Unit 3 Microbiology Flashcards
(17 cards)
How come bacteria be distinguished from one another?
Size shape, metabolism, antigenic features, genetics and staining characteristics 
What are the three types of bacteria?
Cocci
Bacilli
Spirilli
how are cocci drawn
Circle
How are Bacilli drawn? 
Rod shaped 
How are spirilli drawn
Spiral shaped
How is that shape maintained?
By the cell wall
What are the two types of the cell wall
Gram positive and gram negative
What features do gram positive bacteria have?
Thick peptidoglycan layer- retains crystal violet stain
(Purple under microscope )
What features do gram-negative bacteria?
Thin peptidoglycan layer- alcohol will wash crystal violet out
Saffron stains cells red
Have layers of lipopolysaccharides - protect cell from lysosomes and antibodies
Procedure to test gram negative versus gram positive
Heat
Stain with crystal violet
Fix stain with iodine
Decolourise with alcohol
Counterstain with safranin
What colour are gram-positive and gram-negative cells under a microscope? 
Gram-positive are people gram-negative are red
What does bacteria need to survive?
Carbon
-Polysaccharides (starch) to make enzymes
Nitrogen
- amino acids for amino sugars
Vitamins and minerals
PH, temperature, oxygen
What other three types of bacteria when it comes to oxygen?
Obligate aerobes - requires oxygen
Obligate anaerobes- requires absence of oxygen
Facultative anaerobes - grow better in oxygen but can grow without 
what are the two types of counting bacteria
viable and total
what is total count
count all bacterium alive or dead
what is viable counting
counting any cells capable of reproducing (alive)
