ACTIVITY 3: DIFFERENTIAL STAINING: GRAM STAINING Flashcards
______ is a procedure that makes visible the differences between bacterial cells or parts of bacterial cells. This involves the application of more than one ______ to a fixed smear.
Differential staining, dye solution
Among the differential staining techniques widely used is ______.
Gram Staining
______ subjects a fixed bacterial smear to ______ (initial stain), ______ (mordant), ______ (decolorizer), and ______ (counter stain).
Gram Staining, crystal violet, iodine, alcohol, safranin
The ______ procedure is one of the most widely used in basic and applied microbiology.
Gram Staining
The gram staining involves a differential stain which enables us to classify bacteria into two groups: ______, which retail ______, thus appear deep violet; and ______, which retain the counter stain, ______, thus appear red. The varying results are due in part to the differences in the structure and composition of the bacterial ______.
Gram positive bacteria, crystal violet, Gram negative bacteria, safranin, cell walls
______ was identified as a Gram-positive bacterium, meaning it retained the ______ stain and appeared ______ under the microscope.
Staphylococcus aureus, crystal violet, purple
______ was determined to be Gram-negative, as it did not hold onto the crystal violet stain after decolorization and instead absorbed the ______ counterstain, making it appear ______. This differentiation is essential in microbiology, as it aids in bacterial ______ and helps determine the most effective ______ for treatment.
Escherichia coli, safranin, red, classification, antibiotics
Gram-positive bacteria appear ______ because of the unique composition of their cell walls. They possess a ______ layer of ______, which is highly effective in trapping the crystal violet-iodine complex during staining. When ______ or ______ is used as a decolorizing agent, the thick peptidoglycan prevents the dye from being ______. As a result, these bacteria retain the ______ stain, giving them a distinctive deep ______ or ______ color when observed under a microscope.
violet, thick, peptidoglycan, alcohol, acetone, removed, crystal violet, violet, purple
The reason Gram-negative bacteria stain ______ lies in their distinct cell wall structure. Unlike Gram-positive bacteria, they have a ______ ______ layer and an outer membrane composed of ______. During the decolorization step, alcohol or acetone ______ this outer membrane, allowing the ______ stain to be rinsed away. Because of this, when the ______ counterstain is applied, Gram-negative bacteria absorb it, resulting in their ______ or ______ appearance under the microscope.
red, thin, peptidoglycan, lipopolysaccharides, dissolves, crystal violet, safranin, red, pink
Examples of gram-positive bacteria:
Staphylococcus aureus
Bacillus subtilis
Clostridium botulinum
Streptococcus pneumoniae
Lactobacillus acidophilus
Enterococcus faecalis
Examples of gram-positive bacteria
______ is a rod-shaped bacterium found in soil and is often used as a model organism in research.
Bacillus subtilis
Examples of gram-positive bacteria
______, another Gram-positive bacterium, is known for producing the botulinum toxin, which causes botulism.
Clostridium botulinum
Examples of gram-positive bacteria
______ is a Gram-positive bacterium responsible for respiratory infections, including pneumonia.
Streptococcus pneumoniae
Examples of gram-positive bacteria
______ is a beneficial bacterium commonly found in the digestive system and used in probiotic supplements.
Lactobacillus acidophilus
Examples of gram-positive bacteria
______ is a Gram-positive bacterium that naturally occurs in the intestines but can lead to infections under certain conditions.
Enterococcus faecalis
Examples of gram-negative bacteria:
Salmonella typhi
Pseudomonas aeruginosa
Klebsiella pneumoniae
Neisseria gonorrhoeae
Vibrio cholerae
Examples of gram-negative bacteria
______, for example, is a Gram-negative bacterium that causes typhoid fever, a severe infectious disease.
Salmonella typhi
Examples of gram-negative bacteria
______ is another Gram-negative species known for its resistance to antibiotics and its association with hospital-acquired infections.
Pseudomonas aeruginosa
Examples of gram-negative bacteria
______ can lead to respiratory infections such as pneumonia, as well as urinary tract infections.
Klebsiella pneumoniae
Examples of gram-negative bacteria
______ is the bacterial agent responsible for gonorrhea, a common sexually transmitted disease.
Neisseria gonorrhoeae
Examples of gram-negative bacteria
______ is a Gram-negative bacterium that causes cholera, an illness characterized by extreme dehydration due to severe diarrhea.
Vibrio cholerae
In conclusion, the ______ technique is a fundamental tool in microbiology that allows for the classification of bacteria into ______ and ______ groups based on their ______ composition.
Gram staining, Gram-positive, Gram-negative, cell wall
Through this activity, ______ was identified as Gram-positive, retaining the ______ stain and appearing deep ______, while ______ was classified as Gram-negative, losing the primary stain and taking up the ______ ______ counterstain.
Staphylococcus aureus, crystal violet, violet, Escherichia coli, red, safranin
These differences highlight the structural variations between bacterial cell walls, with Gram-positive bacteria having a ______ peptidoglycan layer and Gram-negative bacteria possessing a ______ layer along with an ______.
thick, thinner, outer membrane
