Infection, Immunity and Forensics-notes

7/24/2019 Infection, Immunity and Forensics-notes

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A Y O M I D E O L U B U M M O

Infection, Immunity and

Forensics

AYOMIDE OLUBUMMO


2/29

A.O

Explain the nature of the enetic code

!enetic code is the se"uence of #ases on the D$Amolecule, it is read in roups of three #ases calledcodons%

It can #e descri#e as #ein a triplet code& three #asescode for an amino acid%

Deenerate' there is more than one codon for aparticular amino acid%

$on( o)erlappin' each triplet code is discrete andonly read once

AYOMIDE OLUBUMMO


3/29

A.O

Explain the process of protein synthesis

It is made up of t*o main staes& transcription and translation%

+ranscription occurs in the nucleus

D$A polymerase causes the D$A strands to separate lea)in the#ases exposed%

+he antisense strand acts as a template for the m$A%Free $A nucleotides line up aainst their complementary #ase

pairs%

+he $A nucleotides are -oined toether usin $A polymerase,

in a condensation reaction formin phosphodiester #onds#et*een the nucleotides to form the polynucleotide m$A%

+he m$A strand detaches form the antisense strand and theD$A strands re-oin and recoil%

AYOMIDE OLUBUMMO


4/29

A.O


Before the m$A lea)es the nucleus it underoespost transcriptional chanes in *hich the introns.non codin #ases/ are remo)ed%

+he remainin exons are then ordered%

AYOMIDE OLUBUMMO


5/29

A.O


Follo*in post transcriptional chanes the m$A lea)es the nucleus and enters thecytoplasm *here it underoes translation%

In the cytoplasm the m$A attached to ri#osome *hich is made up of t*o su#units and ri#osomal $A%

At the start of the m$A molecule is a start codon *hich initiates protein synthesis%

+he ri#osome reads the codons and the t$A molecule *ith the complementaryanticodon to codon #ein read lines up aainst it% Each t$A molecule is attachedto a specific amino acid%

+he ri#osome oes alon the m$A readin the codons and fetchin thecomplementary t$A molecules%

+he anticodon of the t$A lines up aainst the codon of the m$A and hydroen

#onds are formed #et*een the codon and anticodon%As the t$A molecule line up,peptide #onds form #et*een the amino acid%

0hen the ri#osome reads the stop codon *hich is at the end of the m$Amolecule, protein synthesis stops and the polypeptide is released%

AYOMIDE OLUBUMMO


6/29

A.O

Explain ho* one ene can i)e rise to a num#er of proteins

+his is due to post transcriptional chanes *hich *as mentioneda#o)e%

+he remainin exons can #e arraned into different orders%

+he order of the exons determines the primary structure of the

protein .se"uence of amino acids/+his then determines the secondary and tertiary three

dimensional structure of the protein%

Determines *hat #onds are formed in theses structures, *hether&ionic #ond #et*een side roups

Disulphide& #ond #et*een side roups containin sulphur

1ydroen

+he structure determines the type thus the function of the protein%

AYOMIDE OLUBUMMO


7/29

A.O

0hat is D$A profilin used for

D$A profilin is used for identification anddeterminin enetic relationships #et*eenindi)iduals%

+he theory #ehind D$A profilin'E)eryone2s D$A is uni"ue except for identical t*ins

It analyses introns #ecause there are a lare num#erof the them and they are hihly )aria#le .mutations

reularly occur here/%

AYOMIDE OLUBUMMO


8/29

A.O

0hy can e)idence from D$A profilin #e inconclusi)e

Due to small area of the D$A #ein analysed

+here are many staes of the D$A profile so errorscan arise%

+he D$A sample may #e contaminated%Identical t*ins *ould ha)e identical profile due to

nearly identical D$A%

AYOMIDE OLUBUMMO


9/29

A.O

1o* is D$A profilin used #y scientist

Used to spot e)olutionary relationships . can spotcommon ancestor/ so is )ery useful in taxonomy%

Used to pre)ent in#reedin in capti)e #reedin

prorammes as in#reedin reduces enetic di)ersity

AYOMIDE OLUBUMMO


10/29

A.O

1o* can D$A #e amplified

+he sample of D$A can #e amplified usin 34. polymerase chain reaction/%

+he )ial containin& a sample of D$A ta5en from sali)a, free D$Anucleotides, D$A polymerase and D$A primers are placed into the 34machine%

+he mixture is heater to a#out 67 derees, this is done to #rea5 the hydroen

#onds #et*een the D$A strands%+he mixture is then cooled to 88 derees to allo* the D$A primers to anneal

