Micro Chap 4/Exam 1
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What is the difference between Eukaryotic and Prokaryotic DNA arrangement?
- Eukaryotes: multiple, linear chromosomes
- Prokaryotes: single, circular chromosome
What is the difference between Eukaryotic and Prokaryotic Protiens associated with DNA?
- Eukaryotes: histones
- Prokaryotes: non-histones
What is the difference between Eukaryotic and Prokaryotic Membrane-enclosed organelles?
- Eukaryotes: have mambrane enclosed organelles
- Prokaryotes: do not
What is the difference between Eukaryotic and Prokaryotic cell wall composition?
- Eukaryotes: (if present) simple molecules
- Prokaryotes: complex molecules
What is the difference between Eukaryotic and Prokaryotic mechanisms of cell division?
- Eukaryotes: mitosis or meiosis
- Prokaryotes: binary fission
What is the difference between Eukaryotic and Prokaryotic groups?
- Eukaryotes: fungi, protists, plants, animals
- Prokaryotes: Bacterium and archea
Define and Describe the following: coccus, bacillus, spiral, spirillum, vibrio
- coccus: round
- bacillus: rods (Sticks)
- spiral: spiral
- spirillum: spiral with no axial filaments
- vibrio: comma shaped
Define and describe the following: diplococcus, streptococcus, tetrads, and staphylococcus
- Diplococcus: pairs of coccus
- Streptococcus- chain of coccus
- Tetrads: four coccus
- Staphylococcus: grape like clusters of coccus
Define and describe the following: diplobacillus, streptobacillus, coccobacillus
- Diplobacillus: pairs of bacillus
- Streptobacillus: chain of bacillus
- Coccobacillus: very short rods that may look like coccus (when in doubt, its a rod)
Why are the shapes and arrangements of bacterial cells important?
They are clues to the MOs identity
What is glycocalyx made of?
made of water, proteins and polysaccarides-means "sugar coating"
its a sticky, gelatinous polymer made inside the cell and secreted to the surface
What is the difference between a capsule and a slime layer?? What makes each one important?
- Capsule: if the glycocalyx is well organized and firmly attached to the cell wall
- -protect against phagocytosis from host, making ti more pathogenic
- Biofilm: if it is unorganized and only loosely attached to the cell wall (slime layer)
- -helps keeps cells lumped together and attached to a surface (attachment allows bacteria to grow)
What are flagella and what are they made of?
They are long filament appendages that propel bacteria. Composed of protein molecules
What are the main parts of a flagella and how does it work?
Move by rotating the filament on a hook attached to the basal body
- the ability of an organism to be able to move by itself
- -towards good environments or away from danger
What kind of "flaggella" do spirochetes have? How does it work?
Axial filaments (endoflagella) located under the outer sheath
creates a corkscrew motion that can burrow through tissues
What are fimbrae and how do they contribute to bacterial pathogenicity?
fimbrae are "sticky whisker" protein filaments that allow adhesion
this makes them more pathogenic because they hang out longer
What are the major functions of the cell wall?
The major function of the cell wall is to maintain osmotic pressure and prevent against lysis in hypotonic environments (50psi)
consists of very strong peptidoglycan
Describe the structure of peptidoglycan
- -Made of protein and sugar chains
- -Very strong and permeable
- -Created by Nag/Nam chains (n-aceytlglucosamine and n-acetylmuramic acid-both modified glucose)
- -Also composed of Teichoic acid and peptide cross links
What is the structure of a Gram + cell wall?
- -Thick layer of peptidoglycan
- -Teichoic acids
What are porins?
small molecules may pass through this tunnel in either direction (water, sugar, ions, and amino acids)
What is the structure of a gram - cell wall?
- -Thin peptidoglycan layer
- -out membrane (phospholipid bilayer)
- -Lipopolysaccaride (LPS) consisting of Lipid A and o polysaccarides
How does the LPS provide protection to the cell?
contrinutes to the cells negative surface charge and protects against phagocytes and complement
How do endotoxins enter an animal's bloodstream?
- Lipid A is is the endotoxin in gram - cells. Free Lipid A molecules in an animal's blood can cause shock!
- -when bacterial cells grows, some lipid A is freed
- -once treated, dead cells denigrate and release Lipid A
What is an Exotoxin?
- Proteins secreted from the cell which are usually very toxic.
- -Gram + cells produce exotoxin, but some Gram - as well
- -botulinum toxin and tetanus toxin are two
What is lysozyme? What is it's effects on gram + cells and gram - cells?
- An enzyme found in tears, saliva, other secretions
- -break the Nag/Nam connection
- -this works on the Gram + cells, but not on the Gram - cells because the cell membrane protects the peptidoglycan
What is penicillin's effect on the cell wall?
