Biomed module 6 obj. 1-3
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What are the medically important microorganism (microbes) asociated with microbiology?
True or false: Prokaryotes have a membrane bound nucleus, membrane bound oranelles, and DNA that is organized into chromosomes
All living cells are clasified as ________ or _________.
What are the five kingdomes that all living organisms are divided into?
Prokaryotes belong to which kingdom?
Monera - consist of all the single celled prokaryons
What is the earths most abundant form of life?
All bactira and prokaryotic organisms
The average size of bacteria are ______ to _____ microns in diameter.
- 0.5, 2.0
- (in comparison the human red blood cell is about 7.5 microns in diametr.)
What do prokaryotes have insteadeof a nucleus?
A nuclear region called a nucleoid which is the cells chromosome.
True or False: All bacteria are prokaryotic cells
Prokaryotes have _______ _______similare to eukaryotic cells. These carry __________ essential to cell function.
Inclusion bodies, molecules
Describe the prokaryotic Cell Structures
- Cytoplasm- semi-fluid substance that fills inner cellular space
- -primarily water with carbohydrates, lipids, and enzymes
- Ribosomes- protein synthesis centers
- Nucleoid (chromosome)
- Inclusion bodies: store molecules essentioal to cell finction
- some prokaryotes
- -secrete a capsule: contributes to pathogenicity
- - have plasmids : Extachromosomal DNA important for transfer of genetic material.
What is a capsule and what is its function?
- A protective structure that serves as a defence mechanism
- Tightly bound to the cell wall
- Consist of complex polysaccharide molecules that form a gel-like comering that surrounds the bacterial cell
- Considered to be a major contrubutor to pathogenicity
What are plasmids?
- Self-replicating extrachromosomal DNA that carry one or more pieces of genetic information
- Not required to sustain life
What is a unique feature of a of the majority of prokaryotic bacterial cell walls?
A semi-rigid cell wall
What is the main function of the cell wall?
Provides shape and stability
What is peptidoglycan?
- Located in cell walls of all bacteria
- It is an immense, covalenly linked molecule arranged in layers resembling multiple layers of a chain-link fence which give the cell support.
True or false: Many antibiotics target the cell wall
True. (i.e. penicillins)
The _____ _________ is present in all living cells (both prokaryotic and eukaryotic) and regulates the ________ of material in and out of the cell.
Cell membrane, transport
About half of all known bacteria possess filamentous organelles of locomotion call _________.
- Are said to be motile
What are pili?
- Tiny tube-like projections from the cells surface
- Associated with adherence
Flagella and Pili are examples of what?
Why is the shape and arrangement of prokaryotic cells important?
- Bacteria are characterized by their shape and size
- Before specific culture information is available, physicians use loction and appearance characteristics to begin andtibiotic therapy.
What are the different kinds of prokaryotic bactirial cells and their shapes?
- Coccus: sperical
- Bacillus: rod
- Coccobacillus: oval- between a cocus and a bacillus
- Vibrio: comma shaped
- Spirilla: loosely coiled
- Spirochete: Tightly coiled
What are the distinctive arrangements some bacteria have?
- Diplo (pair) -Diplococci (spherical, non motile bacteria)
- Stepto (chain) - steptococci
- staphylo (irregular cluster)- staphylococci (grapelike cluster)
- Tetra (group of four)
A widely accepted means of grouping bacteria
A Gram Stain
Gram positive bacteria
- Thich layer of peptidoglycan and teichoic acid causes retention of crystal violet (blue) dye
Gram negative stain
- Thin layer of peptidoglycan and high lipoprotein content; releases crystal violet dye when rinsed with alcohol
- The safranun (pink) counterstain is retained
What are the steps of a Gram stain ?
- 1. A sample is smeared on a slide and fixed with heat.
- 2. the slide is stained with crystal violet (purple) for 1-2 min
- 3. Gram's iodine is used to "fix" the crystal violet (helps to retain the stain).
- 4. Acetone is used to decolorize the slide
- 5. Stain the slide with safranin (pink).
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