.attach/ to the D$A, to mar5 *here to start replication%

+hen heated to 98 derees to allo* the D$A polymerase to assem#lecomplementary D$A strands usin the D$A nucleotides%

+he cycle of heatin and coolin is repeated approximately :7 times to et alare enouh sample%

D$A polymerase not suita#le in machine as its optimum is a#out :8therefore *ould li5e denature at hih temperatures of machine%

AYOMIDE OLUBUMMO


11/29

A.O

1o* is el electrophoresis performed

After amplification, the parts of D$A to #e analyses are cut *ithrestriction endonuclease%

+he D$A is stained, and placed in *ell in aar -elly surrounded #y#uffer solution% . the dye usually used is ethium #romide/

An electric current is passed throuh the solution *hich mo)ed theD$A framents *ith the shorter frament mo)in further% .D$Aa#le to mo)e *ith current due to sliht neati)e chare of molecule/%

+he D$A is then )ie*ed under U; liht and seen as #ands%

+he hiher the num#er of matchin #ands the more closely

enetically related the person is%If position of #ands are identical this can #e used to identify suspect%

AYOMIDE OLUBUMMO


12/29

A.O

0hat is are the 5ey features of the structure of #acteria

1as flaellum *hich rotates to pro)ide mo)ement to the#acteria%

1as capsule, also 5no*n as slime layer used to 5ill immunecells%

It is a pro5aryote and has a peptidolycan cells *all

4ontains infoldin of cell mem#rane called memosome*hich contains proteins for respiration%

4ontains plasmid *hich are circular pieces of non essentialD$A can #e passed on to host%

4ontains circular Dna

4an ha)e pili, *hich can #e used in replication%

AYOMIDE OLUBUMMO


13/29

A.O

0hat are 5ey features of )irus

4ontains capsid *hich contains enetic material%

!enetic material can #e D$A or $A .found inretro)iruses, in this case also ha)e re)erse

transcriptase en7 molecules%

AYOMIDE OLUBUMMO


14/29

A.O

ole of #arriers in protectin the #ody

+here are )arious routes pathoens can ta5e to infect the #ody and these routesha)e #arriers *hich pre)ent entry%

?5in is a physical #arrier it contains 5eratin *hich is hard to penetrate%

3athoens also need antiens to attach to *hich are not present on s5in or #lood%

?5in also secretes se#um *hich has a lo* p1 so creates harsh conditions for

pathoens%?5in has flora *hich are #etter adapted to li)in on s5in therefore outcompete

pathoens

?5in also clots *hen #ro5en to pre)ent entry to pathoens%

Another physical #arrier is the epithelial linin%

It contains ciliated cells *hich s*eep de#ris and mucus that traps the pathoens%

4an also secrete ly


15/29

A.O

0hat is 1I;

1uman immunodeficiency )irus%

First staes asymptomatic,

But *hen immune system fails leads to de)elopment

of AID?% .ac"uired immunodefiency syndrome%Death is not #y a )irus #ut #y a secondary infection

that *ouldn@t cause death to someone *ith afunctionin immune system%

AYOMIDE OLUBUMMO


16/29

A.O

0hat is the series of e)ents that lead to death #y 1I;

!p=>7 molecules attach to cd receptors on the t helper cell%

e)erse transcriptase con)erts $A into D$A, *hich enters the thelper cells%

En


17/29

A.O

1o* is 1I; spread

+he )irus cannot sur)i)e out of the #ody for lon%

+herefore it is spread #y direct contact li5e sex orother exchanes of #loodily fluid%

AYOMIDE OLUBUMMO


18/29

A.ODescri#e the non specific response of the #ody to infection(Inflammation

3latelets or mast cells in the #lood release histamines

1istamines cause )asodilation and increased permea#ility ofcappliaries% +his leads to increased #lood flo* to infected site,alon *ith the #lood, *hite #lood cells tra)el to the infected

site%Inflammation can also lead to s*ellin, redness and pain

*hich can #e com#ated *ith antihistamines%

Better to ta5e antihistmines in ta#let form not cream, as

cream allo*s application directly to infected site so fasterresponse, has a hiher concentration of the antihistaminesand antihistamines in ta#lets may dissol)e due to stomachacid%

