BIOL intro to mircobiology Flashcards
what is a virus?
a virus is an nucleic acid (RNA or DNA) surrounded by a coat of protein; it cannot reproduce or carry out metabolic activities outside of a host cell
how do viruses pick their target?
by specific receptors that are present of the surface of the target cell; ex. CD4 receptors
host range
the number of species that a virus can infect; usually not many but can be
what do viruses bind to host cell by?
viral glycoproteins that attach to CD4 receptors
5 steps in viral replication cycle
attachment, entry, synthesis, assembly, and release
virus attatchment
the virus attaches to a protein on the surface of the host cell
virus entry
after attachment, the virus can enter the host cell (either the virus of only the genetic information)
virus synthesis
entry of the viral nucleic acid can begin synthesis which causes copies of the viral information and proteins to be made by the host
virus assembly
the viral DNA and proteins are packed together to create a new virus (called self-assembly of new virus particles)
virus release
the virus exits the cell
what occurs once the viral nucleic acid is inside the cell?
transcription and translation and DNA synthesis
forms of viral nucleic acid
can be RNA, DNA, and either single or double stranded
what is the result of transcription and translation?
capsomeres or other proteins
what is the result of DNA synthesis?
more copies of the DNA
what is the result of transcription and translation along with DNA synthesis?
causes new viruses to assemble
nucleic acid of HIV
two single strands of RNA
capsid
a protein shell surrounding the virus; present in HIV virus and is coffin shaped
envelope
additional protein coating that occurs when a virus has taken some of the host cell’s plasma membrane, using it for further protection
protease
enzyme in HIV virus that helps digest proteins
intergrase
enzyme found in HIV virus that helps to insert the viral genome into host cells
proteins found inside HIV virus?
gp120 and gp41
gp120
glycoprotein in HIV virus that is involved in the attachment of the virus to CD4 receptors to bind to helper T cells
gp41
glycoprotein in HIV virus that is required for entry into the cell
reverse transcriptase
an enzyme in HIV virus that takes the single strand RNA and converts it to double-stranded DNA
how does attatchment occur for HIV virus?
via gp120 and gp41 proteins to CD4 receptors on helper T cells
how does HIV virus enter the host cell?
when the viral envelope and the host plasma membrane fuse together, allowing for entry and for the capsid to release RNA into the host cell
what happens when the HIV virus enters the host cell?
reverse transcriptase enzyme is activated and this converts ssRNA into dsDNA,; integrase then deposits this into the host cell chromosomes
what releases RNA in the HIV virus?
the capsid
how does synthesis occur for the HIV virus?
host DNA is made to RNA, then transcription creates new viral proteins (integrase, protease, etc.); DNA synthesis also occurs, making more genome RNA
how does assembly occur for HIV virus?
copies of the viral genome (RNA) are packaged with proteins in a vesicle
how do the nucleic acid materials exit in the HIV virus?
via getting packaged into a vesicle and sent outside the cell; within the vesicle the proteins develop into functional components, specifically protease
what makes up the vesicle in the HIV virus?
RNA and mRNA
transcription
produces proteins
translation
produces mRNA (or tRNa, rRNA, or non-coding RNA)
why is AIDs recovery not possible?
because the helper T cells are being destroyed
primary infection or first phase of HIV
flu like symptoms including fever, fatigue, weight loss, diarrhea, aches, and headaches; during this phase HIV and antibody concentration is increasing in the blood, but helper T cell population is declining
second stage of HIV
immune system starts to kick in, so there is an increase in antibodies and a slight decrease in viral cells; this stage can occur for years
third stage of HIV
HIV virus is increasing in the blood while T cells and antibody levels are decreasing
fourth stage of HIV
AIDS is present; the beginning of the decline and T cells and antibody levels are declining rapidly
fifth stage of HIV
AIDS is present, virus continues to increase and there is no immune response; due to this opportunistic infections will persist eventually causing death
AIDS definition (4 criteria)
the presence of several opportunistic infections; the presence of interferon induced by HIV virus; severely low numbers of helper T cells and CD4 cells; and a positive test for HIV virus
what is the extended stage of HIV called?
