Exam 1 Flashcards
What is microbiology?
The study of living things that are too small to be seen without any magnification
What are some microorganisms? (7)
Bacteria Archea Fungi Protists Algae Viruses Helminth warms
Why are microbes important? Give 2 examples
Microbes are important for nutrients and energy cycling
Ex: 1) Photosynthesis, light energy converted into chemical energy
2) Decomposition, break down complex molecules
What are some ways in which humans use microorganisms? (3)
1) Industry, food and chemical production
2) Biotechnology, drug and vaccine production
3) Bioremediation, use of microbes to break down unwanted or harmful waste products
What are the three most important diseases caused by microorganisms in the US?
Influenza
Pneumonia
Septicemia (bloodstream infection)
What are the four most common diseases caused by microorganisms world wide?
Respiratory infections
HIV/AIDS
Diarrheal
TB
Describe Prokaryotes
Unicellular organisms
Lack nucleus and other membrane bound organelles
Include bacteria and archea
Describe eukaryotes
Unicellular OR multicellular
Contain nucleus and membrane bound organelles
What are viruses?
Acellular particles composed of nucleic acid packaged in a protein coat
Who was Robert Hooke?
Used microscopes to examine surfaces and living things
First description of organisms and cells
Who was Antony Van Leeuwenhoek?
Made his own lenses
Observed organisms
Who was Edward Jenner?
Investigated reports that those who developed cowpox did not com down with small pox
First vaccine
Who were Oliver Wendell Holmes and Ignaz Semmelweis?
They made the link between doctors not washing their hands and hospital infections. They noticed that puerperal fever was a common infection during child birth. Semmelweis insisted that doctors washed their hands with calcium chloride solution between patients. Deaths on maternity wards fell from 12% to 1%. Holmes noticed similar link, and also between work on cadavers and subsequent infections.
Who was Joseph Lister?
Developed aseptic technique. He noticed that patients who survived surgery often died soon afterwards of “ward”fever. He suggested to use phenol to sterilize surgical instruments. Death rates fell from 45% to 15%
What is the spontaneous generation hypothesis?
Vital forces in non living matter produced living things
What is the biogenesis hypothesis?
Living things arise from preexisting living cells
Who was Louis Pasteur?
Disproved spontaneous generation. Studied fermentation and food spoilage. Developed pasteurization. Made links between microbes and diseases. Developed vaccines for anthrax and rabies
Who was the “Germ Theory King”?
Robert Koch
First to link a disease to a microbe and outline germ theory. 21 diseases were identified as caused by microbes
What are the Koch’s postulates?
1) The microorganisms must be present in every case of the disease
2) The microorganism must grow in pure culture from diseased hosts
3) The same disease must be produced when a pure culture of the microorganism is introduced into susceptible hosts
4) The same microorganisms must be recovered from experimentally infected hosts
Who was Alexander Fleming?
He discovered the first modern antibiotic penicillin. He also discovered lysozyme, a protective digestive enzyme
Who was Selman Waksman?
Discovered streptomycin and coined the term antibiotic
What is a scientific method?
Deductive reasoning process to investigate the world around us.
What are the five “I”’s of culturing microbes?
1) Inoculation
2) Isolation
3) Incubation
4) Inspection
5) Identification
What is inoculation?
Introduction of a sample into a container of media to produce a culture of observable growth
What is isolation?
Separating one species from another
What is incubation?
Placing a sample under conditions that allow growth. Cells divide and provide observable growth. Different organisms have different temperature preferences.
Inspections and identifications
Make macroscopic and microscopic observations of the growth, biochemical test etc..
What are two isolation methods developed by Robert Koch?
1) Streak plate technique
2) Pour plate technique
What is the difference between a “pure culture” and “mixed culture”?
One type of organism vs. more than one type of organism
How disposal of cultures happen?
Potentially hazardous cultures and specimen are usually disposed of by: steam sterilization or incineration
What is the general purpose of media?
Support growth of many different types of organisms
What are some common examples of media?
Nutrient agar and tryptic soy agar
What is selective media?
One type of organism can grow
What is differential media?
Two types of organisms can grow, but they will difference in appearance
What is complex media?
