Bacterial Structure Flashcards
What defines the shape of the cell wall of bacteria
Peptidoglycan
List the different bacterial shapes that are under the category of spheres (cocci)
single cells pairs (diplococci) chains (streptococci) tetrads (micrococci) grapelike clusters (stapylcocci)
Rods aka bacilli range from _____ to ______ in size and shape
coccobacilli to long rods
Spirals range from _____ to ______ in size and shape
comma-shaped (Vibrio) to 4 to 20 coils (Spirochetes)
Most species of bacteria utilize________for growth generation of unique microbial structure:
carbohydrates (glucose)
What do clostridia utilize for growth generation of unique microbial structure:
amino acids
What do leptospira utilize for growth generation of unique microbial structure:
fatty acids
What is the advantage of using the resources that clostridia and leptospira use for growth
Most bacteria utilize carbohydrate (glucose)
But these use amino acids and fatty acids respectively
therefore they don’t have to compete with most bacteria for resources. This gives them a selective advantage
Describe how gram stain can be utilized to classify gram positive vs gram negative bacteria
- Step 1 is crystal violet and this stain adheres VERY well to the thick peptidoglycan of the gram positive bacteria, and only sort of adheres to the gram negative
2 .then iodine is added - A decolorizer is then used and this removes the color from the gram negative but the crystal violet sticks so well to the gram positive that it does not remove the color from it at this time. If you look under a microscope right now you will see violet gram positive and you won’t see gram negative
- Safranin red is then added and this adheres very well to gram negative but gram positive has the crystal violet predominating, therefore you have violet gram positive and red gram negative
compare and contrast gram positive and gram negative bacteria cytoplasmic membrane
they are identical!
Compare the cell wall of a gram positive bacteria to that of a gram negative
- Gram positive have a tick peptidoglycan layer that serves as the permeability barrier. The peptidoglycan is heavily cross linked between polysaccharide “C” aa of chain A & “D” aa of chain B
- Gram negative have a thin peptidoglycan layer that is cross-linked to a thick outer membrane. this outer membrane serves as the permeability barrier of gram negative
Compare the permeability layers of gram negative and gram positive
gram positive only have the peptidoglycan cell wall layer. and although it is very thick it isn’t as protective as the gram negative
gram negative have the outer membrane (that contains porins and LPS) that serves as their permeability layer. after the outer membrane they have a thin peptidoglycan layer
Describe the difference in amino acids between prokaryotes and eukaryotes
Eukaryotes use only L-amino acids
Prokaryotes use BOTH L and D-amino acids
this use of D amino acids can be a great target for anti-biotics
Descrbe the basic subunit of the peptidoglycan
a disachharide linked to a D/L pentapeptide
-there is cross linking that occurs at this D amino acid
Why is peptidoglycan a site of action for many antibiotics
it is a structure that is unique to the bacteria. therefor if it is targeted in the bacteria it will not harm the human..
this gives it a good specificity
