What is Microbiology? Flashcards by Kelsie Keith

What is microbiology?

Study of organisms too small to be seen by the naked eye.

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Which microorganisms are visible to the naked eye?

Algae, Fungi

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Which microorganisms are multicellular?

Myxobacteria, slime mold

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Which technique(s) can be used to define microbiology?

Culture media for isolation and growth of organisms in pure culture
Biochemical to study cell components
Molecular and genetic techniques

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What are the 5 reasons that explain why microbiology is important?

Microbes are the oldest form of life
Largest mass of living material on Earth
Carry out major processes for biogeochemical cycles
Can live in places unsuitable for other organisms
Other life forms require microbes to survive.

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What attribute(s) do all cells have in common?

Cytoplasmic membrane
Cytoplasm
Ribosomes

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What is the difference between genetic material and a genome?

Cells store their DNA as genetic material, which is then divided into functional units of genes. A genome is a cell’s full compliment of genes.

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What is the difference between chromosomes and plasmids?

Chromosomes are genetic elements carrying genes essential to cellular function. Plasmids are a piece of DNA carrying non-essential genes.

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What are the different characteristic(s) of eukaryotes?

Membrane bound nucleus
Membrane bound organelles
Complex internal organization
Division by mitosis and meiosis

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Eukaryotes include protists. What are protists? What are three examples of protists?

Protists are unicellular or multi-cellular without differentiation into tissues. Three examples are: Protozoa– animal-like microorganisms
Algae– photosynthetic plant-like microorganisms
Slime molds and water molds– filamentous

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Eukaryotes include fungi. What are fungi? What are three examples of fungi?

Fungi are unicellular, filamentous or multicellular. Three examples are:
yeasts
molds
mushrooms

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What are the characteristic(s) of prokaryotes?

No membrane bound nucleus or organelles 
Generally smaller (approx 1 µm diameter)  
Simple internal structure 
Divide by binary fission  
Most are unicellular

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Prokaryotes include bacteria. What are some differences between bacteria and other prokaryotes?

Genetically diverse
Extremely diverse metabolic styles
Includes both pathogens and non-pathogens

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Prokaryotes include archaea. What are some differences between archaea and other prokaryotes?

Genetically and biochemically distinct from bacteria Also have diverse metabolism
Never pathogenic
Most famous for living in extreme environments

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What are the characteristic(s) of viruses?

Acellular infectious particles
Extremely small
Obligate intracellular parasites
Lack independent metabolism

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True or False: Viruses can be classified with other microbes due to their specific ribosomes and ribosomal DNA.

False: Viruses cannot be classified with other microbes because they contain no ribosomes and no ribosomal DNA.

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When did the first anaerobic life appear?

3.8 to 3.9 billion years ago.

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When did the first photosynthetic bacteria oxygenate the Earth?

2 billion years ago.

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When did the first plants and animal appear?

0.5 billion years ago.

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What classification of ribosomes do prokaryotes have? What small subunit (SSU) rRNA genes are they classified by?

70S ribosomes

16S SSU rRNA

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What classification of ribosomes do eukaryotes have? What small subunit (SSU) rRNA genes are they classified by?

80S ribosomes

18S SSU rRNA

What is a polymerase chain reaction, or PCR?

A technique used to synthesize many identical copies of a short sequence of DNA.

What is a phylogenetic tree?

A graphic representation of the evolutionary distance between organisms.

What ribosomal DNA sequence(s) are phylogenetic trees based on?

16S and 18S

What 3 domains of life are organisms organized into on phylogenetic trees?

Bacteria, Eukarya and Archaea

What is the phylogenetic species concept?

A group of strains that share certain diagnostic traits, are genetically cohesive and have a unique recent common ancestor.

In practice, Bacteria and Archaea should have what?

Most (but not all) characteristics in common Greater than 97% sequence similarity in the 16S rRNA gene High degree of genome similarity

What do microbiologists use to classify organisms?

Hierarchical classification

What does Hierarchical classification use to organize organisms?

Kingdom, Phylum, Class, Order, Family, Genus, Species

What are the 5 rules for binomial species naming?

1. Names are latinized 2. Italicized or underlined 3. Genus capitalized, epithet is not 4. Genus name may be abbreviated the second time it’s used: E. coli 5. Trivial names can be used, but do not follow these rules

What did Robert Hooke (1635–1703) contribute to the discovery of microorganisms?

Robert Hooke was the first person to describe microbes and introduce the cell theory- every living thing is composed of cells.

What type of microscope did Robert Hooke use? What was its max magnification?

Hooke used a compound microscope with a magnification of 30x.

Which scientist built microscopes that magnified specimen by 50-300x?

Antoni van Leeuwenhoek (1632–1723)

What did Leeuwenhoek first discover, and what did he call them?

He was the first person to discover bacteria, and named them animalcules.

What did Louis Pasteur (1822–1895) develop?

Developed a method of gentle heating to kill unwanted bacteria – Pasteurization.

Pasteur's pasteurization method included boiling a meat infusion to sterilize it in a long swan-necked flask. As long as the flask remained upright it would stay uncontaminated and sterile. What technique did this method lead to?

The aseptic technique.

Robert Koch (1843–1910) studied Bacillus anthracis, or anthrax, to study diseases. What did he do with this bacteria?

He injected healthy animals with anthrax and re-isolated the bacterium from the animals when they became ill. He determined the two bacteria samples (original and re-isolated) where the same and came up with a set of criteria for relating microbes to disease.

What were the criteria Koch came up with called?

Koch's Postulates

What were Koch's Postulates?

1. The suspected pathogen must be present in all cases of the disease and absent from healthy animals. 2. The suspect pathogen must be grown in a pure culture. 3. The cells from the pure culture must cause disease in a healthy animal. 4. The suspected pathogen must be isolated from the healthy-now-ill animal and be the same as the original.

Solid media provides a simple way to isolate what?

Pure cultures

What temperature does agar melt at? What does it solidify at?

Melts: 97 Celsius Solidifies: 43 Celsius

What does a petri plate usually contain?

Nutrient Broth Medium + 1.5% agar

What is a colony?

a mass of cells that (ideally) arose from one single cell.

What is the streak plate technique?

One edge of a plate is inoculated with a concentrated sample of bacteria Sample is diluted by streaking it across the surface of the plate Plate is incubated Individual cells grow to form colonies

What is the spread and pour plate technique? Where do the bacteria grow in each technique?

Spread Plate: Diluted sample can be spread over the surface of the plate with a sterile spreader. Bacteria grows on the surface of the medium. Pour plate: Bacteria sample mixed with molten agar (~45°C). Bacteria grow in medium.

What do they spread and pour plate technique allow you to determine?

They allow you to. calculate the concentration of bacteria in a population (bacterial titre).

How is the titre determined? What are the units?

Titre= #colonies/(volume)(dilution) | Titre is measured in CFU- colony forming units

Between how many colonies do we count petri plates?

30-300

How do you find the titre between multiple plates?

You take the average.

Why do we not could less then 30 or more that 300 colonies?

Less than 30 colonies is not statistically significant, and more that 300 colonies will give statistically inaccurate counts.

What is Microbiology? Flashcards

Lectures 1-5