Exact chemical composition is unknown, contain break down product of yeast, animal or plant material
What is defined media?
We know the exact chemical compostion
What are two key characteristics of a reliable microscope?
Magnification, the ability to enlarge objects
Resolving power, the ability to show details
What is resolution?
The ability to distinguish two objects as separate objects
What is light microscopy bright field?
Standard lab microscope
Light source is visible light, can be used for live, fixed or stained samples.
What is light microscopy dark field?
Light directed as sample from an angle. Better visual contrast between cells and background. Can view living, mobile cells, no staining is required
What is staining?
Stains enhance difference between cells and background, increase contrast.
Simple stain vs. differential stain
Simple, uses only one stain
Differential, uses at least two stains
Positive stain vs. negative stain
Positive, stains cells
Negative, stains background
Why are electron microscopes better In resolution?
They have shorter wavelength, which means greater resolution. Can examine viruses and internal structures.
What is TEM?
Transmission Electron Microscopy
Electrons pass through the sample, you can view internal structures
What is SEM?
Scanning Electron Microscopy
Electrons are aimed at surface of the structure, being reflected and detected, this will result in a 3D image
What is the functional definition of species?
A group of organisms that interbreed to produce viable offspring
What are the 8 levels of classification?
1) domain
2) kingdom
3) phylum or division
4) class
5) order
6) family
7) genus
8) species
What are the domains of life and who determined them?
Bacteria
Archea
Eukarya
Carl Woese
What is taxonomy?
A group of organisms based on similarities
How can you determine taxonomy?
Look at sequences of RNA sequences/genes Cell morphology colony appearance Bacterial physiology Serological analysis Genetic and molecular analysis
What is the bacterial physiology based on?
Bergy’s manual of the systematic bacteriology
What is the definition of species for bacteria?
Collection of bacterial cells sharing overall pattern of traits that differ from the pattern in other bacteria.
What is a strain or variety?
A culture obtained from a single parent that differs in structure or metabolism from other cultures of the species
What is a “type”?
A subspecies that can show differences in antigenic makeup (serotype or serovar). Susceptibility to bacterial viruses (phage type) and in phatogenicity (phatotype)
How is phenotypical qualities used for identification in clinical diagnosis?
Divide bacteria based on cell wall structure, shape, arrangement, and physiological traits. Used for clinical identification of pathogens not taxonomy
What are the types of coccus (sphere) bacteria?
1) Diplococci: pairs of cells
2) Streptococci: chains of cells
3) Tetrads: four cells
4) Sarcinae: cubes or packets of cocci
5) Staphylococci: grape-like bunches
What are the types of bacillus (rod) bacteria?
1) Diplobacilli: pairs of bacilli
2) Streptobacilli: chains of cells
3) V-shape and palisade arrangement
Vibrio
Curved
Spirillum
Rigid curved spiral
Spirochete
Flexible cork screw
What is a pleomorphic bacteria?
A bacteria that lack a cell wall in varied cell shapes
What is the outer coating membrane of a bacteria called? What are some characteristics of this membrane?
The outer membrane is called Glycocalyx.
It is made of polysaccharide, protein or both
It functions for attachment and protection
There are two types of glycocalyx, what are they?
1) Slime layer, loosely associated with cell surface
2) Capsule, more organized structure, more tightly associated with a cell, it is a key virulence trait
What are biofilms? Give 1 example
3D communities of microorganisms. Cells are embedded in extra cellular polymetric substance of carbohydrate rich. Difficult to remove all cells
Ex. Dental plaque
What are 3 external appendages?
1) Flagella
2) Pili
3) Fimbriae
What are flagella properties/ characteristics?
A molecular motor
3 part structure:
1) filament (propeller), made of flagellin (protein)
2) hook, connect filament and basal body
3) basal body (motor), anchored to a wall and membrane
What is the function of the flagella?
Movement, motility, whip-like movement of the filament propels bacteria
What are the 4 arrangements of the flagella?
1) monotrichous, one flagellum at the end
2) lophotrichous, bunches of flagella at the end
3) amphitrichous, flagella at both ends
4) peritrichous, flagella all over the cell
What is “taxis” and what are the two types of it?
