Lecture 1 Flashcards
Important bacterial characteristics
Prokaryotes
Peptidoglycan cell walls
Binary fission
For energy, use organic and inorganic chemicals, or photosynthesis
Important Archaea characteristics
Prokaryotic
Lack peptidoglycan in cell walls
Live in extreme environments
Name three types of Archaea
1) Methanogens
2) Halophiles
3) Thermophiles
Important characteristics of Fungi
Eukaryotes
Chitin cell walls
Use organic chemicals from their environment for energy
T or F: Yeasts are multicellular fungi
F: Yeast are fungi but are unicellular
How are protozoa characterized?
Considered a kingdom with seven phyla. Generally a unicellular eukaryote that is motile.
How do protozoa move around?
Either through pseudopods, cilia or flagella
How can you differentiate algae?
- Eukaryotes
- Cellulose cell wall
- Photosynthesis
- Produce oxygen and organic compounds
Are viruses living?
No, viruses are not able to replicate without the aid of a living host cell.
Characteristics of a virus
Acellular Consist of DNA or RNA core Core is surrounded by a protein coat Coat may be enclosed in a lipid envelope Are replicated only when they are in a living host cell
Name some multicellular animal parasites.
Parasitic flatworms and roundworms called helminths
What are the three domains of life?
1) Bacteria
2) Archaea
3) Eukarya
What are the kingdoms of the domain Eukarya?
Protista
Fungi
Plantae
Animalia
Who reported that living things are composed of smaller cells?
Robert Hooke in 1665
What is cell theory?
The idea that all living things are composed of cells and come from preexisting cells.
What is spontaneous generation?
The hypothesis that living organisms arise from nonliving matter and that a “vital force” forms life.
What is biogenesis?
The hypothesis that living organisms arise from preexisting life.
What did Francesco Redi’s experiment in 1668 entail?
He had three jars of decaying meat covered with a fine net and three other open jars. He found maggots in the open jars but not in the ones with the fine net. This reveals biogenesis NOT spontaneous generation.
Detail the experiments (similar) of Needham and Spallanzani.
They heated nutrient broth then moved it to a new jar and sealed it. In the second condition they heated nutrient broth in a flask, did not move it but sealed that flask. In the first condition there was microbial growth, in the second there was not.
In 1861 Louis Pasteur did a similar experiment as Needham did in 1745 however with an important difference that was neglected before.
Pasteur heated nutrient broth, did not move it and did not seal it in the first condition. In the second he heated and sealed it in the same flask. Of course in the unsealed flask there was microbial growth (even though it had not been moved). The microbes must have come from the air, not from the jar.
What was the Golden Age of Microbiology?
1857 - 1914 was an era within which Robert Koch and Pasteur uncovered important relationships between microbes and disease, immunity and antimicrobial drugs. Vaccines and surgical techniques were developed.
What is fermentation?
The conversion of sugar into alcohol in the absence of air.
What is responsible for fermentation?
Microbes (fungi) called yeast.
What causes spoilage and souring of food in the presence of air?
Bacteria. Bacteria can also change alcohol into vinegar in the absence of air.
What is pasteurization?
The application of high heat for a short time to kill microbes.
What is the Germ Theory of Disease?
The theory that germs or microbes cause disease. Koch found more specific relationships between types of bacteria and certain illnesses.
Who developed the first vaccination?
In 1796 Edward Jenner created protection from smallpox by producing a vaccination from cowpox.
What is chemotherapy?
Treatment with chemicals.
What were the first synthetic drugs?
Quinine extracted from bark used to treat malaria. Salvarsan, arsenic derivative effective against syphilis.
Chemicals that are produced naturally are called…
antibiotics
Who discovered the first antibiotic?
Alexander Fleming in 1928 by observing that a penicillium fungus made an antibiotic
What is parasitology?
The study of protozoa and parasitic worms.
What is immunology?
The study of immunity
What is interferon?
Interferons (IFN’s) are a group of signalling proteins released from a host cell in response to pathogens. They can help to inhibit replication of a virus as nearby cells will be triggered to step up their defence.
