agar identify Staphylococcus Aureus?
Staphylococcus aureus ferments sugar manittol causing a yellow halo (acidic)
What type of media is used to identify Salmonella?
MacConkeys Agar
What inhibits gram (+) bacteria when using MacConkeys Agar?
Bile salts and crystal violet
When a MacConkeys Agar is used, how can you identify Salmonella?
Many non pathogenic gram (-) bacteria can ferment lactose turning the pH indicator red but Salmonella cannot and remains clear.
Increase in the number of cells
Bacterial growth
Time required for a cell to divide
Doubling/Generation time
What is E. coli's doubling time?
20 minutes
What is Mycobacterium tuberculosis's doubling time?
24 hours
What is the common doubling time for most bacteria?
1-3 hours
If binary fission is unchecked for a species of E. coli, what is the doubling time for 20 generations in 7 hours?
1 million cells
If binary fission is unchecked for a species of E. coli, what is the doubling time for 30 generations in 10 hours?
1 billion cells
If binary fission is unchecked for a species of E. coli, what is the doubling time for 72 generations in 24 hours?
1*1021
Six limiting factors in the environment that stop bacteria from reaching the reporductive maximum.
Lack of food, water, or nutrients
space
accumulation of metabolic waste
lack of oxygen
change in pH
temperature
Name the 4 phases of growth
Lag Phase
Log Phase
Stationary Phase
Death Phase
In the lag phase, bacteria are first introduced into the environment/media. Explain what happens.
Bacteria check out environment, very active metabolically, number of cells changes very little.
How long does the lag phase last?
1hr to several days
In the log phase, bacteria rapidly multiplies causing exponintial growth. Explain what happens.
Population doubles every generation and sensitive to adverse conditions such as antibiotics and antimicrobial agents
In the stationary phase, what happens?
Death rate is equal to the rate of production, they encounter environmental stress producing endospores
In the death phase, what happens?
Death rate is greater than rate of reproduction causing the populations to reduce to a tiny fraction or it dies completely
What causes the death rate to be so high in the death phase?
Limiting factors in the environment
Enumeration of bacteria can be assumed by what process?
Serial dilution
How many bacterial cells in a turbid culture?
10 million per mL
In the history between humans and microbes, identify five issues between the two.
Infection
Disease
Plagues
Epidemics
Pandemics
Continental wide illness
Epidemic
World wide illness
Pandemic
What is another name for the Bubonic Plague?
Black death
This epidemic swept through Europe in the middle ages
Bubonic Plague
What centuries did the bubonic plague effect?
13th and 14th centuries
How many people were killed from the Bubonic Plague? What fraction of the continent was this?
40 million, approximately 1/3 the continental population
Identify two vectors of the Bubonic Plague
Rat
Flea
Identify the Etiology Agent of the Bubonic Plague
Yersinia pestis
Describe the bacteria Yersinia pestis
Gram (-) bacelli
What is the term describing bacteria in the blood?
Bacteremia
Identify the three stages of the bubonic plague infection
Flea bites containing Yersenia pestis
Bacteria enters the blood stream
Bacteria localized in lymph nodes within the axillary and groin regions
Black and blue swelling in the lymph nodes after being infected by the Bubonic Plague
Bubos
What causes Bubos?
Hemorrhaging in the lymph nodes
What is the mortality rate of the Bubonic Plague?
50%
What can the Bubonic Plague be called after infecting the lungs?
Pneumonic Plague
What is the mortality rate of the Pneumonic Plague?
99%
This nursery rhyme refers to the Bubonic Plague
Ring Around the Rosie
Identify the meaning behind each line of the nursery rhyme that refers to the Bubonic Plague.
Ring Around the Rosie - Bubos
Pocket Full of Posies- Posies were thought to keep evil spirits away that caused the Bubonic Plague
Achoo Achoo - sneezing after the bubos occur
We All Fall Down - Death
Where did the saying "I wouldn't touch it with a ten foot pole" come from?
When the people would move bodies that were infected with the Bubonic Plague they would use a 10 foot pole to avoid being affected.
Throughout history who has been winning the battle between humans and microbes?
Microbes
In the past 100 years, the battle between microbes and humans has changed. How?
Humans are taking control of microbial growth.
Where can viles of the Variola virus be found?
Center of Disease Control
CDC
Center of Disease Control
USSR
Institute of virologoy
WHO
World Health Organization
When and where was the Variola Virus eradicated?
Somalia in 1977
Small Pox
Variola Virus
Name two methods of controlling microbial growth.
Physical
Chemical
Destroying all forms of life
Sterilization
Destroying vegetative pathogens or unwanted organisms
Disinfection
Antimicrobial agent used on inanimate objects
Disinfectant
Antimicrobial agent used on live tissues
Antiseptic
Kills bacteria
Bactericidal
Inhibits bacteria growth
Bacteristatic
Seven factors that affect antimicrobial activity
Temperature
Degree of Contamination
Time
Concentration of antimicrobial agents
Sensitivity of the microbe
Activity of microbe
Organic matter
Name three targets of a antimicrobial agent
Cell membrane
Enzymes/Proteins (Cell Wall)
DNA/RNA
What does heat do to a microbe?
Denaturizes proteins and enzymes (Cell Wall)
Lowest temperature at which all microorganisms in a liquid culture are killed in 10 minutes
Thermal Death Point
Minimum length of time in which all microorganisms in a liquid culture are killed at a given temperature.
Thermal Death Time
Two methods of Moist Heat
Boiling water
Autoclave
What type of antimicrobial process is boiling water?
Disinfection
What does boiling water kill?
Vegetative bacterial cells, fungi, and many viruses.
