Lab Exam Study Flashcards
What does the purple colour of the bacteria mean
Gram Positive
What does the pink colour of the bacteria mean
Gram negative
What shape is coccus
spheres
what shape is basillus
rods
what shape is spirrilum
spirals
If the shapes are in doubles, the prefix _ is used
diplo
f the shapes are in chains the prefix _ is used,
strepto
If the shapes are in clusters, the prefix _ is used
staphylo-
why does gram staining work
all bacteria cell walls have a compound called peptidoglycan. If they become purple from gram staining, they have a thick layer of peptidoglycan and are considered gram positive. If they are pink from gram staining, they have a thin layer of peptidoglycan and are considered gram negative
How does staining gram-negative cells work
They have a thin layer of peptidoglycan, and they have an outer membrane composed of lipopolysaccharide. When we put alcohol on the bacteria, it dissolves the lipopolysaccharide and washes away the dye from the cell wall
Why is gram-staining important
The main benefit of a gram stain is that it helps your doctor learn if you have a bacterial infection, and it determines what type of bacteria are causing it. to help identity bacteria present in a sample and to determine which antibiotics to use. Purple means gram positive, pink means gram-negative. Pink is generally more harmful.
What does ELISA stand for
Enzyme-Linked Immunosorbant Assay
What are antibodies
Antibodies are made by people in response to an antigen. They are Y-shaped proteins whose upper “tips” differ in their shapes
What are antigens
Antigens are any part of an invader that triggers the production of antibodies.
What is the relationship between antigens and antibodies
When antigens trigger the formation of antibodies, only those antibodies with the corresponding shape will be produced.
What does a colour change in ELISA mean
Primary antibodies are present in patients blood
How does an ELISA work? That is, what do the steps, in that order, do?
Microwells are provided that contain the antigens to specific diseases. These antigens are firmly stuck to the well (1). The patient’s blood serum is added to the well. If the blood serum contains antibodies that are specific to that antigen (called primary antibodies), they will attach to the antigens (2). Any excess material is washed off. The secondary antibodies are added and they will attach to the primary antibodies if primary antibodies are present. (These secondary antibodies are made from non-human animals and are designed to attach to human primary antibodies.) Secondary antibodies have an enzyme attached (3). Excess material is washed away.
The substrate specific to the enzyme is added. If the secondary antibody with the attached enzyme is present, the enzyme will convert the substrate into something else, causing colour change to occur. The stronger the colour change, the more antibodies are present (4).
Describe the colour change for a positive benedicts test
Red: large amounts of glucose, Orange: moderate, green: trace, blue: non
Describe the colour change for a positive buiret test
Purple: positive, No colour change: negative
