Biology Midterm 2
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. What would you like to do?
- Use light as an energy source.
- Carbon dioxide as carbon source.
- performs photosynthesis.
What is Transduction?
Dna is moved cell to cell by viruses.
What is Transformation?
A living cell acquires fragments of DNA from its environment from dead cells and incoporates them into its own cell.
What is Conjugation?
A small piece of DNA is transferred from a donor cell to a recipient cell, usually through a hollow, tube like connection called a pilus.
How can prokaryotes move?
- Spirochetes have a corkscrew like motion.
- Some cyanobacteria moe up and down in water by adjusting amount of gas in gas vesicles.
- Most common type is by the flagella.
Steps of Gram Staining.
- Crystal Violet.
- Iodine treatment.
- Counter stain (safranin).
What makes a bacteria gram negative?
They have a thin layer of peptidoglycan.
What makes a bacteria gram positive?
They have a thick layer of peptidoglycan outside the plasma membrane.
Where can prokaryotes live?
They can live in every habitat.
What are filaments?
Chains of cells that stayed together after they split.
What are biofilms? Why are they important?
- they are a gel-like polysaccharide matrix.
- Cells in a biofilm matrix are difficult to kill.
What are the common shapes of Bacteria?
- Sphere- Coccus (cocci).
- Rod- bacillus (bacilli).
- Spiral- helical (helices).
Is it easy to trace the evolutionary relationships of bacteria?
- DNA is a problem because of lateral gene transfers.
- Transfer by plasmids or virus, and uptake of DNA by transformation.
- Solution: Need genes from the "stable core" - Nucleotide sequencing of ribosomal RNA is ery useful.
Cannot surie in the absence of oxygen.
Do not use oxygen to burn sugar, but are not damaged by oxygen if it is present.
- Do not use oxygen to burn sugar.
- Obligate anaerobes - molecular oxygen will kill them.
- Facultative anaerobes- can shift there metabolism between aerobic and anaerobic modes, such as in fermintation.
- They obtain both energy and carbon from complex organic compounds.
- Most bacteria and archaea are chemoheterotrophs, as are all animals, all fungi, and many protists.
Get energy by oxidizing inorganic compounds, and use the energy to fix CO2.
Use light as energy source, but get carbon from compounds made by other organisms.
Prokaryotes Vs Eukaryotes
- 1. Prokaryotes divide by binary fission.
- 2. Prokaryotic DNA is a single circular molecule, not in a nucleus.
- 3. Prokaryotes hae no membrane enclosed organelles.
What does all life have/do?
- Conduct Glycolosis.
- Replicate DNA.
- Have DNA that encodes proteins.
- Produce proteins using the same genetic code.
- Have plasma membranes and ribosomes.
- Unique axial filaments that rotate.
- Many are human parasites, some are pathogens, others are free living.
- Extremely small Gram negative coccii.
- Live only as parasites in cells of other organisms.
- Can take up ATP from host cell with translocase.
- Complex life cycle.
- Some are pathogens, causing trachoma, sexually transmitted diseases, and pneumonia.
High GC gram positive
- High G-C/A ratio in DNA.
- Form elaborately branching filaments.
- Some reproduce by forming chains of spores at tips of filaments.
- Most antibiotics are from this group.
- Photoautotrophs; many species fix nitrogen.
- Photosynthetic membranes; plant chloroplasts are derived from endosymbiotic cyanobacteria.
- Flat sheets, filaments, to spherical balls of cells.
- Vegetative cells, spores, and heterocysts.
- Heterocysts are specialized for nitrogen fixation.
Low GC gram positive
- Some produce endospores.
- Endospores become active and divide when conditions improve.
- Closteridium botulinum, Bacillus anthracis, staphylococcus, S aureus.
- Largest group of bacteria-high diversity of metabolic phenotypes.
- Includes some nitrogen-fixing genera.
- E. coli is a proteobacterium.
How are archeae different?
- Based on gene sequencing.
- Famous for living in extreme environments: High salinity, high temperatures, high or low pH, and low oxygen.
- The long-chain hydrocarbons in archaea are unbranched.
How do prokaryotes affect their environment?
- Cheese making, sewage treatment, and production of antibiotics, vitamins, and chemicals.
- They metabolize organic compounds in dead organisms and other organic materials.
- Key steps in the cycling of elements.
Why you should thank a cyanobacteria?
- Cyanobacteria had a large impact on life when they started generative 02 as a by-product of photosynthesis.
- Bacteria in humans produces B12 and K.
- Biofilm that lines human intestines facilitates uptake of nutrients.
- Bacteria are critical in maintaining skin health.
What is Koch's postulate?
- The microorganism is always found in persons with the disease.
- It can be taken from the host and grown in pure culture.
- A sample of the culture causes the diseases in a new host.
- The new host also yields a pure culture.
What are two types of bacterial toxins?
- Corynebacterium diptheriae (diptheria) has low invasiveness, but the toxins it produces affect the entire body.
- Bacillus anthracis (anthrax) has alow toxigenicity, but very high invasiveness- it colonizes the entire bloodstream.
How are viruses put together?
Consist of a nucleic acid core (viral genome) surrounded by a protein coat (capsid).
What would you like to do?
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