Chapter 1: The Microbial World and You

Microbes are

Microbes are

ubiquitous (everywhere)

Bodies possess more _______ than human cells

microbes

Marine microbes contribute to _____ of the Earths O2

Half

Only _______ of microbes on earth are culturable

0.1%

Definition of a microbe

a living organism that requires a microscope to be seen

Microbes are typically _______, not multicellular

cellular entities

Cellular properties of microbes

They have a genome, they metabolize nutrients, and they respond to environmental changes and evolve rapidly

Microbes include

Bacteria, Archaea, Fungi, Protista, Algae, Viruses

Microbes can live

singly

Microbes can form

filaments, chains, or clusters

Size range of Eukaryotic microbes

20-100 micrometers

Size range of Prokaryotes

1-10 micrometers

Size range of Viruses

0.02-0.9 micrometers

Multicellular organisms

Organism made up of many cells

Unicellular organism

An organism made up of one cell.

Two types of microbes

cellular and acellular

cellular microbes are

microbes that are made up of cells, complex

cellular microbes include

fungi, protists, bacteria, archaea

Fungi characteristics

eukaryotic, mostly multicellular, heterotrophic

Fungi examples

molds, mushrooms (multicellular) and yeast (unicellular)

Protist (Protista) characteristics

eukaryotic, unicellular

Protist (Protista) examples

protozoa and algae

Bacteria characteristics

prokaryotic, unicellular

Bacteria examples

E. coli

Archaea characteristics

prokaryotic, extremophiles (live in extreme environments)

Types of Archaea

methanogens, halophiles, thermophiles

thermophiles

thrive in very hot environments, can be aerobic or anaerobic, and sulfur metabolizers

Methanogens

produce methane gas, anaerobic, found in sewage treatment plants

halophiles

requires 12-13% NaCl some up to 25-33%, major aerobic group, grow photosynthetically using bacteriorhodopsin

Acellular microbes are

made up of macromolecules rather than cells (lack cellular structure) and mainly proteins or nucleic acids. more simple.

Acellular microbes include

viroids, prions, viruses

Virus characteristics

Extremely small, acellular, requires a host to reproduce (technically not alive on their own), composed of proteins and nucleic acids (DNA or RNA)

Viroid characteristics

acellular, composed of RNA, typically infect plants

Prion characteristics

acellular, composed of proteins

Prokaryotes are

Bacteria and Archaea

Prokaryote characteristics

-lack a nucleus and organelles, single circular chromosome, asexual reproduction, cell wall is common
-autotrophs and heterotrophs

Autotrophs

Organisms that make their own food

Heterotrophs

Organisms that depend on other organisms for their food.

Eukaryote characteristics

larger, possess nucleus and organelles, reproduce asexually or sexually; multiple, linear chromosomes

Contradictions of microbe definition

-supersized microbial cells (challenges only visible under microscope factor)
-microbial communities (challenges only visible under microscope factor)
-multicellular microanimals (challenges unicellular factor)
-viruses (challenges cellular factor)

Microbes dont fit the definition of species because

they reproduce asexually, and exchange genes in non-standard ways

microbes are classified based on

genetic similarity in DNA sequences

Carl Woese

Compared relatedness of RNA sequences using 16s ribosomal RNA, and revealed a new prokaryotic group. Established the three domains (eukarya, bacteria, archaea)

The 5 Kingdoms

Animalia, Plantae, Fungi, Protista, Monera

Domain Bacteria and Archaea includes kingdom

Monera

Domain Eukarya includes kingdoms

Animalia, plantaea, fungi, protista

Robert Hooke

Used the first microscope (30X) to observe MACROscopic life.

Antonie van Leeuwenhoek

Used microscope lens (200X) to be the first to observe single-celled microbes.

Discovery of microbes led to questions about their organ, leading to the theory of

spontaneous generation

spontaneous generation

Hypothesis stating that life could arise from nonliving matter. (abiogenesis)

Francesco Redi

This scientist disproved spontaneous generation for macroscopic life by showing that maggots do not spontaneously arise from decaying meat.