What is molecular biology?
The study of how DNA directs protein synthesis.
What is microbial genetics?
The study of how microbes inherit traits
What is genomics?
The study of an organism’s genes, has provided new tools for classifying microorganisms
Recombinant DNA
DNA made from two different sources.
What is bacterial conjugation?
The direct transfer of genetic material from one bacteria to another through direct cell-to-cell contact or bridge-like connection.
What are some functions of normal microbiota?
- Prevent the growth of pathogens
- Produce growth factors like folic acid and vitamin K
- Resistance factor
What are some resistance factors in the body?
Skin, stomach acid, antimicrobial chemicals, normal microbiota.
What is a biofilm?
Microbes attach to solid surfaces like rocks, pipes, teeth etc. and grow into masses.
What is an EID?
Emerging infectious diseases: new diseases and diseases increasing in incidence
What is Avian Influenza A
- Found primarily in waterfowl and poultry
- Sustained human-to-human transmission has not occurred yet
What is MRSA?
Methicillin-resistant Staphylococcus aureus
Penicillin resistance a)
Methicillin resistance b)
MRSA resistance to vancomycin c)
a) Developed in 1950’s
b) Developed in 1980’s
c) Developed in 1990’s
West Nile Encephalitis
- Caused by West Nile Virus
- Appeared in New York City, in nonmigratory birds in 47 states
Bovine Spongiform Encephalopathy
Caused by a prion, also CJD
E-coli O157:H7
Toxin producing strain, causes diarrhea
Ebola Hemorrhagic Fever
Caused by Ebola virus: causes fever, hemorrhaging, blood clotting
AIDS
Acquired Immunodeficiency Syndrome caused by HIV, sexually transmitted infection identified in 1981.
What is light microscopy?
Microscope that uses visible light to observe specimens.
Types of light microscopy?
- Compound light
- Darkfield
- Fluorescence
- Confocal
Electron microscopy
Use electrons instead of light. Shorter wavelength of electrons gives greater resolution.
Compound light microscopy
Resolution is the ability of lenses to distinguish two points.
Bright field illumination
Dark objects are visible against a bright background
Darkfield illumination
Light objects are visible against a dark background
Fluorescence microscopy
Uses UV light. Fluorescent substances absorb UV light and emit visible light. Cells may be stained with fluorescent dyes.
How do you prepare a smear for staining?
1) Can use simple stains such as alcohol or a basic dye
2) Can use differential stains that react differently with different kinds of bacteria. eg. Gram stain or Acid fast
Characteristics of gram-positive bacteria
- Tend to be killed by penicillin and detergents
- Thick peptidoglycan cell wall
- Teichoic acids in cell wall
- Penicillin sensitive cell wall
Characteristics of gram-negative bacteria
- Tend to be more resistant to antibiotics because of type of cell wall
- Cell wall includes an outer membrane
- Periplasmic space with thin layer of peptidoglycan
- Tetracycline sensitive
- Releases endotoxins if destroyed
What happens to the purple stain of gram-negative bacteria upon addition of alcohol-acetone?
It becomes colourless
Bacteria that hold on to an acid fast stain have what property?
These are bacteria that have a waxy cell wall, such as Mycobacterium tuberculosis, responsible for TB. It holds onto the acid fast stain (eg. Zeihl-Neelson) and is not decolorized by acid-alcohol. This is useful because it is resistant to the gram stain.
Prokaryotic characteristics
1) Small unicellular organisms that include bacteria and archaea
2) One circular chromosome, not enclosed in a nuclear membrane
3) No histones
4) No organelles
5) Bacteria has peptidoglycan cell walls
6) Divide by binary fission
Eukaryote characteristics
1) DNA is present in nucleus, which is separated from cytoplasm by nuclear membrane
2) DNA found in multiple paired chromosomes
3) Histones
4) Organelles
5) Polysaccharide cell walls
6) Divide with help of mitotic spindle
What is the average size of a prokaryote?
