quiz 2 - final lectures 10,11,12,13 Flashcards
describe a virus
non living
not able of reproducing without host cell
small 20-200nm
genetic info like DNA or RNA contained in capsid (sometimes surrounded by additional membranous envelope)
Class IV, V and VI animal viruses
how many classes of viruses are there
6
describe class I
adenovirus & HPV
ds DNA
special enzymes/proteins
describe class II
parvovirus
ssDNA
special enzymes/proteins
describe class III
reovirus
ds DNA
special enzymes/proteins
describe class IV
coronavirus
rhinovirus
ssRNA, positive strand
RNA is mRNA
special enzymes/proteins
describe class V
influenza
ebola
ssRNA negative (antisense) strand
RNA is template for mRNA
special enzymes/proteins
describe class VI
HIV
ssRNA, retro
RNA is template for dsDNA
reverse transcriptase - special enzymes/proteins
what do all 3 classes of ssRNA viruses have
special enzymes/proteins (glycoproteins in envelope)
definition of contagion
highly contagious airborne virus
more likely to result in epidemic
definition of incubation time
time it takes to produce symptoms of disease
longer incubation time = more spread
definition of virulence of virus
ability to cause disease and kill
rapid killing lowers spread
describe structure of class IV, V & VI (diagram)
single stranded mRNA
capsid proteins
membrane envelope - phospholipid bilayer
spike proteins - membrane/surface glycoproteins
describe HPV (class I) steps of replication (5 steps)
1- entry and uncoating/disassembly
2 - replication
3 - transcription and manufacture of capsid proteins
4 - self assembly of new virus particles and exit from cell
5 - host cell death ->disease
viral gene transcription and translation are… (HPV)
dependent on host enzymes
RNA polymerase
host ribosomes
viral DNA replication is … (HPV)
also generally dependent on
host enzymes
DNA polymerase
describe steps of class VI-corona and class v -influenza (general)
1 goes in
binding to receptor
fusion of viral and plasma membrane (entry)
uncoating/disassembly
RNA replication
Viral RNA
self asembly
1000s exit
host cell death and disease
whats the main difference between class IV and class V
class IV - ssRNA is mRNA
class V - ssRNA to mRNA (transcription)
describe retroviruses - HIV class VI
STDs, blood, injections
no universal vaccine
genetic info as 2 ssRNA molecules
reverse transcriptase, integrase, protease
coat proteins
membranous envelope with gp120
infects - CD4+ immune cells, lymphocytes and macrophages
how many steps of HIV replication
7
describe AIDS symptoms (appear when? and why?)
10 years after infection (latent phase)
BECAUSE
the provirus is not active and viral proteins are not expressed
the immune system of host keeps viral replication under control
describe anti HIV drugs (3 things)
cocktail of antiviral drugs
1 - CCR5 blockers inhibit a non essential cellular protein CCR5 - prevents entry
2 - reverse transcriptase inhibits it’s activity AZT mimics nucleotides (competitive inhibition)
3 - viral proteases that cleave viral poly protein to individual and functional polypeptide chains the drugs inactivate the viral proteases so functional proteins are not made (prevent assembly and exit)
what are bacteriophages
bacterial viruses
reproduce according to lytic and or lysogenic cycle
what are virulent phages
T4
always kills the host (bacteria)
lytic cycle
what are temperate phages
lambda
doesn’t always kill the infected host
lysogenic and lytic cycles
describe lytic cycle
early genes - nucleases to destroy host DNA
middle genes - capsid proteins, head, tail
late genes - protease (lysozyme) to lyse host (bacteria) by damaging cell wall
describe lysogenic cycle
default state of temperate phage only
involves incorporation of phage DNA into bacterial chromosome called prophage (replication occurs together with bacterial DNA replication during cell division)
bacteria are not lysed
phage and bacteria co exist
describe main steps of lytic cycle (5)
attachment
entry of phage DNA and degradation of host DNA
(early, middle)
synthesis of viral genomes and proteins
assembly
(late)
release / exit
generally describe bacterial genetics (prokaryotes)
singular circular chromosome (+/- plasmid)
binary fission (can’t sexually reproduce)
mechanisms to increase genetic variation
genetic variation = diversity
increase chances of survival in ever changing environment
has steps (a,b,c,d)
in the case of pathogenic bacteria - changing environment = host and immune system - solutions?
