Microbio Midterm #1

Characteristics of prokaryotes

1. Simple

2. Smaller

3. Unicellular

Characteristics of eukaryotes

1. Larger

2. Complex

3. Often multicellular

For what fraction of Earth's history were prokaryotes the only life form?

The first 2 billion years

What are the six major groups of microbes?

1. Bacteria

2. Algae

3. Protozoa

4. Fungi

5. Helminths

6. Viruses

What is unicellular?

Composed of one type of cell

What is multicelluar?

Composed of multiple types of cells.

Bacteria

1. Unicellular

2. Account for all prokarytoes

3. Crucial part of the ecosystem

What are three crucial tasks prokaryotes serve in the ecosystem?

1. Nitrogen fixation

2. Photosynthesis

3. Decomposition

Algae

1. Photosynthetic eukaryote

2. Type of protist

3. Most are unicellular, some are multicellular

Protozoa

1. Unicellular eukaryotes (all are unicellular)

2. Not photosynthetic

3. Type of protist

Fungi

1. Eukaryotes that feed on decaying matter

2. Unicellular or multicellular

3. Differentiated by certain cellular structures

Helminths

1. Multicellular eukaryotes

2. Parasitic worms

Viruses

1. Non-cellular (neither eukaryotic or prokaryotic)

2. Infectious particles with no metabolism of their own

3. Reproduce by stealing host function
   

Centi-

10^{-2}

Milli-

10^{-3}

Micro-

10^{-6}

Nano-

10^{-9}

Pico-

10^{-12}

Pathogen

Microorganisms that cause disease

Primary pathogens

Microbes that cause disease in otherwise healthy individuals

Opportunistic pathogen

Microbes that cause disease in individuals with weakened/ damage immune systems; only when opportunity is given

Where are infectious diseases most impactful?

In developing countries/areas with limited healthcare

Why are infectious diseases more impactful in developing countries?

Lack of access to clean water, vaccines, and medicine.

Who first described cells?

Robert Hooke, contributed to the development of the cell theory (1660s)

Cell theory

All living things are composed of cells

Who first observed unicellular organisms?

Antonie van Leeuwenhoek

What is the scientific method?

1. Observe the world

2. Propose a hypothesis to explain what you observe

3. Think of testable predictions based on your hypothesis

4. Perform experiments testing your prediction

5. Results are consistent → hypothesis is supported

6. Results aren’t consistent → hypothesis might be false or needs revision.

7. A hypothesis supported by enough test → theory, with time → law or principle

Spontaneous generation

The outdated idea that life arises spontaneously from nonliving matter

What are Louis Pasteur’s key contributions?

1. Disproved spontaneous generation

2. Developed pasteurization

3. Improved vaccines

Biogenesis

Living things give rise to other living things

Pasteurization

Brief heating of foods to kill most bacteria that cause it to spoil

What did Florence Nightingale contribute?

Founded modern nursing; promoted hygiene to reduce infection.

What did Joseph Lister contribute?

Introduced aseptic techniques in medicine that prevented surgical infections

Aseptic techniques

Redesigning and sterilizing surgical instruments between uses to prevent microbial contamination in medical and laboratory setting. Results in additional reduction in preventable deaths

Germ theory of disease

Disease is caused by tiny, invisible organisms (“germs”). Proposed by Koch and Pasteur, led to the development of vaccines and antibiotics

What did Robert Koch do?

Developed Koch’s postulates linking microbes to disease.

What are Koch’s Postulates?

1. The organism must be present in all cases of the disease

2. Must be able to isolate the organism and grow it in a pure culture

3. Pure culture of the organism must cause disease in a new host

4. Must be able to isolate the organism again from the new host

Who developed the first vaccine and how?

Edward Jenner used cowpox to protect against smallpox.

Jenner’s vaccines method

1. Discover disease

2. Search for a closely related disease that is less harmful

3. Use as a vaccine

Pasteur’s vaccine method

1. Discover disease

2. Kill or cripple the disease organism

3. Use as a vaccine

What’s the difference between Jenner’s and Pasteur’s

Jenner's method uses a weakened or inactivated pathogen to stimulate immunity

Who discovered penicillin?

Alexander Fleming, leaving to the developmented of antibiotics

Antibiotics

Kill or inhibits bacterial growth without harming host cells. Improper use of antibiotics can render them useless

1. Must give a large enough dose

2. Must give the dose for a long time

What’s a domain?

The highest taxonomic rank

What are the 3 domain systems?

1. Domain Bacteria

2. Domain Archaea

3. Domain Eukarya

What’s a kingdom?

A broad classification within a domain

What are the kingdoms in Eukarya

1. Kingdom Animalia

2. Kingdom Fungi

3. Kingdom Plantae

4. Kingdom Protista

What’s a genus?

