1-2 inheritance(2)dfgdfg
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Genetic of MendelianInheritance
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What is Genetic?.
..is the science studies inheritance and changeability
characteristics of living organisms, Which is include thestudy of genes, heredity, and genetic variations
What is an Inheritance?What is an Inheritance?
..it is how the traits, or characteristics, are passed on from..it is how the traits, or characteristics, are passed on from
generation to generationgeneration to generation
What is an Changeability?What is an Changeability?
..is to be capable to acquire new characteristic..is to be capable to acquire new characteristic
quality of being changeable depends of genes andenvironment
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Mendel studies various alternative characteristicin the garden pea presented on the square
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The Law of IndependentAssortent
Alleles for different traits distribute/assortindependently of one another in the
The Law of !egregationDuring the formation of gametes (eggs or sperm!
the two members of gene pairs (alleles segregate(separate from each other.
"alf the gametes carry one allele! and the other half carry
the other allele.
Alleles for a trait are then #recombined# at fertili$ation!producing the genotype for the traits of the offspring
Law of "oinance
%n the monohybrid cross (mating of
two organisms that differ in only one
characteristic! one &ersion isdisappeared/inhibited
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• GenomeGenome# $ollection of all genetic aterial of organis
• Genotype)Genotype) the types of genes /!lleles0 presentthe types of genes /!lleles0 present• #$. )/!!2!a2aa0#$. )/!!2!a2aa0
• -henotype)-henotype) 1ow it loo"s li"e with appearance1ow it loo"s li"e with appearance• #$. )/yellow, green0#$. )/yellow, green0
• 3ominant traits)3ominant traits) traits that are e$pressedtraits that are e$pressed• #$. ) /!0#$. ) /!0
• ecessive traits)ecessive traits) traits that are covered uptraits that are covered up• #$. )/a0#$. )/a0
Genetic $oncepts
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Genetic $oncepts
•34! is mutable and a variation in 34!sequence at a speci'c place of gene /locus0is called an allele
• 5ingle prevailing allele presents in thema6ority of individuals is WIL" type
• Changed version of s gene is M%TA&T
• Given set of !lleles at a locus or cluster ofloci on a chromosome is 'A(L)T*(+
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Genetic $oncepts
# 3iploid organisms contain 7 alleles ofeach gene which set in homologouschromosome. *hose 7 alleles are one frommother one from father.
•!lleles can be identical 8 hoo,ygous -AA
•!lleles can be dierent 8 hetero,ygous -Aa# 5ometimes they called as $arriers
• If only one allele is present 8 hei,ygous-A/
# Case in males for genes on 0 and * chromosomes
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Symbols Should be known
• P – parents
ex. P: AA; aa
• G – gametes
ex. G: A; a
• '/')… - Generatons
ex. !: AA" Aa" aa
• * - hybrd#aton$%rossng
ex. Aa x Aa
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Law of "oinance
in the 1rst generationafter
2reeding of pure linesone
of the characteristics ofparent is disappearedThe Law of !egregationIs shown in the secondgeneration afterbreeding of 'rst generationIndividuals the inhibitedcharacteristic of one of theparents appeared
With ratio 9 :;
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(unnett squaresprobability diagram illustrating the possible ospring
of a mating
Gametes
P+ ,b - ,bP+ -
G+
'+
, , b b
bb,,
,b
')+
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The Law of Independent Assortent
Genes for different traits (olor (yellow and green and Shape
(round and wrinled assort independently of one another in theformation of gametes
345 6 -7/*/ 5 8 -rr*/ 5 8 -7/yy 5
9-rryy
P+ 0011 - yyrr
G+ 01 yr
'+ 0y1r
G+ 01 yr y1 yr
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The Law of Independent Assortent
7atio ofphenotypes
6 / -7/*/
8 / -rr*/8 / -7/yy9 # -rryy
3ro 9: organiss6 # have 2oth of traits "oinant8 # have the 1rst is recessive ; seconddoinant
8 # 1rst doinant ; second recessive9 # 2oth of traits recessive
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Traits are deterined
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Gene for eyecolor /
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"omologous chromosome with double chromatids
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&ow are genes passed on 'rom parent to
%hld(
• Genes n the %ell nu%leus arelo%ated on )* pars o'chromosomes
• +ne set o' )* %hromosomes snherted 'rom ea%h parent
• ,here'ore" o' ea%h par o' genes"
one s nherted 'rom a personsmother" and one 'rom ther 'ather
$hroosoe
Gene
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'ow do alleles di>er? "oinance
Dominant trait (allele e-pressed irregardless of the second allele.
