Microbiology Flashcards
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
What are the two common modes of action for disinfectants?
- Damage to lipids and/or proteins of the cytoplasmic membrane
- Denature microbial enzymes and proteins
How long can influenza viruses survive on hard non-porous surfaces?
Approx. 24-48 hours
How long can Covid-19 survive on stainless steel and plastic?
3-7 days
What is the structure of prokaryotic bacteria?
- Cell membrane surrounded by a cell wall
- Cytoplasm contains ribosomes, plasmids, and inclusion bodies
- Unorganized nucleus (nuclear region)
What are the environmental survival characteristics of fungi?
- Moulds are aerobic
- Yeasts are facultative anaerobes
- Can survive in a variety of environments
What is the survival time for fungal spores in ideal environments?
Up to three months
What are the survival characteristics of protozoa?
- Can live on dead organic matter or living hosts
- Can remain dormant as cysts
- Can survive extreme environments
What is the survival time of Cryptosporidium cysts in water?
Months
What is immunity?
Immunity to a disease is achieved through the presence of antibodies to that disease in a person’s system.
What are antibodies?
Proteins produced by the body to neutralise or destroy toxins or disease-carrying organisms.
Are antibodies disease-specific?
Yes, antibodies are disease specific.
What are the two types of immunity?
- Active immunity
- Passive immunity
What triggers active immunity?
Exposure to a disease organism triggers the immune system to produce antibodies.
How can active immunity be acquired?
- Natural immunity
- Vaccine-induced immunity
What is natural immunity?
Acquired from exposure to the disease organism through infection with the actual disease.
What is vaccine-induced immunity?
Acquired through the introduction of a killed or weakened form of the disease organism through vaccination.
What is passive immunity?
Provided when a person is given antibodies to a disease rather than producing them through their own immune system.
How does a newborn baby acquire passive immunity?
From the mother through the placenta and during breastfeeding.
What is an example of artificially acquired passive immunity?
Receiving antibody-containing blood products such as immune globulin.
What are innate defenses?
Nonspecific defenses that are always ready to protect the body.
What is the first line of defense against pathogens?
The skin and mucous membranes.
What is the second line of defense in the immune system?
Non-specific, innate immune responses that involve immune cells and proteins.
What are examples of second line defenses?
- Inflammation
- Natural killer cells
- Phagocytes
- Antimicrobial proteins
- Fever
What characterizes the third line of defense?
Acquired, specific, adaptive responses that eliminate previously encountered pathogens.
What are the two types of white blood cells involved in adaptive immunity?
- B lymphocytes
- T lymphocytes
What is humoral immunity?
Involves B-lymphocytes producing and secreting antibodies that circulate in body fluids.
What is the role of lymphatic vessels?
To pick up lymph and return it to the venous system.
What is lymph?
Transparent, colorless, watery liquid derived from interstitial fluid.
What do lymph nodes do?
Help protect the body by removing foreign material and producing lymphocytes.
What are the primary lymph organs?
- Bone marrow
- Thymus
What is the function of the spleen?
Cleans the blood of bacteria and viruses, manufactures antibodies, and serves as a blood reservoir.
What is lymphedema?
Condition where the lymph system is unable to circulate normally, causing fluid accumulation and swelling.
What is lymphoma?
Tumors of the tissues and cells of the lymphatic system.
What is Systemic Inflammatory Response Syndrome (SIRS)?
Clinical response to non-specific insult characterized by symptoms like abnormal body temperature and increased heart rate.
True or False: Passive immunity provides immediate protection but lasts only for a few weeks or months.
True
Fill in the blank: The primary function of B cell differentiation is to produce _______.
plasma cells that secrete antibodies
What are the two pressures crucial for fluid flow from blood capillaries to extracellular fluid?
- Capillary hydrostatic pressure
- Capillary oncotic pressure
