Introduction to Bacteria Flashcards
What are the characteristics of gram positive bacteria
Remain coloured with gram staining after washing
No outer membrane (lipopolysaccharide and protein)
Smooth cell wall 70-80 percent peptidoglycan
No porins present
What are the characteristics of gram negative bacteria
Do not retain stain
Wavy wall comes in contact with plasma membrane
Wall 10-20% peptidoglycan
Porins or hydrophilic channels in outer membrane
What is the gram stain appearance of gram positive bacteria?
Purple
What is the gram stain appearance of gram negative bacteria?
Pink
What is the gram stain appearance of cocci?
Spherical
What is the gram stain appearance of bacilli?
Rod shaped
What can you find on the cell surface of bacteria?
Plasma membrane
Penicillin binding sites
Peptidoglycan
Lipopolysaccharides (gram negative bacteria)
What is the function of the murein/peptidoglycan?
Strength
Shape
Counteracts high osmotic pressure of bacterial protoplast
What is the response to lipopolysaccharides in animals and humans?
Strong immune response
What are frimbriae and Pilli?
Thread like projections used for adherence
Fimbriae:
Bristle-like
Multiple present
Adhere to host tissue
Pilli:
Bristle-like
Longer than fimbriae
Single or pairs
What are spores?
Highly resistant dominant structures
Asexual reproduction
Used in unfavourable conditions
How do bacteria replicate?
Binary fission - identical progeny
How is genetic variation increased in bacteria?
Spontaneous mutation
Transfer of DNA
What is a bacteriophage?
Virus which parasitises bacterium
Infecting and reproducing inside it
How do you see an individually cultured bacteria?
Microscope Stain
How do you view a colony of individual bacteria?
Seen by eye, cultured on solid medium (agar)
What is used to identify strains within a species?
DNA typing techniques
