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40 Cards in this Set
- Front
- Back
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What major characteristics or processes do prokaryotes lack that eukaryotes have?
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>2 chromosomes
A defined nucleus Mitosis Membrane bound organelles Histone DNA Particular lipids and sterols |
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What are some biochemical differences between prokaryotes and eukaryotes?
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Prokaryotes use D - Amino Acids
they also use diaminopimilic acid and muramic acid. |
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What are the major shape categories of bacteria?
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Cocci, Bacilli, Vibrios, Spirochetes, Spirilla
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How are many bacteria treated with out affecting the host?
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Prokaryotic have many different biochemical pathways which can be targeted with therapies that only affect the bacteria
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What is the capsule of bacteria?
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A layer of mucilagenous or slime composed of either simple or complex carbohydrates, such as D-Glutamic acid and N-Acetyl glucosamine.
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What type of bacteria have capsules?
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BOTH gram positive and negative
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What is the function of the capsule?
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1. To avoid phagocytosis
2. To allow adherence to surfaces 3. To disguise the cell from the host immune system |
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What is the relationship between the presence of the capsule and virulence?
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Direct: loss of capsule typically results in loss of virulence
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Describe the cell wall of the gram positive bacteria
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Has a thick cell wall mainly composed of peptidoglycans, followed by a periplasmic space and a plasma membrane.
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What part of gram positive cells are anti-biotics targeted at and why?
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The cell wall because there are numerous biochemical pathways to target and mitochondria (which can affect hosts as well) are not affected.
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What is the main action of anti-biotics?
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Inhibition of enzymes
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Describe the cell wall of gram negative cell.
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The cell wall is primarily composed of a cell wall containing peptidoglycans and lipopolysaccharides; the cell wall is surrounded by an inner and outer membrane.
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Why are cell shape and gram reactions critical characteristics?
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Both products are are the consequence of multiple gene products that would make mutation to another shape or gram reaction very complex. This causes the identification process of bacteria based on these characteristics to be very predictable.
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What is the medical significance of the cell wall of bacteria?
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1. Largely determine interaction between host and bacteria
2. Allows serological identification 3. Provides many unique bacterial characteristics |
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What two compounds create the backbone of the cell wall in both gram positive and negative cells?
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N-acetyl Glucosamine
N-acetyl muramic acid (these create peptidoglycan) |
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What type of gram reaction bacteria will antibiotics that affect cell wall biosynthesis work on?
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BOTH!
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What is the function of the cell wall?
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To provide shape, rigidity and to withstand osmotic pressure.
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What are plasmids?
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Small, round, self-replicating DNA elements that typically contain gene non-essential for life such as anti-biotic resistance
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What are flagella?
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Motile cellular appendages; medically important bacteria typically have flagella; they are anti-genic
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What are pili?
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Non motile cellular appendages used for organelle attachment. Can promote colonization of mucosal attachment
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Why has the autoclave invented?
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As a means of killing spores which can withstand boiling
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How do medically important bacteria obtain carbon?
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Organic sources; this makes them heterotrophs.
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What are aerobic bacteria?
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Bacteria that require oxygen for metabolism
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What are anaerobic bacteria?
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Bacteria that cannot utilize oxygen in metabolism and growth can be halted or cells can die if oxygen exposure continues.
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What do all obligate anaerobic bacteria lack?
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Superoxide dismutase (oxygen+water=oxygen +peroxide)
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What are capnophilic bacteria?
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Bacteria whose growth is accelerated by a higher than normal carbon dioxide level.
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What is the fermentation?
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The non oxidative breakdown of carbohydrates in the absence of oxygen
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How are types of fermentation differentiated?
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1. Types of carbohydrates that can be fermented
2. Types of end products |
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What is Nalidixic acid?
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Common anti-biotic that inhibits DNA gyrase, which inhibits supercoiling of DNA required for replication.
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How do bacteria replicate?
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Binary fission
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Why would treating a single bacterial infection with two types of antibiotics be a good protocol to follow if the infection is serious?
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Gene mutate independently and the likelihood of a single bacteria developing resistance to both agents becomes close to zero.
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How do bacteria exchange genetic information?
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1. Transformation
2. Conjugation 3. Transduction |
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What is transduction?
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Transfer of bacterial genetic information through a bacteriophage
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What is transformation?
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The transfer of cell free DNA released by donor cell in various ways to a recipient cell
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What is conjugation?
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The cell to cell mating of two cell types.
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What are F factors?
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Types of plasmids that are involved in conjugation
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What are R factors?
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Plasmids that contain one or more genes for anti-biotic resistance
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What are transposons?
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DNA elements that can be moved from one molecule to another (ie plasmid to chromosome), frequently encode anti-biotic resistance
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What are facultative aerobics?
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Bacteria that do not require oxygen but will use it when it is present
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What are axial filaments?
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Flagella like appendages that originate at the pole and are enclosed by outer membranes. Commonly found in spirochetes.
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