Lecture 12 Flashcards
Prokaryotes are prt of which domains
BACTERIA and archaea
What are the most abundant organisms on earth
Prokaryotes
Where can we find prokaryotes
Air
Soil
Water
On plants
On/in animals
Polar ice caps
Deep sea hydrothermal vents
General prokaryotes structure
- Unicellular, small
- No nucleus
- One circular chromosome as genome
- Cell wall (most)
- Diff ribosome structure
- Asexual reproduction
Similarities of prokaryotes with eukaryotes
Both have dna
Both membrane bound
Both have ribosomes
E or P? Has nucleus
Eukaryote
E or P which is larger on average
Eukaryotes
E or P have membrane bound organelles
Eukaryote
E or P, circular structure of DNA and have less (other is linear)
Prokaryotic
E or P have cell wall composed of peptidoglycan
Prokaryotic
E or P divides by binary fission (other is mitosis)
Projaryotic
Three main shapes of bacteria
Sphere = cocci
Rods = bacilli
Spirals
Most prokaryotes are unicellular but some form
Colonies
Types of coccus arrangements
Coccus = single
Diplococci = 2 together
Streptococci = chains
Clusters = staphlococci
Types of bacillus arrangement
Bacillus = single rod
Diplobacilli = 2 together
Streptobacil = chains
Spirochetes (spirals)
Motile, have a unique axial filament that rotates
Some spirochetes are human parasites, some are
Pathogens
Most prokaryotic are how much diameter
1-10 um
All prokayotic cells contain
- Dna free in nucleoid region
- Cell membrane, cytoplasm, robosomes
- Cell wall
Many prokaryotic cells may also have
- Outer capsules made of polysaccharides or protein
- Flagella/pilli
- Plasmids
Plasmids
Small circular molecules of dna that carry a small number of genes
Capsules functions
- Protects cell from drying
- Helps cell stick or attach to things (bc adhesive nature)
- Protects cell from WBC destruction
What is a colony
Visible mass of microorganismes all originating from a single cell, constitues a clone of bacteria all genetically alike
Colonies can be used to identify bacterias bc
Diff soecies can produce diff colonies
In binary fission, cell grows while
Dna replicates (for daughter to receive exact copy of dna)
Some species could double every minute if there was optimal growth conditions but
Doesn’t occur
Genetic variation in prokaryotes result of their
Rapid reproduction and mutation (rare)
Mutations(rare) can still wuickly increase gen diversity in species with
Short generation times and large populations
Does meiosis occur in bacteria
No
Bacteria can do what gene transfer
Horizontal gene transfer
What is horizontal gene transfer
Mvmt of one or more genes from one species to another
Three types of horizontal gene transfer
- Transformation
- Conjugation
- Transduction
Hor gen transf: transformation
Can pick up pieces of dna from surroundings
Hor gen transf: conjugation
Transfere gen material between two bacterial cells(temporarily joined) via sex pillus
Hor gen transf: transduction
From a virus
Role of fimbriae
Adhere to one another/host cells/substances in eviro
Surface attachment
Function of flagellum
Propels the cell
Organ of locomotion
Function of pili
- motility
- dna transfer (sexual pili in conjugation)
What is an endospore
Dormant though non-reproductive structure
Function of endospore
Ensure survival of bacterium through periods of environmental stress:
-when enviro unfavourable, forms
-survive very dry/hot/Frozen enviro
-hydrate and revive when water available
Three important roles if bacteria
- Decomposers
- Pathogens
- Mutualistic symbionts
Decomposers role
Decomposition or organic materials and recycling of nutrients
Pathogens role
Cause diseases (syphilis, plague, lyme disease…), prokaryotes are the most common animal pathogens, antibiotics exist to kill them
Mutualistic symbionts (herbivores)
Have enzymes to break down what animals don’t (ex plants which contain cellulose)
Mutualistic symbionts in humans
Microbiota/microbiome
What contributes to homeostasis and regulating immune function in human host
Microbial communities
Gut microbiota(most significant microbiota) function
Aid in digestion, protection against pathogens, simulating immune response, vitamin production
Where can we find microbiota
Gut, oral, vagina, skim, respiratory
Human well-being can depend on
Mutualistic prokaryotes