acquiring antibiotic resistance through mutations or other means
developing better virulence genes for attacking host
changing antigenic makeup to avoid immune system of host (similar to RNA viruses)
what is vertical gene transfer
within species
what is horizontal gene transfer
between species
describe mutations (a)
random errors in DNA
can be beneficial - selection
can be harmful - elimination
describe transformation (b)
acquisition of foreign DNA from the environment or surrounding
may involve plasmids or chromosomal DNA
most common way of acquiring antibiotic resistance
(Griffith experiment and e. coli lab 7)
describe transduction (c)
transfer of DNA between donor and recipient bacteria using phase vector (transmission agent)
bacteriophages acquire random genes (from donor to recipient)
virulent or temperate pages during lytic cycle
describe conjugation
and how many types are there
like sexual reproduction
divert transfer of DNA between bacteria using conjugation bridge
2 types
describe type I (conjugation)
involves transfers of DNA from F+ donor to F- recipient
info transferred is the F plasmid
at end - both cells are F+
(R plasmids can be transferred this way too)
describe type II (conjugation)
involved an Hfr donor bacterium
F plasmid has integrated into bacterial chromosome
transfers parts of F factor along with bacterial genes of the chromosome to F- recipient bacterium (acquires bacterial genes that become incorporated into its own chromosome by recombination)
F- recipient doesn’t become F+
what are plasmids
circular pieces of DNA
may contain genes that help
relaxed plasmid replication is independent of bacterial chromosome (opposite of stringent replication)
how are plasmids transferred
by transformation or conjugation type I
what are F plasmids
contain info for formation of sex pili and conjugation
what are R plasmids
F plasmids that contain in addition info for antibiotic resistance
what do plasmids used for cloning usually have
origin of replication
multiple cloning site (MCS)
antibiotic resistance gene
what is cloning
insertion of a gene or any foreign DNA into a bacterial plasmid making 1000s of copies of genes of interest
why do we do cloning (3 reasons)
study gene structure (gene and promoter sequence)
produce recombinant protein in bacteria - then be used for medical or industrial purposes
manipulate gene of interest by introducing mutations, introducing the DNA into organism of interest (GMOS)
how many steps of cloning are there
5
describe generally (diagram) of steps of cloning
1- bacteria plasmid DNA
2 - restriction digestion
3 - ligation (used ligaments seals plasmid and DNA)
4 - transformation (competency and heat shock)
5 - cell division and selection on plating
describe step 1 of cloning
isolation or purification of DNA genomic or cDNA from source (organism of interest)
isolation of plasmid DNA from bacteria
describe step 2 of cloning
restriction digestion of DNA and bacterial plasmid DNA with same restriction endonucleases
describe restriction enzymes (step 2 of cloning)
cut within DNA
cleave ssDNA at recognition sites (palindromic)
hydrolyze phosphodiesther bonds on both strands
blunt ends and sticky ends
describe function of restriction enzymes (step 2 of cloning)
have evolved to digest foreign DNA (phage)
prevent its insertion into bacterial chromosome
prevent phage replication
host DNA is methylated (not digested bc of this)
describe step 3 of cloning
ligation of foreign DNA into bacterial plasmid (ligase + ATP) anneal compatible
sticky ends
not all plasmid DNA will incorporate foreign DNA or DNA of interest
describe diagram of step 3 of cloning (plasmid DNA used as vector)
plasmid used for cloning
MCS - multiple cloning site, insertion of foreign DNA (multiple restriction sites)
AMPR, Bla, beta lactamase - destroys ampicillin (allows bacterial growth in the presence of antibiotic ampicillin)
origin of replication
describe step 4 of cloning
transformation of recombinant plasmid into bacteria by heat shock
describe bacteria before transformation in step 4 of cloning
AMP S - un transformed
describe bacteria after transformation in step 4 of cloning
AMP R - resistant
describe step 5 of cloning
