Lecture flashcards
The study of organisms too small to be seen with the human eye
Microbiology
Microbiology includes several sub-disciplines:
By organism type & by application
By organism type: 1) Bacteriology 2) Virology 3) Mycology 4) Parasitology By application: 1) Food microbiology 2) Environmental microbiology 3) Forensic microbiology
The existence of microorganisms was hypothesized for many centuries before their actual discovery. _______ _______ asserted the existence of unseen microbiological creatures living in earth, water, air and fire.
Mahavira (6th century BC)
Microbiology born as a science in?
1674
- Dutch drapery merchant
- Ground lenses to view fabric
- Used lens to peer into a drop of lake water
– First glimpses of microbial world – Called organisms “animalcules”
Anthony van Leeuwenhoek
Theory of Spontaneous Generation
The theory states that?
“organisms can arise from non-living matter”
The theory of spontaneous generation had its supporters and detractors. Detractors included?
– Francesco Redi
– Louis Pasteur
– JohnTyndall
* Each contributed to disproving the theory
Spontaneous generation debate led in part to scientific method which is?
1) Observation leads to question
2) Question generates hypothesis
3) Hypothesis is tested through experiment(s)
4) Results prove or disprove hypothesis
– Accepted hypothesis leads to theory/law – Reject or modify hypothesis
- Italian biologist and physician
* Demonstrated maggots found on rotting meat came from eggs of flies landing on meat
Francesco Redi
- Considered the father of modern microbiology
- Demonstrated that air is filled with microorganisms
- Identified the cause of fermentation
- Developed the germ theory of disease
Louis Pasteur
To show air is filled with microbes Pasteur developed? Was able to demonstrate infusions remained sterile even if flask was left open
Swan-necked flask
Studied causative agents of disease
– Anthrax
– Examined colonies of microorganisms
Robert Kosh
Koch’s Contributions
Koch’s Contributions
1) Simple staining techniques
2) First photomicrograph of bacteria
3) First photomicrograph of bacteria in diseased tissue
4) Techniques for estimating CFU/ml
5) Use of steam to sterilize media
6) Use of Petri dishes
7) Techniques to transfer bacteria
8) Bacteria as distinct species
Louis Pasteur demonstrated that yeast in grape juice reproduced and produced?
Bacteria also fermented the?
Alcohol with or without exposure to air
– Facultative anaerobes
Grape juice producing acid
Many scientists were skeptical of Pasteur’s results. Some scientists could not reproduce same results. Who was able to explain discrepancies?
John Tyndall was able to explain discrepancies
Tyndall concluded different infusions required different?
Boiling times. Some infusions were sterile after boiling for five minutes, others did not achieve sterility after five hours of boiling. He attributed contamination to a heat-resistant life-form later called an endospore. German botanist Ferdinand Cohn discovered endospores in the same year
Who was able to establish endospore role in disease transmission
Robert Koch
The Theory of Spontaneous Generation was disproved and the Golden Age of Microbiology was born
– Golden Age was from?
1854–1914
Golden age of microbiology.
Between ___ and ___ most disease-causing bacteria
were discovered
Between 1875 and 1918
What did the Golden Age of Microbiology do?
1) Time of great interest in the study of microorganisms
2) Between 1875 and 1918 most disease-causing bacteria
were discovered
3) Work on viruses began
4) Lead to the initiation of prevention and treatment of disease
How do microbes have enormous impact on human existence?
– Microorganisms have killed more people than have ever been killed in war
– Without certain microorganisms life could not exist. Some microorganisms produce oxygen and nitrogen which are key elements for all living organisms
–Microorganisms are decomposers. Responsible for the breakdown of a wide variety of materials
Describe the food production of microbiology
Food production
– Beer, wine, bread, soy products, sauerkraut
– Fermentation of milk to produce numerous products like yogurt, cheese, and buttermilk
Describe microbiologies role in bioremediation
Use organisms to degrade environmental waste. Degrade PCB’s, DDT, clean up oil spills and treat radioactive waste
Bacteria can synthesize numerous products such as?
– Ethanol
– Pesticides
– Antibiotics
– Dietary amino acids
Define genetic engineering
Introduce genes of one organism into an unrelated organism to confer new properties on the organism
Benefits of genetic engineering
1) Applications include engineering organisms to produce medically important products and vaccines
2) Engineered plants resist disease
3) Potentially therapeutic
– Gene therapy
More people died worldwide of what in the 1918 epidemic than died in WWI, WWII, the Korean War and the Vietnam war combined
Influenza
Modern sanitation, vaccination and effective antimicrobial treatments have reduced?
Incidences of the worst diseases
Resurgence of old diseases. Diseases thought to be “defeated” increasing in frequency. Often more serious. Causative agents usually resistant to treatment. Reasons for resurgence?
1) Increase travel.Visitors to foreign regions bring organisms from home and bring other organisms home with them
2) Unvaccinated individuals susceptible to infection. Causative agents of controlled diseases are still around and infect vulnerable individuals
All living things can be classified in one of three groups. Also known as domains. Organisms in each domain share certain properties. These properties distinguish them from organisms in other domains. Three domains are?
