The cells wall of bacteria Z contains high concentrations of phospholipids along with proteins and relatively low amounts of lipopolysaccharide. When bacteria Z is gram stained, it will most like be colored?

Question

A.  Purple
B.  Pink
C.  Blue
D.  Clear, it does not retain any stain

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
 
Gather Content
· What do you already know about gram staining? How does it relate to the question?
 
Choose Answer · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
 
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

B.  Pink

Clarify Question
· What is the key concept addressed by the question?
            · You have discovered a new bacteria species: bacteria Z. You analyze its cell wall and determine that it contains a lot of phospholipids, some proteins, and some carbohydrates. Is this a gram-negative or gram-positive bacterium? What color will it be after gram staining?
· What type of thinking is required?
        o This question is an “apply” question. You need to apply your previous knowledge (about gram staining, gram-negative bacteria, and gram-positive bacteria) to a new situation.
 
Gather Content
· What do you already know about gram staining? How does it relate to the question?
        o During gram staining, you use crystal violet and iodine, which stay under the peptidoglycan layer of gram-positive cells. In gram-negative cells, there are pores between sections of the peptidoglycan layer, which allow the crystal violet and iodine to escape.
        o You then use saffranin, which stains all of the cells. The gram-positive cells are already purple, so their color does not change much. The gram-negative cells change from clear to pink.
        o Is bacteria Z gram-positive or gram-negative? How are the cell walls of these two groups different? How could this help you answer the question?
 
Choose Answer · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o First, determine whether bacteria Z is gram-negative or gram-positive. Use the information about the contents of bacteria Z’s cell wall. Which type of bacterium is going to have a lot of phospholipids, a few proteins, and a few carbohydrates in its cell wall?
        o Then, use this information to determine what color the bacterium will be after gram staining.
 
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o This question gave you information about a new bacterium, then asked you to determine what color it would be after a gram stain. The question required a two-step process to answer. First, you needed to determine whether bacteria Z is gram-positive or gram-negative. Then, you needed to use that information to determine what color it would be after a gram stain.
        o If you got the correct answer, great job!
        o If you got an incorrect answer, where did you get stuck?             · Bacteria Z had a lot of phospholipids, a few carbohydrates, and a few proteins in its cell wall. Did you figure out whether it was gram-positive or gram-negative?
            · Gram-positive bacteria have a huge layer of peptidoglycan (a carbohydrate) for a cell wall.
            · Gram-negative bacteria have a thin layer of peptidoglycan surrounded by the plasma membrane on one side and the outer membrane on the other. These membranes are made of phospholipids and proteins.