Disease Flashcards
What is a disease
Disorder with a specific cause and recognisable signs and symptoms
Define Pathogen
A cellular or non-cellular agent of disease
What is an infection
Invasion and growth of a pathogen within the body of a host
Vector
An animal, usually an insect, that transmits pathogens from host to host
What is an antigen
Compounds which trigger an immune response, including the production of antibodies
Non-self antigens
Any foreign molecule or particle which acts as an antigen in the organism concerned
Self antigens
Any molecule or particle that originates from within the body
Allergens
A type of antigen that produces an abnormally vigorous immune response in which the immune system fights off a perceived threat that would otherwise by harmless to the body- reactions are allergies
Cellular pathogens
Bacteria, Protists, Fungi, Worms and Arthropods
Non-cellular pathogens
Viruses, viroids, prions
What are prions
Misfolded pieces of protein in the brain cells- lethal and can’t be destroyed
What do prions result in?
Cellular malfunction and brain degeneration
How do Prions infect cells
Come in contact with normal form of protein in a mammal’s brain cell, prions induce normal protein to form abnormal shape, resulting chain reaction continues until prions accumulate to dangerous levels, cellular malfunction and brain degeneration
Similarities and differences in the two types of prions
Primary structures (amino acids) are identical, but the secondary structure is different so the brain can’t identify it as non-self
What are viruses made of?
Consist of a protein coat (capsid) surrounding a nucleic acid (DNA Or RNA), all forms are pathogenic (pathogens)
Viruses
Only attack certain cells in your body as the cell thinks its ingesting something it wants but is really a virus
Enveloped and non-enveloped viruses
Enveloped contains an outer envelope that surrounds the capsid making it harder to be detected by cells. Non- enveloped may stand out to cell.
Life cycle of virus
Attachment, Penetration, Uncoating, replication, assembly, release
Attachment stage
Specific binding site between viral capsid proteins and specific receptors on the host cellular surface
Penetration stage
Virus enters host cell through receptor-mediated endocytosis. Some viruses instead inject their genome into the bacterial cell across cell wall while the viral capsid remains outside
Uncoating stage
Process in which the viral capsid is removed by viral enzymes or host enzymes which results in releasing their viral genomic nucleic acid.
Replication stage
Multiplication of the genome.
Assembly stage
Following the self-assembly of the virus particles, some modification of the proteins often occurs
Release stage
Viruses can be released from the host cell by lysis, a process that kills the cell by bursting its membrane and cell wall if present.
What are retroviruses
Family of RNA Viruses which transcibe their own DNA in host cell before reprogramming host cell to make viruses
Types of virus disease
Influenza, AIDS, common cold, chickenpox, smallpox
What is an epidemic
Rapid spread of infectious disease to a large number of people in a given population (small region) within a short period of time, usually two weeks or less
What is a pandemic
Epidemic of an infectious disease that had spread through human populations across a large region (across continents)
Viroids
Short circular pieces of naked DNA
What do viroids infect
Only found to infect plants. Transmission is via insect vectors and physical contact
Prokaryotic cells
Bacteria
Bacterial features
No membrane bound organelles, singular circular chromosome, possess ribosomes, smaller- Most bacteria don’t cause disease
Bacterial toxins
Some bacteria produce toxins, while these toxins are recognised as foreign by the human immune system, it is typically only after they have damaged particularly tissue and cause disease
Types of toxins
Exotoxins- secreted toxins (most common)
Endotoxins- Parts of the outer membrane that are released when bacteria die
Treatment for bacterial infection
An antibiotic is a substance used in the treatment and prevention of bacterial infections that act by either killing pathogenic bacteria or by inhibiting their growth
Types of antibiotic
Broad-spectrum- kill against a range of bacteria
Narrow-spectrum- Target a particular group of bacteria according to their cell wall structure
How to not become antibiotic resistance
Need to take full bottle of antibiotic to kill resistant bacteria (resistance ones may reproduce and be harder to kill)
How do they become resistant
Share plasmids with bacteria to become resistant to antibiotics- The plasmids move from one cell to the other, taking the antibiotic resistance gene with them
Zone of Inhibition
Zone in which the bacterial growth has been inhibited on agar plate
Other treatments for bacterial infections
Antiseptics (on body)- Chemicals that destroy or inhibit growth of pathogens on the body (typically alcohol-based)
Disinfectants (on objects)- Chemicals used to destroy or inhibit growth of pathogens on surgical instruments and other objects
Bacterial diseases
Tetanus, Salmonella, Cholera, Syphilis
Protists
Unicellular eukaryotic organisms which absorb nutrients from their hosts
