Untitled Deck Flashcards
What are prokaryotes?
Organisms lacking internal membrane-bound structures.
What is the size range of prokaryotic cells?
Cells with diameters ranging from 0.5-5 μm.
What are the three most common shapes of bacteria?
Sphere (cocci), rod (bacilli), and spiral (spiral, spirochete, helical, twisted rod).
Are prokaryotes unicellular or multicellular?
Unicellular, but may aggregate temporarily or permanently in colonies.
What is the function of cell walls in prokaryotes?
Maintain shape, provide protection, and are chemically different from eukaryotic cell walls.
What is peptidoglycan?
A component of prokaryotic cell walls, cross-linked by short polypeptides unique to each species.
What does the Gram stain indicate?
It is influenced by the amount of peptidoglycan in the cell wall.
What characterizes Gram-negative bacteria?
They have an outer membrane containing lipopolysaccharide (LPS) and a thin shell of peptidoglycan.
What characterizes Gram-positive bacteria?
They have a thick, homogenous sheath of peptidoglycan 20-80 nm thick.
What is a glycocalyx?
A gelatinous, sticky substance surrounding the cell, made of sugars and/or proteins.
What are the functions of glycocalyces?
Attachment, inhibits killing by white blood cells, and acts as a receptor.
What are the two types of glycocalyces?
Capsule (attached firmly for protection) and slime (water soluble for attachment).
What is the function of flagella?
A motile whiplike structure capable of rotating 360° extending beyond the cell surface.
What are the types of flagellar arrangements?
Monotrichous, amphitrichous, lophotrichous, and peritrichous.
What are fimbriae?
Non-motile, sticky proteinaceous extensions for adhesion to surfaces.
What are pili?
Protein tubules used to move across substrates or transfer DNA between cells.
What is the prokaryotic genome?
A single, circular, double-stranded DNA molecule containing all genetic information.
What is a genophore?
Term that specifically refers to the bacterial chromosome.
What are plasmids?
Small rings of DNA not essential for survival but provide genes for resistance and unique metabolic capabilities.
What is horizontal gene transfer?
Transfer of DNA from one organism to another of different species within the same generation.
What is binary fission?
Asexual reproduction through the division of a single individual.
What is transformation in prokaryotes?
Organism takes up genes from the environment, even across species lines.
What is conjugation?
Direct transfer of DNA from one organism to another.
What is transduction?
Transfer of genes through viruses (phage) that inject prokaryotic DNA into a recipient.
What is an F plasmid?
A piece of DNA that allows bacteria to form sex pili and donate DNA during conjugation.
What is an R plasmid?
Contains multiple antibacterial resistance genes and regulates conjugation and transfer of plasmids.
What is transposition?
A process of excising and transferring an entire sequence of DNA to integrate into another part of DNA.
What are transposons?
Transferrable genetic elements also known as ‘jumping genes’ that can carry additional genes.
