Lecture 2 Flashcards
What are the 7 differences between prokaryotic and eukaryotic cells?
Nucleoid/nucleus ; 1/46 chromosomes ; membrane-bound organelles ; ribosome sizes (16S/18S) ; sexual reproduction (prok = conjugation) ; meiosis/mitosis/binary fission ; cell size
Define “bacteria”
small unicellular microorganisms that live freely (not part of a higher structure like organ/tissue)
What are the 3 problems with living freely?
nutrition (efficiency and need to adapt if lack) ; occupation (adherence and needing to form biofilms) ; resistance to damaging agents (such as antibiotics)
Why is surface area important for a cell?
for transport of nutrients from outside to inside of the cell or release of waste from inside to outside
What were to happen if we had the same surface area as bacteria?
increase nutrient consumption, increase waste excretion, and shorter generation time
What is the benefit/consequence of having a smaller surface area when it comes to metabolic rate?
increase in metabolic rate = complete processes faster
What is the generation time for E.coli?
20 minutes
What is the benefit of the ability of bacteria to grow fast?
faster infection time, can easily change and adapt faster, can pass the adaptation to next generation
What is a consequence to us due to the ability of bacteria to grow fast?
poses a challenge against antibiotics
What components would you typically find in a bacteria’s cytoplasm?
nucleoid chromosome, plasmids, ribosomes, inclusion bodies
Describe the characteristics of a bacterial chromosome?
no-membrane, double-stranded, circular, bigger than plasmids
How many copies of chromosomes do bacterial cells have?
one per cell
How many copies of plasmids do bacterial cells have?
as many as one or more per cell
What are plasmids?
Extrachromosomal genetic material that bacterial cells can survive without
Why are plasmids important?
helps with adaptation and survival, includes pathogenetic and antibiotic-resistant genes
What are inclusion bodies?
aggregates of a particular compound (ie: protein A)
Where are inclusion bodies found?
cytoplasm
Function of inclusion bodies?
used for storage
Where can you also find inclusion bodies in gram- bacteria?
periplasm
What is a cell envelope?
describes everything that is outside of the cytoplasmic membrane
What are the functions of the cell envelope?
protect cytoplasm, facilitates adherence (ie: adhesin on cell wall) and colonization (chains or grape clusters)
What defines the outer-membrane?
lipopolysaccharide
What are the components of gram+ cell envelope?
cytoplasmic membrane > THICK peptidoglycan > Teichoic acid and LTA (lipoteichoic acid)
What is murein?
peptidoglycan
What is Teichoic acid?
acidic polymers usually found on gram+ cell walls
What is lipoteichoic acid?
teichoic acid with fatty acid chain on N terminus
Function of lipoteichoic acid
stabilizes cell envelope
What are the components of gram- cell envelope?
cytoplasmic membrane > periplasm > THIN peptidoglycan > outer-membrane
What are the 2 main types of membrane proteins?
integral and peripheral
What are the main functions of the cytoplasmic membrane?
permeability barrier, protein anchor, energy conservation
What is another form of energy that bacterial cells use other than ATP?
in the form called “proton-motive force”
What is “proton-motive force”?
bacterial cytoplasmic membrane functions like a battery = transfer of protons across membrane = generates energy used for process such as transport
Where would a bacterial cell use the “proton-motive force” and why?
cell envelope because ATP is only present in cytoplasm, not cell envelope
What is the cell wall made out of? (macromolecule)
carbohydrates
What type of bond is used to link the sugar molecules?
ß(1,4) glycosidic bond
What are the 2 sugars that compose the peptidoglycan?
N-acetyl Murmuric acid (murein) and N-acetyl Glucosamine (glucose)
What links the sugar chains to each other and why?
amino acids for stability
What isoform do the amino acids take within the peptidoglycan cell wall?
D-isoform
What is a glycine interbridge?
5 glycine interbridge in thick peptidoglycan (gram+ ONLY)
How is the cell wall differentiated between species?
sequence of amino acids that hold sugar chains together
Which bacterial species will have the glycine interbridge?
gram+
Apart from the 20 amino acids, where can rare/unique amino acids be found? How can this benefit the bacteria?
within cell walls of bacteria, benefits in antimicrobial resistance
Where are the cell-wall building block synthesized in bacteria?
in the cytoplasm
What is UDP?
protein that helps transport the sugar chain across cytoplasmic membrane into exterior of cell or periplasm
What is the first antibiotic discovered?
penicillin
What does penicillin target? How does this affect the bacteria?
inhibits further cell wall synthesis and begins to break down exisiting cell wall ==> eventually will lyse bacteria
What is a good thing to look at when choosing an antibiotic to use?
