Unit 6 Flashcards
Milk is _________ lowering the number of pathogenic bacteria using heat for a short period of time without changing its taste.
Pasteurized
Beef jerky is an example of using _________ to preserve food.
Desiccation (super dry)
What is UHT sterilized?
UHT, or Ultra High Temperature, is a food processing method that sterilizes liquid foods by heating them to a high temperature for a short time
Degerms:
removes germs from something (like skin)
Autoclave meaning:
Sterilize using high-pressure saturated steam at a specific temperature, typically 121°C, for a set period of time.
Disinfect meaning
Eliminate most or all harmful microorganisms (except some spores) on its surface, typically using chemical agents.
Filter meaning:
Remove particles or impurities from a liquid or gas by passing it through a porous material that traps contaminants
Sanitized meaning:
Reduce the number of harmful microorganisms on a surface or object to a safe level, usually through cleaning or chemical treatment
How can a bacterium gain antibiotic resistance?
2 ways
- Random mutation
- Or through gene transfer from another bacterium
What happens when a person is given an antibiotic?
(think about antibiotic resistance)
It kills the cells that are not resistant but the ones that are survive and are able to multiply freely
Transformation vs Transduction vs Conjugation
Transformation: when a cell picks up a piece of DNA from its surroundings
Transduction: when a bacteriophage transfers the gene from one cell to another
Conjugation: when R plasmids or R factors transfer the genes to other bacterial cells
What is meant when a bacterium is said to become “resistant” to an antibiotic?
The bacterium is neither killed nor inhibited by the antibiotic
When a patient is treated with antibiotics, the drug will __________ of all of the sensitive ______
kill or inhibit the growth; bacterial cells
The process of acquiring antibiotic resistance by means of bacteriophage activity is called
Transduction
What is a Missense mutation?
A single nucleotide change results in a different amino acid being incorporated into the protein, which can alter the protein’s function
What is a Nonsense mutation?
A single nucleotide change converts a codon into a stop codon, prematurely terminating protein synthesis and often resulting in a nonfunctional protein
What is a Silent mutation?
A single nucleotide change that does not alter the amino acid sequence of the protein due to the redundancy of the genetic code, typically having no effect on protein function
What is a Frameshift insertion?
An extra nucleotide is added to the DNA sequence, shifting the reading frame and often resulting in a completely different and usually nonfunctional protein
What is a Frameshift deletion?
A nucleotide is removed from the DNA sequence, shifting the reading frame and often leading to a drastically altered and usually nonfunctional protein
Which mutation would not result in antibiotic resistance?
Silent mutation;
because there is no effect
R-plasmids are most likely acquired via ___
bacterial conjunction
The figure represents a Petri plate. The gray area is where bacteria A is growing(large), the black area is where bacteria B is growing (tiny). The white area is a zone where neither organism is growing. What is the best interpretation of what is observed on the plate?
Bacteria B is producing an antibiotic that inhibits the growth of bacteria A
Why do antimicrobial agents active against mycobacteria have to be administered for months or years rather than the typical 10-30 days prescribed to treat other infections?
Mycobacteria reproduce very slowly;
Mycobacteria take 12-24 hours to reproduce, in part due to their complex cell walls. Therefore, drugs against these bacteria must be administered over long periods of time
An antimicrobial disk on a Kirby-Bauer plate that shows no zone of inhibition indicates that the microbe being tested is __________ to the drug.
resistant;
A zone of inhibition measures the effectiveness of a drug; a disk with no zone at all would clearly indicate a microbe resistant to that drug.
Susceptible:
(disk)
The microorganism is inhibited or killed by the antimicrobial agent, as evidenced by a clear zone of inhibition around the disk.
Intermediate:
The microorganism shows partial inhibition, meaning it may be inhibited at higher concentrations of the antimicrobial or under specific conditions
Synergistic:
The effect of two or more antimicrobial agents working together, where their combined effect is greater than the sum of their individual effects
Antibiotic resistance:
This occurs when bacteria evolve to become resistant to the effects of an antimicrobial drug that was previously effective
Selective toxicity:
This refers to the ability of a drug to harm pathogens without damaging the host’s cells, which is crucial for effective treatment
Narrow spectrum of action:
This refers to an antimicrobial that targets a limited range of microorganisms
Ex. only Gram-positive bacteria
A broad-spectrum antimicrobial:
This is an antibiotic that is effective against a wide range of microorganisms
Amoxicillin is very effective for treating infections with Gram-positive bacteria but rarely causes side effects in humans. This is an example of _____
selective toxicity
Which activity can be shown to increase resistance among microbial populations?
taking ______ drugs for ______ infections;
taking antibacterial drugs for viral infections;
Taking antibacterial drugs when they are not needed (such as for viral infections) contributes to the development of antibiotic resistance. This misuse or overuse can encourage bacteria to evolve and become resistant to the drugs.
How does resistance to drugs spread in bacterial populations?
Horizontal gene transfer between bacteria spreads R (resistance) plasmids
Drug-resistant populations of microbes arise when ______
exposure to drugs selectively kills sensitive cells, allowing overgrowth of resistant cells
