Microbiology and infection control Flashcards
What are the 4 main ways bacteria are classified?
- Morphology
- Staining
- Encapsulation
- Oxygen requirements
What are the 3 main shapes of bacteria?
- Cylindric (bacilli)
- Spherical (cocci)
- Spiral (spirochetes)
(A few coccal, many bacillary, and most spirochetal species are motile.)
What colour are gram positive and gram negative bacteria after they have been stained?
- Gram-positive bacteria retain crystal violet dye (DARK BLUE) after iodine fixation, alcohol decolorization, and counterstaining with safranin
- Gram-negative bacteria, which do not retain crystal violet, appear red.
what is the shape of a bacillus?
(Rod-shaped)
What shape is a Spirilla or spirochete?
(Spiral)
What shape is a coccus
(Sphere)
What shape is a Vibrio?
(Comma-shaped)
Are bacteria Prokaryotic or eukaryotic cells?
Prokaryotic
What are Prokaryotic cells?
Any organism that lacks a distinct nucleus and other organelles due to the absence of internal membranes.
What are eukaryotic cells
Any cell or organism that possesses a clearly defined nucleus
What bacteria structure protects the bacteria and gives it shape?
Cell Wall: The cell wall is an outer covering that protects the bacterial cell and gives it shape.
Do bacteria have a nucleus?
No because they are prokaryotic
what are bacteria cell walls composed of?
peptidoglycan.
Which bacteria structure helps bacteria move?
Flagellum - long, whip-like protrusions that aid in cellular locomotion.
Flagella: Plural
How do antibiotics work against bacteria?
Antibiotics are chemicals that kill or inhibit the growth of bacteria and are used to treat bacterial infections.
What is antibiotic resistance?
Bacteria are termed drug-resistant when they are no longer inhibited by an antibiotic to which they were previously sensitive. The emergence and spread of antibacterial-resistant bacteria has continued to grow due to both the over-use and misuse of antibiotics.
How is antibiotic resistance spread?
Antibiotic resistance can either be inherent or acquired. Some bacteria are naturally resistant to some antibiotics due to their physiological characteristics. This is inherent resistance. Acquired resistance occurs when a bacterium that was originally sensitive to an antibiotic develops resistance
are viruses considered a form a life?
No-viruses today are thought of as being in a grey area between living and nonliving
What is the approximate size of a bacteria?
between 0.2 and 2.0 micrometer (avg 1000nm)
What is the approximate size of a virus (in nm)
20-400nm
What does a virus need to reproduce?
A virus needs a living host cell in order to reproduce
What do all viruses have in common?
All viruses have capsids.
Name two types of genetic material than can be found in viruses.
DNA or RNA
What is the function of the Capsid?
The capsid has three functions:
It protects the virus.
It contains special sites on its surface that allow the virus to attach to a host cell.
It provides proteins that enable the virus to penetrate the host cell membrane.
What are the two life cycles of a virus has called?
The Lytic Cycle
The Lysogenic Cycle
Which of the two cycles does the virus DNA (or RNA) become incorporated into the host cell DNA?
The Lysogenic Cycle
What is a bacteriophage?
The viruses that infect bacteria are called bacteriophages
Why are viruses not classed as “living”, give TWO reasons for this.
They are not made of cells,
they do not use and obtain energy,
they do not respond to the environment.
they need a living host
Name 3 differences between an cell and a virus.
viruses do not have nucleus where as cells will
viruses reproduce only with a host cell, cells reproduce asexually or sexually
Cells grow and develop, viruses do not
Some bacteria can live either with or without oxygen and are known as what?
Anaerobic bacteria: This type of bacteria would only become active in the absence of free oxygen. They live in deep soil or muddy water.
Some bacteria cannot survive / grow when oxygen is not present and are known as?
Aerobic bacteria: This type of bacteria require plenty of free oxygen for growth.
what is facultative anaerobic bacteria
This type of bacteria would be active no matter if there is free oxygen or not.
what is Microaerophilic bacteria
This type of bacteria would be the most active in the presence of a little free oxygen.
What micro-organism causes “TB” in humans?
The germ is called Mycobacterium, which differentiates itself from normal bacteria with a special outer membrane made of mycolic acid
What shape are TB?
small bacillus
what immunisation (hint: 3 letters) is available to help protect you from TB?
BCG Vaccine
How many stains are used in a gram stain?
2: water-soluble dye called crystal violet & counterstaining, usually with safranin
What colour are gram positive bacteria following the gram stain?
