Thestudying of heredity and variationin livingorganisms
Thepassingonoftraitsor
characteristicsfromone
generation tothenext
i Hereditarycharacteristics
aretransferredfromgametes
Eachorganisminherits passeddown
certaingeneralcharacteristicswhichareunique to a particularspecies mmP9ᵗᵈᵗᵗ
as
specialcharacteristicsfrombothparentsthatmakeorganismuniqueas anindividual offspring
GENES
AsectionofDNA series ofnucleotides thatcontrols a hereditarycharacteristic
basicunitofheredityinliving
the organisms
eachorganism hasitsownuniquegene
combinationdetermined the
by sequence
ofnitrogenousbasesontheDNAmolecule
Acompletesetofgenesof aparticular
organismisknownasthegenome
everysomatic
Nearly
cellinanindividualhave
anexactcopyofallgenes
Is
inthatorganism ofaseriesofgenes
madeup
chromatid
upofonehelicalDNAmolecule
made
Austrianmonk
performedexpirementsonpeaplantstostudytheinheritance ofcharacteristicsfromonegenerationtoanother
throughhisfindings heformulatedthebasiclawsofgenetics heisARA thefatherofGenetics
Hisexpirements
peaplants showclearobservablecontrastingcharacteristics egtall shortplants smooth windedseedsyellow
naturallyselfpollinating donotcrosspollinate andgreenseedsgreenandyellowpodspurple
whitemovers
,Mendelcutoffantherscontainingpollenandthenperformedcrosspollinationhimselfusingpollenofhischoice
hepaintedtheripepollenontothestigmawithasmallbrush hecouldcontrolthecross
initially hedid allhisexpirementsonparentplants thatwere truebreeding for a specific
characteristics whenselfpollinationtakesplace allthe
offspringproducedhavethesamecharacteristic
astheparent
Mendeldrewthefollowingconclusions
egwhenatallpeaplantselfpollinatesand
ahereditarycharacteristicisdeterminedbytwofactors onlyproducestallpeaplants itisa true
Thetwofactorsarearrangedas apair plantforthetallcharacteristic
breeding
TheywerenamedgenesafterMendel'sdeath
pqiEfE.sn Ete9TaiTa
s
mother
NegenepairiscartednelTromosomes
genehasaspecificlocationona chromosome
each
ofahomologouschromosomepair thelocus
Note aparticulargeneoccursintwodifferenttermsthataffectthesamecharacteristicindifferentways
theseformsarecalledALLELES
Differentversionsofthesame genefoundinthesamelocusonhomologouschromosomes
wehave2 for gene
alleles e ach because wehavetwocopiesofeachgenebecausewehavetwocopiesofeachchromosome
onealleleisinheritedfromthemotherandtheotherfromthefather
differentalleles differentinformationaboutthesamecharacteristic
contain trait
onealleleof agenepaircanmaskanotherthisisthedominantallele
themaskedalleleisnotvisiblyexpressedintheorganismandisrecessive
bywaysofchromosomes inthegametes
Allelesarepassed
made theprocessofmeiosisinsexorgans
by
Normalbodycellssomaticcellsarediploid 2n
haveapairofhomologouschromosomesand
thfflefsame different
Sexcells gametes arehaploid n
haveonechromosomefromthehomologouspair oneofthetwoalleles
, Amalegamete n fuseswithafemalegamete n toformadiploidzygote2n
divides mitosisandformsafoetus
by
whichhastheallelesfromboth
parents
arenohomologous
there
Ige9995 aggromosomes
pairs
chromosome
as
ieiiaii.EE as seneggiege
IranImager infantsones chain EEEda9Minber
ofchromosomes
eg299Eachskin egspermcells ara
Aslettersofthealphabet usuallythefirstletterofthenameofthedominanttrait musthavealowercasewhich
differentto
IEaffapletely
Thecapitalrepresentsa dominantallele
Thelowercase of thesame letterrepresents a recessiveallele
eg thedominanttraitis tallness therecessivetrait is shortness
weuse t and t torepresentthem
, GENOTYPE PHENOTYPE observablecharacteristicsofanorganism
compositionof the
genepair 2alleles fora specifictrait
DOMINANT
thistraitwillbeexpressedinthephenotypeoftheoffspring
adominantalleleonlyneedstobeinheritedfromoneparentinorderforthecharacteristictoshowup
inthephenotype
if agenotypehasonedominantallele capitalletter itwillbeseeninthephenotype
RECESSIVE
thistraitwillbesuppressed inthepresenceof adominantallele
arecessiveallelewillonlybeexpressedinthephenotypeif it isinheritedfrombothparents
if a genotypehastworecessivealleles lowercaseof thesameletters itwillbeseeninthephenotype
Afterfertilisation thezygoteandall ofitscellswillhavetwoallelesforeachgene onefromeachparent
willbefoundinthesamelocuson
eachchromosomeinahomologouspair
Ifthepairofallelesata locusarethesame organismishomozygousforthatparticulartrait
Ifthepairofallelesat a locusareyggrgtiqgggm.isheterozygousforthatparticulartrait
