Exam 2 Flashcards
study for exam 2
Cell theory
- Cells are the smallest unit of life
- All life is made of one or more cells
- Cells can only come from other cells
Bacteria
- No nuclear membrane
- Circular chromosomes
- No DNA packaged in histones
- Simple RNA polymerase enzyme for protein making machinery
- Formeylmethionine start codon
Archaea
- No nuclear membrane
- Circular chromosomes
- DNA packaged in histone proteins
- Complex RNA polymerase enzyme for protein making machinery
- Methionine start codon
Eukaryotes
- Nuclear membrane
- No circular chromosomes
- DNA packaged in histones
- Complex RNA polymerase enzyme for protein making machinery
- Methionine start codon
Cyanobacteria
- Photosynthetic, oxygen-producing bacteria (formerly known as blue-green algae).
- Single celled and colonial
Stromatolites
- Mineralized deposits caused by cyanobacterial mats
- Direct evidence of life 3.5 BYA
MRSA
- 1/3 people carry S. aureus on their bodies
- 1/5 carry MRSA
- Sub-dermal infection that causes skin rash, boils, fever, loss of limbs, death
Penicillin
- first discovered by Alexander Fleming in 1928 (by accident)
- Difficult to synthesize
- Chemical structure confirmed by Dorthy Crowfoot Hodgkins in 1945
- Drastically reduced death due to disease
Clostridium difficile
- Another antibiotic-resistant bacterial species
- Increasing prevalent in hospitals (becomes an issue after treatment with antibiotics)
- Causes severe diarrhea, intestinal cramping, death
- Linked to 30,000 deaths/year in US
gut microbiome
- the microbial communities present in the animal gastrointestinal tract
- Probiotics are supplements with “good” bacteria
Human Ecosystem
- human body contains 500-1000 different species of bacteria
- 10 times more bacterial cells than human cells (about 100 trillion human cells)
nitrogen fixation
process of converting nitrogen gas into nitrogen compounds that plants can absorb and use
nitrogen fixation process
- atmospheric nitrogen not in an easily usable form in nature
- Bacteria break apart the strong and stable bonds of atmospheric nitrogen
- Nitrogen is converted into molecules with a single nitrogen atom, and is then usable by plants
bacterial & plant alliance
- A plant secretes a bacteria- attracting compound
- Bacteria enter the roots
- The plant delivers sugars to the bacteria
- Bacteria produce and release usable nitrogen into the plant
- The plant distributes and absorbs the nitrogen
Halophiles
Can survive being embedded in salt crystals
Thermophiles
Archaea that thrive in very hot environments (above the boiling point of H20), such as volcanic springs
Acidophiles
Can live in a pH 1
horizontal gene transfer
transfer of genes between cells of the same generation
Transformation
(genetics) modification of a cell or bacterium by the uptake and incorporation of exogenous DNA
Transduction in bacteria
..type of bacterial recombination (create genetic diversity) in which there is an exchange of bacterial DNA through bacteriophages - viruses that infect bacteria. There are two types of transduction: generalized and specialized transduction.
Conjugation in bacteria
Bacterial cells can join together and pass plasmid DNA from one bacterial cell to another. This process can take place between bacteria of different species and is of concern in terms of passing plasmid-located genes for antibiotic resistance.
Concepts to define a bacterial species
- Morphological: determined through enrichment cultures
- Phylogenetic: determined through direct sequencing
Enrichment
- Can be grown in either liquid or solid medium
- the easiest bacteria to culture are usually ecologically isignificant
Shapes of bacterial cells
Coccus (circles)
Rod (bacilli)
Spirillum (corkscrew/spiral)