plating and selection
antibiotic resistance - selection for bacterial with plasmid on medium
each col out has identical bacteria carrying same plasmid
each colony carries different plasmid
colonies can be screened (colony hybridization)
radioactive probe = bait, fluorescent, ssDNA sequence complementary to gene of interest
describe cloning using PCR plasmid (steps)
1 - isolate source DNA, plasmid DNA
2 - PCR with specific primers that anneal to ends of gene of interest
3 - PCR products and plasmid
4 - ligation
5 - transformation
6 - plating and selection on ampicillin medium
what is a library
pool of recombinant clones
storage of genes from organism/cell of interest
library can be screened at a later date for gene of interest
what is cDNA
complementary DNA
made from mRNA of cell of interest that has been reverse transcribed using reverse transcriptase
what are the advantages of cDNA
better source of genetic info (bacterial expression plasmid)
no eukaryotic promoter sequence
no intron sequences
bacteria can therefore express foreign protein (eukaryotic intron and promoter won’t be recognized by bacteria)
describe steps of cDNA library (6 steps)
1 - mRNA - reverse transcriptase
2 - cDNA - restriction digestion
3 - cDNA fragments - ligation into plasmid
4 - library of cDNA plasmids - transformation
5 - library of bacterial cDNA clones
6 - plating and selection
what is genomic DNA
isolated from chromosomes of cells
what are the advantages of genomic DNA
uncertain about expression of gene of interest (low levels mRNA made - may be hard to clone as cDNA)
interest in studying gene sequences and regulatory sequences (splicing has removed introns in mRNA and in cDNA, mRNA doesn’t contain promoter and upstream regulatory sequences)
what is polymerase chain reaction
amplification of DNA sequence of interest
describe PCR
used in forensic sciences, paternity testing and cloning, hiv, covid tests
synthesis reaction test tube in vitro reaction
(also entails cutting amplified with restriction enzyme, ligation into plasmid, transforming bacteria, selecting recombinant plasmid of interest
name and describe PCR ingredients (5)
DNA source - 2 strands template
heat tolerant DNA polymerase (TAQ polymerase)
specific primers to delimit region of interest to be amplified (2 F & R DNA primers)
dNTPs
thermocycler = adjusts temp rapidly automatically for each step
describe 3 steps of PCR
repetition 20-30x
1 - denauturation at 94c
2 - annealing/hybridization with specific F & R primers 45-65c
3 - elongation/extension (complementary strand to region of interest is synthesized with TAQ polymerase at 72c
what are RFLPs
restriction fragment length polymorphisms
describe RFLPs
polymorphisms are regions of genome that are variable between individuals
distinguished based on patterns of DNA fragment sizes follow restriction digestion of DNA
describe 3 steps of RFLPs
DNA isolation
restriction digestion
AGE - agarose gel electrophoresis
describe RFLPs and alleles (genes)
sickle cell anemia - recessive aa, mutation in B globin gene - defective hemoglobin and defective RBC - anemia
aa = recessive
AA = dominant
Aa = heterozygous carrier
what is DNA sequencing
method to sternum if cloned DNA is the one of interest if there is a polymorphism (single gene mutations associated with inherited diseases)
synthesis reaction in vitro reaction
name and describe ingredients of DNA sequencing (5)
DNA of interest - one template strand
DNA polymerase
primer for specific DNA (one primer, provided 3’ OH)
dNTPs
ddNTPs - fluorescently labelled (ddGTP - green…)
what are dideoxyribonucleotides
stop elongation/extension reaction whenever they get incorporated into the daughter strand synthesized
produce DNA strands or fragments of different sizes lengths and colours
whats the difference between dNTP (deoxyribonucleotides) and ddNTP (dideoxyribonucleotides)
dNTP - OH anchor for synthesis
ddNTP - H synthesis stops
name the 2 types of immunity
innate
adaptive - acquired
describe innate immunity
rapid response against a broad range of microbes (non specific)
cells - macrophages, neutrophils, natural killer cells
name the types of innate immunity
external
internal
name the 3 major subcategories of innate external
