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85 Cards in this Set
- Front
- Back
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define cell
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basic unit of life or smallest fundamental unit os all cellular organisms
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what are the key subcellular structures?
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-plasma membrane
-cytoplasm -nucleus or nucleoid -ribosomes |
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what are the 4 types of macromolecules contained in the cell?
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-nucleic acids ( DNA & RNA)
-polysaccharides -lipids -proteins |
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what are some characteristics of cells?
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- use carbon and energy sources via metabolism
-reproduce through cell division - has open and dynamic system to communicate and exchange materials with environment |
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a bacteria that has a single shape is called
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monomorphic
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define pleomorphic bacteria
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bacteria that have variable or multiple shapes
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list unicellular microorganisms that are prokaryotes
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bacteria archaea
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list multicellular microorganisms that are eukaryotes
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mold, some algae
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list unicellular microorganisms that are eukaryotes
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protozoa, yeast and some algae
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how do eukaryotic cell reproduce?
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via mitosis
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how do prokaryotic cells reproduce?
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via binary fission
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how do we classify and identify MOs?
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-by morphology (size & shape)
-by cell arrangement |
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list bacteria shapes
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-coccus (round)
-bacillus (rod) -vibrio (curved) -spririllum ( rigid, spiral) -spirochete( flexibles, spiral) -filaments (long) |
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list bacteria cell arragements
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-single
-pair (diplococci or diplobacilli) -chain ( strepto) -mycelium (filament network) -cluster (tetrad -----4) (sarcinae---8) (staph-----grape like) |
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what does the bacteria small size affect?
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-cell physiology
-growth rate (rapid) -ecology |
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what is the advantage for bacteria being small?
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-high surface area that provides a rapid mass exchange with environment
-forms large population easily that have rapid impact on the environment and other organisms -more cell division will cause more spontaneous mutation |
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where is the plasma membrane found?
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inside bacteria cell wall and it encloses the cytoplasm
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how is the plasma membrane structure refered to?
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fluid mosaic model
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what is the plasma membrane made of?
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phospholipid
( an ester = glycerol +fatty acids + phosphate linked by ester bonds) |
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what is the fluid mosaic model?
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- phospholipid bilayer with embedded proteins
- is highly flexible &dynamic because each phospholipid can rotate easily within the same layer |
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what is the phospholipid bilayer?
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two parallel rows composed of :
-polar heads------- hydrophilic facing the exterior -non polar tails-----hydrophobic facing the interior |
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where are membrane proteins found?
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embedded in the bilayer
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name the types of membrane proteins?
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-intergral proteins
-peripheral proteins |
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where are intergral proteins found and what is their function?
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-embedded within the membrane
-involve in proteins transport by forming spores - can change their own conformation to move molecules in and out of the cell |
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what are peripheral proteins and what are their functions?
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-loosely associated with membrane and easily removed
- usually enzymes for breaking down large molecules or for ATP production |
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what are other molecules in bacterial cell membrane?
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-carbohydrates
-sterols -hopanoids |
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what are sterols and were are they found?
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-rigid planar stucture that strengthens the membrane
-found in mycoplasma and eukaryotes |
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what are the functions of the cell membrane?
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-barries that separates the inside form the outside of the cell to prevent leakage of cytoplasm
-regulate transport by allowing small uncharged substancs to pass through ( water, O2, CO2) the selective permeable bilayer -use transport proteins to carry large charged substances -location of metabolic processes -detect and response to chemicals in surroundings with receptors molecules in membrane |
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where is the location of bacterial cell wall?
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semi rigid stucture exterior to cell membrane
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what is bacterial cell wall made of ?
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peptidoglycan
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what are the functions of the cell wall?
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-define cell shape
-structure support against mechanical damage -protect form osmotic lysis -may contribute to pathogenicity |
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what is peptidoglycan?
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a meshlike polymer of glycans and peptide
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what is a glycan?
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a polysaccharide of 2 sugar derivatives NAM & NAG
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what does NAM stand for
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N-acetylmuramic acid
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what does NAG stand for
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N-acetylglucosamine
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what is the peptide made of?
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-peptide side chain that link to NAM
- peptide interbridge which crosslink adjacent peptidoglycan |
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what are the two groups of bacteria based on their response to gram stain?
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-gram positive
-gram negative |
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what are the characteristics of gram positive bacteria?
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- stain purple
-thick peptidoglycan cell wall -cell wall is located outside the cell membrane -has teichoic acid |
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what are the characteristics of teichoic acid?
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- polymer of glycerol or ribitol
-present in peptidoglycan layer or attached to plasma -carry a lot of negative charges making cell surface negative |
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what is the composition of gram negative bacteria?
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-stain pink
-thin peptidoglycan layer located between the outer and plasma membrane - has outer membrane -has periplasma |
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what is the outer membrane made of?
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- LPS
-proteins -phospholipid bilayer |
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what does LPS stand for?
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lipopolysaccharide
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what does LPS contain?
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- O-side chain made of polysaccharide
-Core polysaccharide causing negative charges on cell surface -Lipid-A an endotoxin |
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what are the proteins found in the outer membrane and their functions?
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- porin that form channels for transport
-lipoproteins that connect outer membrane to peptidoglycan |
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what is the perisplasmic space?
