Microbiology Flashcards
What are bacteria?
Prokaryotic cells that play an important role in human disease and health
Where can bacteria be found?
Skin, body and everyday objects in our environment
What is the cell envelope?
The combination of the cell wall, the plasma membrane and the capsule
What is the cell wall?
it is a structure made up of peptidoglycan molecules and helps the bacterial cell with protection and maintaining shape
What makes a bacteria gram positive?
It will have a thick layer of peptidoglycan cells above the plasma membrane - this retains the stain dye
What makes a bacteria gram negative?
It will have a thin layer of peptidoglycan cells sandwiched between the surface membrane and the plasma membrane - this cannot retain stain dye
What different shapes of bacteria can be found?
- Cocci (round shaped)
- Bacilli (rod shaped)
- Spirilla (spiral shaped)
- Pleomorphic (multiple forms)
What is a capsule?
It will help protect a bacteria against phagocytosis and help the bacteria adhere to surfaces. Not all bacteria have a capsule but capsules are considered an important virulence factor for those that do.
What is the plasma membrane?
The membrane found in all cells that separates the interior of the cell from the outside environment
What are the functions of the plasma membrane?
- Holds everything within the cell
- Responsible for cells relationship with external environment
- Acquires nutrients
- Eliminates waste
- Selectively permeable
- Important in respiration
- Important in photosynthesis
- Important in the synthesis of lipids and cell wall components
What does selectively permeable mean?
It means it allows some molecules and ions to pass in and out but prevents the movement of others
What components would you find within the cytoplasm of a bacterial cell?
- Ribosomes
- Nucleoid
- Plasmids
What do ribosomes do?
They are the location of protein synthesis. they will either be within the cytoplasm producing proteins that remain within the cell or they will be plasma membrane associated ribosomes which produce proteins that reside in the cell envelope or get transported out the cell
What does a nucleoid do?
They contain the cells chromosomes and the genes needed to provide the instructions for protein synthesis. some are circular double stranded DNA and some have a linear chromosome. some bacteria cells can have more than one.
What are plasmids?
They are small double stranded DNA molecules that can live independently of the chromosome, they can be circular or linear and have very few genes. they can confer to a selective advantage (ex, ABX resistance)