skin
mucous membranes - mucus with lysozyme
secretions - acidic pH, salive, tears, lysozyme
describe mucous membranes of innate external
lysozyme - digests bacterial cell wall
nostrils
digestive tract
ears, mouth,lips
genital area
anus
name the 4 major subcategories of innate external
antimicrobial proteins and molecules
phagocytosis - macrophages and dendritic cells
inflammatory response
natural killer cells - target cancer and viral infected cells
describe antimicrobial proteins and molecules of innate internal
complement system - proteins in blood form MAC (membrane attack complex) - pore in the membrane of invading microbe
interferons - secreted by viral infected cells, signal infection, short term resistance
defensins - NO and free radicals (stored in granules, released only around microbes)
describe phagocytosis of innate internal
toll like receptors on macrophages
recognize general features
peptidoglycan cell wall and sugars on surface of bacteria
flagellin in flagella
dsRNA in viruses
describe inflammatory response of innate internal
chemokines released by macrophages to attract more phagocytic cells to site of infection
histamines released by mast cells - dilation and increased permeability of
capillaries - extravasation if phagocytic cells
fever - systemic generalized response
describe acquired - adaptive immunity
slower responses for specific microbes
cells - macrophage, antigen presenting cells, lymphocytes
humoral response - B lymphocytes, antibodies
cell mediated response cytotoxic T lymphocytes (killing of target cells)
name and describe 3 cell types of blood and their %
55% plasma - liquid
1% white blood cell
44% red blood cells
describe stem cell lineages
2
lymphocytes - B cells or T lymphocytes (in circulation, in blood, lymph)
myeloid - all other blood cells
describe white blood cells
lymphocytes derived from lymphoid stem cells - adaptive immunity
B cells - made in bone marrow
T cells - made in thymus
describe macrophages
innate and adaptive immunity
what type immunity are dendritic cells involved in
acquired
what type immunity are neutrophils involved in
innate
what type of cells are macrophages and dendritic cells
phagocytosis cells
antigen presenting cells (apc)
what are lymphocytes
acquired immunity
B and T lymphocytes
name the 3 types of lymphocytes
Th - helper cells
Tc - cytotoxic cells
B cells
describe Th helper cells
central role in humoral and cell mediated response
stimulate activation of Tc and B cells by recognizing foreign antigens displayed on apcs
secrete cytokines which activate T and B cells
describe Tc cytotoxic cells
destroy infected body cells, cancer cells and foreign graft tissue
Tc cells required in T cell mediated response
activated by infected cell/cancer cells and by T helper cells
describe B cells
secrete defensive proteins called antibodies
involved in humoral response
activated by antigens and T helper cells
what is the humoral response
production of antibodies by differentiated B cells called plasma cells
what is cell mediated response
specific killing of target cells (viral or bacterial infected cells, cancer or any foreign cells) by Tc cells
describe (basic) the 3 steps of the 2 responses
1 - presence of antigen
2 - phagocytosis (uptake), digestion and displays of antigen fragments by macrophages
3 - activation of T helper lymphocytes
describe step 2 (more detailed) of responses
final products =
MHC - major histo compatibility complex - unique proteins and define immune identity
antigen fragment displays (apc macrophage)
describe antigen
generally foreign protein that elicits immune response
freely circulating
bound - presented in context of self MHC
describe step 2 of response for type I
found on surface of all body cells
presents foreign antigens
each MHC I-antigen is recognized by a specific T cytotoxic TCR
signals to Tc that a cell is infected
describe step 2 of response for type II
found on surface of apc cells and b cells
presents foreign antigens
each MHC-II antigen is recognized by specific t helper (t cell recollected TCR)
activation of humoral and cell mediated responses
describe CD4 (in relation to 3 steps of responses)
surface protein in Th cells