clinical latency
how does penicillin act?
it destroys the cell wall, allowing the bacteria to become susceptible to osmosis drives, causing the cell to shrivel or burst
what drugs inhibit cell protein synthesis?
aminoglycerdies, tetracyclines or macrolides
common mechanisms of antimicrobial action (6)
inhibition of cell wall synthesis, inhibition of protein synthesis, disruption of cytoplasmic membrane, inhibition of general metabolic pathway, inhibition of DNA or RNA synthesis, and inhibition of pathogen attachment to the host cell
what drug disrupts cytoplasmic membrane?
polymyxins or polyenes
what drugs inhibit the general metabolic pathway?
sulfonamides, trimethoprim, or dapsone
what drugs inhibit DNA or RNA synthesis?
actinomycin or nucleotide analogs
what drugs inhibit the pathogen to attach to the host cell?
arildone or pleconaril
what mechanisms of antimicrobial action can be dangerous to humans
inhibition of protein synthesis, inhibition of RNA/DNA synthesis, inhibition of general metabolic pathway, and disruption of cell membrane; this is because humans share all these characteristics with microorganisms
spectrum of action
the range of organisms a particular antimicrobial drug can affect; can be narrow-spectrum drugs or broad spectrum drugs
narrow spectrum drugs
will only affect a small or single amount of species
example of narrow spectrum drugs
penicillin or polymyxin
what type of bacteria does penicillin target?
gram-positive
what type of bacteria does polymyxin target?
gram-negative
super infectious
reinfection or second infection caused by a microorganism when it is resistant to treatment
broad-spectrum drugs
can affect a wide range of species, however can be dangerous as they can harm the natural flora and make you vulnerable to opportunistic infections
example of broad spectrum drugs
sulfonamides or erythromycin
antibiotic resistance
occurs when some bacteria mutate during replication, making them resistant to the drug; the result of this is that the non-mutated bacteria will die but the mutated ones will not and replicate, making them harder to fight in the future
where are antibiotic resistance bacteria often found?
in hospitals
3 levels of defence
intrinsic, innate, and acquired
intrinsic defence
natural barriers of the body like the skin and the mucous membranes
innate immunity
general immune response that will attack all infectious agents through mechanisms like macrophages, cytokines, and the complement cascade
acquired response
aka adaptive response; specific response that will use T and B cells, or memory cells as an immune response
what produce the innate response?
cytokines
what triggers the adaptive response?
the innate response; cytokines, natural killer cells, and dendritic cells
macrophages
wandering cells that digest foreign materials via phagocytosis and bring them back to the immune system
what attracts the macrophage to the site of infection
chemotaxis
phagosome
a vesicle creating by macrophages that stores the infectious agent
how does the macrophage engulf the material?
phagocytosis
phagolysosome
occurs when a phagosome and a lysosome fuse, in which digestive enzymes will digest the foreign material to destroy the pathogen
what does a phagolysosome do after digesting material?
with fuse with the cell membrane and release its contents by exocytosis
residual body
the remaining vesicle of debris of the pathogen after phagocytosis
how does the pathogen leave the cell after phagocytosis
the residual body will fuse will the plasma membrane and spill out the debris into the interstitial fluid
chemotaxis
the movement of the phagocyte toward the pathogen due to the secretions of complement proteins, normal microbial components, damaged tissues, and defensins
interferons
unaffected neighbouring cells will produce these to cause antiviral cells to be attracted to the site
how was interferon discovered?
in 1957 by chicken cells
two major interferon molecules
interferon alpha and interferon beta (gamma also exists but no need to know this)
how are interferons produced?
affected cells by viruses release viral nucleic acids and interferons and these interferons will bind to receptors on neighbouring unaffected cells, causing them to transcript and translate inactive antiviral proteins, and these degrade mRNA and bind to ribosomes, stopping viral replication
what are interferons produced by?