– Bacteria
– Archaea
– Eukarya
Define strain
Variations within a species. Not all organisms from the same species/types are necessarily the same
Briefly describe bacteria and archaea
– Both are single-celled organisms – Contain no membrane bound nucleus – Termed PROKARYOTES = pre nucleus – Pro=pre – karyote = nucleus – Do not contain any other organelles – Cytoplasm is surrounded by rigid cell wall
Describe eukarya
– Organisms contain membrane bound nucleus
– Termed EUKARYOTE = true nucleus
– Eu = true
– karyote = nucleus
– Contains internal organelles
– Making organism more complex. Example = mitochondria
– May be single celled or multicellular
Most common cause of human infection. Members widely diverse
Bacteria
Most prominent features of bacteria include
1) Specific shapes
* Rod-shaped, spherical and spiral
2) Rigid cell walls
* Responsible for cell shape
3) Multiply by binary fission
* One cell divides into two
* Each cell is genetically identical to the first
4) Some bacteria are motile
* Move by means of flagella
Archaea share a number of attributes with Bacteria
– Same shapes
– Multiply through binary fission
– Move by means of flagellum
Archaea exhibit significant differences, which are?
– Chemical composition of cell wall differs from organisms in other domains
– Organisms of Archaea domain found in extreme environments such as extreme temperatures and environments with high concentrations of salts
Microbial world includes Eukarya which are
– Algae
– Fungi
– Protozoa
What are algae?
1) Diverse group
2) Includes single and multicellular organisms
3) All contain chlorophyll which the pigments absorb the energy of light which is used in photosynthesis. Some contain other pigments.
4) Usually found near surface waters
5) Have rigid cell wall. Distinct from bacterial cell walls
Fungi are diverse single celled and multicellular organisms: – Single-celled =
– Multicellular =
– Single-celled = yeast
– Multicellular = molds, mushrooms
Gain energy from organic materials. Found wherever organic materials are present
Fungi
What are protozoa?
– Microscopic, single-celled organism
– Found in water, animal hosts, and on land
– Complex
– Much larger than prokaryotes
– Do not have a rigid cell wall
– Gain energy from organic matter
– Most are motile. Means of motility is diverse and a feature of their classification
Viruses, Viroids, Prions are?
1) Non-living elements
2) Called agents (not organisms)
3) Usually consist of only a few molecules found in living cells
Viruses contain a protein?
Coat surrounding nucleic acid. Essentially protein bag of nucleic acid
Viruses termed obligate intracellular parasites. They must have?
Host machinery to replicate. Inactive outside of host
What are viroids?
1) Viroids are simpler than viruses. They still require host cell for replication
2) Consist of a single short piece of RNA –Contain no protective protein coat
3) Viroids smaller than viruses
4) Generally cause plant diseases
What are prions?
1) Infectious proteins. There is no nucleic acid
2) Responsible for at least seven neurodegenerative diseases:
– Animal disease like scrapie in sheep and mad cow disease in cattle
– Human disease like Kuru and Creutzfelt-Jakob
Atomic number is?
The number of protons in the nucleus
What is atomic mass (atomic weight)?
The sum of masses of protons, neutrons, and electrons
Consist of a single type of atom
Element
99% of all living matter is made up of four elements?
What makes up additional 0.5%?
1) Carbon (C)
2) Oxygen (O)
3) Hydrogen (H)
4) Nitrogen (N)
Additional 0.5% is phosphate (P) and sulfur (S)
Atoms combine by sharing or transferring valence electrons, this is called?
Chemical bonds
Two or more atoms held together by chemical bonds
Molecule
A molecule composed of one or more elements
Compound
Covalent bonds achieve stability through?
The sharing of electrons between atoms. Creates a strong bond; difficult to break. Requires significant energy, usually in the form of heat. Never breaks spontaneously at physiological temps. Needs an enzyme to break at lower temps.
Covalent bonds can be?
Polar or non polar
Universal solvent is
Water because of its polar property
Ionic bonds are formed by?
Gaining or losing electrons. Electrons completely leave first atom and become part of outer orbital of second atom.
The loss and gain of electrons leads to?
Charged atoms called ions. An atom that loses an electron becomes positively charged. An atom that gains an electron becomes negatively charged.
Charged atoms are attracted to each other & form a bond between ions
Ionic bond
Ionic bonds are weaker than?
Covalent bonds. They dissociate in water, they are easily broken at room temp., approximately 100 times weaker than covalent bonds.
Important among weak forces holding biological molecules together
Ionic bonds
Hydrogen bonds are
Weak bonds formed from the attraction of positively charged hydrogen atoms. Hydrogen atoms in polar covalent bonds are attracted to negatively charged atoms or molecules (most commonly, oxygen, or nitrogen).
Hydrogen bonds occur between molecules such as
Water and DNA
Weakest of the biological bonds
Hydrogen bonds
Constantly being formed and broken at room temp.
Hydrogen bonds
At room temp. the average lifetime of a single hydrogen bond is?
A fraction of a second
Large numbers of hydrogen bonds can?
Hold molecules together firmly (DNA)
Bonding properties of water
1) Water molecules are cohesive
2) Water is an excellent solvent
3) Remains liquid at wide range of temps
4) Absorb considerable amounts of heat energy without change temp.
5) Participate in many chemical reaction inside cells
Acidity is measured as?
pH
What is pH?
Defined as concentration of H+ ions. Potential Hydrogen