binds to type II receptor
interaction between apc and Th cells
activation of Th cells
cytokines = immune hormone that stimulate lymphocytes
describe humoral response
produce antibodies to provide response to pathogens and toxins
describe structure of humoral response
quaternary
2hc 2 lc held by s-s bonds
each chain has constant and variable regions
what are variable regions responsible for in humoral response
antigen specificity
describe b cell receptors - humoral response
BCR
antibody anchored in membrane of B cells
first to encounter free antigen or microbe
describe functions of humoral response (3 steps)
viral neutralization
opsonization
activation of complement system and pore formation (MAC)
where are the variable and constant regions (humoral response)
light and heavy chains
antigen binding sites
how many antigen binding sites per antibody (humoral response)
2
describe clonal selection recognition
antigens circulating in the body are recognized by B cells that specifically interact with these via their B cell receptors - only lymphocytes that recognize antigen are activated
describe clonal selection cell division
proliferation of activated B cells to form 2 clones of daughter cells
describe clonal selection differentiation
one clone consists of short lived plasma B cells which secrete antibodies with same antigen specificity as the initial B cell receptor on naive cell
how many steps in activation of humoral pathway
6
describe step 1 of humoral pathway
presence of antigen
describe step 2 of humoral pathway
processing of antigen and presentation in context of MHC II on surface of macrophage and B cell
describe step 3 of humoral pathway
T helper cells activation
binding of TCR+CD4 to MHC antigens complex
cytokines released by APC
describe step 4 of humoral pathway
B cell activation
by cytokines and by direct interaction with activated T helper cells
describe step 5 of humoral pathway
clonal selection - proliferation and differentiation into clones of plasma and memory cells
describe step 6 of humoral pathway
antibody secretion and antigen activation
describe primary response
first exposure of the B lymphocytes to a particular antigens (antibody concentration is maximal within 14 days after first encounter)
describe secondary response
second exposure to same antigen
much more rapid - 1 week
stronger - 1000x higher concentration of antibodies
memory cells generated in first encounter rapidly differentiate into plasma cells
immunization by vaccination
describe antibody concentration in relation to primary and secondary response
first peak is first encounter
second peak is second encounter (much higher, lasts longer bc memory cells)
describe Tc cells in cell mediated response
cytotoxic T cells
specialized in killing target cells infected with virus or cancer cells
TCR binds to antigens on surface of tater cells in context of MHC
describe TCR in cell mediated response
T cell receptor
resembles BCR with two chains (one alpha one beta)
anchored in membrane
antigens binding site
name and describe 2 types of TCR (cell mediated response)
cytotoxic TCR - binds to antigen bound to MHC I of infected cells
helper TCR - binds to antigen bound to MCHII of apc (macrophages and B cells)
describe TCR diversity
similar to BCR and antibody diversity - highlight specific to antigen
describe ~3 steps of cell mediated response
binding to apc
MHCII
activation T helper
describe cell mediated response (important info)
Th cell activation - cytokines
Tc cells activation and clonal selection (TCR to antigen class I MHC on surface of infected or cancer cell, cytokines)
perforin secretion - pores in target cell membrane
proteolytic enzymes (granzymes) initiates apoptosis in target cell
memory Tc cells
name 3 types of impaired immune function
exaggerated allergies - IgE antibodies
self - directed - autoimmune disease
immunodeficiency
describe exaggerated allergies
IgE antibodies
allergens bund specifically to IgE molecules expressed on surface of mast cells
binding can cause cross linking of adjacent IgE receptors and thus trigger release of histamines by mast cells
inflammation and other symptoms
describe self - directed - autoimmune disease
