Chapter 3 : Bacterial cell structure Flashcards
Bacteria have different arrangements, what are the names of the different cocci arrangements?
Cocci- spheres that are single or associated in arrangements
Diplococci- in pairs
Streptococci- chains of cocci divided in 1 plane
Staphylococci- random clusters
tetrads- divided into 2 planes to form a square
Sarcina- divided in 3 planes looks like a cube
Bacteria have different arrangements, what are the names of the different bacilli arrangements
Coccobacilli- short and wide
Vibrios- comma shape
what do spirilla look like?
rigid spiral shaped bacteria
What do spirochetes bacteria look like?
flexible spiral shaped
Organisms that are variable shape are called ?
Pleomorphic
The plasma membrane and all its surrounding layers external to it is called?
cell envelope
What does the cell envelope include?
capsule or slime layer
cell wall
plasma membrane
Function of the plasma membrane
Selective permeability for getting nutrients and getting rid of waste
How is the plasma membrane structured and what is the dynamic of it ?
composed of two lipids sheets 7 to 8 micrometers
Hydrophilic- polar interaction with water
Hydrophobic - non-polar and interact with each other
Microbes can only take in dissolved particles across permeable membrane via what mechanisms?
Passive diffusion
facilitated diffusion
primary and secondary active transport
group translocation
In passive diffusion, molecules move from a lower concentration to a higher concentration T o F.
f- They move from high to lower concentration
What molecules are able to move easily via passive diffusion?
water, O2 and CO2
What is the movement across the plasma membrane with the help of transport proteins called?
Facilitated diffusion
What is the difference between channels and carrier proteins
Channel is pore-like in the membrane that allows the substance to pass through\
Carriers are more substrate-specificity
Transports molecules against the concentration gradient and is an energy-dependent process of Atp or proton motive force
Active transport
What is primary active transport?
Uses energy from ATP hydrolysis to move substances against gradient with no modifications
What transport mechanism would you use do ATP binding cassette transporters and what do they consist of?
Primary active transport
2 hydrophobic spanning domains
2 cytoplasmic associated ATP binding domains
Transport mechanism that uses potential energy of ion gradients to co-transport substance without modifying is?
secondary active transport
What does the substance move through in a secondary transport mechanism?
symport
antiport
Energy-dependent transport that chemically modifies the molecule as it is brought into the cell is ?
Group translocation
best known translocation system is PTS, what occurs in this process?
it imports sugars while phosphorylating them
What is the purpose for siderophore to be secreted by bacteria
help aid them in iron uptake since it is essential in building molecules
Bacterial cell wall function
maintain shape
helps protect cells from osmotic lysis
no tonic materials
contribute pathogenicity
what are the two alternating sugar that forms the meshlike polymer peptidoglycan
N-acetylglucosamine ( NAG
N-acetylmuramic acid ( NAM
What composes the outer membrane of a gram-negative bacteria ?
lipids, lipoproteins and lipopolysaccharides
Gram-negative bacteria contain teichoic acids in their cell wall T o F
False only gram postive
What are the importances of LPS?
negative surface charge
stabilize outer membrane
permeability barrier
host defense protection
acts as endotoxin
In hypertonic environments, water moves into the cell and swells T o F ?
False: water leaves cell and cytoplasm shrivels up
What are the three parts that make up LPS?
Lipid A
Core polysaccharide
O side chain ( O antigen) O for out
If cells are treated with lysozyme or penicillin what occurs to the bacterial cell?
They lyse in hypotonic solution due to the weakening of peptidoglycan
What is the relationship between extracellular vesicles and bacteria?
small membrane-bound molecule that help in cell to cell interaction via transferring genetic information and toxin mol.
additional layers that occur that bacteria have are?
capsules - polysaccharides well organized
slime layer- polysaccharides unorganized
Glycocalyx- polysaccharide extension to stick to surfaces
S-layer- a geometric pattern of proteins aid in protection of ion and PH fluctuations
Protective advantages of capsules
resistant to phagocytosis
protect from desiccation
advantages of slime layer in bacteria
facilitate motility
formed rings at the center of a dividing cell that constricted as daughter separates is and example of what ?
Ftsz cytoskeleton molecule
S- layer functions:
protect from ion and PH fluctuation
prevent osmotic stress
maintain shape and rigidity
adhesion
host defenses
What is the purpose of the MreB cytoskeleton molecule?
maintain shape by positioning PEP. in synthesis machinery
purpose of CreS cytoskeleton molecule
maintain curve shape
The subunits for bacterial ribosome
It is composed of ribosomal RNA and protein
16s and 23s and 5s = 70s ribosome
what contains the location of chromosomes and associated proteins?
Nucleoid
What does the bacterial DNA look like?
1 closed circular DS DNA molecule
The function of external structures in bacteria?
Protection
attachment
horizontal gene transfer
cell movement
Small circular piece of DS DNA that contains genes that can give bacteria advantage in some situations
Plasmids
Describe what are pili and fimbriae
short, thin, hairlike,
mediate motility
attachment
DNA Uptake
What is the sex pili?
the external structure of the bacteria that can copy and send genetic material from another plasmid
Thread like, locomotor appendages extending outward from plasma membrane and cell wall are called?
Flagella
If a flagelllum is rotating CW what is the affect on the bacteria ?
disrupts run and causes cell to stop and tumble
What is spirochete motility?
multiple flagella form axial fibril that surrounds cell
What is chemotaxis?
Movement towards a chemical attractant or away
In response to nutrient depletion in a bacterial cell, what forms?
Endospores
What is the endospore structure?
Exosporium
Spore coat- protein
Cortex- Thick PEP
Core- Nucleoid and ribosomes
what does sporulation produce in a bacterial cell?
produces a dormant cell that can survive the harsh nutrient depleted environment
