Ch 3 microbiology (part 2 of test)

Microbiology

What is the chromosome structure of prokaryotes

single, circular DNA molecule in nucleoid

What is the chromosome structure of eukaryotes?

multiple linear DNA molecules enclosed in nucleus

Are there membrane-enclosed organelles in prokaryotes?

No

Are there membrane-enclosed organelles in eukaryotes?

Yes (mitochondria, golgi apparatus)

What is the cell wall composition of prokaryotes

Peptidoglycan or pseudomurein (bacteria and archaea)

What is the cell wall composition of eukaryotes

chemically simple when present. Cellulose, chitin

what is the mechanism of cell division in prokaryotes

Binary fission

what is the mechanism of cell division in eukaryotes

mitosis

Describe the shape and arrangement of the bacterial cell coccus pl cocci

round shape “O”

Describe the shape and arrangement of the bacterial cell bacillus pl bacili

rod shape

Describe the shape and arrangement of the bacterial cell spirillum (aka spiral)

Spiral shape

Describe the shape and arrangement of the bacterial cell diplococcus ex.gonorrhea

pair of spherical cells “OO”

Describe the shape and arrangement of the bacterial cell streptococcus ex. Staph

chain-like circles “OOOOO”

Describe the shape and arrangement of the bacterial cell tetrads ex: harmless skin bacteria

Four spherical coccus in shape of a square

Describe the shape and arrangement of the bacterial cell staphylococcus

Clump of coccus

Describe the shape and arrangement of the bacterial cell diplobacillus

2 rod-shaped bacillus

Describe the shape and arrangement of the bacterial cell streptobacillus Ex. Anthrax

chain-like bacillus

Describe the shape and arrangement of the bacterial cell coccobacillus

Very short rod

Describe the shape and arrangement of the bacterial cell vibrio

Curved

What is a capsule in prokaryotic cells

sticky, protective outer layer that surrounds the cell wall of some prokaryotic cells, prevents phagocytosis

What is the capsule of prokaryotic cell made of

polysaccharides (complex sugars), can also consist of polypeptides (proteins), or both

Why are encapsulated bacteria generally more virulent than similar, but noncapsulated bacteria

because the capsule acts as a biological shield against the host’s immune system, allowing the pathogen to survive, multiply and spread

what is a biofilm AKA slime layer Ex: slippery rocks, dental plaque, artificial joints

bacteria enclosed in glycocalyx they’ve secreted, attached to a surface

What is biofilm made of

made of glycocalyx

in what ways are biofilms problematic

they’re difficult to kill with antibiotics or disinfectants, must scrub it off! problematic if its somewhere in the body

Describe the chemical composition of a bacterial flagella

flagellin (main structural component protein), Hook proteins, and basal body complex (rotary motor assembly)

Describe the basic structure of a bacterial flagella

Filament (outermost region), Hook (attaches to the filament), and basal body (engine)

Describe the action and function of flagella

Action: spin like boat propellers , function: motility, adhesion , and colonization to help pathogenic bacteria penetrate the mucus layers and spread through host organism tissues

Define motility

The ability of an organism or cell to move independently using its own metabolic energy. Bacterium’s ability to navigate its environment

Describe how axial filaments (endoflagella) cause the characteristic “corkscrew” swimming that allows spirochaete bacteria to move through body fluids

they work from inside the cell envelope rather than extending outward into the surrounding medium, like a screw into wood

Describe the structure of fimbriae and how they contribute to bacterial virulence

Hairlike appendages, made of protein molecules. Allow bacteria to attach to surfaces

What is the major function of the bacterial cell wall

To prevent osmotic lysis

What is the structure of a Gram-positive cell wall

Has a thick, rigid layer of peptidoglycan located directly outside the cytoplasmic membrane

Describe the structure of a Gram-negative cell wall

Structurally more complex, has a thin inner layer of peptidoglycan surrounded by an additional lipid bilayer. more dangerous

Describe the structure of peptidoglycan (PGN)

Strong and porous.

In peptidoglycan, what are the NAG-NAM chains?

they are sugar chains. Alternating chains of two amino sugars linked together. They form rigid parallel rods around the bacterial cell

In peptidoglycan, what are tetrapeptide side chains

directly attached each NAM molecule is a short chain of four amino acids, helps protect the cell wall from being easily degraded by host digestive enzymes

In peptidoglycan, what are peptide cross-links

Adjacent glycan strands that are tied together by covalent cross-links between their tetrapeptide side chains.

Describe the use of teichoic acids in the structure of the gram-positive cell wall

They strengthen the cell wall and maintain shape under osmostic pressure, help with cell division and growth, help keep the ion balance, and assists the cell to adhere to host surfaces

Describe the lipopolysaccharides (LPS) role in gram-negative cell wall

they are large molecules found exclusively in the outer membrane, serving critical structural, protective, and disease-causing roles.

what does the lipopolysaccharides Lipid A (endotoxin) do

hydrophobic fatty acid tails insert directly into the outer layer of membrane, physically securing it. When gram-negative bacteria multiply or die (lyse), lipid A is released into the host environment

What does the O polysaccharides (O-antigen) do in the lipopolysaccharide (LPS)

Serves as protection against complement and phagocytosis, physically distance host immune proteins and phagocytes from reaching the bacterial cell surface, PHYSCIAL SHIELD FROM LYSIS

How does LPS help the cell

Contributes to cell’s negative surface charge, protects against bile, phagocytes, and complement proteins (host defense against bacteria)

How do endotoxins enter an animal’s bloodstream, and the effects of endotoxin on the animal

Endotoxins (specifically lipid A) enter the bloodstream when gram-negative bacteria break down or breach mucosal barriers.

Once in the bloodstream, endotoxins bind to host immune receptors on macrophages and monocytes set off an overwhelming inflammatory cascade. Fever, chills, vasodilation, hypotension, SEPTIC SHOCK, ORGANFAILURE

What are porins

pore-forming proteins found in the outer membranes of Gram-negative bacteria. They act as water-filled channels that allow small molecules to passively diffuse into and out of cell

What are the components of peptidoglycan? (3)

NAG-NAM chains, tetrapeptide side chains, peptide cross-links

What are the structural components of Gram-positive cell walls? (2)

peptidoglycan layer, teichoic acid

What are the structural components of Gram-negative cell walls? (5)

peptidoglycan layer, outer membrane, Lipopolysaccharide (LPS) consisting of lipid A (endotoxin) and O polysaccharides, porins

Do gram-positive bacteria produce endotoxins or exotoxins?

exotoxins

Do gram-negative bacteria produce endotoxins or exotoxins

Both

Why are both penicillin and lysozyme more damaging to gram-positive bacteria than gram-negative

gram-positive bacteria don’t have a protective outer membrane

what does penicillin do to peptidoglycan layer? what does lysozyme do

penicillin interferes with the formation of peptide cross-links in growing PGN. lysozyme cuts NAG-NAM bonds