immune system loses self - tolerance and attacked self (self antigens) targeted cell death
lupus, celiac, type I diabetes, multiple sclerosis
describe immunodeficiency
destruction of cells of the immune system will lead to immunodeficiency and i ability to combat pathogenic diseases and cancer
genetic - SCID
loss of T helper cells - AIDS
humoral and cell mediated responses impaired - increased infections and cancer
describe active immunity
develops when an organisms own lymphocytes produce B and Tc cells specific to an infectious agent
describe passive immunity
process of injecting antibodies specific for a particular antigen or infection into a person who has never encountered antigen (not immune to it)
compare active and passive immunity (ex)
vaccinations vs breast feeding
name and describe vaccines
produce memory cells useful to combat future infections
inactivated vaccines
Acellular vaccines
attenuated vaccines
mRNA vaccines
describe nervous system
cns - brain and spinal cord (central)
pns - all nerves innervating the body (peripheral)
name 2 types of cells of action potential
neurons
neuroglia
describe neurons (and 2 types of neurons)
transmit nervous impulses
sensory
interneurons
motor neurons
describe neuroglia (2 types of cells + def)
feed and support neurons
oligodendrocytes - envelop neurons of cns, form protective myelin sheath
schwann cells - envelop axons of motor and sensory neurons pns, form protective myelin sheath
definition of dendrites
extension of cell body, synapse with other neurons
definition of axon hillock
nervous impulse (ap) initiation site
definition of axon
transmission of ap
definition of axon terminals
synaptic transmission
ap generation (gen)
movement of ions Na+ and K+ across voltage gated channels
across pm
ap transmission (gen)
lateral movement of ions Na+ along membrane
synaptic transmission (gen)
neurotransmitters bind to ligand gated receptor channel
describe 2 steps of action potential
generation = movement of ions across membrane, change in membrane potential, axon hillock
propagation = involved lateral movement of ions, axon
describe membrane potential
caused by separation of ions and counter ions
all cells have membrane potential also called resting potential in neurons
generally negative inside
how (and name) many steps can generate membrane potential
2
electrogenic pump
ion channel
describe electrogenic pump
the Na+/K+ ATPase pump which pumps three Na+ out of cell against 2K+ into cell
creates charge separation
slow and energy requiring
essential to establish gradients across membrane (pumps Na+ out and K+ in)
describe ion channel
facilitated diffusion of specific ions
- resting channels are always open
- voltage gated channel - open and closed based on Em
fast, not energy requiring
influx = diffusion into cell
efflux = diffusion out of cell
describe action potential generation
measured in one spot overtime
movement of ions across membrane
THRESHOLD VALUE (if below = no ap, if above = full ap)
how many steps of ap generation
5
name all 4/5 steps of action potential generation
rest
stimulation to threshold
depolarization
repolarization
hyperpolarization
describe step 1 of ap generation
rest - resting potential
Na+/K+ pump
K+ resting channels - K+ efflux
Na+ channels leaky - some Na+ influx
Overall -70mV - close to Eeq K+
describe step 2 of ap generation
stimulation to threshold
few Na+ gates open
describe step 3 of ap generation
depolarization
threshold reached - all Na + gates open (massive Na+ influx +40mV)
at peak - Na+ gates close and K+ gates open
Na+ voltage gated channels are inactivated (not leaky, cant be opened again)
describe steps 4 and 5 of ap generation
repolarization and hyper polarization
K+ efflux -> Em ~ Eeq K+ ~ 80mV
describe refractory period
period in space and time when second ap can’t be triggered
name and describe 2 types of refractory period
absolute - a second ap can’t be triggered because Na+ V channels inactivated
relative - a second ap could be triggered but stimulus needs to be stronger to reach threshold
describe rest open and inactivated (also order)
rest - closed but a little leaky, minimal Na+ influx
open - Na+ influx
inactivated - inactivation peptide, tight shut, no influx
