Prokaryotes (flashcardable)
Why is it important to know about prokaryotes?
Food Agriculture Disease Energy/environment Biotechnology
Use of prokaryotes and food
- preservation (find ideal enviro)
- fermentation e.g. beer and yeast
- food preparation (being more hygienic)
Use of prokaryotes and agriculture
- nitrogen fixation e.g. rhizobium and legumes
- nutrient cycling
- animal husbandry e.g. digestion of cellulose in animals
Use of prokaryotes and disease
- better hygiene
- vaccines and antibiotics
Use of prokaryotes and energy/environment
- methanogenic bacteria
produce methane and harvest light energy - microbial biomass and existing waste to create biofuel
Use of prokaryotes and biotechnology
- gm organisms
- producing pharmaceutical and therapeutic chemicals
Prokaryotic cell shape and affect of SA
- diameter of 1um and length of 2 - 50um
- SA limiting factor: diffusion and also increasing SA ration generates larger population = more mutations and therefore faster evolution (also haploid) so adapt quickly
How bacterial membrane lipids are different from eukaryotic lipid membranes
- bacteria can be saturated or monounsaturated vs eukaryotic is polyunsaturated
- bacteria have no sterols
What affects the fluidity of bacterial membrane
- temperature: higher temperature is more fluid and lipids can move around
- longer chains (more carbon) make it more stable
- is important as prokaryotes cant control their own environment so must be able to adapt
What are the different transport systems in the bacterial membrane
Simple system
Group translocation
ABC system
Simple system of transport
Driven by energy in proton motive force
Group translocation transport
Chemical modification (phosphorylation) of transported substance ( driven by phosphoenolpyruvate)
ABC system of transport
Periplasmic binding proteins involved
Energy generated by ATP breakdown
Role of the cell membrane
- permeability barrier
- protein anchor
- energy production and conservation
Gram neg
- folded cell membrane
- peptidoglycan cell wall with periplasm and 2 membranes
- 2nd membrane contains lipopolysaccharide complex
Gram pos
- peptidoglycan wall
- techoic acid (slight neg charge helps bind cell wall and membrane)
Lipopolysaccharide complex
Polysaccharides (core and O) and A lipid
Associates to several proteins to form membrane and replaces the phospholipids
Peptidoglycan
Only in bacterial cells
Repeating nag and nam sugar derivatives with amino acids
Glycosidic bonds
Amino acids form tetrapeptide bonds between chains = rigidity
(Archaeal pseudo peptidoglycan = nag and Nat)
Prokaryotes vs eukaryote DNA
Pro = haploid vs eu = diploid Pro = genome looped and not surrounded by nucleus Pro= no nuclear membrane and no simultaneous transcription and translation Pro = no proteins for dna packaging
Plasmids
Circular dna containing genes with special properties e.g anti bac resistance
Helps evolution and can have multiple in a bacteria
Useful for biotech
Fimbriae
Enables organisms to stick to cells surface and form biofilms on surfaces
Pilli
Used for conjugation (genetic exchange)
Peritrichous = flagella
Flagella all the way around the cell
Move via spiralling
Polar flagella
At one end
Move via whipping
Lophotrichous
Mutliple at one end
Move via whipping
Structure of a flagellum
Helical and constant length between curves (like wavelengths)
Grows from base and breaks if too long
L and P ring fixes in place
MS and C ring twists
Fli proteins cause rotation (electrostatic charge enables drive)
Para crystalline structures
Cell wall type with protein/glycoproteins with hexagonal symmetry
Act as sieve = only allow molecules at certain Mr through (excludes large e.g. viruses)
Capsules and slime layers
Made either polysaccharides or proteins and constantly replenished
Used for:
Movement and attachment
Bio films
Prevents drying out and desiccation (virus attack)
Marks it hard for phagocytic cells to recognise = immunity
Magnetotaxis
Orientating along earths magnetic field lines
Some cells contain magnetosomes (little piece of metal) that make this happen
Gas vesicles
Buoyancy aids = decrease density
Aquatic plants = float and photosynthesise
Spindle shapes and hollow, made of protein