Taxis is the movement towards or away the stimuli
- chemotaxis: in response to chemical
- phototaxis: in response to light
What are the 2 flagella movements?
Run: counter clockwise flagellar rotation propels bacteria forward
Tumbling: clockwise rotation
What are spirochetes? Give 2 examples
Helical cells with axial filaments, located between cell wall andouter sheath. Rotation leads to a corkscrew motion
Ex.
1) Treporema pallidum: syphilis
2) Borrelia burgdorferi: Lyme disease
What is fimbriae? Give 2 examples
Short rods, appendages made of protein used for attachment.
Ex.
1) Neisseria gonorrhoeae: gonorrhea
2) Escherichia Coli: food poisoning
What are pili (plural) pilus (singular)?
Long rigid tubular structure, used for DNA exchange.
What is a cell envelope?
Cell membrane and cell wall, maintains cell integrity.
What are the two groups of envelope and their characteristics?
1) Gram positive: thick peptidoglycan layer and cell membrane
2) Gram negative: outer membrane, thing peptidoglycan layer and cell membrane
What is a peptidoglycan?
A disaccharide polymer made of
- N-acetylmuramic acid (NAM)
- N-acetylglucosamine (NAG)
- peptide crosslinks
What is the difference peptidoglycan in Gram Positive and Gram Negative?
- Gram Positive: there is indirect peptide interbridge between tetrapeptides
- Gram negative: there is direct connections between tetrapeptides
What are the characteristics of a Gram negative cell wall?
Thin peptidoglycan layer
Outer membrane is a barrier to antibiotics
What are the characteristics of a mycobacterium? Give 2 examples
Provide resistance to many chemicals and dyes. Identified using acid fast stain. Gram positive cell wall structure.
Ex. 1) mycobacterium tuberculosis
2) mycobacterium leprae
What are the characteristics of mycoplasma? Give one example
No cell wall, cell membrane reinforced by sterols, very small
Ex. Mycoplasma pneumoniae
What are the 5 internal contents of the cell?
- Cytoplasm
- DNA
- Ribosomes
- Inclusions
- Endospores (not all bacteria)
What are 3 characteristics of bacterial chromosome?
- Single, circular double stranded protein
- Contains information for synthesizing proteins
- Not surrounded by a membrane
Which region in the cell is the chromosome found?
Nucleoid
What type of DNA do bacteria have? What are some characteristics of it?
Plasmids: Extrachromosomal, circular double stranded Replicate on their own Transferable Carry advantageous genes
What are inclusions?
They do accumulation of nutrients (storage), vary in size, number and content
What are some types of inclusions? (5)
- Poly b-hydroxybutarate (PHB): energy
- Metachromatic granules: phosphate storage
- Sulfur granules: energy
- Gas vesicles: buoyancy
- Magnetosomes: magnetotaxis
Name the innermost layer to the outermost of an endospore:
Core-> cortex -> spore coat -> exosporium
How is endospore generated?
Sporulation, stimulated by the lack of nutrients. Endospore formation happens inside of the mother cell, DNA must be replicated.
What are endospore structures?
Survival structures that are metabolic innactive, formed when cells run out of nutrients. Very resistant to heat, chemicals, etc. contains DNA, ribosomes and RNA, which are the essential components for resuming metabolism and growth
What are the 4 steps of sporulation cycle?
- Activation
- Germination
- Outgrowth: new vegetative cell
- Not reproduction
Eukaryotic cell wall are rich in….
Carbohydrates
What defines fungi cell walls?
Chiatin
What are some characteristics of eukaryotic cell membrane?
Phospholipid bilayer, stabilized by sterols, for example cholesterol in animals
DNA is __________ into RNA
Transcribed
RNA is _________ into proteins
Translated
What is an endomembrane system? Give some examples
Series of single membranes bound organelles.
Ex. Endoplasmic reticulum, Golgi apparatus, vesicles, lysosomes, vacuoles….
What is an endoplasmic reticulum?
Network of sacs and tubules made of membrane
What are two forms of endoplasmic reticulum?
Rough ER and smooth ER
Rough ER synthesizes…..
Protein
Smooth ER synthesizes……
Lipids
What are vesicles responsible for?