Blue/purple
Which component of a bacteria takes up the stains
Cell wall. Gram-positive (Thick)/Gram-negative (Thin)
Which group of bacteria take up the primary stain?
Gram-positive
What are the three main classes of protozoans that are of major medical importance? - the first letter of each has been included below:
Amoebae
Flagellates
Sporozoans
Name the 5 main species of protozoa and the disease they cause from each of the above classes? -
Entamoeba histolytica- Causes amoebic dysentery
Giardia lamblia- Causes Giardiasis
Trypanosoma- Causes African sleeping sickness.
Plasmodium- Causes Malaria
Toxoplasma gondii- Toxoplasmosis
How is Entamoeba histolytica acquired?
The ingestion of cysts in fecally contaminated food or water.
The world’s most common cause of water-borne diarrhoea is caused by which type of Protozoa?
Giardia
What is the vector for Plasmodium and what disease does this protozoa cause?
Mosquitoes and they cause malaria
Name three ways that protozoan infections can spread in humans
- contaminated water
- cats
- insect bites
How many phases are in a bacterial growth pattern- What are these? (i.e. The Growth Curve)
4;
- Lag phase
- Log phase
- Stationary phase
- Death or decline phase
Explain the lag phase (growth curve)
- No increase in number of living bacterial cells
Explain the Log phase (Growth Curve)
Exponential increase in number of living bacterial cells
Explain the stationary phase (Growth curve)
Plateau in number of living bacterial cells; rate of cell division and death roughly equal
Explain death or decline phase (Growth Curve)
exponential decrease in number of living bacterial cells
Which reproductive cycle results in diploid cells?
Lysogenic
sexual (conjugation between 2 individuals).
When would the yeast produce diploid cells?
When a cell of one mating type encounters one of the other mating type, they initiate a series of events that leads to conjugation. The result is a diploid cell
Which has more chromosomes; Haploid or Diploid cells?
Haploid (1) cells have half the number of chromosomes (n) as diploid (2)
What is a spore?
a spore is a reproductive structure that is adapted for dispersion and surviving for extended periods of time in unfavorable conditions.
What is a spore?
a spore is a reproductive structure that is adapted for dispersion and surviving for extended periods of time in unfavorable conditions.
What Ph is best for bacteria
6-8 Ph as most bacteria are nuetrophiles
What is cell lysis
Lysis is the breaking down of the membrane of a cell, often by viral, enzymic, or osmotic mechanisms that compromise its integrity
What is a toxin
a poison of plant or animal origin, especially one produced by or derived from microorganisms and acting as an antigen in the body.
What is the structure of bacteriophage, from Top to bottom
Capsid head Nucleic acid(DNA) Collar Sheath Baseplate Spikes Tail fiber
What are the 5 stages of the lytic cycle
- Attachment
- Penetration
- Biosynthesis
- Maturation
- Lysis
Explain binary fisson in bacteria
- DNA locates mid-cell
- DNA Replicates
- DNA separates
- Cell wall folds
- Cells divide
Explain the malaria life cycle
- First the infective parasite injects sporozites
- these go to the liver then reform as merozites which destroy lots of red blood cells
- these go to gametocytes and eventually back to a mosquito to start the process again
what is direct transmission
when a pathogen is transmitted directly from an infected individual to you
what is indirect transmission
When an inanimate object serves as a temporally resovoir for an infectious agent
What is vertical transmission
Transmission from mother to child
What is a plasma membrane
A selective barrier which encloses a cell
What is Cytosol
Located in the plasma membrane jelly like fluid that supports organelles
What is cytoplasm
the cytosol and all organelles other than the nucleas
What is a Ribosome
The organelles where proteins are made
What is DNA in a cell
Genetic material
From outside to in label a bacteria
- Capsule + flagellum- pilli can also be on the outside
- Cell wall
- plasma membrane
- Cytoplasm
- Ribosomes
- Plasmid
- DNA
5 steps of gram staining
- fixation
- Crystal violet
- iodine treatment
- Decolorization
- Counter stain with safranin
What is the spore life cycle
- Conidia (Spores)
- Germination
- Hyphae and subsurface hyphae
- Aerial hypha
- conidiophore
Name all the parts of a yeast cell
- Cell wall
- cell membrane
- cytoplasm
- mitochondria
- Nucleus
name all parts of an envelope virus
- Antigen on outside (little spikes)
- Envelope
- Capsid
- Dna/Rna