John Needham

Advocated for spontaneous generation by pouring boiled broth into covered flasks, which yielded microbial growth. <b>most likely only because of dirty flasks and cross contamination</b>

Spallanzani

Refutes John Needham's experiment by using sterilized flasks and observed that microbes only grew if flasks were left open.

Virchow

All cells come from pre-existing cells (cell theory)

Louis Pasteur discovered that

microorganisms causes fermentation and disease. He also pioneered pasteurization.

Pasteurization

process of heating liquids to kill harmful microbes and prevent spoilage.

Discovering that microorganisms cause disease led to the development of the

germ theory of disease.

Pasteur refutes idea that

Oxygen is required for growth. Used swan neck flask that admitted air and prevented travel of microbe-carrying dust. Only if the flask was tipped, their would be contamination

Robert Koch

first to establish scientific principles for linking a specific microbe to a specific disease

Robert Koch established the

chain of infection through his work on Koch's postulates

study of tuberculosis was difficult because microbes werent in blood they were in

lung tissue

to minimize contamination, these techniques were developed

aseptic pure culture

18th century inoculation

deliberately cutting into small pox pustule and using the same contaminated instrument to cut it into someone healthy, in hope of yielding immunity. Was not safe.

Edward Jenner

Discovered the small pox vaccine using cowpox, less virulent (dangerous) than smallpox.

Louis Pasteur pioneered the development of

attenuated vaccines, which involve using weakened (attenuated) forms of a pathogen to stimulate an immune response without causing the disease. He successfully developed such vaccines for diseases like rabies and chicken cholera

vaccination

preparation used to stimulate the immune system and provide immunity. can be made from attenuated pathogens, inactivated pathogens, or mRNA

attentuated vaccine

specific type of vaccine that uses a live but weakened form of the pathogen, which can still replicate but does not cause illness in healthy individuals. It stimulates a strong and long-lasting immune response.

Paul Ehrlich discovered an arsenic derivative (a synthetic drug), ____, that was effective against syphilis.

Salvarsan

Use of antiseptics was for

living tissue

Use of disinfectants was for

inanimate objects

Semmelweis and Lister

develop aseptic techniques, which prevented pathogens from entering the body during childbirth or surgery and saw a decrease in post-op infections

Antibiotics are

chemicals produced by bacteria and fungi that inhibit or kill other microbes

Alexander Fleming

discovered penicillin

Benefits of Microbes

1.Photosynthesis (account for 50% of the earths oxygen
2. Decomposition (nutrient recycling)
3.Biotechnology (manufacture of industrial products,food, and drugs)
4. Bioremediation (microbes used to clean up pollutants and waste in natural environments)

Winogradsky

used enrichment culture and discovered chemolithotrophy

microbial genomes

Bacterial chromosomes are a single circular loop
Eukaryotic chromosomes are multiple and linear

Prokaryote genomes average

500 kb to 5 million bp in size

Genome Analysis

used to form hybrid DNA molecules for our own use

gene therapy

the transplantation of normal genes into cells in place of missing or defective ones in order to correct genetic disorders.

metagenomes

genome sequencing and analysis of environmental samples

Microbiota

the term for the microbes that are normally present in and on the human body; usually beneficial

human cells share

communalistic and mutualistic relationships with our microbes

transient microbes

do not normally reside, just passing through
most are harmless, some pathogens

infectious disease

pathogens successfully enters host, and establishes itself and produces disease symptoms

Pathogens possess virulence factors which

determine success of causing infection and your resistance

Biofilms

Colonies of bacteria that adhere together and adhere to environmental surfaces.

EIDs (emerging infectious diseases)

new diseases and diseases increasing in incidence. Viral and bacterial in origin. Many are zoonotic diseases.

How do EIDs arise?

-mutation
-acquisition of new genes
-recombination of genomes
-cultural and environmental factors