isrecessive
Thepassingonoftraitsor
characteristicsfromone
generation tothenext
i Hereditarycharacteristics
aretransferredfromgametes
Eachorganisminherits passeddown
certaingeneralcharacteristicswhichareunique to a particularspecies mmP9ᵗᵈᵗᵗ
as
specialcharacteristicsfrombothparentsthatmakeorganismuniqueas anindividual offspring
GENES
AsectionofDNA series ofnucleotides thatcontrols a hereditarycharacteristic
basicunitofheredityinliving
the organisms
eachorganism hasitsownuniquegene
combinationdetermined the
by sequence
ofnitrogenousbasesontheDNAmolecule
Acompletesetofgenesof aparticular
organismisknownasthegenome
everysomatic
Nearly
cellinanindividualhave
anexactcopyofallgenes
Is
inthatorganism ofaseriesofgenes
madeup
chromatid
upofonehelicalDNAmolecule
made
Austrianmonk
performedexpirementsonpeaplantstostudytheinheritance ofcharacteristicsfromonegenerationtoanother
throughhisfindings heformulatedthebasiclawsofgenetics heisARA thefatherofGenetics
Hisexpirements
peaplants showclearobservablecontrastingcharacteristics egtall shortplants smooth windedseedsyellow
naturallyselfpollinating donotcrosspollinate andgreenseedsgreenandyellowpodspurple
whitemovers
,Mendelcutoffantherscontainingpollenandthenperformedcrosspollinationhimselfusingpollenofhischoice
hepaintedtheripepollenontothestigmawithasmallbrush hecouldcontrolthecross
initially hedid allhisexpirementsonparentplants thatwere truebreeding for a specific
characteristics whenselfpollinationtakesplace allthe
offspringproducedhavethesamecharacteristic
astheparent
Mendeldrewthefollowingconclusions
egwhenatallpeaplantselfpollinatesand
ahereditarycharacteristicisdeterminedbytwofactors onlyproducestallpeaplants itisa true
Thetwofactorsarearrangedas apair plantforthetallcharacteristic
breeding
TheywerenamedgenesafterMendel'sdeath
pqiEfE.sn Ete9TaiTa
s
mother
NegenepairiscartednelTromosomes
genehasaspecificlocationona chromosome
each
ofahomologouschromosomepair thelocus
Note aparticulargeneoccursintwodifferenttermsthataffectthesamecharacteristicindifferentways
theseformsarecalledALLELES
Differentversionsofthesame genefoundinthesamelocusonhomologouschromosomes
wehave2 for gene
alleles e ach because wehavetwocopiesofeachgenebecausewehavetwocopiesofeachchromosome
onealleleisinheritedfromthemotherandtheotherfromthefather
differentalleles differentinformationaboutthesamecharacteristic
contain trait
onealleleof agenepaircanmaskanotherthisisthedominantallele
themaskedalleleisnotvisiblyexpressedintheorganismandisrecessive
bywaysofchromosomes inthegametes
Allelesarepassed
made theprocessofmeiosisinsexorgans
by
Normalbodycellssomaticcellsarediploid 2n
haveapairofhomologouschromosomesand
thfflefsame different
Sexcells gametes arehaploid n
haveonechromosomefromthehomologouspair oneofthetwoalleles
, Amalegamete n fuseswithafemalegamete n toformadiploidzygote2n
divides mitosisandformsafoetus
by
whichhastheallelesfromboth
parents
arenohomologous
there
Ige9995 aggromosomes
pairs
chromosome
as
ieiiaii.EE as seneggiege
IranImager infantsones chain EEEda9Minber
ofchromosomes
eg299Eachskin egspermcells ara
Aslettersofthealphabet usuallythefirstletterofthenameofthedominanttrait musthavealowercasewhich
differentto
IEaffapletely
Thecapitalrepresentsa dominantallele
Thelowercase of thesame letterrepresents a recessiveallele
eg thedominanttraitis tallness therecessivetrait is shortness
weuse t and t torepresentthem
, GENOTYPE PHENOTYPE observablecharacteristicsofanorganism
compositionof the
genepair 2alleles fora specifictrait
DOMINANT
thistraitwillbeexpressedinthephenotypeoftheoffspring
adominantalleleonlyneedstobeinheritedfromoneparentinorderforthecharacteristictoshowup
inthephenotype
if agenotypehasonedominantallele capitalletter itwillbeseeninthephenotype
RECESSIVE
thistraitwillbesuppressed inthepresenceof adominantallele
arecessiveallelewillonlybeexpressedinthephenotypeif it isinheritedfrombothparents
if a genotypehastworecessivealleles lowercaseof thesameletters itwillbeseeninthephenotype
Afterfertilisation thezygoteandall ofitscellswillhavetwoallelesforeachgene onefromeachparent
willbefoundinthesamelocuson
eachchromosomeinahomologouspair
Ifthepairofallelesata locusarethesame organismishomozygousforthatparticulartrait
Ifthepairofallelesat a locusareyggrgtiqgggm.isheterozygousforthatparticulartrait
isrecessive
