Ch. 3 Bacterial and Archaea Structure and Function Flashcards
how do prokaryotes differ from eukaryotes?
in size and simplicity
what are the most common shapes of bacteria?
cocci and rods
what 2 things determine bacterial arrangement?
- plane of division
2. separation or not
what is the average bacterial size?
varies
what shape are cocci (S. Coccus)?
spheres
list 3 types of cocci and their shape and arrangement
- diplococci (S. diplococcus): spheres in pairs
- streptococci: spheres in chains
- staphylococci: spheres in grape-like clusters
what is a tetrad?
4 cocci in a square
what is a sarcinae?
cubic configuration of 8 cocci
what shape are Bacilli (S. bacillus)?
rods
list 4 types of Bacilli and their shape
- coccobacilli: very short rods
- vibrios: resemble rods, comma shaped
- spirilla (S. spirillum): rigin helices
- spirochetes: flexible helices
describe the shape and arrangement of mycelium
network of long, multinucleate filaments
describe pleiomorphic organisms
organisms that are varibale in shape
what is the size of the average bacterial rod?
6 um
what is the size of viruses compared to bacteria?
MUCH MUCH smaller
in a bacterial cell, what are flagella, and what is their purpose?
thin, rigid filaments sticking out of capsule; allow for movement
in a bacterial cell what are fimbrae and what is their purpose?
the TALL structures sticking out of capsule, aid in adhesion and attachment
in a bacterial cell what are pili and what is their function?
the SHORT structures sticking out of capsule, aid in adhesion and attachment like fimbrae, but ALSO function in conjugation
in a bacterial cell, what is the capsule and what is its function?
the outer coating of the cell, functions in protection, binding, and avoiding phagocytosis
in a bacterial cell, what is the plasma membrane and what is its function?
a semi-permeable membrane between the capsule and the cell wall that allows for transport of substances in and out of the cell
in a bacterial cell what is the cell wall and what is its function?
the innermost layer, provides structure
in a bacterial cell what are ribosomes and what is their function?
small, circular dots all around cell, function in protein synthesis
in a bacterial cell, what is the cytoplasm and what is its function?
the goo inside the cell, contains water, enzymes, ribosomes, and circular DNA
in a bacterial cell, what is circular DNA and what is its function?
super tightly coiled and only one per cell, holds genetic material
in a bacterial cell, what is a plasmid and what is its function?
a little circle thing, contains extra genetic material, gives enhanced abilities like antibiotic resistance
what charge do both gram negative and gram positive bacteria usually carry?
negative
how are gram negatvie and gram positive bacteria named?
for how they stain
what are the big differences between gram negative and gram positive cell walls?
- gram positive has a very thick layer of peptidoglycan
2. gram negative have an inner AND an outer plasma membrane
can a bacteria live without a plasma membrane?
no, it is an absolute requirement
what are the 3 functions of the bacterial plasma membrane?
- encompasses the cytoplasm
- selectively permeable barrier
- interacts with external environment
list 3 ways the bacterial plasma membrane interacts with the external environment
- has receptors for detection of and response to chemicals in surroundings
- has transport systems
- metabolic processes
what is the structure of the bacterial plasma membrane?
amphipathic lipid bilayers (polar head, nonpolar tail) with floating membrane proteins
what are the 2 types of membrane proteins?
- integral
2. peripheral
describe peripheral plasma membrane proteins (2)
- loosely conneected to membrane
2. easily removed
describe integral membrane proteins (2)
- amphipathic- embedded within membrane
2. carry out important functions
what is peptidoglycan? (2)
- rigid structure that lies just outside the bacterial cell plasma membrane
- mesh-like polymer of two alternating sugars forming long strands
what are the two types of peptidoglycan/cell walls based on gram stain?
- gram-positive: stains purple, thick peptidoglycan layer
2. gram-negative: stains pink or red; thin peptidoglycan and outer membrane
list the 4 functions of the bacterial cell wall
- maintains shape of bacteria
- helps protect from osmotic lysis
- helps protect from toxic materials
- may contribute to pathogenicity
do all bacteria have a cell wall?
ALMOST all
what are gram positive cell walls made of? (3)
composed primarily of peptidoglycan,
may contain teichoic and lipoteichoic acids,
and some will have a layer of proteins on the surface of the peptidoglycan
what charge do teichoic acids carry?
negatively charged
what are the 3 functions of teichoic acids?
- help maintain cell envelope
- protect from environmental substances
- may bind to host cell
what are lipoteichoic acids? (2)
- longer than teichoic acids
2. enter lipid bilayer
what do lysosomes target in peptidoglycan of bacterial cell walls?
sugar links
what do some antibodies target in the peptidoglycan of bacterial cell walls?
protein links
describe peptidoglycan structure (Studying Brooke: when you come to this card be able to draw it, I MEAN IT)
interlocking NAM and NAG sugars, held on top of each other by protein links/polypeptide bridges
what is NAM?
N-Acetylmuramic acid
what is NAG?
Acetylglucosamine
where is the periplasmic space located in gram-positive bactera? is it bigger of smaller than gram-negative?
lies between the plasma membrane and the cell wall; smaller space than gram-negative
does the periplasm have a lot of proteins in gram positive bacteria?
no; relatively few
describe gram-negative cell walls (4)
- more complex than gram-positive
- consist of a THIN layer of peptidoglycan surrounded by an outer membrane
- outer membrane composed of lipids, lipoproteins, and LPS
- no teichoic acids
what is the outer membrane of gram-negative cell walls composed of?
- lipids
- lipoproteins
- lipopolysaccharides (LPS)
what is the peptidoglycan layer also called?
murein layer
how does the periplasmic space differ in gram negative bacteria from gram positive? (2)
- more space taken up (20-40%) of cell volume
2. many enzmes present
list 3 enzymes/proteins that are present in the periplasmic space of gram negative bacteria
- hydrolytic enzymes
- transport proteins
- other proteins
where does the outer membrane lie in gram negative bacteria?
outside the thin peptidoglycan layer
what connects the outer membrane of gram-negative bacteria to the peptidoglycan layer?
Braun’s lipoproteins, also called lipoproteins
what is another outer membrane protein in gram negative cell walls and what is its function?
porin: transport in/out of cell
what lies on top of the outer membrane of gram-negative bacteria?
lipopolysaccharides (LPS)
what are the 3 parts of lipopolysaccharides from innermost to outermost?
- lipid A (innermost, closest to outer membrane)
- core polysaccharide
- O side chain (O antigen)
how is lipid A of LPS attached to the cell?
embedded in the outer membrane
where are the core polysaccharide and O side chain of LPS found?
extend out from cell, lipid A anchors them to outer membrane
list the 6 functions of lipopolysaccharides (LPS)?
- contribute to negative charge on cell surface
- helps stabilize outer membrane structure
- may contribute to attachment to surfaces and biofilm formation
- creates a permeability barrier
- protection from host defenses (O antigen)
- can act as an endotoxin (lipid A)
describe how LPS can provide protection from host defenses
the O antigen is a unique sequence among/within bacterial cells, most host cells don’t recognize or have defenses to it
what can the O antigen of LPS be used for?
to help identify types of bacteria
describe how LPS can act as an endotoxin
lipid A triggers the immune system; when the response of immune system is too big or there are too many bacteria, hosts can experience fever, chills, or another bad response
list the macroelements (macronutrients) that are found in organic molecules such as proteins, lipids, carbohydrates, and nucleic acids (6)
- Carbon
- Oxygen
- Hydrogen
- Nitrogen
- Sulfur
- Phosphorus