bacterial cytology – Flashcards
Unlock all answers in this set
Unlock answers| Prokaryotes |
no nuclear membrane single circular chromosome (haploid) transcription and translation occur simultaneously (coupled) respiration is via the cytoplasmic membrane no cytoplasmic membrane bound organelles  |
| eukaryotes |
nucleus is bound by nuclear membrane multiple chromosomes-DNA associated with histones (diploid) transcription occurs in nucleus and mRNA moves into cytoplasm for translation respiration via mito cytoplasmic membrane bound organelles |
| whats in the cell envelope |
cytoplasmic membrane cell wall (peptidoglycan) capsule outer membrane |
| cytoplasmic membrane |
lipid bilayer semi-permeable 70% protein 30% phospholipids No sterols -exception is mycoplasma  |
| membrane function |
transport site of attachment for enzymes DNA replication Electron Transport (energy generation) Oxidative phosphorylation Cell wall biosynthesis |
| periplasmic space |
found only in gram negative bacteria space between outer and cytoplasmic membrane contains degrative enzymes, nucleases, phosphatases, penicillinases |
| cell wall |
rigid give bacteria its shape protects from osmotic lysis target for antibiotics |
| glycocalyx |
viscous material extending from the bacterial cell adhesive polymer secreted by bacteria  |
| slime layer (S) |
| glycocalyx loosely attached to the cell wall |
| capsule |
glycocalyx bound tightly to the cell wall covers cell surface composed of polysaccharide polymers except for Bacillus subtilis; used in certain vaccines has K antigens  considered a virulence factor |
| what is Bacillus subtilis capsule made of? |
| poly-D-glutamic acid |
| capsule function |
antiphagocytic hinders opsonization mediates adhesion of bacteria to human tissues helps in lab id via Quellung reaction |
| k antigens |
| determines serological types |
| Pili |
hairlike structures on the surface of bacteria smaller diameter than flagella  composed of pilin (pilE) |
| Capsules are considered virulence factors in what bacteria |
pneumococci meningococci |
| Pili are important virulence factors in what bacteria |
E. Coli N. gonorrhoeae |
| F- pili |
| involved in bacterial conjugation |
| common pili |
| involved in cell adherence/attachment |
| Pili in Neisseria |
undergo phase and antigenic variation tips may have lectins tha bind to specific sugars |
| where is the antigenic variation found in Neisseria pili |
| variable C terminus |
| What is the mechanism of antigenic variation |
| evades host immune system by changing surface proteins: pilin outer membrane proteins by gene conversion |
| Flagella |
organelles for locomotion composed of 3 parts composed of flagellin has H antigen used in id of Salmonella/Enterobacteriacea undergo phase variation |
| what are the three parts of flagella |
basal body hook filament |
| what is flagellin |
| helically coiled protein subunits |
| what does flagella do and what is the energy for this action |
propel cells by rotation motion proton motive force |
| what are flagella's four arrangements |
monotrichous lophotrichous ampitrichous peritrichous |
| what two species of bacteria undergo the swarming phenomena |
Proteas Bacillus |
| what is bacterial chemotaxis |
process of moving in specific direction in response to environmental stimuli swim counterclockwise toward an chemoattractant swim clockwise away from repellents |
| chemotaxis signaling pathway |
terminates at flagella motor starts with the binding of chemoattractancts/repellants to chemoreceptors in the membrane either methylation or demethylation of methyl accepting chemotaxis proteins that triggers the rotation of flagellum and tumbling |
| cytoplasmic inclusions |
storage granules (metachromatic) storage mechanism when nutrients are low id feature in Corynebacterium diphtheriae |
| different types of cytoplasmic inclusions |
polymetaphosphates-volutin granules (babes ernst) glycogen- like polymers poly beta hydroxybutyric acid |
| ribosomes |
protein synthesis 70S= 50S +30S 60% RNA and 40% protein 30S subunit (16S RNA and 21 proteins) 50S subunit (23S RNA, 5S RNA and 34 proteins) Â |
| Spores |
found in gram-positive bacteria are dormant and dehydrated resistant to heat, chemicals, drying, freezing contains chromosome, proteins, ribosomes, and high concentrations of calcium dipicolinic acid |
| when are spores formed |
| in response to nutritional deprivation |
| sporogenesis |
spore mRNA transcribed chromosome is duplicated core is formed along with the cortex protein coat is formed exosporium is formed  |
| germination |
conversion of spores to vegeatative cells outgrowth |
| what stimulates germination |
| disruption of outer coat: stress, pH, heat |
| what does germination require |
| water, triggering nutrient (alanine) |
| teichoic acid |
rich in glycerol phosphate/ribitol phosphate attached via phosphate groups to muramic acid in PG found in gram positive bacteria |
| teichoic acids function |
activate alternative pathway of complement adhesion of bacteria to host cells involved in the antigencity of the cell wall |
| what is lipoteichoic acid function |
| anchors wall to cell membrane and function as an epithelial cell adhesion |
| outer membrane |
| covalently attached to PG through lipoprotein layer |
| cell envelope-gram negative bacteria |
reinforced cell shape provided protection excludes hydrophobic protein an asymmetric bilayer external layer composed of LPS |
| what penetrates outer membrane slowly |
| antibiotics |
| porins |
outer membrane proteins trimeric proteins has a pore that allows chemicals and nutrients traverse the outer membrane along with hydrophilic solutes |
| what are the three regions of LPS |
lipid a core polysaccharide o antigen |
| somatic o antigens |
repeating carbohydrate units attached to the core and extends away from the cell distinguishes serotypes of a species accounts for antigenic diversity among serotypes if its missing there is sensitivity to bile salts and antibiotics |
| core polysaccharide |
has an outer (structural variability)Â and inner (low structural variability)Â core has 2-keto-3-deoxyoctulosonis acid (KDO) associated with serologic specificity branched 9-12 sugars |
| lipid a |
responsible for toxicity of endotoxin pyrogenic consist of a chain of phosphorylated D-glucosamine disaccharide units with fatty acids attached  |
| Beta hydroxymyristic acid |
| most commonly observed lipid a in fatty acids |
| synthesis of LPS |
lipid a and core portion synthesized on inner surface of cytoplasmic membrane repeat units of the O antigen are assembled on a bactoprenol molecule finished o antigen chain transferred to core lipid a structure |
| lipooligosaccharide (LOS) |
present in Neisseria gonorrheae, N. meninigitidis lacks o antigen portion of lps readily shed from the bacteria important virulence factor |
| pathophysiology of LPS |
stimulate innate immune responses activates B cell and induces macrophages release cytokines (interleukin 1,6 and TNF) complement and coagulation cascades are activated fever and shock DIC death from massive organ dsyfunction |
| lysozyme/penicillin |
hydrolyzes the band between N acetyl glucosamine and N-acetylmuramic acid treatment of gram positive bacteria produce protoplasts "" of gram negactive bacteria produce spheroplasts |
| mycoplasma |
no cell wall variable morphology sterols in cytoplasmic membrane |
