Bacteriology - Background 2 Flashcards
What are the components of peptidoglycan?
- N-acetyl-glucosamine
- N-acetyl-muramic acide
linked by peptide bridges
The cytoplasmic membrane is present in Gram + and - bacteria. What is it also known as in Gram - ?
Inner membrane
Do Gram + bacteria have an outer membrane?
No. Only a cytoplasmic membrane
Does the cytoplasmic membrane have function?
Yes. Nutrient uptake and transport, electron transport to create energy for itself
Which 3 characteristics don’t the Gram + have?
- Porin proteins
- Lipopolysaccharides (LPS)
- Phospholipids
What is lipopolysaccharide (LPS) also known as?
Endotoxin, because it is a potent stimulator of the immune system. It causes the release of IL-1, IL-6 and TNFalpha which results in sepsis or endotoxic shock
Which membrane of the Gram - bacteria is LPS found in?
The inner membrane
What is contained in the cytoplasm of bacteria?
- Nucleoid
- Plasmids
- Ribosomes
- Endospores
What are the characteristics of the nucleoid?
- No membrane
- Haploid, circular, double stranded chromosome
What are the characteristics of plasmids?
- Circular dsDNA
- Can replicate independently of the chromosome
- Genetic information encoded is not necessary for survival
- Can be transferred to other bacterial cells and passed to daughter cells
- Can carry advantageous genetic information like antibiotic resistance
What are the ribosome structure of Prokaryotes and Eukaryotes?
Prokaryotes: 70S (50S + 30S)
Eukaryotes: 80S (60S + 40S)
Which bacteria can have endospores (Gram + or -)?
Gram+
Which are examples of bacteria with endospores?
Bacillus and Clostridium
Which are the factors affecting bacterial growth?
- Temperature
- Oxygen
- pH
- Salt
What are organisms that cause spoilage of food called?
Psychrophiles
What are bacteria that affect humans called?
Mesophiles (temp 32-40 degrees)
Which are the 2 enzymes that certain bacteria carry that allows it to detoxify toxic oxygen radicals?
- superoxide dismutase which will take the toxic oxygen radical and convert it to hydrogen peroxide.
- hydrogen peroxide further needs to be made non-toxic and the enzyme that does that is catalase
Do obligate anaerobes have superoxide dismutase and catalase?
No, therefore they are killed by toxic derivatives of oxygen.
Do facultative anaerobes require oxygen?
No, they grow best in the presence of oxygen but can grow without it by using aerobic or anaerobic respiration or fermentation.
What are aerotolerant anaerobes?
They can grow in the presence of oxygen, but are obligate fermenters.
What are examples of facultative anaerobes?
- Staph aureus
- Streptococci
Which cell type has a thicker peptidoglycan layer?
Gram+
Which cell type contains foreign proteins?
Gram -
