Exam 2. Chapter 4 Flashcards
Exam 2 Prokaryotic cell Viruses Helminths
Characteristics of Cell life
Heredity Reproduction Growth and Development Metabolism Responsiveness Transport of Nutrients
Living cells parts
Cytoplasm, surrounded by a membrane
DNA chromosomes
Ribosomes
Metabolic capabilities
Appendages
Motility: flagella and axial filaments
Attachment: fimbriae and pili
External structures
Flagella
Fimbriae
Pili
Glycocalyx
Cell Envelope
Cell wall
Cell membrane
Inside the Cell
Cytoplasm Nucleoid Plasmids Ribosomes Inclusions Cytoskeleton
Flagella
Filament
Hook
Basal body: how the flagella attach to the cell membrane. The rings at the basal body attach to the cell membrane, through the cell wall. (L-ring, peptidoglycan) and cell membrane
Monotrichous
Single flagellum at one end.
Lophotrichous
Small tuft from the same site
Amphitrichous
Flagella at both ends
Peritrichous
Flagella all over the surface
Amphilophotrichous
Tufts at both ends
Periplasmic Flagella
axial filaments
Internal flagella in periplasmic flagella
very specific
Only associated with spirochete bacteria with a flexible cell wall
Syphilis, Lyme, Leptospirosis
Fimbriae
Fine hair-like bristles
Functions as attachment and protection
Virulence factor
Pili
Rigid tubular structure made of protein
Functions to join cells for DNA transfer called conjugation
Glycocalyx
External coatings of cell wall made of sugars and proteins.
Protects cells from dehydration and nutrient loss
Attachment during the formation of biofilms as the EPS (extra polymeric substance) hardens
Inhibits killing by white blood cells by phagocytosis, adding to the pathogenicity
Slime Layer
All organisms have this
Loosely organized and attached
Capsule
Highly organized, tightly attached
Glycocalyx types
Slime layer
Capsule
EPS
Extra Polymeric Substance
hardens to form biofilms
makes it difficult to penetrate
Cell Envelope
External coverings outside the cytoplasm Cell Wall Cell Membrane S-layer It maintains cell integrity
Gram-Positive
Thick peptidoglycan and cell membrane
Gram Negative
Thin peptidoglycan, outer cell membrane and inner cell membrane.
Peptidoglycan
Unique molecule Only found in bacteria Primary component Highly structured NAM, NAG, DAP Without this, it will be difficult to maintain shape
NAM
NAG
DAP
and antibiotics
NAM: N-acetyl muramic acid
NAG: N-acetyl glucosamine acid
They come together forming a latticework creating the peptidoglycan molecule
They are held by bridges held together by DAP
Helpful to have an antibiotic that targets a molecule that is only found in bacteria.
Penicillin resembles DAP and bacteria cell will take it in and cause it to have a weak cell wall. Organisms are now subject to lysis from changes in osmotic pressure.
Very useful with Gram +
Gram + cell wall
Mostly peptidoglycan
Teichoic acid and Lipoteichoic acid
Gram - cell wall
Thin peptidoglycan layer Two periplasmic space Outer membrane LPS Porin proteins in the upper layer to regulate in/out molecules
LPS
Lipopolysaccharides
Endotoxin
May become toxic when releases during infections
A bacteriocidal antibiotic will kill all cells and now we can go into shock from all those endotoxins being released into our body.
Bacteriostatic might be better, it won’t kill it but it will prevent it from growing
Mycoplasmas
non-typical cell walls
Don’t have a cell wall
Mycoplasma pneumonie: walking pneumonia
Cell membrane stabilized by sterols (cholesterol)
Pleomorphic (irregular shape)
Non-typical cell walls
Some lost their cell wall For example, penicillin caused cell walls to fail but they still continue to grow. L-form Spheroplasts Protoplast
Mycobacterium
Gram + cell structure and has a lipid mycolic acid
Acid Fast needed to diagnose
Pathogenicity and a high degree of resistance to certain chemicals and dyes.
L-form irregular cell wall
L = Lister the Lister institute that found these organisms
It can continue to undergo binary fission and function and continue as if it was normal
Protoplast
2 meanings
- when talking just about the cell envelope omitting
the cell wall
- In this case, an actual bacteria that normally have a cell wall but lost it
S-layer
Found in both Gram+ and Gram-
A self-assembling highly structured layer of protein
Common in Archaea since they don’t have peptidoglycan
Sometimes this is the only structure in Archaea
S-layer
Found in both Gram+ (outside of peptidoglycan) and Gram- (Outside of LPS)
A self-assembling highly structured layer of protein
Common in Archaea since they don’t have peptidoglycan
Sometimes this is the only structure in Archaea
Cytoplasm
A dense gel-like solution of sugar, amino, and salts
70-80% water
Serves as a solvent for materials used in the cell
Chromosome
Single, circular double-stranded DNA
Contains all genetic information
Plasmids
Free small circular, double-stranded DNA
Extrachromosomal (not part of it)
Not essential for growth or metabolism
Can provide significant advantages to survival in adverse environments
Influences metabolic diversity,
antibiotic resistance usually found here
Virulence factors influence
Can move in and out from chromosome (epesome)
Nucleoid
Chromosomes: single, double-stranded circular DNA that contains all genetic info.
Highly coiled
Ribosomes
RNA and protein
The site of protein synthesis
70s
Inclusions and Granules
Intracellular bodies
Bacteria can use them when environmental sources are depleted
Inclusions and Granules
Intracellular bodies
Bacteria can use them when environmental sources are depleted
Could have waste products
Very specific to specific bacteria
Cytoskeleton
Recently found, it was though that peptidoglycan was the only structural part
Similar to Eukaryotes
Actin filaments common
Help with structure
Peptidoglycan will still be more abundant
Order of layer in endospores
Core
Cortex
Spore Coats
Exosporium
Endospores
Other than prions, the most resistant structure
Hand sanitizer won’t work, only water and soap to remove them
Anthrax, food illnesses, Bacillus species
Diseases related to endospores
Clostridium tetani, botulinum, Anthrax, gangrene
pathogens that are serious and fatal
endospores make it difficult to treat
Reasons for Survivability of endospores
All the layers may add extra protection
Calcium takes the place of water so it’s dehydrated remaining inactive.
Since it has no water many environments are less harmful. Like high heat, won’t damage the endospore the way it would a regular cell.
Depicolinic acid combines with Calcium and it adds resistant characteristics
Small acid-soluble proteins increase and help condense and protect DNA
Resistant to boiling and ordinary cleaning methods
Exosporium
Lipids, carbohydrates and proteins
Spore Coat
Thin protein layers of heavily cross-linked coat proteins
Outer Membrane
Unknown
Cortex
Peptidoglycan
Core
DNA, RNA, ribosomes, essential enzymes
Pleomorphism
Irregular shape
Variation in cell shape and size
Palisades
A form of pleomorphism
Corynebacterium pseudodiphtheriticum
Archaea vs Bacteria
Archaea do not have peptidoglycan
Flagella is thinner in Archaea
Archaea has Cannulae and Hami
Is very rare for Archaea to have capsule or slime layers while most bacteria do
Archaea shares 3 RNA sequences with Eukarya when bacteria only shares 1
Their cell membrane is monolayer unlike bacteria which have a monolayer
Their ribosomes are 70s like bacteria, however, the structure is different
