1- Bacterial Extracellular Structures Flashcards
What types of ‘social’ behaviours do bacteria exhibit?
Cooperation
Cheating
Spiteful behaviours
What is the social group bacteria live in called?
Biofilm
Give 3 examples of costs to being a multicellular organism?
Increased disease transmission
Increased competition for resources
Social exploitation- others steal
Where are pseudomonas bacteria found? Give the process observed in a lab of biofilm formation in pseudomonas.
In the soil, pseudomonas is a common soil microbe
Process : In water, cells aggregate together to form a multicellular mat, this allows them to access oxygen. Once mat formed, individuals ‘cheat’ => the revert to being unicellular and do not contribute to the mat but take the benefit it provides. This occurs throughout the population and the mat collapses => all return to unicellular in solution
Most life on the planet is unicellular. True or False?
True
Approximately how many more bacteria cells than human cells do we have?
~10 times more bacterial cells than human cells, with ~7 trillion bacteria living in/on every person
What are the main functions of pili?
How many pili approx. are on a bacterium?
Are pili generally found in gram positive or gram negative bacteria?
Adhesion to mucosal surfaces and other bacteria
Formation of a biofilm
Sex pili transfer genetic material between bacteria
Motility- Twitching/crawling
Establish an infection, adhesion and virulence
~1-2 pili per cell
Mostly gram-negative bacteria
What are the main functions of Flagella?
Are they mostly present in gram-negative or gram-positive bacteria?
Motility
Attachment to solid surfaces/tissues
Help bacteria cling together
Adhesin proteins at tips allow for specific attachemnt
Present in both gram-positive and gram-negative bacteria
Give examples of differences in bacterial cells from eukaryotic cells.
No mitochondria - cytoplasmic membrane carries out these metabolic functions
No ER- ribosomes free in the cytoplasm or bound to inner face of cytoplasmic membrane
Single chromosom => nucleoid, with NO nuclear membrane, free in cytoplasm.
Compare and contrast gram-positive and gram-negative cell envelopes.
Gram-positive :
- Very thick cell wall
- Encloses plasma membrane
- No outer membrane
Gram-negative:
- Thin cell wall
- cell wall between outer membrane and plasma membrane
- Large periplasmic space between cell wall and plasma membrane
What unit ribosomes do bacteria have?
What subunits are the composed of?
70S ribosome units
Composed of 30S and 50S…the overlapping results in 70S and not 80S
What polymer are bacterial cell walls composed of?
What structure does it take?
What features make it suitable for its function?
Peptidoglycan (a.k.a Murein)
Unique to bacteria
Glycan chains connected by peptide cross links
Provides mechanical strength & durability BUT is flexible, elastic and porous
Dynamic-> can grow, degrade and separate in cell division
What are glycan chains composed of?
Saccharide sugars (peptidoglycan monomers) linked by Beta-1,4 glycosidic linakges
What two sugars form peptidoglycan?
What is the difference between them?
NAM => N-acetyl muramic acid
NAG => N-acetyl gluosamine
Only difference = NAM has a lactic acid group attached
What is the general structure of the peptide side chains?
5 amino acids:
1) L-alanine (most)
2) D-Glutamate (most)
3) L-diaminopimelic (lots of variation, amino acid with free amino group to bind
side chains together)
4) D-alanine (NEVER varies-side chain binding)
5) D-alanine (most)
