Exam 1 9/7 Nguyen Micro Flashcards
Prokaryotes do not have:
nucleus or organelles
Prokaryotes include what organisms?
Bacteria and Archaea
Who described 3 domains for evolutionary tree?
Carl Woese
Eocyte hypothesis
2 domains; predicts that eukaryotes originate within the archaea and sharing a common ancestor with eocytes; archaea has the most branches on the eocyte tree
Bacteria can be seen inside:
epithelial cell
_____ provides higher resolution and sub-cellular features
Transmission electron microscopy (TEM)
_____ allows you to see 3D images of microbes
Scanning electron microscopy (SEM)
Viruses that infect bacteria
Bacteriophages and phages
Compare prokaryotic/eukaryotic ribosome
Prokaryote has 70S, eukaryote has 80S
Prokaryotes has ____ instead of a nucleus
Nucleoid
Prokaryotes are haploid/diploid
Haploid (most)
Prokaryotic cell wall contains:
peptidoglycan
Prokaryote size
less than several micrometers
Describe the nucleoid region
- not membrane enclosed; contains genetic material (dsDNA)
- Single circular chromosome
Nucleoid
70S ribosome consists of:
30S and 50S subunits
80S ribosome consists of:
60S and 40S subunits
Beta-hydroxybutryrate
type of cytoplasmic granules - stores lipids
Inclusion bodies have what substances in them?
- metabolites (lipids, polysaccharides)
- ions
What is the benefit of bacteria having inclusion bodies?
Some bacteria can store sugar or fats away to use during starvation mode to survive
In prokaryotes, there is an absence of ____ in the phospholipid bilayer, except in:
sterols; mycoplasmas (no membrane), some sphingolipids in bacteroides, variety of fatty acids, hopanoids (lipid)
Describe cell wall in gram-positive bacteria
Thick layer of peptidoglycan
Describe cell wall in gram-negative bacteria
Thin layer of peptidoglycan later between inner and outer membrane
What sugars make up peptidoglycan?
NAG and NAM (N-acetylglucosamine, N-acetylmuramic acid)
The bond between NAG and NAM is:
B-1,4 glycosidic linkage
What enzyme performs glycosidic bond between NAG and NAM?
transglycosylase
Cross-bridges
Formed between adjacent NAM molecules - amino acids form pentaglycine cross link to increase stability and strength in cell wall
Bactoprenol
membrane carrier that transfers monomers from cytosol to external site for peptidoglycan assembly
Bacterial enzyme _____ assembles peptidoglycan layers
Transpeptidase (forms cross bridges)
In addition to peptidoglycan, gram positive cell wall contains:
teichoic acid and/or lipoteichoic acid
What are teichoic/lipoteichoic acids made of?
polysaccharides polymers (ribitol or glycerol phosphate)
Where are teichoic/lipoteichoic acids linked?
Linked to NAM, plasma membrane via diacylglycerol (DAG)
Gram negative cell wall does not contain:
teichoic acids
Periplasmic space found in? What is found in it?
Found in Gram - bacteria; enzymes to resist antibiotics
_____ contains LPS
Gram - bacteria
Lipopolysaccharide consists of:
O-polysaccharide, core polysaccharide, Lipid A
In bacteria, _____ cleaves Beta lactam ring to defend against _____
Beta-lactamase; penicillin
Which component of LPS is antigenic?
O-antigen –> variable polysaccharide; species-specific repeat units (repeat 40 units)
Which component of LPS is endotoxin?
Lipid A –> toxic glycophospholipid
Lipid A components
Disaccharide diphosphate; fatty acids
LPS endotoxin may induce:
fever(pyrogenic), shock as physiological response
LPS causes host to secrete:
cytokines, proteases, toxic oxygen radicals
Lysozyme is found in:
saliva, tears
Lysozyme function
hydrolyzes Beta-1,4 bond between NAG and NAM, antibacterial
Penicillin inhibits the action of what enzyme?
transpeptidase
Gram stain steps
- fixation
- crystal violet
- iodine treatment
- decolorization
- counter stain safranin
True or false: gram positive bacteria is more susceptible to penicillin
True
True or false: gram negative bacteria is more susceptible to penicillin
False - more resistant
What is glycocalyx?
polysaccharide (dextran) coating on outer bacterial surface, allows adhesion
What types of bacteria have glycocalyx?
Rods, cocci
True or false: capsule is found within cell wall layer
False - it is a layer around the bacterial cell, it is around the cell wall
Capsule inhibits:
Phagocytosis (anti-phagocytic)
Capsule correlates with _____
virulence
Capsule mediates bacterial _____
adhesion
Examples of antigenic capsular proteins
K-capsular antigen on E. coli
Vi-antigen on Salmonella Typhi
Pathogenicity
ability to cause disease
Virulence factors
attributes that increase disease severity or ability to become infective
Quellung reaction
antibody mediated - capsules contain different antigens, can stain for specific ones; bind and cause swelling of capsule
Motility is achieved via:
flagella
What does the H refer to in E. coli O157:H7
H antigen - flagellar
Flagellar anchors in gram-positive bacteria
P-ring protein (Peptidoglycan side)
M-ring (membrane side)
Flagellar anchors in gram-negative bacteria
- L-ring protein (LPS)
- P-ring protein (periplasm)
- SM-ring proteins (surface cytoplasmic membrane; membrane)
- C-ring protein (cytoplasm)
Rank the size of flagellum, pilus, fimbrae
fimbrae<pilus<flagellum
Fimbrae function
attachment
Pili function
sense environment, gene transfer, attachment; crucial virulence factors in many pathogenic bacteria
Type I pili components
FimA - main rod/shaft protein
FimH - bacterial adhesion, fibrillar tip
Type I pili is mainly used for _____
adhesion
Type II pili
sex or fertility pilus (F-pilus); used during conjugation, transfer plasmids/DNA, transfer antibiotic resistance
F-type pilus is ____ and ____
long and flexible
P-type pilus is ___ and ___
short and rigid
Type III Pili function
“secretion channel” between bacterium and host cell; injector; delivers proteins but NOT DNA
Type IV pilus function
twitching/gliding motility
Type V pili function
bacterial adhesion, co-aggregation and biofilm formation –> gingivitis and severe periodontitis
Which type of pilus has important virulence factors of oral pathogen?
Type V
Coccus
Round
Bacillus
rod shaped