the host cell when it is invaded by a virus
how are interferons released from the host cell?
exocytosis
what activates antiviral proteins during interferon process?
double stranded RNA of the viral material
what do interferons cause?
flulike symptoms that make us sick
what is the primary purpose of interferons?
to save neighbouring cells from the virus
what response are interferons involved in?
innate response
what microbe are interferons involved with?
viruses
3 types of complement activating pathways
classic pathway, alternative pathway, and lectin pathway
classic activating complement pathway
when antigens bind to antibodies
alternative complement pathway
pathogens produce endotoxins and glycoproteins
lectin complement pathway
microbial polysaccharides bind to activating molecules; lectin is a molecule found in microorganisms
what is the result of the complement cascade?
the membrane attack complex and lysis of cells
functions of complement cascade (5)
cytolysis, activation of inflammation, production of cytokines, opsonization, and solubilization of immune complexes
cytolysis
bursting of bacteria cells
opsonization
causes pathogens to clump together, making it easier for immune cells to find them
cytokines
signalling molecules of the immune system
solubilization
breaks up antigen-antibody complexes that can damage organs
how can a microbiota become an opportunistic pathogen?
by being introduced into an unusual site in the body or to changes in populations; ex. E coli are mutualistic in the colon but can cause diseases in other areas of the body
what do E coli produce?
vitamin K
what bacteria often replace E coli in the gut, causing infection
C. Diff; this is commonly caught in hospitals
how do yeast infections develop?
when fungi move into the vagina following the destroying of bacteria from antibiotics
what are yeast infections treated with?
erythromycin
what type of microbe is often treated with narrow-spectrum drug?
viruses; ex. acyclovir
contamination
the presence of microbes in or on the body
infection
successful invasion of the body following contamination; requires a microbe to successful reproduce in the host body and for the host to initiate an immune response
3 major portals of entry in the body
skin, mucous membranes, and placental (parenteral sometime considered a fourth; bite or contaminated needle)
other portals of entry into the body
the ear, conjunctiva, nose, mouth, penis, vagina, urethra, and anus
why is the skin an inhospitable enviornment?
because sebum is produced by sebaceous glands increasing pliability, sweat kills bacteria by osmosis, and the shedding of skin also sheds microorganisms
openings in the skin that microbes may enter in
sweat glands, sebaceous glands, or cuts
mucous membranes
most common portals of entry and include the respiratory tract, the GI tract (intestines), and the conjunctiva; are epithelial cells that secrete a mucous fluid
pathogenicity
the ability of a microorganism to cause disease; is yes or no
virulence
the degree of pathogenicity to infect a host and cause disease; it determined by virulence factors
virulence factors (5)
traits of the pathogen that interact with the host and determine how it enters the host, adhere to host cells, gains access to nutrients from host, escapes the host’s immune system, and prevents removal from host by immune system
why is virulence not a measure of the severity of the disease
to infect a host does not always cause severity of the disease; ex. rabbit fever is very virulent but not severe
three types of virulence factors
enzymes, toxins, and antiphagocytic factors
two examples of enzyme complexes
hyaluronidase and collagenase, and coagulase and kinase
enzymes and pathogens
enzymes are secreted proteins that help the pathogen to dissolve chemicals of structures in the body; ex. hyaluronidase and collagenase
coagulase and kinase
coagulase causes blood proteins to clot, providing a hiding place for bacteria within the clot; when the immune system stops looking for it, kinase will then digest the clot, allowing it to circulate in the bloodstream
toxemia
when toxins enter bloodstream and affect many sites in the body
enzyme and toxin relationship
enzymes can be toxins
toxins
chemicals that harm tissues or trigger host immune responses and cause damage
2 types of toxins
exotoxins and endotoxins
exotoxins
produced by living bacteria and destroy host cells or interfere with host cell metabolism; are more common is gram-positive bacteria
example of a exotonin
cytotoxin
cell wall of gram-negative bacteria
rich in lipopolysaccharide, particularly lipid A
why are antibiotics bad for gram-negative bacteria?
