week 3: Infectious Diseases, Viruses Flashcards
what are the two major types of infectious diseases?
Bacteria and Viruses
what are the seven routes of transmission?
- direct contact - touching, kissing, sexual relations
- Indirect contact - touching an object that an infected person has been touching.
- airborne contact - breathing in air that carries a pathogen.
- Food-borne infection - eating something that is contaminated by microorganisms.
- Animal borne pathogens - animals spreading through bites, feces
- water borne diseases - coming into contact with contaminated water
- perinatally - mothers can pass a disease to the child
what are 4 UNCONTROLABLE risk factors when it comes to infectious diseases?
Heredity
Aging
Environmental Conditions
Organism Resistance
what are 7 CONTROLABLE risk factors when it comes to infectious diseases?
stress
nutrition
physical fitness level
sleep
drug use
hygiene
high-risk behavior
describe endemic
the constant presence of a disease in a given geographic area
what is a hyperendemic
the disease is highly prevalent and effect all age groups equally.
describe holoendemic
a high level of infection beginning early in life and affecting mostly children.
is bacteria eukaryotic or prokaryotic
bacteria is a prokaryotic organism, lacing a nucleus.
an important feature of bacteria is the cell wall. what does the cell wall contain
peptidoglycan
gram stain is used to classify bacteria cell wall composition. what it:
gram-positive
gram-negative
gram-positive bacteria have simpler walls and contain a large amount of peptidoglycan
gram-negative bacteria have less peptidoglycan and an outer membrane that can be toxic
give an example of a bacterial disease
tuberculosis
cholera
salmonella
plague
what are the two ways a bacteria will produce a disease in humans
- it will break down cells for food
- release toxins that interfere with normal activity
describe exotoxins
(3 points)
- soluble in body fluids
- mainly produced by gram-positive bacteria
- plasmids or phages carry most of the genes for toxins
name two types of exotoxins
neurotoxin - targets nervous system
enterotoxin - targets cells lining gastrointestinal tract
describe cholera
cause and symptoms
caused by the gram-negative bacteria VIBRIO CHOLERA enterotoxin
intestinal infection
symptoms of severe diarrhoea
what is a staphylococcal infection?
bacteria that are usually always on our skin but cause an infection if it enters a cut or break in the skin
give two examples of staphylococcal infections
scarlet fever
strep throat
pneumonia
what bacterial organism causes tuberculosis and what are the symptoms?
mycobacterium tuberculosis
symptoms include fever, chills, fatigue and malaise, weight loss, and persistent cough
describe endotoxins
part of outer membrane surrounding gram-negative bacteria. the effect is exerted when the bacteria dies and the cell walls undergo lysis and release the toxin.
what are the symptoms of an endotoxins
chills, fever, weakness, general aches, blood clotting, tissue death, shock and death.
what measures have been used to reduce the incidence of bacterial infections
improvements in public health
-better water supply
-sanitation
-food quality
vaccinations
treatments using antibiotics and anti-viral drugs
what is a virus?
viruses are submicroscopic infectious agents that replicate only inside the living cells of other organisms
what is composed of theses two principle parts:
the genome that is made of nucleic acid and a protective shell that is made of protein (capsid)
virus
what are 3 structural characteristics of a virus
- 10 to 300 nm in diameter
- nucleic acid genome (DNA or RNA) surrounded by a protein coat called a capsid
- many animal viruses are surrounded by a membranous envelope.
what are 4 things a viral genome might encode for
- Replicases
- Coat proteins
- Movement proteins
- Attachment proteins
what is capsid made of
protein subunits called capsomeres
what is a viral envelope?
derived from membranes of host cells. Viral glycoproteins on the envelope bind to specific receptor molecules on the surface of a host cell.
how does a virus recognize a cell it can infect
it matches its surface marker with a receptor site on a cell
what is a bacteriophage or phages
bacteriophages are viruses that infect bacteria
how does a phage infect a host cell
a protein tail piece attaches the phage to the host cell and injects the phage DNA inside.
what are the two reproductive mechanisms used by phages
lytic cycle and the lysogenic cycle.
describe the lytic reproductive cycle used by phages (4 points)
cycle results in death of the host cell. produces more phages and breaks open the cell wall, releasing the progeny viruses. a virulent phage is one that only uses the lytic cycle. bacteria defend using restriction enzymes that cut up the phage.
describe the lysogenic reproductive cycle used by phages (4 points)
replicates the phage genome without destroying the host cell. the viral DNA is incorporated into the host cell’s chromosomes. the integrated viral DNA is knows as a prophage. the phage DNA is copied and passed on to all the daughter cells when the cell divides.
explain norovirus (3 points)
- a diverse group of viruses in the group caliciviridae.
- causes inflammation of the stomach and intestines causing diarrhoea and vomiting.
- it only takes a small amount to particles to infect someone.
describe coronavirus
- family of enveloped positive-sense single-stranded RNA viruses
- one of the largest RNA
- acts like mRNA and can be transcribed by the hosts ribosomes. this is due to the 5’ and 3’ ends.
which virus attacks the cells in the body designed to protect us from infection (immune system cells)
HIV
what cells specifically does HIV infect
infects white blood cells carrying the CD4 cell surface protein.
what is the effect of genetic variation
give rise to new strains which increases virulence
renders vaccines ineffective
name 2 processes of genetic variation
- mutation
- Recombination - viruses exchange segments of the genome.
what is a prion?
are slow-acting, virtually indestructible infectious proteins that cause brain diseases in mammals.
