Lecture 4 - Bacteria and Fungi Flashcards
What are bacteria?
prokaryotes
What is the structure of bacteria?
they have DNA loose in the cytoplasm as there is no nucleus
they have a cytoplasmic membrane as well as a cell wall
What do some prokaryotes contain?
a capsule which is an extra layer
What do flagella on bacteria do?
help them to be more mobile
bacteria can have more than 1 flagella
What do pili on bacteria do?
help the bacteria attach to surfaces
How is genetic info contained inside eukaryotes?
in the nucleus inside a nuclear envelope
Size of prokaryotes vs eukaryotes?
prokaryotes are smaller cells whereas eukaryotes are larger cells
Organelles in eukaryotes vs prokaryotes?
eukaryotes have organelles whereas prokaryotes don’t
Cell wall in prokaryotes?
they have cell walls (peptidoglycan)
Cell wall in eukaryotes?
some have cell walls e.g. fungi and plants
Ribosomes in eukaryotes?
80S ribosomes
Ribosomes in prokaryotes?
70S ribosomes
What are cocci?
round bacteria
What are rods?
elongated bacteria
What is the bacterial cell wall?
it is unique to bacteria and is critical for maintaining shape and structural integrity
Example of straight rod bacteria?
Escherichia
Example of a spore forming rod?
Bacillus
Example of a branching rod?
Actinomyces
Example of a spiral rod?
spirochaeta
Example of a coccus?
staphylococcus
Grams staining method?
crystal violet
then iodine
then decolourisation
then safranin counter stain
What is grams staining used for?
to distinguish between two different types of bacteria
Why is iodine used in grams staining?
the retain the dye in the cell wall
Gram positive bacteria?
have a thick cell wall and retain the purple dye
PURPLE
Gram negative bacteria?
have a thinner cell wall and after safranin staining appear pink
PINK
What is the cell wall like in gram positive bacteria?
very thick cell wall made of several peptidoglycan layers on top of the cytoplasmic membrane
contains strands of sugar which are linked by peptidic bonds and form a rigid structure that gives bacteria their shape
Gram negative bacterial cell wall?
there are two cytoplasmic membranes (inner and outer) with a peptidoglycan layer in the middle
also contains proteins called porins
What do porins allow?
some antibiotics to enter the gram negative cell and act on the peptidoglycan
Bacterial cell division?
First the bacterial cell replicates its genetic material and then divides into two daughter cells
it is very rapid and millions of bacteria cells can be formed in minutes
What does the capsule on bacteria do?
it is an extra layer of protection to protect from
What does the capsule protect the bacteria from?
desiccation/antibiotics/disinfectants
phagocytosis/immune system
What is the capsule usually made from?
polysaccharides (sometimes polypeptidic)
sugars
Why can parts of the capsule be used in design of vaccine?
it is usually antigenic
Order of the layers of bacteria?
plasma membrane, then the cell wall, then the capsule
Endospore formation steps?
1) DNA is replicated
2) cellular division of cytoplasmic membrane
3) prespore formation begins
4) cortex formation
5) spore coat formation begins
6) maturation begins, exospore formation
7) mother cell releases mature spore (free spore)
When are endospores formed by bacteria?
when they go into survival mode
What do endospores allow resistance to?
extreme temperatures, harsh conditions, disinfectants
When will a freespore regenerate?
it will regenerate the mother cell when the conditions are right
What are the two categories of fungi?
yeasts and moulds
What are yeasts?
unicellular
What are moulds?
multicellular
What are fungi?
eukaryotic cells
What do fungi have?
a cytoplasmic membrane rich in ergosterol
Cell wall of fungi?
they do have a cell wall, but it is not the same as bacteria
How does cell division occur in yeasts?
in a similar pattern as bacterial cells, with the formation of a daughter cell
What do moulds contain?
several cells which join to form a branch like structure
What is sporangium?
a pack of spores
What is the phialide in moulds?
connects the spores to the hyphae (stem_
what are sporangiophore?
a specialised hyphae
Moulds life cycle?
they form branches (filamentous morphology) and then spore production occurs, the spores disperse and any one spore can germinate if its finds the right medium
What can spores regenerate?
the multicellular fungus
Gram positive cocci?
staphylococcus aureus
streptococcus pyogenes
enterococcus faecalis
Staphylococcus aureus?
colonises the skin and nares (not always pathogenic)
skin/respiratory/bone/joint infections, endocarditis, toxic shock syndrome, food poisoning, sepsis
Streptococcus pyogenes?
skin (epysipelas, cellulitis), throat infections (pharyngitis), scarlet fever, sepsis
Enterococcus faecalis?
part of the intestinal flora
UTI, endocarditis, sepsis
Gram positive rods?
clostridium botulinum
clostridium difficile
clostridium perfringens
clostridium tetani
Clostridium botulinum?
botulism
Clostridium difficile?
pseudomembranous colitis
Clostridium perfringens?
gas gangrene
Clostridium tetani?
tetanus
Gram negative rods?
Escherichia coli (enterobacteriaceae)
pseudomonas aeruginosa (non-enterobacteriaceae)
Escherichia coli?
part of the intestinal flora
some strains can cause gastroenteritis, UTI, neonatal meningitis
Pseudomonas aeruginosa?
part of skin flora and environmental (usually doesn’t cause problems)
opportunistic pathogen, frequent cause of HAI, major cause of infection in cystic fibrosis
infections of burn injuries, pneumonia, UTI
Gram negative cocci?
neisseria gonorrhoeae, neisseria meningitidis
Neisseria gonorrhoeae?
gonorrhea (STD)
Neisseria meningitidis?
pneumonia, meningitis, septicaemia
Other bacteria?
mycobacterium tuberculosis - causes tuberculosis and is not gram positive/negative
Medically important yeasts?
candida albicans, cryptococcus neoformans
Candida albicans?
part of the normal gut flora
opportunistic pathogen in immunocompromised patients e.g. someone on chemotherapy
oral/genital infections, septicaemia
Cryptococcus neoformans?
meningitis in immunocompromised patients
widely found in pigeon faeces
Medically important moulds?
aspergillus
Aspergillus?
some toxin producers (aflatoxin from A flavus)
opportunistic pathogen in immunocompromised patients (aspergillosis)
What does aspergillus release?
spores, if these are inhaled they can cause lung infection
