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52 Cards in this Set
- Front
- Back
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according to the cell theory of life
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a single cell is the smallest unit of life and is capable of carrying out all of the basic processes of a living organism
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5 important characteristics of all living organisms
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ability to reproduce
ability to take in food, produce energy, grow ability to excrete wastes ability to respond to the environment susceptible to mutation |
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cell envelope
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cell membrane - diffusion barrier, always present
cell wall - usually present, maintains cell shape, protects from osmotic lysis by preventing excessive swelling glycocalyx - external layer of slime, protects bacterium from host immune system, freezing and dessication, helps bacteria to stick together |
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functions of the cytoplasmic membrane
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semipermiable barrier
allows some substances to diffuse into and out of the cell but it prevents other substance from entering or leaving the cell defines the border between the living matter within the cell and nonliving matter that is outside enzymes and ETC embedded in the cytoplasmic membrane of bacteria |
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cytoplasmic membrane composition
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composed of a lipid bilayer that has protein molecules embedded within it
50/50 protein vs lipid lipids are phospholipids |
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function of cell wall
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gives cell its shape
protects cell from osmotic lysis not rigid allows water diffusion |
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composition of the bacterial cell wall
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made of petidoglycan
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petidoglycan
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made of long chains of modified sugars that are cross-linked by chains of amino acids known as peptide chains
amino acids like d-alanine, ornithine, diaminopimelic |
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modified sugars
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n-acetylglucosamine (NAG) and n-acetylmuramic acid (NAM)
chitin mad of NAG |
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gram positive positive cell wall
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thick layers of peptidoglycan are held together by teichoic acid molecules
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gram negative cell wall
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thin layer of peptidoglycan covered by an outer membrane
OM contains lipopolysaccharide or endotoxin periplasmic space is the compartment between the inner and outer membrane |
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lipopolysaccharide (LPS)
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a component of the gram negative outer membrane
lipid A portion is embedded in the membrane O-antigen is a sugar polymer that sticks out on the outer surface R-core is a cluster of sugars that joins lipid A to O-antigen also know as bacterial endotoxin is a pyrogen, potent nonspecific activator of teh immune response that causes the host to develop a fever released from dead cells that are decomposing and some is released from dividing cells |
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teichoic acids
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component of thich cell walls of the gram positive bacteria
polymers of sugar acids helps bind together the layers of peptidoglycan in the thick cell walls helps anchor the cell wall to the cell membrane |
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bacterial capsule
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layer of organic polymers that coats the outside surface of a bacterial cell like a layer of gravy on a meatball
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functions of bacterial capsule
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protect cell from drying out or freezing
help the bacterium to stick to surfaces and other bacterium protect the cell from recognition by the host's immune system and phagocytosis storage of sugars or other nutrients that may be abundant when the bacterium is makeing the capsule but may be broken down and used for food at a later time |
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different species make different types of capsules
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most commone materials are polysaccharides
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bacterial capsule clinical significance
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strains of streptococcus pneumoniae that make a capsule are more virulent than strains that do not make a capsule
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streptococcus pneumonia
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polysaccharide capsule that is poorly antigenic
protects bacterium from the host immune system makes it more virulent |
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streptococcus mutans
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dextran capsule (polysaccharide) helps the bacterium to stick to the surface of a tooth
calcium leeched from the enamel mineralizes the capsular matrix |
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xanthomonas campestris
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soil bacterium that causes soft rot of vegatables
is protected from freezing and dessication (drying) by a polysaccharide capsule |
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bacterial appendages
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structures that are found on the outside of the cell
simple protein tubules fimbrae sex pilus flagella |
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fimbrae
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fibers that help bacteria stick to surfaces and to each other
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sex pilus
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special fimbri that is used during conjugation
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flagella
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rotating heliccal fibers that act as propellers
-monotrichous (one hair) -lophotrichous (a tuft/clump of hair) -amphitrichous (on both sides) -peritrichous (all around) -axial filaments (inside the periplasmic space) |
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pilli or fimbrae
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pili are hollow tubes of protein that stick out of the outer surface of bacteria
pili are about the same diameter as flagella but are shorter and straight pili help bacteria to stick to surfaces and to each other some pili are virulence factors that allow pathogenic bacteria to stick to host cells other pili are important for the formation of biofilm |
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f-pilus
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special pilus found in some strains of e. coli
causes two cells to stick together so DNA can be transferred from one to the other through conjugation |
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bacterial flagella
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consists of a single protein fiber that is external to the cell membrane
it is a helical tube of protein that rotates like a propeller or corkscrew |
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chemotaxis
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purposeful movement of a microbe or a cell i a chemical concentration gradient either towards the source of an attractant or away from the source of a repellant
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run and tumble motion
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form of movement in a semi-random fashion
progress in the right direction occurs when the average length of a run in the correct direction is longer than the average length of a run in the wrong direction |
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function of bacterial endospore
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endospore is a tough resting state that allows bacteria to survive a period of harsh conditions such as when the soil dries out or they run out of food
not a reproductive structure because sporulation begins with a single vegatative cell and ends with a single spore are the toughest form of life on earth |
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endospores are very resistent to...
