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29 Cards in this Set
- Front
- Back
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What are the major characteristics of eukaryotic cells
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A. Membrane bound Nucleus
B. Multiple chromosomes and mitotic apparati C. Membrane bound organelles D. Membranes contain sterols |
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What are the major characteristics of prokaryotic cells
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A. Nucleus is not surrounded by a membrane
B. Single, circular chromosome C. No membrane bound organelles D. Membranes lack sterols E. Multiply by fission |
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What are the gross morphological types of bacteria
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Cocci, Bacilli, and Spiral
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What are the steps of the gram stain
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1. Heat fix bacteria on glass and stain with crystal violet (purple or blue color)
2. Fix crystal violet inside the cell with I2-KI 3. Wash with acetone/alcohol 4. Counterstain (red or pink if negative) |
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How do gram positive bacteria react to the gram stain
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They retain the crystal violet and appear blue
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How do gram-negative bacteria respond to the gram stain
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The crystal blue is washed out, and they appear pink due to the counterstain
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What are the two main cell envelope differences between gram positive and negative bacteria
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Gram negative contain an outer membrane and periplasmic space
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What is the structure and function of the peptidoglycan
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Possessed by almost all bacteria; responsible for cell shape; protects against mechanical and osmotic injury; target of many antibiotics; substrate for lysozyme
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What are the major components of the bacterial cytoplasmic membrane
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Phospholipids (PE,PG and CL) and proteins
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What are the characteristics of the outer membrane that gram negative bacteria contain
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Phospholipids; very few enzymatic activities; receptors; porin proteins; LPS; murein lipoproteins; barrier function
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How is the outer membrane of enteric organisms characterized
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By the Enterobacterial common antigen (ECA)
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What are the characteristics of the periplasmic space of gram negative bacteria
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20-40% cell mass; Contains low weight solutes, degradative enzymes, binding proteins, peptidoglycan; contents can be released by osmotic shock
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What are zones of adhesion
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Areas of continuity between the cytoplasmic membrane and the outer membrane (300/cell). Involved in the translocation of a variety of molecules from the cytoplasmic membrane to the outer membrane
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Where can capsules be found
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Gram positive or negative bacteria. Not all bacteria contain a capsule
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What do capsules consist of
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Either polysaccharides or polymers of specific amino acids
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What are the functions of capsules
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Virulence factors (less susceptible to phagocytosis; Protect against desiccation)
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What are the four different types of flagella
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A. Monotrichous (polar, single)
B. Lophotrichous (polar, several) C. Amphitrichous (bipolar, single) D. Peritrichous (cover entire surface) |
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Can bacteria detect differences in the concentration of an attractant or repellant over the length of the cell
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No. They detect gradients in a temporally dependent manner
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What are the two types of pili (fimbriae)
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Common (somatic) pilli (responsible for adherence to environment)
Sex (Responsible for adherence to other cells, found on F+ cells) |
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Where are endospores found
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Only gram positive bacteria, mostly rods
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What are some characteristics of endospores
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High resistance; contain almost no water; contain Ca2+ and dipicolinic acid; Require environmental shock to induce germination
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Does the nuclear body (nucleoid) contain ribosomes?
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No
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What are mesosomes
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Invaginations of the cytoplasmic membrane. Septal mesosomes function in cell division and lateral mesosomes function in secretion
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What are the bacterial ribosomes
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70S, comprised of 50S and 30S
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What are bacterial biofilms
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Structured communities of bacterial cells in a self produced polymeric matrix that adhere to an inert or living surface. Can provide survival and antibiotic resistance
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What bacterial cell components are found only in gram-negative bacteria
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Periplasmic space, outer membrane, zones of adhesion
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How does the peptidoglycan layer (cell wall, murein) of gram negative bacteria differ from the murein layer of gram positive bacteria
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Gram negative have a layer that is only one molecule thick. Gram positive have multiple layers that are cross linked in three dimensions
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How is the direction of flagellar motion related to the swimming/tumbling behavior of motile bacteria
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Counterclockwise=swimming
Clockwise=tumbling |
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What are the functions of bacterial endospores
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Provide resistance, ensure survival
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