choose what will minimize its effects to only bacterial species, not eukaryotic cells
What is the downside to using an antibiotic?
targets normal flora as well
Functions of periplasm?
transport across cell envelope and helps in protein folding
What are the proteins contained in periplasm?
hydolytic enzymes, binding proteins, chemoreceptors, and molecular chaperones
What is the purpose of molecular chaperones in the periplasm?
for proteins that are meant to be excreted/secreted = need to go through cell envelope and fold in the periplasm –> transport to outer membrane
What differentiates outer-membrane and inner-membrane?
outer-membrane has lipopolysaccharide on the outer leaflet of outer-membrane
What are trimeric porins?
integral membrane protein found on gram– that act as a channel for certain molecules to pass through outer-membrane (dictates size of what can pass through)
What are unique characteristics of the outer-membrane?
lipopolysaccharide and trimeric porins
What binds to the inner-leaflet of the outer-membrane and what is it’s function?
lipoprotein binds to peptidoglycan and stablizes cell envelope
What are surface appendages on bacterial cells?
structures located on the surface of bacterial cells
Which type of bacterial do surface appendages apply to?
all 4 types of bacteria
What are the 4 types of surface appendages?
flagella, pili, capsule, S-layer
What is the function of flagella?
motility
What is a petrichous arrangement of flagella and which family does it characterize?
flagella coming from all over the bacterium, family I
What is a polar arrangement of flagella and which family does it characterize?
more than 1 flagella all bunched up on one side of the bacterium, family II
Which family of flagella will we be dealing most with in this class?
Family I
What is chemotaxis?
movement towards substances that attract or move away from those that repel
How will petrichous flagella move?
bind together as one
Which way does the bacterium move forward with flagella (counter-clockwise or clockwise)
counter-clockwise
What species of bacteria is flagella best mostly studied from and what type of bacteria are they?
E.coli and Salmonella, gram–
What are the 3 main parts of the flagellum structure?
basal body, hook, filament
What are the 4 rings of the basal body?
C (Cytoplasmic), MS (motor surface), P (Peptidoglycan), L (lipopolysaccharide)
What is the protein that makes up the filament of the flagella?
flagellin
About how many proteins compose the flagella?
40 different proteins for assembly
What types of bacteria can have a flagella?
All 4 types but we focus on gram– for the most part
In what order does assembly of flagella start?
basal body > hook > filament
Does a bacterium always have a flagella?
no, only assembles when it needs it (ie: need to move)
What is a pili also called?
fimbriae
What is a pili?
shorter and thinner appendage than flagella and can have 2x as more than flagella on the surface
What is the main function of a pili and what is it also used for?
adherence and conjugation
What is the most-studied pili and which species was it found in?
P-pili in uro-pathogenic (UTI-causing) E.coli
Where does the pili get assembled?
on the surface of outer membrane
How many different proteins does the pili get assembled with?
10
Which proteins play a key role in the P-pilus assembly?
C and D
What role in the P-pilus assembly does the “C” protein do?
outer-membrane usher = kind of a porin that helps transport protein across and assemble on top of it
What role in the P-pilus assembly does the “D” protein do?
periplasmic chaperone for assisting protein folding; brings proteins to C protein
What is a variation of the P-pilus?
Type I pilus
What is a capsule
polysaccharide encasing the bacterium
What is the function of a capsule?
protection and sometimes attachment
Do all bacterium have capsules?
not all and they don’t always have it
What is an S-layer?
2-dimensional array of protein on bacterium surface
What is the function of an S-layer?
additional protection to the cell
Do all bacterial species have the same S-layer?
No, arrangement of S-layer lattices are species dependent
What is an endopsore?
what the bacteria develops into during mid-binary fission when it is living in extreme harsh conditions
What is the function of an endospore?
for the bacterium to survive
Which type of bacteria can develop into endospores? What species?
gram+ bacillus and clostridium
What is a vegetative cell?
a typical bacterial cell without an endospore
How does endospore formation begin?
duplicates chromosome, acts as if cell is getting ready to divide but there is no septum
What kind of cell division does endospore formation take place? What happens after this division?
asymmetrical division; smaller piece will become a spore and the rest will lyse
What chemical compound is specifically found in spores?
dipicolinic acid
What is a function of dipicolinic acid?
helps spore become resistant to harsh environment
During endospore formation, which layer will the spore be present?
cytoplasm
Does an endospore have any metabolic activity? Why or why not?
No because the endospore is at an “inactive” state since it’s only goal is to survive and waits for the harsh environment to pass until it becoems a vegetative cell again
What mechanism/pathway plays an important role in pathogenesis?
protein secretion (virulence factors)