AYOMIDE OLUBUMMO


19/29

A.ODescri#e the non specific response of the #ody to infection(lyso


20/29

A.ODescri#e the non specific response of the #ody to infection(interferon

Interferon is a protein released #y infected cells%

+hey act on )irus and inhi#it the action of )irus thusstoppin their spread%

+hey also acti)ate other mechanisms of the nonspecific immune repsonse%

AYOMIDE OLUBUMMO

A O


21/29

A.ODescri#e the non specific response of the #ody to infection(phaocytosis

A phaocyte is a type of *hite #lood cell%

It reconises the antien on the pathoen as foreinand enulf it in a phaocytic )acuole%

0ithin the )acuole, the pathoen fuses *ith alysosome *hich contains lyso


22/29

A.O

0hat is a + cell

A + cell is a type of *hite #lood cell found in thelymph%

It has antien receptors *hich it uses to #ind to

pathoens *ith a complementary antien%econises and identifies cells as self and nonself%

In the case that it #inds to a non self antien.pathoen/ it is acti)ated underoes mitosis to

differiate into t helper cells, t 5iller cells and tmemory cells

AYOMIDE OLUBUMMO

A O


23/29

A.O

0hat are the different t cells and *hat do they do

+ helper cell released cyto5ines *hich acti)ates the #effector cells

+ 5iller cells 5ill infected cells

+ memory remem#er the antien allo*in for rapidsecondary response in the case of reinfection% +he tmemory cells are responsi#le for immunity%

AYOMIDE OLUBUMMO

A O


24/29

A.O

0hat is a # cell

A B cell is a type of *hite #lood cell, that contain ananti#ody on the surface of the cell%

4yto5ines released from the t helper cell acti)ates in

cell and lead to the production of # effector cells.other*ise 5no*n as plasma cells/ *hich o on toproduce anti#odies%

4yto5ines also cause production of # memory cells

*hich also *or5 to heihten secondary response%

AYOMIDE OLUBUMMO

A O


25/29

A.O

0hat are anti#odies

Anti#odies are proteins produced #y B effector cells%

+hey ha)e :D structure *hich is held toether #ydisulphide #rides% +hey ha)e t*o antien receptors

sites%+hey ha)e a constant reion

+hey also ha)e a )aria#le reion%

AYOMIDE OLUBUMMO

A O


26/29

A.O

0hat do anti#odies do

+hey cause alutination, they do this #y forminanti#ody(antien complexes *hich case thepathoens to come toether%

Alutination is important as it places the pathoensin one place ma5in it easier to #e enulfed% It alsostops the spread to pathoens%

Also neutralise toxins produced #y pathoens #y

formin toxin(anti#ody complex *hich is enulfed%Bloc5 receptors on pathoen so they cannot #ind to

host cells%

AYOMIDE OLUBUMMO

A O


27/29

A.O

0hat is immunity

0hen your immune system can ma5e the anti#odiesneed to fiht and 5ill pathoens *hen they infect the

#ody%

It can #e passi)e or acti)e%3assi)e immunity is *hen the anti#odies needed to

fiht the infection is produced #y another oranismand introduce into your #ody%

Acti)e immunity is *hen your immune systemproduces the anti#odies needed to fiht theinfection%

AYOMIDE OLUBUMMO

A O


28/29

A.O

1o* can you de)elop immunity . passi)e/

3assi)e immunity can #e de)eloped naturally orartificially%

3assi)e natural immunity( *hen the anti#odies are

passed from mother to child throuh #reastmil5%3assi)e artificial immunity( *hen anti#odies are

in-ected into the #ody, this is the case to treattetanus, the tetanus anti#odies act on the tetanus

toxins%

AYOMIDE OLUBUMMO

A O


29/29

A.O

1o* to de)elop immunity .acti)e/

Acti)e immunity can also #e de)eloped naturally or artificially%Acti)e natural immunity( *hen infected the #ody@s response is slo* #ecause

no memory cells are present, so the #ody has to ma5e numerous t cells *ithdifferent antien receptor until it creates an antien receptor that iscomplementary to the forein antien% +his can ta5e a *hile% +he t helper

cells then #inds to the pathoen and releases cyto5ines to acti)ate # effectorscells and the appropriate anti#ody% +his is the primary response. theresponse *hen infected #y ne* pathoen/% +his response is slo* and onlysmall "uantities of anti#odies are produced%

B memory and t memory cells are also produces so in the case of reinfectionthe secondary response is trier *hich is more rapid and leads to production

of a larer "uantity of anti#odies%Acti)e passi)e immunity( de)eloped #y )accination in *hich you are in-ected

*ith harmless dose of pathoen in order t et your #ody to produce memorycells that *ill allo* for rapid response in the case of reinfesction%

AYOMIDE OLUBUMMO

Infection, Immunity and Forensics-notes

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