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Mutation
Mutation is a change in the DNA that can sometimes cause a change in the gene product, which is the target of the antimicrobial.
Destruction or Inactivation
Many bacteria possess genes which produce enzymes that chemically degrade or deactivate the antimicrobial, rendering them ineffective against the bacterium.
Efflux
Certain bacteria can often become resistant to antimicrobials through a mechanism known as Efflux. An efflux pump is essentially a channel that actively exports antimicrobial and other compounds out of the cell.
Conjugation
Conjugation is mediated by a particular kind of circular DNA called a plasmid, which replicates independently of the chromosome. Many plasmids carry genes that confer resistance to antimicrobials. When two cells are in close proximity to each other, a hollow bridge-like structure, known as a pilus, forms between two cells. This allows a copy of the plasmid, as it is duplicated, to be transferred from one bacterium to another.This enables a susceptible bacteria to acquire resistance to a particular antimicrobial agent.
Transformation
During this process, genes are transferred from one bacterium to another as "naked" DNA.
Transduction
In this process, bacterial DNA is transferred from one bacterium to another inside a virus that infects bacteria. These viruses are called bacteriophages or bacterial phage.
Cell competence
ability of a cell to take up extracellular (naked) DNA from its environment
Naked DNA
purified DNA sequence with no associated proteins
DNA supercoiling
over or underwinding of a DNA strand; an expression of the strain on that strand. Supercoiling is important in a number of biological processes, such as compacting DNA.
Topoisomerase
an enzyme that maintains the supercoiling of DNA; inhibited by fluoroquinolones
Enzyme Inhibitors
inhibit folic acid synthesis
Peptidoglycan
forms a mesh-like layer outside the plasma membrane of most bacteria, forming the cell wall.
30S Ribosome
tetracyclines use to decode mRNA
Selection Pressure
an agent of differential mortality or fertility that tends to make a population change genetically; any reason for organisms with certain phenotypes to have either a survival benefit or disadvantage.
B-Lactam
aka Penicillin; inhibit cell wall synthesis
Tetracyclines
inhibit protein synthesis and alters cell wall; bind to 30S ribosomal unit; effective against certain gram positive and negative bacteria
Fluoroquinolones
inhibits topoisomerases which block DNA replication; inhibit early fracture healing and increase rates of tendinitis; work on some gram positive and gram negative
Sulfa Antibiotics
inhibit folic acid synthesis and growth of gram positive and negative bacteria; does not work on human cells
Bacterial Cell Virulence Factors
Plasmid, Capsule, Pili, Endotoxins, Endotoxin LPS layer (in Gram Negative)
Nucleoid
contains bacterial DNA, RNA and proteins
Plasmid
contains code responsible for antibiotic resistance and other characteristics
Ribosomes
performs protein synthesis by reading RNA
Cell Wall
holds bacterial cell together and protects surface
Cell Membrane
holds parts of cell together; responsible for diffusion and transport of materials
Capsule
protects the cell and inhibits phagocytosis by the host cell
Flagella
help cell move
Pili
allow bacteria to attach to other cells
Endotoxins
released into the body when gram negative dies
What color does Gram + turn when stained
purple
What color does Gram negative turn when stained
red
A chemical removes the cell wall, but leaves the rest of the organism untouched. What does the bacteria lose?
The ability to have a gram stain result
Are bacteria ever naturally resistant?
No
What structure distinguishes prokaryokic and eukaryotic cells?
A nuclear membrane
Antibiotic
A substance produced by or derived from a microorganism and able in dilute solution to inhibit or kill another microorganism
Antibiotic Resistance
Resistance to one or more antibiotics, usually due to additional genetic information