Microbiology Flashcards
(61 cards)
What is a prion?
A type of protein that triggers normal proteins to fold abnormally
Which diseases are most commonly associated with prions?
Creutzfeld-Jakob disease (CJD), variant CJD (Mad cow disease)
What are the characteristics of Eukaryotes?
- Uni or multicellular
- Slow growth
- Larger
- Nucleus
- Nucleoli
- Histone associated DNA
- Membrane bound organelles
- Cell membrane
What are the characteristics of Prokaryotes?
- Uni-cellular
- Rapid growth
- Smaller
- Nuclear region
- No nucleolus
- No DNA associated proteins
- No membrane bound organelles
- Cell wall containing muramic acid
- Cell membrane
How can bacteria be distinguished by their reaction to dye?
If bacteria stain red, they are gram-negative; if they stain blue/violet, they are gram-positive
What is the cell wall composition of gram-positive bacteria?
Thick layer of peptidoglycan
What is the cell wall composition of gram-negative bacteria?
Thin layer of peptidoglycan with an outer layer containing lipopolysaccharide (LPS)
What role do endotoxins play in gram-negative bacteria?
- Vital for survival
- Contribute to structural integrity
- Protect from chemical attacks
- Can cause toxic effects leading to multiple organ failure, septic shock, or sepsis
What are exotoxins?
Toxins that can cause damage to the host by destroying cells or disrupting cellular metabolism
List the types of endotoxins.
- Enterotoxins - GI tract
- Neurotoxins - cause paralysis
- Pyrogenic - release cytokines
- Tissue invasive - skin IgA
What are examples of exotoxins?
- Tetanus
- Botulism
- Diphtheria
- Staphylococcus aureus
What shapes can bacteria have?
- Coccus or Cocci - round
- Spirillum or Spirilla - spiral
- Bacillus or Bacilli - rod or cylindrical
What is an example of a gram-negative bacteria?
E. Coli
What is an example of a gram-positive bacteria?
Staphylococcus Aureus
What is cellulitis?
A common bacterial infection of the dermal layer caused by Streptococcus Pyogenes or Staphylococcus Aureus
What are the characteristics of protozoa?
- Single cell
- Mostly reside in soil and water
- Two-stage life span - mobile, cystic
- Some are parasitic (e.g., Giardia lamblia)
What are the characteristics of fungi?
- Can be multicellular
- Can be beneficial (e.g., bread, alcohol, cheese, penicillin)
- Generally cause local infections but can lead to systemic infections
What are common pathogenic fungi?
- Athlete’s foot (Tinea pedis)
- Thrush (Candida albicans)
What is the structure of viruses?
- Consist of DNA or RNA core
- Surrounded by a protein coat called a capsid
- Some have an additional envelope
What is the lytic cycle of a virus?
- Attachment to the cell
- Injection of DNA or RNA
- Synthesis of viral DNA or proteins
- Assembly of virus replicas
- Rupture of cell membrane leading to cell death
What is the lysogenic cycle of a virus?
- Attachment to the cell
- Injection of DNA or RNA
- Integration of viral DNA into host cell
- Cell replication continues with viral DNA until cellular distress occurs
What is a bacteriophage?
A non-living vessel that contains either DNA or RNA and can attach to bacterial membrane receptor sites
What is a retrovirus?
A virus that must produce DNA from RNA, such as HIV
What factors influence the antimicrobial action of disinfectants?
- Concentration of the chemical agent
- Temperature of use
- Kinds of microorganisms present
- Nature of the material bearing the microorganisms