Microbiology Ch 4 Flashcards
Name characteristics of Prokaryotes
1) DNA is not enclosed in a membrane & is usually a single, circularly arranged chromosome
2) DNA is not associated with histones
3) Lack membrane enclosed organelles
4) Cell wall contain peptidoglycan
5) Divide through binary fission
Name Characteristics of Eukaryotes
1) DNA is found in cell’s nucleus and is found in multiple chromosomes
2) DNA is associated with histones
3) Have membrane enclosed organelles
4) Cell walls are chemically simple
5) Cells divide through mitosis
Histones
chromosomal proteins found in Eukaryotes
Binary Fission
DNA is copied and cell splits into two cells
involves fewer structures and processes than eukaryotic cell division
Mitosis
chromosomes replicate and identical set is distributed into each of two nuclei
*the two cells are identical to each other
Monomorphic
maintain a single shape
Pleomorphic
having many shapes
Name Cocci Arrangements
1) diplo= in pairs
2) strepto= in chains
3) tetrads= divided in two plains and remain in groups of four
4) sarcinae= divide in three plaines and remain in cubelike group of eight
5) staphylo=clusters
Name Bacilli Arrangements
1) single
2) diplo= in pairs
3) strepto=in chains
* coccobacilli-special case that look oval and rod-like
Special Bacteria Shapes
1) Spiral bacteria which includes: vibrio, spirilla(flagella), spirochete (axial appendages)
2) Also star shaped and rectangular bacteria
Glycocalyx
“sugar coat”
A general term to describe substances that surround the cell, protects the bacteria from phagocytosis
Capsule
- glycocalyx that is firmly attached to the cell wall
- presence can be determined thru gram staining
- most important in determining bacterial virulence
Flagella
-long filamentous appendages that propel bacteria
Motility
the ability of an organism to move by itself
Arrangements of Bacterial Flagella
1) atrichous- lacking flagella
2) peritrichous- flagella at multiple sites
3) polar- flagella at polar ends
a. monotrichous- flagella at one pole
b. lophotrichous- tuft of flagella from one pole
c. amphitrichous- flagella at both poles
Taxis
movement towards or away from stimuli
e.g. phototaxis and chemotaxis
Serovars
variations within a species of gram negative bacteria
Endoflagella
aka axial filaments
- bundles of fibrils that arise at the ends of the cell beneath an outer sheath and spiral around the cell
- rotation causes the cell to move
Fimbriae
allow bacteria to adhere to surfaces
Pili
facilitate DNA transfer from one cell to another
*longer than fimbriae and only 1-2 per cell
Bacterial Cell Wall
- made of peptidoglycan which is a polymer of disaccharide (NAM and NAG)
- antibiotics interfere with peptidoglycan synthesis
Lysis
destruction caused by rupture of plasma membrane and loss of cytoplasm
Gram Positive Bacteria
- cell wall consists of many layers of peptidoglycan
- cell wall contain “teichoic acid” which consists of an alcohol (e.g. glycerol or ribitol) and phosphate
Gram Negative Bacteria
- cell wall consists of a thin layer of peptidoglycan and an outer membrane
- peptidoglycan is bonded to lipoproteins in the outer membrane and is in the periplasm
Teichoic acid
- may regulate the movement of cations
- polysaccharides provide antigenic variation
Wall teichoic acid is linked to
peptidoglycan
Lipoteichoic acid is linked to
the plasma membrane
Outer membrane of gram negative cells walls
consists of lipopolysaccharides, lipoproteins, and phospholipids
*important structure because is offers from protection against phagocytes, complement proteins, and antibiotics
Atypical Cell Walls
1) mycoplasma- lack cell walls, have lipids called sterols in plasma membrane that may protect them from lysis
2) archaea- wall-less or have walls of pseudomurein (lack NAM and d-amino acids)
Staining
coloring a microbe with dye that emphasizes certain structures
-stain consists of a cation and anion
Smear
- a thin film of a solution of microbes on a slide
- usually fixed to attach the microbes to the slide and to kill the microbes
Negative Staining
staining the background instead of the cell
Chromophore
a colored ion
- in basic dyes=cation
- in acidic dyes=anion
Simple Stains
- use of a single basic dye
- purpose: highlight the entire organism
Mordant
a chemical additive that intensifies staining
Differential Stains
used to distinguish between bacteria
-includes acid fast and gram stain
Gram Stain
-classifies bacteria into gram positive and gram negative
Acid Fast Stain
binds strongly only to bacteria that have a waxy material in their cells
Special Stains
used to color and isolate specific parts
Damage to cells walls
1) lysozyme
2) results in protoplasts or spheroplasts
