Week 3 - Clinical Lab Med Exam Questions and Answers
With complete solution–Expert Verified | Latest Questions
2025
bacteria: single celled organisms without organelles or nuclei
DNA is tangled in: nucleoid DNA
bacteria are surrounded by: plasma membranes and a cell wall
the plasma membrane is made of: lipid bilayer (like humans)
cell wall is made of: peptidoglycan
gram negatives have an additional: outer membrane of lipopolysaccharide
gram positive have a thickened: peptidoglycan layer
gram staining is the process of differentiating bacteria according to their: cell
walls
steps of gram staining: apply crystal violet dye and iodine
stains plasma membranes and cell walls purple
1/4
, apply mordant
-sets the stain
decolorize w alcohol solvent (acetone)
-removes plasma membranes
-doesn't affect G+
-G- become colorless
Counterstain w safranin (pink)
-stains peptidoglycan
in gram stain what color are gram +: purple
in gram stain what color are gram -: pink
alternative techniques exist for bacteria that don't stain well: may have
envelope components that resist acid/ethanol based staining ingredients then
use: acid fast staining
acid fast staining is notably used for what: mycobacterium tuberculosis
gram negative bacteria have what in the outer membrane that is a potent
2/4
With complete solution–Expert Verified | Latest Questions
2025
bacteria: single celled organisms without organelles or nuclei
DNA is tangled in: nucleoid DNA
bacteria are surrounded by: plasma membranes and a cell wall
the plasma membrane is made of: lipid bilayer (like humans)
cell wall is made of: peptidoglycan
gram negatives have an additional: outer membrane of lipopolysaccharide
gram positive have a thickened: peptidoglycan layer
gram staining is the process of differentiating bacteria according to their: cell
walls
steps of gram staining: apply crystal violet dye and iodine
stains plasma membranes and cell walls purple
1/4
, apply mordant
-sets the stain
decolorize w alcohol solvent (acetone)
-removes plasma membranes
-doesn't affect G+
-G- become colorless
Counterstain w safranin (pink)
-stains peptidoglycan
in gram stain what color are gram +: purple
in gram stain what color are gram -: pink
alternative techniques exist for bacteria that don't stain well: may have
envelope components that resist acid/ethanol based staining ingredients then
use: acid fast staining
acid fast staining is notably used for what: mycobacterium tuberculosis
gram negative bacteria have what in the outer membrane that is a potent
2/4
