Microorganisms Flashcards
What are the two main types of cells?
Prokaryotes and Eukaryotes
What is the largest group of bacteria?
Proteobacteria
What type of stain is the Gram stain?
Differential stain
What color do Gram-positive bacteria appear after staining?
Purple
What color do Gram-negative bacteria appear after staining?
Red
What are the two major groups of bacteria based on Gram staining?
Gram-positive and Gram-negative
How many genera and species of Proteobacteria have been identified?
More than 460 genera and 1600 species
What are some genera of Gram-positive bacteria?
- Bacillus
- Clostridium
- Lactobacillus
- Streptococcus
- Mycoplasma
What is a key function of fungi?
Production of antibiotics
What type of fungi are responsible for the decomposition of complex organic matter?
Saprotrophic fungi
What type of fungi cause diseases in plants and animals?
Parasitic fungi
How many fungi are known to infect humans?
About 200 fungi
What is the general innate immunity of humans towards fungi?
High degree of innate immunity
What is the significance of the genus Streptomyces?
Best known and most studied member of Gram-positive bacteria
What is Amanita caesarea commonly known as?
Caesar’s mushroom
What does the term ‘mycorrhiza’ refer to?
Symbiotic association between fungi and plant roots
What is the primary structure that increases nutrient uptake in ectotrophic mycorrhiza?
Fungal sheath
What are the characteristics of fungi?
- Heterotrophic for carbon
- Eukaryotic cell structure
- Filamentous in most groups
- Cell wall present
- Spores produced in reproduction
- Non-motile except in reproduction in some fungi
What is a hypha?
A filament of fungi
What is the network of branched hyphae called?
Mycelium
What are ‘fairy rings’?
Patterns formed by the growth of fungi
What are the two major types of fungal spores?
- Sexual spores
- Asexual spores
What is the significance of asexual spores?
Produced in large numbers for dispersal
What type of fungi are Chrytridiomycetes?
Lower fungi
What are zygospores?
Sexual spores produced by Zygomycetes
What is the generation time (g) for Escherichia coli?
17 minutes
What environmental factors affect microbial growth?
- Nutrient availability
- Temperature
- pH
- Aeration
- Moisture content
- Presence of inhibitory substances
What are the three phases of a typical bacterial growth curve?
- Lag phase
- Exponential phase
- Stationary phase
What is the survival structure formed by Bacillus and Clostridium?
Endospores
What are the characteristics of endospores?
- Most resistant forms of life
- Can withstand extreme conditions
- Remain viable in a metabolically inactive state for years
What is Gruinard Island known for?
Testing anthrax as a biological weapon
What was the outcome of the Amerithrax investigation?
Investigation into anthrax letter attacks post-9/11
What is the importance of identifying Bacillus anthracis strains in investigations?
Essential for identifying and eliminating criminal suspects
What is the significance of identifying the exact strain of Bacillus anthracis?
It is essential in the investigation of rax letter attacks.
This demonstrates the importance of accurate microbial identification in forensic science.
How has forensic science evolved in relation to DNA evidence?
It has increasingly depended on DNA evidence for the identification and elimination of criminal suspects.
This trend has influenced microbial forensics as well.
What role does DNA fingerprinting play in microbial forensics?
It is fundamental to the identification of specific micro-organisms used in biocrimes.
Microbial forensics has adapted DNA techniques from general forensic science.
What are bacterial endospores?
They are structures that differ physically and chemically from vegetative cells.
Endospores have a much lower water content and contain calcium dipicolinate.
How do endospores differ from vegetative cells in terms of water content?
Endospores have 15% water compared to 70% water in vegetative cells.
This difference contributes to their resilience.
What compound is found in large amounts in bacterial endospores?
Calcium dipicolinate.
This compound is less abundant in vegetative cells.
What are bacterial cysts?
Modified vegetative cells that develop a thick, resistant cell wall.
An example is the rod-shaped vegetative cell in Azotobacter.
What are the characteristics of Azotobacter cysts?
They are resistant to desiccation, mechanical disintegration, and UV & ionising radiation.
However, they are not especially heat resistant.
True or False: Bacterial cysts are especially heat resistant.
False.
Unlike endospores, cysts do not exhibit significant heat resistance.
Fill in the blank: Endospores contain a much lower water content, approximately _______.
15%.
Fill in the blank: Vegetative cells contain small quantities of calcium dipicolinate as an intermediate in the synthesis of _______.
lysine.
