Chapter 11: Microbes: Secret Lives of Single Cells Flashcards
Microbes
Small life, single cell, microscopic organisms
Microbes Steps
1) The most abundant organisms on earth
2) Huge genetic diversity
3) Highly adaptive, exist in extremely hostile environments (temp, chemical, pressure)
For every human cell in your body there may be
10 microbial cells
What are microbes
1) Found in all 3 domains (bacteria, archaea and eukarya)
2) Minimal evolutionary relatedness
3) Viruses are not currently classified as living, but are microbes
All bacteria and archaea members are
Microbes
All eukaryotic microbes are known as
Protists
Bacteria
Simplest organisms alive; cell membrane, cytoplasm, some proteins and genetic material
Bacteria categorized by shape:
1) Bacillus (rod)
2) Coccus (round)
3) Spirillum (spiral)
Bacteria categorized by Gram staining
1) Negative (penicillin-resistant)
2) Positive (penicillin-susceptible)
Colonies of different bacterial types have
Different physical appearances
Reproduce asexually via
Binary fission (cloning)
Genetic exchange possible
1) Conjugation: exchanging DNA with another cell of the same species
2) Transduction: gaining DNA from viral capsid
3) Transformation: Scrouning for DNA
Metabolism
Bacteria can get energy from many sources:
1) Chemoorganotrophs
2) Chemolithotrophs
3) Photoautotrophs
Chemoorganotrophs
Eat organic molecules
Chemolithotrophs
Eat inorganic molecules
Photoautotrophs
Synthesize energy from sunlight (photosynthesis) (responsible for oxygen in earth’s early atmosphere)
1) Bacteria can be useful:
1) Used in food production (yogurt, cheese, bread, etc.)
2) Used in food digestion (mircobes are capable of breaking down cellulose)
3) Normal (relatively harmless) flora coat your entire body, preventing the growth of harmful colonies
Bacteria can be harmful:
1) Pathogenic organisms
2) Antibiotic resistance
Pathogenic organisms causes
Disease
Not all pathogens are always
Harmful, and many are normally benign, but under certain circumstances become pathogenic
Antibiotic resistance
The process of bacteria evolving to survive exposure to antibiotics (penicillin initially was a highly effective antibiotic, but is now rarely used due to increased resistance)
Archaea
Although outwardly similar to bacteria, archaea are dramatically different genetically
Many archaea (along with some bacteria) are found in
Extreme environement (extremophiles)
Archaea also thrive in
Less extreme environment, such as your gut
Because archaea can survive in
Unusual environements, they may be useful to humans
Enzymes from extremophiles function at
Higher or lower temperatures ranges
Organisms that can metabolize toxic or hazardous materials can help
Dispose of waste or clean up spills
Study organisms for
Outer space/colonizing research
Viruses technically not living organisms:
Viruses (outside host: virion) are protein coated genetic material contained in capsids, not cells, sometimes with a few enzymes
If host cell is a bacteria virus is a
Bacteriaphege
Viral life cycle
1) Viral genome enters host cell
2) Viral genome is replicated and transcribed
3) Viral mRNAs are transmitted and proteins processed
4) Particle assemble inside host, then burst or bud to exterior
Viruses can cause
Many harmful diseases, including the common cold, the flu (influenza), rabies and HIV/AIDS
Viral diseases are categorized by
Genetic material like RNA or DNA-based
DNA viruses do not evolve particularly quickly due to
The many DNA checkpoints in the replication process
RNA viruses can evolve very quickly due to
The lack of checking mechanisms in RNA replication
Influenza caused by an
RNA virus
Influenza possible to have
Multiple flu viruses enter a single cell, including those that infect different species
Influenza can get strains that incorporate
Multiple species surface proteins and thus infect multiple species as seen in swine or bird flu
Large outbreaks of disease can lead to
Pandemic such as the Spanish flu of 1918
HIV/AIDS
Although an RNA based virus, HIV is also retrovirus
HIV/Retrovirus contains
Reverse transcriptase, allowing synthesis of DNA from RNA to be inserted into the hosts DNA
HIV/AIDS highly prone to errors in
Transcription, leading to enormous variation in each new generation (many new mutations)
HIV/AIDS once inserted, HIV targets the immune system mutating to
Gain access to the white blood cells that attack it
Once a suitable mutation occurs HIV develops into
AIDS
AIDS infections are characterized by
A collapse of the immune system
White blood cells (that recognize pathogens and trigger the immune response) are, what?
Killed off, allowing for multiple other infections to develop
