Lecture 2 Flashcards

Question

Colony forming unit

Answer 1

A SINGLE colony is created from a SINGLE bacterium that replicates many times until there are enough cells to see with the naked eye A COLONY FORMING UNIT (CFU) refers to the single bacterium that started the colony Because, all cells within the colony are identical, each colony represents ONE colony forming unit THE DOTS YOU CAN SEE IN A PETRI DISH

Answer 2

AKA cell membrane, plasma membrane Main component is a phospholipid bilayer Also contains many different types of proteins, carbohydrates and cholesterol Surrounds the contents of every living cell Thin, flexible The cytoplasmic membrane is a selectively permeable barrier

Answer 3

Unicellular Prokaryotic Lack internal membranes Small

Answer 4

Move substances (nutrients, toxins, waste products) into and out of cells Some antibiotics are designed to only target bacteria cells by using these transporters to move into the cell

Answer 5

Proteins that bind to “signals” from the outside environment Tell the bacteria cell to: start or stop replicating move away from harm produce enzymes to metabolize nutrients produce enzymes required to inactivate specific antibiotics

Answer 6

Bacteria do not have mitochondria Energy producing machinery is located along folds/invagination in the cytoplasmic membrane (called mesosomes)

Answer 7

Bacteria use these proteins to attach to specific cells in the host animal Certain bacteria can only attach to certain cells Essential for infection

Answer 8

Any protein or portion of a protein on the surface of a bacteria cell that can be recognized by the ANIMAL’s immune system Antigens are the molecular “ID tags” that are found on all cells Different bacteria have different surface antigens Often used as a method of identifying different strains of the same species

Answer 9

Enclose the cytoplasm Barrier function Regulates movement of molecules in and out of the cell Interacts with the environment – via signal receptors Site for energy production Attachment – part of the infection process

Answer 10

Fluid or gel that fills the cell 60-70% water Cytoskeleton Molecular scaffold Metabolically active Biochemical reactions

Answer 11

Complex structures consisting of protein and ribosomal RNA Site of protein synthesis Where the RNA is “read” and used to assemble proteins in the process known as translation

Answer 12

A single strand of circular DNA contains all essential genes Fewer genes than in eukaryotic cells Strand of DNA is organized by DNA binding proteins and supercoiled into a tight bundle The bundled chromosomal DNA is located in the nucleoid The immune system can recognize bacterial DNA

Answer 13

“Extra”, small, circular pieces of DNA containing 1 or 2 genes NOT part of the chromosomal DNA Located outside the nucleoid Genes located on plasmids are not essential to life, but are beneficial to survival by providing an evolutionary advantage

Answer 14

Proteins that provide antibiotic resistance such as the beta- lactamase enzyme (resistance to penicillins) Genes for specific toxins or attachment proteins Genes that enable the bacteria to produce capsules

Answer 15

Can have none, one or more than one different plasmid Plasmids replicate independently of the chromosomal DNA Once a bacteria acquires a plasmid, it will duplicate itself inside the cell until there are 100’s to 100,000’s of copies per cell Very resistant to degradation may remain stable in the environment after the bacteria cell has died

Answer 16

During replication – any time the bacteria cell divides, plasmids also duplicate and an equal number of plasmids are transferred to the “daughter” cell Transformation – process where the cell membrane opens up and allows the bacteria cell to take up a plasmid from the environment Bacterial conjugation – process where there is direct contact between 2 bacteria cells through the creation of a temporary cytoplasmic membrane bridge that allows transfer of plasmids

Answer 17

All bacteria (except Mycoplasma) have a cell wall Rigid - surrounds the cytoplasmic membrane Names are based on staining properties The type of cell wall is used to help identify the genera

Answer 18

Gram - or Gram + or acid fast

Answer 19

Maintains shape of bacteria Protects cell from lysis due to osmotic pressure Helps protect from toxic materials Including antibiotics Small molecules (< 2nm) can diffuse between peptidoglycan chains; large molecules are excluded Helps with attachment Prevents phagocytosis by white blood cells in the immune system

Answer 20

Lysozymes - enzyme found in tears and saliva Beta-lactams - class of antibiotics (including penicillins and cephalosporins) prevents proper synthesis of the cell wall

Answer 21

Primary component is peptidoglycan 2 different polysaccharides linked together alternately to make long chains Peptide cross-links Short polypeptide chains

Answer 22

Gram stain is a specific method of staining bacteria Separates most bacteria genera into 2 major groups based on differences in cell wall structure Gram positive- purple Gram negative- pink Whether bacteria are Gram positive or Gram negative is important with respect to certain growth requirements, pathology and treatment during an infection

Answer 23

Thick cell wall - makes up 40-90% of total cell mass 20-80 layers of peptidoglycan Layers joined by peptide cross-links Enzyme called transpeptidase is required to make these cross-links Teichoic acid Long molecules that help embed the cell wall to the cytoplasmic membrane May have additional teichoic acids on surface of cell wall that help bacteria attach to other bacteria and/or animal cells

Answer 24

Gram positive bacteria are susceptible to the beta-lactam class of antibiotics Penicillins, cephalosporins Beta-lactam antibiotics bind to and block function of the transpeptidase → prevents formation of the peptide cross-links between peptidoglycan strands Without cross-links, cell wall cannot withstand osmotic pressure and cell lyses