1ecessi&e trait that is only e-pressed when the second allele is the same (e.g. blue
eyes are homo$ygous for the recessi&e allele.
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Genotype 2 phenotype
"ow does a genotype ratio differ from the phenotype ratio3
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&ow to analy#e the genotype under the
phenotype(
P: ( x aa
0ellow green
P: AA x aa
!: All /ellow
P: Aa x aa
!: /ellow 0 Green
1ato :
+ ti f M d li i h it
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+=ception of Mendelian inheritance
Interediate Inheritance -
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The Iportance of the +nvironent
The environental inuences the e=pression ofthe genotype so the phenotype is altered
'ydrangea
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Gene varia
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Mendelian patterns of Dominant
and recessi&e traits
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2endelan patterns o' nhertan%e
• 2ore then )344 dseases are nherted by 2endelan nhertan%e
• Around 567 are %aused by the mutaton o' the gene
• Around 87 o' dseases are nherted wth dre%t 2endelan
nhertan%e
• !rom Approxmate )9444 human gene about 57 are mpl%ated n
human genet% dsorders.
• Around 47 o' those sngle gene dsorders are presented a'ter puberty
• 7 are man'est a'ter reprodu%te perod
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(edigree analysis faily tree
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Sngle gene dsorders %hara%ter#es by ther patterns o' transmsson n
'amles. ,o study and obtan transmsson and ealuate the reealng
rsk Pedigree analysis s used• ,he extended 'amly dep%ted n su%h a pedgrees s indred4
• ,he member who s the 'rs n kndred tree s proband4
• =rothers and ssters are Sibs4
• !amly o' Sbs 'orms Sibships4
• Parents" Sbs and o''sprng o' the proband %reares the 'irst degree
• Grandparents and grand%hldren" un%les and aunts" nephews and ne%es" and hal'-sbs
%reates 5he Second Degree4
• !rst %ousns are 5hird degree.
• >ouples who hae one or more %ommon an%estors are consanguineous.
• ?' there s only one a''e%ted s isolated or sporadic @dependng on mutaton case.
(edigree analysis / faily tree
(edigree analysis
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(edigree analysis
(edigree analysis
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Mendelian patterns in huaninheritance
6idow7s pea
Autosomal dominant trait
(edigree analysis
Attached earlobe
Autosomal recessi&e trait
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$lassi1cation of geneticdisorders
Male
Alterations insingle genes
@ariants ingenes
$hroosoali
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!oe edical conditions are caused
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!ected gene locus is located in autosoes and around 9=>>
disease are "nown ) 3ominant inheritance is presented in
) 'oo,ygous /!!0 ) the most severe form of disease ) 'etero,ygous /!a0 8 ess severe form of disease,incomplete dominance or career.3isease spectrum in hetero@ygous)carriers of mutation is broad,
from carrier to lethal.
Autosoal doinantinheritance
AB> or ;>> of vertical transmission
Aboth Male and emale are similarly aected
AIncidence of autosomal dominant diseases is = in ;>>>
Ain case of mild phenotype the mutation is mostly inherited by one of
the parents
haracteri$ed by
Autosoal doinant
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Autosoal doinantinheritance
Autosoal doinant
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Parents
Gamet es
A>ected A>ected %na>ect
ofspring
Autosoal doinantinheritance
Autosoal doinant
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>ln%al Patterns
AMarfan syndrome
A!chondroplasia
A1untington disease
A4euro'bromatosis type ;ACardiomyopathy /hypertrophic0
A5"eletal dysplasia
Aamilial hypercholesterolemia
Aamilial !denomatous -olyposis /!-0
A-rader)willi
• 4eurological diseases /ata$ias, paraplegia, dystonia,inherited dementia0
A amilial cancer syndromes /breast, colon,
endocrinologically0
Autosoal doinantinheritance
Autosoal doinant
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!rachnodactyly /long 'ngers0 3islocated len
Marfan syndroevariable e$pressivity between members of the same family as the
protein coded for has dierent functions within the body.