can cause endotoxins to be released when the bacteria dies
antiphagocytic factors
block phagocytosis through 2 ways: incomplete phagocytosis or blocked by the capsule
incomplete phagocytosis
the pathogen can survive and live inside the phagocyte, causing it to reproduce within the cell and be protected by the immune system, it can also release lipid A, causing toxemia
mother stem cell for all blood cells
pluripotent stem cell
what two cells arise from pluripotent stem cells?
myeloid stem cells and lymphoid stem cells
what do myeloid stem cells develop into?
RBCs, platelets, mast cells, granulocytes, and monocytes
what do lymphoid stem cells develop into?
T lymphocytes, B lymphocytes, or natural killer cells
granulocytes
neutrophils, eosinophils, and basophils
neutrophils
most abundant WBC; are granular and multilobed; function for phagocytosis and chemical destruction of microbes
eosinophils
granular and biloped cells; function to combat the effects of histamine in allergic reactions like antihistamines; also destroy parasitic worms and phagocytosis antigen-antibody complexes
basophils
function to release inflammatory chemicals like histamine
rubor
inflammatory property referring to redness
calor
inflammatory property referring to heat
tumor
inflammatory property referring to swelling
dolar
inflammatory property referring to loss of function or pain
agranulocytes
monocytes and lymphocytes
monocytes
agranular and have a horseshoe shaped nucleus; migrate from the bloodstream to be phagocytes
lymphocytes
agranular and second most abundant WBC; round nucleus with a little indent; consists of T and B cells which are active in the adaptive immune response
anatomy of lymphoid tissue
reticular fibres which are a loose CT; these create a filter for microbes and damaged cells passing through the lymphatic system
how is lymph created?
it is filtered from the interstitial fluid to return proteins to the bloodstream
3 functions of the lymphatic system
drains excess interstitial fluid, transports dietary lipids and lipid soluble vitamins (A, D, E, and K), and carries out the immune response
how are dietary lipids absorbed into the lymphatic system?
they are wrapped in a micelle in the small intestine, diffuse into the blood by then being wrapped in a chylomicron, and then are absorbed into a lacteal through a villus
anatomy of lymphatic vessels
are similar to venules but have thinner walls and more valves
lymph nodes
bean shaped organs with masses of B and T cells
lymphatic vessels in the skin
lie in the subcutaneous tissue and follow the same route as veins
lymphatic vessels of the viscera
follow the arteries, forming plexuses around them
what tissues lack lymphatic vessels?
avascular tissues like cartilage or epidermis, the CNS, some of the spleen, and the red bone marrow
what do lymphatic vessels start as?
lymphatic capillaries
lymphatic capillaries compared to blood capillaries
lymphatic capillaries are more permeable, can absorb large molecules like proteins and lipids, are larger in diameter, and have a one way flow structure
permeability of lymphatic capillaries
when pressure is greater it the ISF, the overlapping endothelial cells will separate slightly, allowing for fluid to enter
anchoring filaments
part of lymphatic system and are filaments of elastic fibres; when there is excess ISF, the anchoring filaments are pulled on by the surrounding tissues, making the opening between the endothelial cells larger
how are lymphatic vessels unidirectional?
the endothelial cells will not move apart when the pressure is greater in the lymphatic vessels relative to the ISF
how are minivalves formed in lymphatic vessels?
the adjacent endothelial cells overlap loosely enough that they create mini valves
lacteals
specialized lymphatic capillaries found in the small intestine which carry dietary lipids
chyle
lymph contains lipids from the small intestine
flow of lymph
lymphatic capillaries > collecting vessels > trunks > ducts
where does the lumbar trunk drain lymph from?
the lower limbs, the walls and viscera of the pelvis, the kidneys, the adrenal glands, and the abdominal wall
where does the bronchomediastinal trunk drain lymph from?
the thoracic wall, the lungs, and the heart
where do the subclavian trunks drain lymph from?
the upper limbs
where do the jugular trunks drain lymph from?
the head and the neck
where does the intestinal trunk drain lymph from?
the stomach, intestines, pancreas, spleen, and some of the liver
2 main channels for lymph
the thoracic duct and the right lymphatic duct
cisterna chyli
where the thoracic duct begins; anterior the the second lumbar vertebrae
where does the cisternal chyli receive lymph from?
