Lesson 3 - The Prokaryotic Cell

glycocalyx

• a very important component of biofilms

• an extracellular polymeric covering the entire bacterium and is composed of polysaccharide

• bacterial virulence (capsule)

• Specific identification for an organism

• used as antigens in certain vaccines

glycocalyx / slime layer

adherence of bacteria to human tissues

pleomorphic

many shapes not just one

bacillus anthracis
streptococcus pneumonia
klebsiella pneumonia

examples of bacteria with capsule

diplo

when bacteria comes in pairs

strep

when bacteria comes in chains

staph

when bacteria comes in clusters

slime layer

loosely associated with the cell

capsule

condensed, well-defined layer closely surrounding the cell

glycocalyx
flagella
axial filaments
fimbriae and pili

external to the cell wall

gram-positive
gram-negative
atypical cell wall

the cell wall

cell membrane
cytoplasm
nucleoid
ribosomes
endospores

internal to the cell wall

pili

• rigid, shorter, hairlike filaments

• composed of protein called “pilin”

• antigenic

• for motility

• bacterial DNA transfer (sex __)

fimbriae

• may be found at the poles or covering the entire bacterial cell

• for adherence to surfaces

axial filaments

• “endoflagella”

• unique structure found in spirochetes for their motility

conjugation process

the DNA from the F⁺ cell is transferred to other cell

flagella

• long, threadlike appendages that move the bacteria toward nutrients and other attractants (chemotaxis)

• made up of proteins called “flagellin”

• highly antigenic (H-proteins)

peptidoglycan

• “murein” and “mucopeptide”

• a complex, interwoven network that surrounds the entire cell

• composed of carbohydrate backbone, tetrapeptide side chains and peptide cross-bridges

• found in bacteria

outer membrane

found in gram-negative bacteria for extra protection

DAP

• unique in bacterial cell wall

• (important amino acid)

D-Alanine

• cross-linking peptidoglycan strands

• (important amino acid)

cell wall

• outermost component common to all bacteria

• provides rigid support

• maintains the characteristic shape of the cell

• allows the cell to withstand media of low osmotic pressure

mesosome

• invagination of the plasma membrane

• plays important role in cell division

  • serves as the origin of the transverse septum that divides the cell in half

  • the binding site of the DNA that will become the genetic material of each daughter cell

plasmid

• extrachromosomal, double stranded circular DNA molecules

• replicates independently of the bacterial chromosome

fertility plasmid (F-plasmid)

gene for conjugation
(important plasmid)

resistance plasmid (R-plasmid)

resistance to antibiotic)

recombinant insulin production

insulin + plasmid = extract insulin

teichoic acid

• present on a gram-positive cell wall

• septic shock

• inflammation

plasma (cytoplasmic) membrane

• composed of a phospholipid bilayer that do not contain sterols

• selective permeability and transport of solutes

• electron transport and oxidative phosphorylation

• excretion of hydrolytic exoenzymes and pathogenicity proteins

• synthesis of precursors of the cell wall

• bearing of receptors and other proteins for chemotactic and sensory transduction systems

nucleoid

• area in the cytoplasm where the DNA is located

• feulgen-positive

• absence of nuclear membrane and mitotic apparatus

• circular

• prokaryotic cells are haploid

cytoplasm

has two distinct areas:

• an amorphous matrix containing the ribosomes, nutrient granules, metabolites and plasmids

• inner nucleoid region containing the DNA

granules

serve as storage areas for nutrients

inclusion bodies

storage body

sulfur granules

storage sulfur

volutin / metachromatic

storage of polyphosphate

carboxysome

enzyme

transposons

• “jumping genes”

• pieces of DNA that move readily from one site to another, either within or between DNA’s of bacteria, plasmids or bacteriophages

• code for drug resistance enzymes, toxins or other metabolic enzymes

• cause mutations in the gene into which they insert

ribosomes

sites of protein synthesis with the size of 70s

50s

large subunit of ribosomes (prokaryote)

30s

small subunit of ribosomes (prokaryote)

60s

large subunit of ribosomes (eukaryote)

40s

small subunit of ribosomes (eukaryote)

endospores

• resting cells that are formed in response to adverse conditions

• resistant to heat, dehydration, radiation and chemicals (due to calcium dipicolinate)