Lecture 8 Flashcards
What does PCR stand for and what is it used
for?
Polymerase chain reaction. Its used for
replicating a specific piece of DNA in a test
tube.
What are some advantages and potential
applications of CPR?
Advantages of PCR:
Sensitive: Can amplify a single gene copy
Specific: Can be made to amplify a specific
gene in a complex mixture
Rapid: Can replicate target DNA from a few
copies to billions of copies in a few hours
Some important uses of PCR
• Identify the presence and abundance of a
specific gene in a sample
• E.g. for clinical diagnostics, or crime scene
investigation (CSI)
• Identify the presence and abundance of
microbes in a sample
• E.g. PCR targeting SSU rRNA genes
• Combined with sequencing, can be used to
identify microbes
• Isolate a specific gene from a sample for
molecular cloning
What are the components in PCR?
- Template DNA
- Primers
- DNA polymerase
- dNTP
Which components determines the specific
region of DNA that will be amplified?
TEMPLATE DNA
Why is the TAQ DNA polymerase used?
“Taq” polymerase isolated from the
thermophile Thermus aquaticus • Remain
active at elevated temperatures used in PCR
What are the 3 steps in PCR?
- Denaturation
- Priming
- Extension
How does repetition in the steps result in
exponential amplification of the specific
region of template DNA?
Amplified DNA from one step acts as
template in the next step, resulting in
exponential amplification
What is sterilization, disinfection,
decontamination, sanitization, antisepsis,and degermination?
1. Sterilization: Process or chemical agent (sterilant) that destroys orremoves all viable microorganisms (including viruses) 2. Disinfection: Physical process or a chemical agent (disinfectant) to destroy vegetative pathogens but not bacterial endospores 3. Decontamination/Sanitization: Cleansing technique that mechanically removes or inhibits microorganisms to reduce contamination to safe level 4. Antisepsis/Degermation: Reduces the number of microbes on the human skin
Which can be used on the skin?
Decontamination/ sterilization
Antisepsis/ degermation
Why is killing bacterial endospores
considered the gold standard of sterilization>
Bacterial endospores have traditionally been
considered the most resistant microbial
entities
What is the relative resistance to antimicrobial agents among bacterial endospores, vegetative Gram positives, vegetative Gram negative cells, and enveloped viruses?
1. Endospores are among the most resistant 2. Viruses are usually the most susceptible 3. Gram negatives (outer membrane) are typically more resistant that Gram positives and fungi
How is microbial death defined?
Permanent termination of an organism’s vital
processes
What are factors that might affect the
amount of time a given sterilization
technique needs to be applied?
- The nature of the microorganisms in
the population
- State of microbes in the population
- Temperature and pH of the
environment
- The concentration (dose, intensity) of
the agent
- The presence of solvents, interfering
organic matter, and inhibitors
What is sepsis and asepsis?
Sepsis: The growth of microorganisms in theblood and other tissues
Asepsis: State of being free from disease-
causing contaminants (such as bacteria,
viruses, fungi, and parasites) or,
contact with microorganisms.
What is the difference between microbicidal
and microbiostatic?
Have the suffix –cide or –cidal, meaning
“killing” or “to kill”
Stasis and static mean “to stand still” (used
as suffix –static)