R and L lumbar trunks and the intestinal trunk
where does the thoracic duct receive lymph from?
the left jugular vein, left subclavian vein, and left bronchomediastinal trunk, as well as the cisterna chlyi (which receives from lumbar and intestinal trunks)
what does the thoracic duct drain into?
the junction between the left internal jugular vein and the left subclavian vein
where does the right lymphatic duct drain into?
the junction between the right internal jugular vein and the right subclavian vein
skeletal muscle pump for lymph
the contraction of skeletal muscles compresses the lymph vessels to force the lymph up towards the subclavian/jugular intersect
respiratory pump
decreases in pressure in the thoracic cavity due to breathing causes lymph to move up from the abdominal region into the thoracic region
what cell does HIV target
helper T cells
how does protein synthesis occur?
nucleic acid is transcribed into mRNA to make proteins such as capsids
tRNA
found in HIV virus capsid which helps with translation of RNA sequence
criteria for infection
for the microbe to successfully reproduce in the host body and for the host to initiate an immune response
endotoxin
associated with gram-negative bacteria and when they die, they release stored products from their cell wall (lipid A), causing toxic effects in hosts
toxic effects of endotoxins
shock, fever, inflammation, diarrhea, and abnormal blood clotting)
3 reasons why antibiotics can be harmful
they have cause bacteria to release endotoxins, they can disrupt the normal flora, and they can create antibiotic resistance
hyaluronidase and collagenase
hyaluronidase dissolves hyaluronic acid to digest tight junctions between cells, then collagenase digests the collagen in the basement membrane to reach underlying CT’s or bloodstream
what is key to the process of viruses picking their targets
viral glycoproteins
what must occur for the viral genome once it enters the host cell?
it must become uncoated and separated from the protein
self-assembly of new virus
the viral DNA and proteins are assembled together to create a new virus
how does the host machinery copy viral DNA?
via ex. DNA polymerase III or ligases
what does the host machinery transform viral DNA into?
capsomeres
what HIV component becomes active only after release from the host cell?
protease
what happens to gp 41 and gp 120 proteins after the virus enters the host?
they remain part of the cell wall
function of ribosomes in HIV virus replication
they translate mRNA into viral polypeptides
what is the host DNA broken up into for the HIV virus?
genome RNA and mRNA
pseudopod
arm-like extensions that are made of cytoplasm; found in macrophages and these are used for phagocytosis
what do active antiviral proteins bind to?
ribosomes
5 major lymph nodes
submaxillary group, cervical group, axillary group, subtrochlear group, and inguinal group
submaxillary lymph node group
found in the floor of the mouth
cervical lymph node group
near the sternocleidomastoid muscle
axillary lymph node group
underarm and upper chest
supratrochlear lymph node group
above the bend in the elbow
inguinal lymph node group
found in the groin
anatomy of neutrophils
granular, are multilobed (2-5), cytoplasm is light purple, and nucleus is dark purple
anatomy of eosinophils
granular, are biloped, nucleus is dark purple, and cytoplasm is stained red/orange
anatomy of basophils
are granular, cytoplasm is dark blue/purple, and nucleus is dark purple (bilobed); hard to see because it is very granular
anatomy of lymphocytes
are agranular, have a large nucleus with a small indent, and are dark purple (but not as dark as basophils), and cytoplasm is sky blue but hard to see
anatomy of monocytes
are agranular and have a kidney shaped nucleus (dark purple); cytoplasm is grey-blue and looks foamy
anatomy of platelets
much smaller than cells and have no nucleus
