Module 1--Introduction to Microorganisms Flashcards
What is microbiology?
It is the study of microscopic living organisms.
When did microorganisms start to appear on Earth?
Around 4 billion years ago
What structures are universal to all bacterial cell?
- Cytoplasmic membrane
- Cytoplasm
- Nucleus or nucleoid and ribosomes
- Cell wall
What processes are universal to all bacterial cells?
- Metabolism
- Growth
- Evolution
What are the characteristics of some bacterial cells?
- Differentiation
- Communication
- Genetic exchange
- Motility
What was Louis Pasteur’s contribution?
He disproved theory of spontaneous generation
What was Robert Koch’s contribution?
He definitively demonstrated the link between microbes and infectious diseases and pioneered the use of agar in solid media.
What are proteobacteria?
Major phylum of gram-negative bacteria
Gram-positive and Gram negative bacterial membrane lipids contain:
Fatty acids joined to glycerol via ester linkages
Archaeal membrane lipids contain:
Repeating isoprene units joined to glycerol via ether linkages
Both gram-positive and gram-negative cell walls have:
Peptidoglycan
What is the difference between gram-positive and gram-negative cell walls?
Gram-negative cell wall has outer membrane, while gram-positive cell wall does not have.
What is peptidoglycan?
A rigid structural layer that provides strength to the cell wall
What does the repeating polysaccharide unit of peptidoglycan composed of?
N-acetylglucosamine (G) and N-acetylmuramic acid (M)
What is the difference between the peptidoglycans in gram-positive and gram-negative cell walls?
Peptidoglycan is thinner and hidden in gram-negative cell wall
Crosslinking in gram-positives occurs via:
Formation of peptide interbridge
Crosslinking in gram-negatives occurs via:
NH2 group of DAP of one glycan chaining to COOH group of D-alanine on adjacent chain
Crosslinking of the repeating G+M unit of peptidoglycan provides:
Structural integrity
What does the gram-positive cell wall contain?
- 90% peptidoglycan
- Teichoic acids embedded
- Lipoteichoic acids which are covalently bounded to membrane
