WEEK 11: 11.1 Structure & Classification of Bacteria Flashcards
(31 cards)
What are eurkaroytes . give examples
an organism that has organelles eg. protists (unicellular parasites & some algae) , fungi (yeast)
What pathogens are classified as eukaryotes?
Malaria
Candidiasis
What are prokaryotes . give examples
do not have organelles
bacteria, mycobacteria, mycoplasma
includes many pathogens
What are acellular organism? give examples
non-living organisms
bacteriophage- infect bacteria
viruses- infect eukaryotic cells
Why are bacteria important?
Global ecosystems- nutrient cycling of carbon, nitrogen, phosphorus occur due to bacteria
Saprophytes- turnover of organic matter eg. composting, recycling
Economic biotechnology- production of ethanol, amino acids, food supplements, antibiotics, genetic manipulation
What are the drawbacks of bacteria
Causes spoilage in foods and biofilms
Pathogens: infectious disease of plants and animals, bioterrorism
Bacteria can cause fatal secondary infections in some viral diseases
Where is the bacterial genome located?
loosely arranged in the cytoplasm - the site of gene expression & metabolic activity
What does the bacterial genome comprise of?
the chromosome and can consist of plasmid DNA
What is a chromosome?
a single circular double stranded DNA
What is plasmid?
circular double stranded DNA molecule
What does the genome dictate within a cell
its metabolic and biosynthetic capacity
What effect does genome size have on growth requirements
larger genomes tend to have less needy growth requirements, eg. E coli needs minimal salts and glucose to grow, chlamydia with a smaller genome needs to be within a host to synthesise ATP
What are 3 ways in which bacteria can share DNA
transformation: uptake of free DNA from environment
conjugation: transfer of DNA by direct cell-cell contact using specialised pili
transduction: transfer by bacteriophage (i.e. bacterial viruses)
What is the function of the plasma membrane?
selective/semi-permeable membrane lipid bilayer, which maintains homeostasis by maintaining the sodium potassium gradient
- site of energy ATP generation: electron transport chain
- range of transport nutrients that import nutrients and export wastes & toxins
What is an endospore?
has a complex intra-cellular structure produced by bacteria, a survival structure
resistant to temp, dessication, radiation, chemical agents, etc.
What are the different shapes of cell walls?
rods (bacilli)
spirals
spheres (cocci)
What key component is the cell wall made of
peptidoglycan
What is the function of peptidoglycan?
it protects against osmotic pressure and provides shape to bacteria
What is gram positive
a thick peptodoglycan layer in which molecules diffuse through interbridge gaps. it is embedded in teichoic acids that are involved in attachment. it consists of simple systems to secrete proteins
What is gram negative, and what else does it consist of?
a thin peptidoglycan layer
consists of outer non energised membrane (OM)
Describe the OM
it functions as a second membrane, and has porins that allow the transfer of molecules across it, and has a lipopolysaccharide attachment
What kind of staining technique is used to reveal bacterial shape and arrangement, describe it
Gram stain - rapid & easy to perform
acid fast staining- used for mycobacterial species
what is mycobacterium, and how does its cell wall differ?
an infectious pathogen
its cell wall is waxy & hydrophobic, with an outer lipid layer, mycolic acids, peptidoglycan and arabinogalactan
What are the different external structures to the cell wall?
flagella - used for motility
fimbriae/pili - used for attachment and conjugation
capsule - used for attachment and protection from phagocytosis