- Penicillin inhibits the formation of the peptide cross-links in new and growing cells, causing lysis
- -works on gram +
- -we have created ampacillin for Gram - cells
What is the plasma membrane?
- a differentially permeable barrier composed of the lipid bilayer (polar head and nonpolar fatty acid tails), integral proteins, and peripheral proteins
What is the function of the phospholipid bilayer and membrane protiens?
- It functions as a deferentially permeable barrier
- -carbon dioxide, oxygen pass through freely while water, ions, sugars, amino acids, and proteins bounce off
most are transporters
What is simple diffusion?
Molecules pass directly through the PBL (oxygen and carbon dioxide)
What is facilitated diffusion?
- Molecules are assisted across the membrane by substrate specific transport proteins
- -monosaccarides, amino acids, vitamins, ions
- *no ATP used because it follows the concentration gradient, however it does also occur against the gradient
What is Osmosis?
Water moves across membrane both by simple diffusion and by passing through aquaporin proteins
Why is osmosis important to microbiology?
- 1. If the cell wall is damaged and cell is in a hypotonic ECF, the cell bursts
- 2. Bacteria in hypertonic environments grow poorly
What is Active transport?
- Protein pumps that are substrate specific carry ions, sugars, amino acids, and sometimes antibiotics across the membrane
- *uses ATP
- -against concentration gradient
How do you tell if the ECF is hypertonic or hypotonic?
- -This always deals with the amount of substrate in the ECF.
- -If there is more substrate in the ECF, it ishypertonic and water will leave the cell.
- -If there is more subtrate in the cell, the ECF is hypotonic and water will enter the cell
What is the bacterial chromosome and where is it located?
- -Bacterial chromosome is located in the Nucleoid
- -a single, continuous, circular thread of double stranded DNA (no envelope or histones)
- -attached to the plasma membrane
What is a plasmid and how is it different from the bacterial chromosome?
- A plasmid is a small, circular, double stranded DNA molecule that are extrachromosomal genetic elements
- -replicates independently of chromosomal DNA
- -not essential to survival
- -may be transferred to another bacteria
- Advantages: may carry genes for
- -antibiotic tolerance
- -tolerance to toxins
- -production of toxins
- -synthesis of protiens
What is the function, composition and structure of the Prokaryotic ribosome?
- Function: site of protein synthesis
- Composed of: 2 sub-units, consisting of protein and ribosomal RNA (rRNA)
Svedberg measure of density
What is the difference between prokaryotic and eukaryotic ribosomes and why is this relevant for antibiotic treatment?
- prokaryotic is 70S while Eukaryotic are 80S
- -certain antibiotics can interfere with protein synthesis in 70S while not harming host
What are the general function of inclusion and name 3 different types?
- Inclusions: reserve deposits
- 1. metachromatic granules: hold polyphosphate for ATP production
- 2. polysaccaride molecules: contain glycogen and starch
- 3. Lipid inclusions: lipid nutrient reserves
What are two bacteria that develop endospores and what diseases do they cause?
- Bacillus-respiratory problems (B. anthracis for example)
- Clostridium-digestive problems (C. difficile causes major diarrea)
What environmental stimulus triggers sporulation?
Sporulation is triggered when a key nutrient, such as carbon dioxide or nitrogen is depleted for unavailable
What are the major events of sporulation?
- 1. sporeseptum begins to isolate newly replicated DNA and small protein of cytoplasm
- 2. Plasma membrane starts to surround DNA, cytoplasm, and membrane isolated in step 1
- 3. Spore septum surrounds isolation portion forming endospore (forming 2 membranes)
- 4. Peptidoglycan layer forms between membranes
- 5. Spore coat forms
- 6. endospore is freed from cell
What is the structure of the endospore? Describe these aspects: spore coat, peptidoglycan layer, DNA, cytoplasm including ribosomes and enzymes, and water content
- Endospore only contains the essentials: DNA, small amounts of RNA, ribosomes, and enzymes
- -surrounded by spore coat and peptidoglycan later
What causes germination of the endospore?
- Germination takes the endospore from dormant to vegetative
- - triggered by physical or chemical damage to the endospores coat
- -causes endospores enzymes to break down extra outer spore coat and water enters
What makes spore formers more durable and what does this mean for treatment?
- Vegetative cells are easy to kill, but endospores are not. Their thick spore coat keeps out antibiotics and makes it very hard to treat while endospores are dormant.
- -hardest MO to treat
Why is a spore not considered a reproductive structure?
The endospore is only one cell. It is not means of reproduction, but of survival
What is the endosymbiotic theory?
- The idea that mitochondria and chloroplasts used to be bacteria
- -both have their own circular DNA
- -both are enclosed with a double membrane (PLB)
- -both have 70S ribosomes
- Advantages for the small cells:
- -big cell is a source of nutrients
- -big cell is a source of protection
- Advantages for big cells:
- -small cells produce more ATP
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