Transport, move material around the cell from the ER to golgi
What is the Golgi apparatus composed of and what is its function?
Golgi is a stack of membranous sacs responsible for protein folding, packing, modification and sorting.
What are lysosomes composed of and what are their function?
Lysosomes contain enzymes that lyse substances, digest complex molecules , break down damaged cell components (autophagy) and ingested material
What are mitochondria responsible for?
Site of energy, production and biosynthesis
What do chloroplasts do and where are they found?
They convert light energy into chemical energy and they are found in plants and protists
What is the endosymbiosis theory?
Chloroplasts and mitochondria appear to have originated as free living bacteria. Because they contain their own genome, replicate separate from cell cycle and have double membrane.
What is the cytoskeleton composed of?
Microtubules (largest)
Microfilaments (smallest)
Intermediate filaments
What is the microtubule function?
Move eukaryotic cells: flagella and cilia
What are two types of microscopic fungi and their morphologies?
- Yeast: round, ovoid cells
2. Hyphae: long filaments
What are some characteristics of yeast?
Form loose colonies with uniform texture and appearance. Cells may divide by fission or budding
What are some filamentous fungi characteristics?
Grow in mass of hyphae called mycelium. Have a hairy texture. Hyphae may be divided by cross walls
What are the types of fungal reproduction and their characteristics?
- Asexual: hyphae can elongate, fragments can form a new colony. Scores formed by mitosis and released, mitotic division of yeast cells
- Sexual: meiosis to reproduce haploid cells
What is the fungal classification based on?
Mating structures
What are the different types of protists?
Sarcondina
Mastigophora (flagellates)
Ciliophora (ciliates)
Sporozoa (apicomplexa)
What are viruses?
Acellular pathogens
What is the only way that viruses can replicate?
Inside host cells, intracellular parasites
What is the structure of a virus?
Capsid (protein coat) protects nucleic acid genome
Capsid + DNA called the nucleocapsid
Some virus have a membrane coating, what is it called?
Viral envelope
What are the three types of viruses?
Helical
Polyhedral
Complex
What is the viral genome?
DNA: ds or ss, linear or circular
OR
RNA: usually ss, may be ds
Function of nucleic acid
Carries genes necessary for host cell invasion and for directing host machinery to assemble new viruses
What may be present in the virus particle? Give some examples
Some pre-formed enzymes may be present in the virus particle:
Polymerase: DNA or RNA
Replicate: copy RNA
Reverse transcriptase: synthesis of DNA from RNA
What does reverse transcriptase do?
Synthesis of DNA from RNA
Replicase
Copy of RNA
How the replication of animal viruses happen?
- Attachment
- Entry
- Synthesis
- Assembly
- Release
Explain attachment and entry
It is the interaction between the virus surface and the host cell surface (adsorption)
Genome enters the host cell
Genome is released from capsid (uncoating)
How does the host range of a virus work?
Adsorption depends on a virus happening to interact with the surface of a cell with appropriate surface receptors
Hepatitis B infects…..
Liver cells
Polio virus infects….
Primate intestinal and nerve cells
Rabies infects….
Various mammalian cells
HIV infects….
Certain blood cells CD4 + T cells
Synthesis
Viral components produced
Assembly
New viral particles constructed
Release
Exocytosis or cell lysis
What is the cytopathic effect that the viruses cause to the host cells?
Virus induced damage to cells
Changes cell in size and shape. Cytoplasmic inclusions bodies. Cell fusion into mutinucleated cells. DNA alterations and cancerous transformation. Cell lysis
What are the two types of viral infection?
Persistent infection and latent infection
Persistent infection
Host cell not immediately lysed
Can shed viruses for an extended period
Latent infection
Viral genetic information incorporated into host genome. Can be reactivated later.
Ex. Measles virus in brain cells
Herpes simplex virus: cold sores and genital herpes
Herpes zoster: chickenpox and shingles
What are the medical importance of viruses?
Most common causes of acute infections
Some infections have a high mortality rate
Possible connection of viruses to chronic afflictions of unknown cause
How does replication of bacteriophage happens?
Only DNA enters the cell, so no uncoating necessary