What type of microbes can resist the heat of boiling water?
Endospores and some Viruses
How long can Hepatitis A last in boiling water? What about it's endospores?
20 minutes
20 hours
What type of antimicrobial process is an autoclave?
Sterilization
What is an autoclave?
Steam under pressure
What does increased pressure do to boiling water?
Increases temperature
In an autoclave, if 15 psi is exerted on boiling water, what temperature can be reached?
121 degrees Celcius
What is the time and temperature required for no known microbe to survive?
121 degrees Celcius for 15 minutes
What does a Kilit Ampule do?
Grows Bacillius stearothermophilis
How does a Kilit Ampule work?
The spores of Bacillius stearothermophilis are inserted into a kilit ampule along with fermentable sugar incubated at 55 degrees celcius and is watched for fermentation. When fermentation occurs, the pH indicator will change from purple to yellow.
Identify three methods of dry heat
Direct flaming
Incineration
Hot air sterilization
How can direct flaming dry heat be accomplished? What is its effectiveness?
Innoculating loop and needle, 100% effective
How can incineration dry heat be accomplished?
Disposable waste is burned to ash.
When is hot air sterilization dry heat necessary?
When a substance could be damaged by moist heat.
What is hot air sterilization?
Oven set at 170 degrees celcius for 2 hours.
This method removes microbes from solutions that might be damaged by heat
Filatration
What is the diameter of each pore of the filtration process? Why is this important?
.22 u, bacteria is .2-2 u
What is a fault of the filtration method?
Does not collect all viruses
What can filtration be used for?
Culture media
Enzymes
Vaccines
Antibiotics
Name two types of radiation.
Ionizing radiation
Non Ionizing radiation
What is ionizing radiation?
Gamma rays and xrays
What type of substances are penetrated by ionizing radiation?
Most
What is ionizing radiation used on? Example?
Substances that can be damaged by heat
Eg, plastic, catheters, and surgical gloves
What is non ionizing radiation?
UV light
What is the purpose of non ionizing radiation? Example
Reduce microbial population
Eg, Hospital rooms, nursery, operating rooms
What is a thymine dimer?
A bulge in DNA strands from a thick bond
What is pastuerization?
A disinfectant that removes unwanted organisms.
A microbe that can survive very high temps can be described as what?
Thermoduric
HTST
High temp for short time
What is the temp and time of HTST pastuerization?
72 degrees celcius for 15 seconds
Before HTST pastuerization what was the ideal temp and time for pasturization?
63 degrees celcius for 30 minutes
Identify the two types of genetic material
DNA
RNA
Nucleotides
What does DNA stand for?
Deoxyribose Nucleic Acid
What does RNA stand for?
Ribonucleic Acid
Identify the three parts of a nucleotide
Phosphate group
Pentose Sugar
Nitrogenous Base
What are the complimentary base pairs of DNA?
Adenine - Thyrosine
Cytosine - Guanine
In RNA what base is replaced in the complimentary base pairs?
Thyrosine with Uracil
Identify the proper stucture of DNA
Double Helix
Polymers of Nucleotids
Complimentary Base Pairing
Antiparallel (5' - 3')
How many chromosomes does bacteria have? What is it called?
One. ccDNA
Where does DNA Replication occur?
At the replication fork
What enzyme connects the okasaki fragments?
DNA ligase
What are the two strands of the replication fork?
Leading Strand
Lagging Strand
Which strand of the replication fork continues replication?
Leading Strand
Which strand of the replication fork discontinues replication?
Lagging strand
What enzyme begins the replication fork?
DNA helicase
What enzyme occurs at the leading strand?
DNA polymerase
What does RNA polymerase do?
RNA primer
What does DNA polymerase do?
Extends primer and digests 5' RNA
What three enzymes occur at the Lagging Strand?
RNA polymerase
DNA polymerase
DNA ligase
Explain bidirectional replication.
the nucleus of a cell is split into two by starting at an origin of replication and going opposite ways until reaching a termination site.
What is another name for protein synthesis?
Central dogma of molecular genetics
Diagram Protein Synthesis
DNA ---Transcription---> mRNA ---Translation---> Protein
mRNA
messenger RNA
What is it called when one strand of DNA is used as a template to form a complimentary strand of mRNA
Transcription
3 Ways RNA differs from DNA
RNA is single stranded - DNA is double stranded
Ribose - Deoxyribose
A-U ; C-G | A-T ; C-G
Where the DNA helicase "unzips" the double strand.
Promotor
What form does the genetic code come for DNA?
Triplet code
What form does the genetic code come for mRNA?
Codons
What form does the genetic code come for tRNA?
Anti codons
What do codons code for?
Amino Acid
How many amino acids are there in the human body?
20
There are three codons that DO NOT code for an amino acid, what are they called?
Nonsense codons
How many bases per codon?
3
If there are 3 base codes and 4 bases, how many total codons are there? How many do not code for an amino acid?
64 possible, 3 do not code for amino acids.
What are codons called that code for amino acids?
Sense codons
True or False? Amino Acids can be coded for by more than one codon.
True
Degenerative code can be described as two things. What are they?
Degenerative
Universal
This codon is a sense codon, its a special codon to start translation.
AUG
Three pieces of translation
rRNA
tRNA
anticodon
Three steps of Translation
Initiation
Elongation
Termination
what does rRNA stand for?
Rhibosomal RNA
what does tRNA stand for?
Transfer RNA
What is an anticodon?
three base sequence that is complimentary to the codon on mRNA
This forms 70s rhibosomes when discussing genetics.
rRNA
This transfer amino acids to rhibosomes for protein synthesis when discussing genetics.