0.2 - 1.0 um x 2-8 um
What are some basic bacterial shapes?
- Bacillus (rod-shaped)
- Coccus (spherical)
- Spiral
i) Spirillum (larger diameter corkscrew)
ii) Vibrio (somewhat curved)
iii) Spirochete (smaller diameter corkscrew)
What are the different arrangements of bacteria?
- Pairs: diplococci, diplobacilli
- Clusters: staphylococci
- Chains: streptococci, streptobacilli
Structure external to cell wall: Capsule vs Slime layer composed of…
Glycocalyx, sticky and composed of polysaccharide, polypeptide or both
- Made inside the cell and secreted to the surface
- If it is organized and firmly attached it is called a capsule
- If it is unorganized and loose it is called a slime layer
What is important about a capsule?
They prevent phagocytosis.
Characteristics of flagella
- Outside of cell wall
- Made of chains of flagellin
- Attached to a protein hook
- Anchored to wall and membrane by basal body
What are axial filaments?
- Also called endoflagella
- In spirochetes
- Anchored at one end of a cell
- Helps cell to move with rotation
Fimbriae and Pili
Interchangeable term
- Fimbriae allow attachment
- Pilli facilitate transfer of DNA during conjugation
What is a bacterial cell wall made of ?
Peptidoglycan which is a polymer of a disaccharide composed of N-acetylglucosamine and N-acetylmuramic acid
What are the types of teichoic acid in gram-positive cell walls?
1) Wall teichoic acid links to peptidoglycan (cell wall)
2) Lipoteichoic acid links to the plasma membrane
What is the role of teichoic acid?
They assume a role in cell growth, prevent cell breakdown and provide antigenic specificity.
What is the outer membrane of gram-negative cell walls composed of?
Lipopolysaccharide, lipoproteins and phospholipids
What is the function of the outer membrane of gram-negative cell walls?
- Strongly negatively charged, evading phagocytosis and action of compliment
- Nutrients can enter through porins that form channels, to sustain metabolism
- When gram negative bacteria die, they release lipid A endotoxin (fever, shock and blood clotting)
- Polysaccharide act as antigen
What is the difference in what alcohol does to gram-positivevs negative bacteria?
Gram-positive: Alcohol dehydrates peptidoglycan and the crystal violet-iodine crystals remain.
Gram-negative: alcohol dissolves outer membrane and leaves holes in peptidoglycan (rather than simply dehydrating it) so that the CV-I washes out.
Give an example of an atypical cell wall in bacteria?
1) Mycoplasma are the smallest bacteria and lack cell walls. Instead they have sterols in their PM that protect them.
2) Archae lack wall or have walls composed of polysaccharides and proteins but not peptidoglycan. Walls of pseudomurein (lack NAM and d-amino acids).
Are acid-fast cell walls typical or atypical?
Acid-fast cell walls are atypical.
- They are similar to gram-positive cell walls
- Have a waxy lipid or mycolic acid that prevents uptake of dyes.
eg. Mycobacterium or Nocardia
What is a protoplast?
Wall-less cell
What is a spheroplast?
Wall-less gram-positive cell
Are protoplasts and spheroplasts susceptible to osmotic lysis?
Yes, lysozyme digests disaccharide in peptidoglycan.
What are L-forms?
L-forms are wall-less cells that swell into irregular shapes
How does penicillin kill bacteria?
It inhibits peptide bridges in peptidoglycan.
What does a typical plasma membrane consist of?
Phospholipid bilayer Peripheral proteins Integral proteins Transmembrane proteins Sterols Glycocalyx carbohydrates
Describe the types of inclusions one could find in a cell?
1) Metachromatic granules (volutin)—phosphate reserves
2) Polysaccharide granules—energy reserves
3) Lipid inclusions—energy reserves
4) Sulfur granules—energy reserves
5) Carboxysomes—Ribulose 1,5-diphosphate carboxylase for CO2 fixation
6) Gas vacuoles—protein-covered cylinders
7) Magnetosomes—iron oxide (destroys H2O2)
