Introduction to Bacteria Flashcards
What are the main structures of a typical bacterial cell?
Chromosome,
Cytoplasm
Cell wall
Ribosome
Penicillin binding proteins Peptidoglycan,
Lipopolysaccharide
Capsule
Flagella
Fimbriae
Plasmid
Bacteriophage
Spores
Discuss the chromosome
A single chromosome in bacteria but no nucleus.
Discuss the cytoplasm
Very thin, elastic and semi- permeable membrane around the bacterial cell content.
Made of phospholipids.
Allows passage of water and uncharged small molecules but otherwise forms a barrier.
There are proteins in the membrane.
Discuss the cell wall
Rigid structure, gives cell strength and shape but it is permeable.
Made from peptidoglycan
Discuss the ribosome
Consist of RNA and associated with proteins, their function is to synthesise proteins.
Divided into subunits
Bacteria have 70S ribosomes with large (50S) and small (30S) subunits
Subunit in small subunit called 16S
Discuss penicillin binding proteins
Enzymes which synthesise peptidoglycans.
Discuss peptidoglycans
Gives the cell strength and shape, these are made of carbohydrates that are cross linked with amino acids.
Discuss lipopolysaccharides (LPS)
A component of gram negative cell wall.
They protect peptidoglycans from bile salts, lysosomes and also blocks antibiotics from getting into the cell.
Discuss the capsule
Polysaccharide layer outside the cell wall.
Discuss the flagella
Hairlike structure used for motility
Discuss the fimbriae
Shorter and thinner than flagella and are important in mediating adhesion between bacteria cell and host cell.
Discuss the plasmid
Often, the genes carried in plasmidsprovide bacteria with genetic advantages, such as antibiotic resistance.
Discuss bacteriophage
A bacteriophage is a type of virus that infects bacteria.
Discuss bacteria spores
To protect bacteria against ecological degrading agents.
How are gram positive bacteria seen under the microscope?
Purple
How are gram negative bacteria seen under the microscope?
Red
What are the different shapes a bacteria can be?
Cocci - spherical
Bacilli - rod shaped
Spiral - corkscrew
What are spores?
Highly resistant dominant structures.
A unit of asexual reproduction
Used in unfavourable conditions
The most dormant form of bacteria since they exhibit minimal metabolism and respiration, as well as reduced enzyme production.
What is an example of a spore?
Bacillus subtilis
A Gram-positive, catalase-positive bacterium, found in soil and the gastrointestinal tract of ruminants, humans
How can individual bacteria be seen?
Only with a microscope
How can colonies of individual bacteria be seen?
Cultured on agar - can be seen by wyw
What are the key differences between gram positive and gram negative bacteria?
+ve
Retain stain
No outer membrane
Smooth cell wall w/ 70-80% peptigoglycan
No porins
-ve
Does not retain stain
Outer membrane (lipopolysaccharide and protein)
Wavy wall that comes in contact with the plasma membrane - contains 10-20 percent peptidoglycan.
What can you find on the cell surface of bacteria?
Plasma membrane
Penicillin binding sites
Peptidogylcan
Lipopolysaccharides (in gram negative bacteria)
How do bacteria replicate?
Binary fission - identical progeny
How is genetic variation increased in bacteria?
Spontaneous mutation
Transfer of DNA
A bacteria name is the combination of the genus and the species. What is the difference?
The genus name forms the first part of the name for each species within the genus.
What is the difference in the cell wall between gram positive and gram negative bacteria?
Gram positive cell wall is thick as it has layers and layers of peptidoglycan and then the plasma membrane contain proteins.
Gram negative cell wall is thinner as even though it has an outer membrane layer and a inner membrane layer, it only has one layer of peptidoglycans.