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heat
radiation dessication lack of nutrients antimicrobial chemicals physical abrasion |
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structure of bacterial endospores
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endospore coat is highly modified cell wall that contains special coat proteins and dipicolinic acid in addition to peptidoglycan
dipicolinic acid chelates calcium ions, the spore coat is somewhat mineralized core of the spore contains everything found in the cytoplasm of a vegatative cell except it is nearly metabolically inert and contains less water than normal cytoplasm |
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anthrax
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caused by inhalation of spores from bacillus anthracis
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tetanus and gas gangrene
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caused by contamination of a wound site by clostridium
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botulism
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caused by eating food that is contaminated by clostridium botulism
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chromatophore
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membrane structure found only in photosynthetic bacteria
contains light harvesting pigments that allow the cell to absorb sunlight and produce energy means "colored body", from the color of the light harvesting pigments (green, purple, yellow-green) |
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bacteriochlorophyll and carotenoids
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light harvesting pigments produced by photosynthetic bacteria
bacteriophylls are similar to plant chlorophyll except they often absorb different wavelengths of light they are different colors many photosynthetic bacteria are purple or yellowish green rather than the more bluish green of land plants unlike plants, bacterial photosynthesis does not always involve the production of oxygen |
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mesosome
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an invagination of the cytoplasmic membrane
discovered using transmission electron microscopy and some microbiologists believe that it is an artifact of the drying staining process most commonly seen in actively growing gram + bacterial cells |
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possible functions of mesosome
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increases the surface area of the cell membrane and is a site for placement of membrane bound enzymes, such as those involved in cell wall biosynthesis
is the site for the attachment of the DNA to the cell membrane could play a role in chromosome separation before cell division, but that has not been proved |
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inclusion bodies
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insoluble particles that accumulate in some bacterial cells under certain conditions including:
media conditions, availability of specific nutrients or oxygen and culture age some can be visualized using special staining techniques are usually some form of stored material some are metabolic waste products while others are stored nutrients some bacteria accumulate starch granules, other accumulate granules of sulfur, polyphosphates or poly-hydroxybutyrate |
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common types of inclusion bodies that are found in bacterial cells
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starch
protein lipoid granules polyhydroxybutyrate sulfur iron |
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differences between the archaea and bacteria
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1. cell memmbrane lipids--fatty acids in bacterial lipids have straight chains, fatty acids in archaea have branching chains
2.cell wall composition--bacterial cell wall is made of petidoglycan, archaea cell walls are made of other compounds 3. RNA polymerase in archaea is more like eukaryotic cells |
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structures seen in eukaryotic cells but not in prokaryotes
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ER
mitochondria chloroplasts cytoskeleton phagolysosomes nuclear membrane snRNPs |
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ER
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complex network of internal cell membranes that is attached to both the cytoplasmic membrane and the nuclear membrane
ribosomes are often attached |
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mitochondria
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membrane bound "energy producing" factories that are not seen in bacteria
most are rod shaped and they are the size of a small to average bacterial cell essential for survival of most types of eukaryotic organism have their own DNA and RNA and ribosomes and are capable of synthesizing some of their own proteins thought to have evolved from endosymbiotic gram - bacteria and are considered to be "autonomous organelles" |
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chloroplasts
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membrane bound photosynthetic organelles that are not seen in photosynthetic bacteria
have their own DNA/RNA and ribosomes and are capable of synthesizing their own proteins thought to have evolved from endosymbiotic photosynthetic cyanobacteria and are considered to be "autonomous organelles" contain chlorophyll that is found in plant cells and thus are resposible for the green color of leaves |
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components found in eukaryotic cells
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cytoskeleton
phagolysosomes nuclear membrane snRNPs |
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cytoskeleton
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network of microfibers and microtubules that helps a eukaryotic cell to maintain its shape
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phagolysosomes
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membrane bound compartments that can enclose food particles or bacteria that can be digested by enzymes and oxidative chemicals that are pumped into this compartment
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nuclear membrane
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keeps the transcription machinery separated from the translation machinery
that is: mRNA synthesis occurs in the nucleus but protein synthesis occurs in the cytoplasm that is outside the nucleus |
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snRNPs
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small nuclear ribonucleic acid-protein particles are involved in the processing of mRNA molecules in Eukaryotic cells
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eukaryotic flagellum
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long whip-like structure
small and less complex than flagella consists of a single protein fiber that is not membrane bound usually has 11 protein fibers in a membrane bound structure whipping motion of a eukaryotic flagellum is mechanically much more sophisticated than the rotation of a bacterial flagellum |