order - rest open inactivated rest open inactivated
describe ap propagation (3 main periods/things)
peak of AP - Na+ influx
refractory period (membrane repolarizing, Na+ V channels inactivated)
resting potential
describe step 1 of ap propagation
ap is self propagating
depolarization ahead of ap opens Na+ channels - threshold is reached ahead -> ap is triggered
describe step 2 of ap propagation
ap only moves in one direction, never behind because of refractory period
deplorarization behring the ap doesn’t affect the inactivated Na+ channels - absolute refractory period (ap doesn’t move backwards)
describe step 3 of ap propagation (image description)
resting potential
refractory period
ap
resting potential
(horizontal order across axon)
describe myelinated axons
conducts the ap by saltatory conduction
faster - zone of depolarization jumps from node or ranvier to next
cheaper - gradients not maintained
Ms - autoimmune disease caused by destruction of myelin sheath (oligodendrocytes)
describe synapse
small space that separates presynpatic cell (neuron) from a postsynaptic cell (another neuron, gland or muscle cell)
ap cannot always be transmitted
chemical synapses
how many steps seen for synaptic transmission
9
describe step 1 of synaptic transmission
wave of ap arrives at terminal branch (axon terminus) of a presynaptic cell
presynaptic terminal membrane is depolarized
describe step 2 of synaptic transmission
Ca2+ voltage gated channels open
allow movement of ion down electrochemical gradient into presynaptic cell (influx)
describe step 3 of synaptic transmission
increase in intracellular Ca2+ causes vesicles inside presynaptic cell containing neurotransmitter (nt) to fuse with membrane of terminal branch
describe step 4 of synaptic transmission
release of nt into the synapse (synaptic cleft)
describe step 5 of synaptic transmission
binding of nt to ligand gated receptor channels of the postsynaptic cell
describe step 6 of synaptic transmission
ligand gated channels depend on nt :
Na+ influx (epsp) corresponding depolarization post synaptic membrane potential
K+ efflux (ipsp) corresponding hyperpolarizarion post synaptic membrane potential
describe step 7 of synaptic transmission
hyper polarized membrane is an inhibitory signal (ipsp) and depolarized membrane is excitatory signal (epsp) for post synaptic cell
describe step 8 of synaptic transmission
transmission of signal terminated when nt detaches from ligand gated channel
describe step 9 of synaptic transmission
ipsp s and epsp s are summed in time (temporal summation) and in space (spatial summation)
- ap is fired at axon hillock of post synaptic cell if overall summation results in depolarization or above threshold potential
- if not then no ap fired
what does EPSP and IPSP stand for
excitatory post synaptic potential
Inhibitory post synaptic potential
describe regulation of lysogenic cycle
when cells are stressed (irradiation or chemicals) lytic cycle is induced
when repressor protein is expressed lytic cycle is inhibited
when repressor protein inactivated the lytic cycle is activated
describe step 1 of HIV replication
entry
gp120 binds to receptors CD4 and CCR5 on CD4+ cells (macrophages and Th cells)
describe step 2 of HIV replication
fusion of viral and cell membrane
release of capsid
describe step 3 of HIV replication
synthesis of dsDNA
reverse transcriptase (viral enzyme)
describe step 4 of HIV replication
integration of viral dsDNA into host chromosomes
provirus
integrase (viral enzyme)
hiv positive for life
describe step 5 of HIV replication
transcription and translation of viral proteins using host enzymes (DNA RNA protein)
describe step 6 of HIV replication
packaging and exit of new viral particles surrounded by host membrane
describe step 7 of HIV replication
death of macrophages and Th cells
AIDS
what is CD4
cellular receptor
what is CCR5
cellular coreceptor
describe resistance to HIV
lack CCR5 co receptor on surface of T cells
describe temporal summation (graph)
ap peak
E1 twice
describe spatial summation (graph)
ap peak
E1 + E2
describe spatial summation (epsp and ipsp)
no ap
cancellation
depolarization at E1
hyper polarization at I
E1 + I
