microbio exam 1

prokaryotes vs eukaryotes

proks lack true nucleus and histones, have peptidoglycan to make up cell wall, and lack membrane-bound organelles

ALL bacterial cells possess

cytoplasmic membrane, cytoplasm, ribosomes, cytoskeleton, and one (or a few) chromosome(s)

MOST bacterial cells possess

cell wall and glycocalyx

bacteria average size

1 micron (1 micrometer)

pleomorphism

variations in cell wall structure caused by slight genetic or nutritional differences

cocci shape

spherical/ball-shaped but can also exist as oval/bean-shaped

bacilli shape

cylindrical/rod shaped; quite varied in actual form

coccobacillus

when a rod is short and plump

vibrio

rods that are gently curved (macaroni)

spirillum

rigid helix, twisted twice or more along its axis (corkscrew)

spirochete

a more flexible form that resembles a spring (slinky)

branching filaments

a few bacteria produce multiple branches off a basic rod structure

diplococci

pairs

tetrads

groups of four

sarcina

cubical packet of eight, sixteen, or more cells

streptococci

chains

staphylococci

irregular clusters

diplobacilli

pair of cells with ends attached

streptobacilli

chain of several cells (attached horizontally)

palisades

cells of a chain remain partially attached by a small hinge region at the ends (attached vertically)

spirilla

bacilli arrangement; only sometimes in short chains

spirochetes

bacilli arrangement; rarely remain attached after cell division

S layer

single later of a protein linked together like tiny chain link fences

on top of cell wall and only present in some bacteria

glycocalyx

coating of repeating polysaccharide or glycoprotein units

outside cell wall

can be slime layer or capsule

slime layer

type of glycocalyx

loose, protects against loss of water and nutrients

capsule

type of glycocalyx

more tightly bound, denser, and thicker

flagella primary function

motility (movement/mobility)

flagella structure

filament, hook (sheath), and basal body

polar arrangement

flagella attached at one or both ends of the cell

monotrichous

single flagellum

lophotrichous

small bunches or tufts of flagella emerging from the same site

amphitrichous

flagella at both poles of the cell

peritrichous

flagella are dispersed randomly over the surface of the cell

not a polar arrangement

chemotaxis

movement of bacteria in response to chemical signals

run or tumble

run

rotation of flagellum counterclockwise, resulting in a smooth linear direction

tumble

reversal of the direction of the flagellum, causing the cell to stop and change course

fimbriae

small bristle-like fibers sprouting off the surface of many bacterial cells

fimbriae function

allow tight adhesion between fimbriae and epithetial cells, allowing bacteria to colonize and infect host tissues

pilus/pili main function

used in conjugation between bacterial cells (acts as a bridge for genetic exchange; how antibiotic resistance spreads)

type IV pilus can

transfer genetic material, assist in attachment (like fimbriae), and make a bacterium motile (like flagella)

microorganisms

bacteria, archaea, protozoa, fungi

__ can’t be treated with antibiotics because they aren’t cells

viruses

viruses are composed of

a small amount of DNA or RNA surrounded by a protein coat and sometimes a membrane

prions

no DNA or RNA but are still infectious

genetic engineering

manipulates the genetics of microbes, plants, and animals for the purpose of creating new products and genetically modified organisms

recombinant DNA technology

makes it possible to transfer genetic material from one organism to another and deliberately alter DNA

bioremediation

uses microbes already present or introduced intentionally to restore stability or clean up toxic pollutants

pathogens

microbes that cause disease

spontaneous generation/abiogenesis

the belief that invisible vital forces present in matter led to the creation of life

biogenesis

the belief that living things arise only from others of their same kind

louis pasteur contributions

studied roles of microorganisms in fermentation of beer and wine

disproved spontaneous generation with his swan-necked flask experiments

conducted first studies linking human disease to infection

robert hooke

first to see and name cells

oliver wendell holmes and ignaz semmelweis

discovered importance of hand washing in hospital setting

joseph lister

used aseptic techniques in surgery

robert koch

established link between certain pathogens and the diseases they cause

discovery of restriction enzymes (1970)

allows scientists to use enzymes to cut DNA

PCR technique (1980s)

PCR can detect tiny amounts of DNA and then amplify them

used to discover new organisms, diagnose infectious diseases, and in crime scene investigation

small RNAs (2000s)

have critical roles in regulating cell activity

led to new approaches to how diseases are treated

scientific names are ?? when written in print and ?? when written by hand

italicized, underlined

nanotubes (nanowires) structure

thin long tubular extensions of the cytoplasmic membrane

nanotubes function

used as channels to transfer amino acids or to harvest energy by shuttling electrons to iron-rich substances

S layer is or is not present in all bacteria

is not

s layer is only produced when

bacteria are in a hostile environment

capsules have increased

virulence (disease-causing abilities)

capsules can be responsible for forming

biofilms

cell envelope order going outermost way

cytoplasmic membrane → cell wall → glycocalyx

cell wall gives cell

rigidity from peptidoglycan

gram-positive cell wall

thick, homogenous sheet of peptidoglycan

contains teichoic acid and lipoteichoic acid

gram-negative cell wall

single, thin sheet of peptidoglycan

contains outer membrane over peptidoglycan

thinness of gram negative cells make them more susceptible to

lysis by physical pressure

outer membrane contains

lipopolysaccharides (LPS) and porin proteins

lipopolysaccharide

signaling molecules and receptors

endotoxin

endotoxin abundance can lead to

massive inflammation by immune system or sepsis/septic shock

porin proteins

membrane channels that allow certain chemicals and affect entry of antibiotics

gram negative cell is __ difficult to inhibit or kill than gram positive

more

due to outer membrane; acts as extra barrier and is resistant to certain chemicals

examples of acid-fast bacteria

mycobacterium (causes TB)

norcardia (causes lung infections/pneumonia)

acid-fast bacteria contain _ and stain _

peptidoglycan

gram-positive

bulk of acid-fast bacteria cell wall is composed of

mycolic acid

mycolic acid

not easily destroyed by phagocytes

makes bacteria highly resistant to certain chemicals and dyes

all archaea cell walls

lack true peptidoglycan structure

mycoplasmas naturally

lack a cell wall

stabilize cell against lysis

L forms

bacteria that naturally have a cell wall but lose it during their life cycle

resistant to antibiotics

cytoplasmic membrane is

selectively permeable

bacterial DNA is aggregated in the

nucleoid

plasmids

nonessential pieces of DNA

ribosomes

site of protein synthesis (in human cells too)