Bacteriology W7 Flashcards
What is the study of fungi
Mycology
What are fungi
Heterotrophs - cant make own food
Principle decomposers in every ecosystem
Fungi structure
• fungi are composed of filaments called hyphae (singular: hypha).
• fungi have cell walls (like plants) but the cell walls are composed of chitin
• fungi do not have flagella at any phase of their life cycle
Other fungi characteristics
• store ‘food’ in the form of glycogen (as do animals)
• generally the cells are haploid (1 set of chromosomes)
• produce secondary metabolites
• grow as hyphae or yeasts, the hyphae exhibit apical growth
• produce spores by means of sexual and asexual reproduction
Cell membrane contains …
Ergosterol (animal have cholesterol and plants have sitosterol)
Human infections
Due t similarity of human and fungal cells, fungal infections are difficult to treat
Athletes foot, ringworm and thrush
Plant infections
Fungi cause major crop diseases
The great bengal famine 1943
Chemical production
the diverse nature of fungal metabolic pathways generates many commercial products:
• ethanol
• organic acids (citric acid)
• enzymes (amylase, pectinase, protease)
• antibiotics (penicillin G)
Protozoa
No cell wall
Heterotrophic
Motile
Specialised vacuole function for food digestion a nd water elimination
Asexual reproduction - mitosis - but can be sexual during some parts of their life cycle
Bacteria
• cell wall is composed of peptidoglycan
• bacteria can have an outer membrane consisting of lippolysaccharides and proteins
• cytoplasm consists of cytosol
• ribosomes are granular inclusions that coordinate synthesis of proteins
• thylakoids are flattened discs with light-sensitive pigment molecules
DNA in nucleiods with no surrounding membrane
Prokaryote vs eukaryote : size
Prokaryote : 0.5-2 um
eukaryote : 2-200 um
Prokaryote vs eukaryote : nucleus membrane
Prokaryote : no
eukaryote : yes
Prokaryote vs eukaryote : chromosomes
Prokaryote : 1, circular
eukaryote : >1
Prokaryote vs eukaryote : division
Prokaryote : binary fisison
eukaryote : mitotic division
Prokaryote vs eukaryote : mitochondria
Prokaryote : no
eukaryote : yes
Prokaryote vs eukaryote : chloroplasts
Prokaryote : no
eukaryote : yes
Prokaryote vs eukaryote : internal membranes
Prokaryote : relatively simple
eukaryote : complex (ER, golgi)
Prokaryote vs eukaryote : ribosomes
Prokaryote : 70S ribosomes
eukaryote : 80S ribosomes
Aerobe
Need O2
Anaerobe
Cannot tolerate O2
Psychrophile
-5 to +15 degrees
Mesophile
+10 to +45 degrees
Thermophile
+30 to +85 degrees
Acidophile
Grow under acidic conditions
Neutrophile
Need pH around 7
Alkaliphile
Need high pH
Not halophile
Up to 2.5% salt
Halotolerant
Up to 6.5% salt
Halophile
Yo to 20-25% salt
Bacterial conjugation
Have a f-(female) and f+(male) bacteria
Come together and there id a conjugation of cells and copy of th F factor transferred into the f- cell
F- then becomes f+ and both cells synthesise a complementary DNA strand
Both cells now f+ and seperate
Transformation
occurs when a bacterium picks up fragments of DNA released by dead bacteria or secreted by live bacteria
Transduction
is when bacteriophages (viruses) carry portions of bacterial DNA from one cell to another
Mutation
is a major source of variation in prokaryotes
How can antibiotic resistance transfer between bacteria’s
By plasmid transfer
Endospores
Not all bacteria produce
• endospores are a method of survival, not reproduction
• some bacteria form endospores when environmental conditions become unfavourable
• spores can endure for hundreds of years
• endospores are DNA and a portion of cytoplasm encased in a tough cell wall; they are resistant to extremes in temperature, drying, and harsh chemicals
Gram negative
have a cell wall, low amount of peptidoglykan, are not sensitive against penicillin or lysozyme, are sensitive against mechanical pressure (E.coli, Pseudomonas aeruginosa)
Gram positive
have a cell wall, high amount of peptidoglykan, are sensitive against penicillin, lysozyme, are not sensitive against mechanical pressure (Bacillus anthracis, Streptococcus mutans)
Gram - vs + structure
Gram positive bacteria have a thick peptidoglycan layer and no outer lipid membrane
Gram negative bacteria have a thin peptidoglycan layer and have an outer lipid membrane.
Endotoxins from gram negative bacteria
are the most common cause of toxic reactions resulting from contamination of pharmaceutical products with pyrogens
• their pyrogenic activity is much higher than that of most other pyrogenic substances
• these endotoxins are lipopolysaccharides (LPS)
Physiological effects of pyrogens
• dependant upon route of administration
• effects are dose dependant
• effects are dependant on the general state of health of the patient
• low doses induce an asymptomatic inflammatory response
• moderate doses induce fever and changes in plasma composition
• high doses result in shock, multiple organ failure and death
BP test for pyrogens
• product is administered initially to 3 rabbits at a dose of no greater than 10ml/kg
• rabbits are housed in carefully controlled conditions and their temperature is monitored before the test product is given
• temperatures are taken (rectally) at 30 minute intervals for 3 hours post administration
BP Test for Bacterial Endotoxins
• LAL Test – Limulus Amoebocyte Lysate Test based on the endotoxin induced coagulation of the blood of the Horseshoe crab Limulus Polyphemus
• test is based on observation that horseshoe crab blood forms clots when exposed to endotoxins
• Amoebocyte extract from horseshoe crab blood is mixed with a sample suspected of endotoxin contamination, and a reaction is observed if endotoxins are present
• about 1000 x more sensitive than the Test for Pyrogens