A group of closely related species

What’s considered a species in eukaryotes?

An organism that can interbreed and produce fertile offspring.

What’s considered a species in prokaryotes?

Organisms that are similar

Strain

A subpopulation in a species that has some slight differences between themselves and other members of the species

ex. E.coli 0157:H7 (pathogen), E..coli K12 (laboratory strain)

The six “I’s”

1. Inoculation

2. Incubation

3. Isolation

4. Inspection

5. Information gathering

6. Identification

What are the different types of microscopes

1. Bright-field

2. Dark-field

3. Fluorescence

4. Electron microscopy

Bright-field

1. Forms an image when light is transmitted through the specicment

2. Can be used for both live, unstained materials, and preserved stained materials

Dark-field

1. Uses peripheral light that is reflected off the sides of a specifiment itself

2. Used for live cells

Fluorescence

1. Ultraviolet light is used ot illuminate the speciemen

2. For tagged antibodies

Electron microscopy

1. Forms an image with a beam of electrons that can be made to travel in wavelike patterns.

2. Black and white images

3. Used for internal structures of cell and viruses

What is a dichotomous identification key?

A tool used to identify organisms based on a series of yes or no choices

What are the methods of identification?

1. Specimen collection and culturing

2. Identification methods

Specimen collection

Sample sites for either direct examination, culturing

What are some of the main concerns in sample collection?

1. Sampling handling

2. Transport

3. Storage

What are the identification methods?

1. Phenotypic

2. Genotypic

3. Serological

Phenotypic

Identifies microbes based on observable characteristics:

1. Microscopic and macroscopic morphology

2. Physiological/biochemical

Microscopic morphology

Looking at cell shape and arrangement through different types of staining

Macroscopic morphology

Observing visible characteristics such as appearance of a culture or colony; visible to the naked eye

Advantages of micro and macroscopic morphology

1. Easy, fast

2. Inexpensive

Disadvantages of micro and macroscopic morphology

1. Less specific

2. Imprecise

Physiological/biochemcial

Testing bacteria for ability to carry out various reactions

e.g. ferement carbohydrates, growing on high salts, break down gelatin

Advantages of physiological/biochemcial

Capable of identifying nearly any microbe, with enough test

Disadvantages of physiological/biochemcial

1. Relatively slow

2. Need pure culture first

MALDI-TOF

Cell samples are hit with a laser, ionizing the samples, then analyzing

Advantages of MALDI-TOF

Fast and accurate

Disadvantages of MALDI-TOF

Expensive equipment

Genotypic methods

Techniques used to analyze genetic material, such as DNA and RNA, for microbial identification and characterization:

1. PCR

PCR

A rapid technique that can test for the presence of specific DNA sequences from tiny amount of DNA within hours

Advantages of PCR

Fast and precise

Disadvantages of PCR

Requires specific primers (you have to know what you’re looking for)

Serological methods

Techniques that use antibodies to detect microbial antigens:

1. Antibody testing

2. Serotyping

Antibody testing

Determines if a patient is producing antibodies against a pathogen using a known antigen

Serotyping

Testing an isolated microbe with specific antibodies to see if they have the right antigen

Advantages of serological test

Fast and sensitive

Disadvantages of serological test

Require a specific antibody for each microbe being test for

What is a serovar?

A distinct strain of a bacterial species, identified by surface antigens

What’s an atom?

Smallest divisible component of matter. Made up of protons, electrons, neutrons

Proton

A positively charged particle

Electron

A negatively charged particle

Neutron

An uncharged particle

What’s a molecule?

Made of two or more atoms that share electrons

Covalent bond

Molecules with shared electrons

Ionic bond

Electron transfer among oppositely charged ions to fill valance shell

Hydrogen bond

Weak attraction between a hydrogen atom from one molecule and a oxygen or nitrogen atom of another molecule

What are the 6 elements that make up most of the molecules in all living things?

1. Hydrogen

2. Carbon

3. Nitrogen

4. Oxygen

5. Sulfur

6. Phosphorus

What does pH measure?

How acidic or basic a substance is

Acidic

When a solution has a high concentration of hydrogen ions

pH <7

Neutral

pH = 7

Basic

When a solution has a low concentration of hydrogen ions and a high concentration of hydroxide ions (also known as alkaline)

pH = >7

What are the four major macromolecules?

1. Carbohydrates

2. Lipids

3. Amino acids

4. Nucleotides

Carbohydrates

1. Made of C, O, and H atoms

2. Hydrophilic

3. Crucial part in energy metabolism and cellular structure

Lipids

1. Made of a long C-H chain with O atoms

2. Hydrophobic

3. Crucial part in energy storage and cellular structures

Amino acids

1. Made of C,O, H, N (sometimes contains S)

2. Make proteins that do almost all the work in a cell