Answer 25

Thin ~ 10% of total cell mass Multiple layers: Peptidoglycan layer Closest to the cytoplasmic membrane 1 to 2 layers only Outer membrane Complex - composed of two lipid layers Inner layer is a single sheet of phospholipids Outer layer is single sheet of lipopolysaccharide (LPS) Periplasmic space Space between the cytoplasmic plasma membrane and outer membrane

Answer 26

Molecule that makes up the very outmost layer of a Gram-negative cell wall Part of the outer membrane layer Important to the bacteria for establishing infection; important to host while fighting off an infection 3 parts: O-antigen Core polysaccharide Lipid A(aka endotoxin)

Answer 27

Repeats of polysaccharide units “Smooth” – bacteria with long O chains “Rough” - bacteria with very short or lacking O chains Hydrophilic Certain species or strains are distinguished by the specific sugar molecule in their O chain

Answer 28

Establish infection WBCs are unable to grab “smooth” bacteria; WBCs can easily phagocytose rough cells O-antigens take part in attaching to epithelial cells Some bacteria can alter the sugars that make up the O-antigen; variation over time allows the bacteria to evade the immune system

Answer 29

when trying to fight off infection Sometimes, immune system can recognize sugars in the O chain and targets these cells for destruction Presence of O chain will trigger non-specific inflammation

Answer 30

Aka endotoxin “Tail” made up of lipid chains Same in all Gram negative bacteria Hydrophobic Function to hold the LPS molecule in place Normally hidden from the environment - if Gram negative bacteria dies, small amount is released into environment One of strongest activators of inflammation

Answer 31

Condition in the body where overwhelming inflammation causes blood vessels to dilate → drops blood pressure → systemic shock Caused by sudden release of large amounts of lipid A during a Gram negative infection Lipid A enters circulation and turns on systemic inflammation Can be fatal if not treated right away

Answer 32

Some bacteria are neither Gram + nor Gram - Do not have the cell wall structures described above Acid-fast bacteria Cell wall structure is very similar to Gram-positive, but contain large numbers of mycolic acid (waxy molecules) in the cell wall E.g. Mycobacterium Mycoplasma Do not have a cell wall Plasma membrane more resistant to osmotic pressure Very pleomorphic

Answer 33

Space between cytoplasmic membrane and start of peptidoglycan layers in Gram positive cell Space between cytoplasmic membrane and OUTER MEMBRANE in Gram negative cell peptidoglycan layer is in the periplasmic space Contains many proteins Proteins to digest macronutrients Proteins to break down toxic compounds (including antibiotics) before they can cross the plasma membrane Synthesis and storage of pathogenic factors (i.e., collagenase, some toxins)

Answer 34

Threadlike appendages that allow motility Only found on some bacteria All spirochetes and spirilla, half bacilli, rarely on cocci Proteins that make up flagella may be recognized and targeted by the immune system or used to identify the bacteria (i.e., act as antigens) The number and placement of flagella is used to identify bacteria Can have one or more flagella Location on cell and number of flagella determines the type of movement Example. If polar flagellum (one end of cell), will act like a propeller and push bacteria in one direction. Bacteria with many flagella that act together tend to move faster Cannot see flagella under a light microscope; but can see if fast motility is present or not Only some bacteria are motile

Answer 35

Can move towards environments that are more supportive of growth (increased nutrients), also ideal temp, moisture, presence or absence of oxygen Can move away from harmful substances (antibiotics, disinfectants, metabolic waste)

Answer 36

Fastest Flagella acts like propeller to swim through liquids

Answer 37

Corkscrew motion due to periplasmic flagella; is specific to spirochete bacteria

Answer 38

Mediated by fimbriae; crawling on surface or through liquids

Answer 39

Pushed by slime

Answer 40

Bacteria have sensors (aka receptors) on their cell surface that identify what is in the environment Activation of a receptor results in the bacteria turning on or off genes involved in motility Process of identifying and then moving toward or away from a chemical is called chemotaxis

Answer 41

Moves towards attractants

Answer 42

Move away form repellants

Answer 43

Short, thin, hair-like, protein structures that extend outwards from the cell wall May be up to thousands per cell Primary function is attachment to surfaces

Answer 44

Few per cell; very large protein threads that extend from cell wall 2 functions: Attachment to other cells and surfaces Forms the initial connection between 2 bacteria during the conjugation process.

Answer 45

Sugar units are well organized Attached to cell and not easily removed - rigid Primary functions are (1) resistance/protection (including from drying out, exposure to chemicals, phagocytosis) and (2) attachment

Answer 46

Not uniform; sugar units form loose coating around the cell wall and is easily removed Primary functions (1) resistance/protection, (2) attachment; (3) formation of biofilms, (4) motility

Answer 47

Resistant to phagocytosis – macrophages cannot grab onto bacteria Protects from drying out in the environment – capsules/slime contains water Protects from some detergents Protects from bacteriophage (viruses that infect bacteria) Protects from antibiotics Improves attachment Slime may aid motility

Answer 48

Some bacteria produce polysaccharides that are secreted AROUND the cell wall

Answer 49

Communities of bacteria (and yeast) embedded in a matrix that attaches to a surface A biofilm can be made up of single or hundreds of different species of bacteria Matrix sticks microbes to one another and onto a surface - either living or inanimate; usually moist

Answer 50

Cell attachment to surface (by receptors, flagella, fimbriae) Cells produce exopolysaccharides Biofilm matures – number of bacteria increase; size of matrix increases Cells from biofilm disperse and can reattach elsewhere Common to: standing water, roughened surfaces, surgical implants, catheters, heart valves, teeth Biofilms are self-sustaining; very hard to treat with antibiotics or disinfectants