Universal Features
- Central Dogma of Life Excluding retroviruses
- DNA -> RNA -> Proteins
- Universal Structure and Processes
- Cell Membranes
- DNA structure and replication
- RNA Synthesis (A,C,G,U)
- RNA Polymerase
- Ribosomes for translation
- Metabolic pathways
- Universal genetic code (codons/amino acids)
Prokaryotes
- Heterotrophs
- Gets nutrients elsewhere.
- Doesn't make food themselves.
- Prokaryotes Bacteria and Archaea
- Have a single circular double stranded DNA.
- Replicate by binary fission, not mitosis.
- They move around by spinning a flagella like a propeller.
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- Flagella are made from flagellin proteins
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- The flagellin proteins are outside the cell membrane.
- No organelles.
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- Carry plasmids
- Extra little pieces of DNA.
- Independent tiny circles of DNA.
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Can carry antibiotic resistance genes.
- Horizontal Gene Transfer Lateral Gene Transfer
- Can occur in more complex organisms such as aphids absorbing bits of fungi.
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- Conjugation
- "Bacterial Sex" via plasmids.
- Transformation
- Uptakes/absorbs environmental/external DNA bits.
- Transduction
- Phage virus-mediated transfer of genomic bits.
- Endosymbiotic Theory
- Chloroplasts in plants came from engulfing cyanobacteria and not killing it.
- Mitochondria came from engulfing proteobacteria and not killing it.
Bacteria
- Gram Stains
- Bacteria have peptidoglycan, eukaryotes don't.
- Detects the presence of an outer layer of peptidoglycan.
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- Gram Positive
- One cell wall with large peptidoglycan layer outside.
- Gram Negative
- Two cell walls with small peptidoglycan layer in-between.
- Antibiotics
- Inhibit the ribosomes in bacterial cells.
- These selectively target bacteria and don't kill archaea or eukaryotes.
Common Phyla
- Actinobacteria
- Antibiotics were first discovered as natural weapons in actinobacteria against other bacterias.
- Cyanobacteria
- First cells to photosynthesis sunlight -> O2.
Bacterial Shapes
- Bacteria Shapes
- Rod-shaped
- Spherical
- Spiral
Locations
- Different bacteria grow in different environments.
- Such as oxygen environments (aerobic/anerobic).
Bacteria can communicate via pheromones. Can trigger bioluminescence among colonies.
Bacterial Colonies
Archaea
- Archaea
- Have no peptidoglycan.
- Extremophiles
- Hyperthermophiles
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- Hadobacteria
- Thermophiles
Cell Specialization
- Fixation
- Taking inorganic compounds and combining it with molecules into organic compounds.
- Metagenomics
- We sample DNA from the environment and identify organisms by DNA sequencing.
Cell Types
- Spores
- Hearty cells survive harsh conditions, can reactivate later to reproduce.
- Heterocysts
- For nitrogen fixation.
- Vegetative Cells
- For carbon fixation, photosynthesis.
Pathogens
- Pathogens
- Can outcompete and outgrow, causing illness.
Common Pathogens
- Chlamydias
- Spirochetes
- Proteobacteria
How to Identity a Pathogen
_Koch's Postulates
- Is present in every case of the disease.
- Organism must be cultured from the sick patient.
- Bacteria must be able to induce the disease.
- Bacteria must be recoverable from newly infected individuals.