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-space between plasma and outer membrane filled with fluid containing transport protein and hydrolitic enzyme
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what are the functions of the outer membrane?
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- give stucture
- more permeable than plasma membrane - protects against phagocytes, lysozymes, antibiotic -toxic to animals because of lipid A ( endotoxin) -varies in antigens, endotoxins, viral receptors |
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what can cause cell wall damages?
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-lysozymes
-penicillin -spheroplast -protoplast -osmotic lysis |
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how does lysozyme damage cell wall?
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by cleaving the bond between NAM & NAG
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how does penicillin damage the cell wall?
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-it inhibits peptidoglycan synthesis by actin on newly made ones
-has no effect on already made cell wall - will inhibit transpeptidase from making crosslink between peptidoglycan chain |
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what is a spheroplast?
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cell with damaged cell wall
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what is a protoplast?
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cell without cell wall
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what kind of solution will damage cell with or without damaged cell wall?
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hypertonic solution
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what is osmotic lysis?
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cell rupture due to excessive water entering cell
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what are some exception to cell wall structure?
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-acid fast bacterium
- wall-less bacteria -archaea |
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characteristics of acid fast bacteria
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-mycobacterium and norcadia
- high lipid content in cell wall (mycolic acid) -resistant to many chemicals -identified by acid fast stain |
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characteristics of wall- less bacteria
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-mycoplasma and ureaplasma
- sterols in cell membrane that give strenght and rigidity - have no cell wall (protoplast) - are pleomorphic, and osmotically sensitive |
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name the cell surface stucrures
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-glycocalyx
-S-layer |
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what is glycocalyx?
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-sticky gelatinous layer of polysaccharide or peptides or both
- can be capsule: organized and firmly attached -can be slime layer: unorganizedand loosely attached to cell wall |
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what is S-layer?
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-layer of protein or glycoprotein
-floor tiles like |
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functions glycocalyx and S-layer
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-attach to various surfaces ( bioflim)
-protect from dessication -protect from nutrient loss -protect from chemical enviroment -protect from osmotic stress( S-layer) -protect from host defense -protect from viral infection -facilitate motility of gliding bacteria (slime) |
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what are the appendages?
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-fimbriae
-pili -flagella |
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what are fimbriae and their function?
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short hair like filaments of proteins up to 1000/cell for attachment
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what are pili and their function?
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longer thicker protein filaments for conjugation and acts as receptors for certain bacteriophages
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what are flagella and what is their function?
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-long rigid appendages that anchored in the cell wall and the cell membrane that help cell for motility
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what are the 3 parts of the flagella?
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-filament: hollow rigid cylinder made of protein flagellie
-hook: short curved segment link filament to basal body -basal body: series of ring driving flagellar motor |
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how does flagella rotate?
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-counterclockwise: cell run forward
-clockwise: cell tumbles |
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why do bacteria move around?
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to respond to stimuli in the environment
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define taxis
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directed movement toward or away from stimulus
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what are the different taxis?
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-chemotaxis: from chemicals
-phototaxis: from light -magnetotaxis: to orient in magnetic field |
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in bacteria E.coli O157:H7 where does the O and H mean?
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O: has an O antigen that comes form the outer membrane of gram negative bacteria from the O-side chain
H:has the H antigen from the flagella |
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what is the ecological significance of motility?
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-explore new resourcces for survival advantage
-interact with other cells |
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what is the cytoplasm?
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all contents inside the plasma membrane including: nucleoid, ribosome, inclusion bodies, proteins, enzymes, ions, 80% of water
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what is the nucleoid and what is its function?
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not membrane bounded, irregular shaped that is the nuclear area containing DNA, nucleoid, proteins, RNA
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what is bacterial chromosome and what its functions?
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one circular double stranded DNA highly coiled to fit within te cell
-it serves as the genetic material that govern growth, reproduction |
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what is the plasmid and its function?
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-small circular double stranded DNA that is an extra chromosomal DNA that replicates independently of chromosome
-contain a few genes that may confer selective advantage -its transfer via pili between closely related cells |
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what are ribosomes and give their function?
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-complex of rRNA and proteins made of 2 subunits: 30s+50s=70s
-site of proteins synthesis |
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what are inclusion bodies?
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internal granules enclosed by a single layered protein or lipid membrane that store materials for future use
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what are the type of inclusion bodies?
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-lipid inclusion: provide C,P, energy
-polysaccharide granule: C, energy -poly-B-hydroxybutyrate granule: C, E -cyanophycin granule -polyphosphate granule -sulfur granule -magnetosome -gas vacuole |
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what are vegetative cells?
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actively growing cells susceptible to environment stress
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what are endospores?
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-differenciated dormant cell that do not divide nor metabolize
-formed in unfavorable environment -structurally and functionally different from vegetative cells |
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what bacteria produce endospore?
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-bacillus
-clostridium |
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what is conjugation?
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a process to transfer DNA molecules from one cell to another
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define sporulation
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endospore formation that occur when vegetative cell is starved
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define germination
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process for endospore to return to vegetative state activated by certain environment signal
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process of germination
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-spore swelling due to absortion of water
-rupture of spore coat -start metabollic activity -vegetative cell |