Autosoal doinantinheritance
tall staturewithelongatedthin limbsand 'ngersD
high ris" ofheartdefects.
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Achondroplasia ) /Autosoal doinant• ! form of dwar'sm.
•Incidence of one case among every ;>,>>> birth.•1etero@ygous individuals have the dwarf phenotype.•Achondoplasia is caused by a mutation in the fibroblast growth receptor
8 ('G'18 gene in 9p:.8
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-enetrance and #$pressivity
• Sometmes phenotyp% expresson o' abnormal genotype
may be mod'ed by e''e%ts o' aging" other surrounding loci or effect of en&ironment.
• ,hs leads the d''%ultes n dagnoss and pedgree analyss.
Penetrance ;,he probablty o' phenotyp%
Bxpresson
Chen gene expresson s less 447
%alled 1educed Penetrance
,hs s the per%entage o' predsposton to
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*he e$panded C!G segment leads to the production of anabnormally long version of the huntingtin protein.
• *he elongated protein is cut into smaller, to$ic fragmentsthat bind together and accumulate in neurons, disruptingthe normal functions of these cells.
• *his process particularly aects regions of the brainthat help coordinate movement and control thin"ingand emotions
'untingtonFs disease•! degenerative disease of the
nervous system
•#$pression if aected by age/penetrance0 and 4o obviousphenotypic eect until the individual isabout 9B to EB years old.
•(eople with 'untington diseasehave 8: to ore than 94 $AGrepeats in 'TT gene located inchroosoe Hp9:.8
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&euro1aused by 2utatons n the E! gene•Incidence of one case among every 9B,>>> birth
•-henotype is e$presses in adults with ;>>, butsometimes 3isease characteri@ed with di>erentpenetrance aected by age and hetero@ygousgenotype from light pigmentic spots to severe form of
tumor disease.
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$orrelation of genotype and
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$orrelation of genotype andphenotype
Locus "eterogeneity –
• some gene has ther allel% araton ?n d''erent lo%us o'
the %hromosomes.
– Bx. 1etnts pgmentosa has autosomal domnant @6 lo% andre%esse @)6 lo%" F-lnked @9lo%.
$orrelation of genotype and
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$orrelation of genotype andphenotype
Phenotypic "eterogeneity –
• some gene ges a arous phenotype.
– 2utatons n the 2EA gene %ause Bmery-
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P:
-arent who are carriers for the same autosomalrecessive condition have one copy of the usualform of the gene and one copy of an altered gene
Autosoal recessiveinheritance
!utosomal recessive disease occurs only in 1omo@ygouscondition /
when
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Parents
Affected>naffected
(carrier>naffected
Sperm/Eggs
>naffected
(carrier
inheritance
Autosoal recessive
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Autosoal recessiveinheritance
Autosoal recessive
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Autosoal recessiveinheritance
•ecessive Mutations are hoo,ygous or copound/
hetero,ygous•Carrier of hetero@ygous mutations are clinically unaected•-arents of an aected child are usually healthy and are carriers
of a hetero@ygous mutation
A*he ris" for a healthy person to be a genetic carrier of arecessive disease is ;:;> to ;:7>>
7isE astiation54JK hori,ontaltransissionKected
•Currently, in human around E>>>E>>> autosomal recessivediseases are "nown so far•Incidence of autosomal recessive diseases: 4. in 9Knew
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>ln%al Patterns
• Sickle Cell disease
• Cystic fibrosis (:)"944
• Phenylketonuria (PKU) :9"444
• Congenital deafness
• Batten Disease
• Spinal muscular atrophy :4"444
• !ecessi"e blindness
• #aple syrup urine disease
• &emo%hromatoss - :644
Autosoal recessiveinheritance
•! particular form of deafness is inherited as a
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! particular form of deafness is inherited as arecessive trait by Mendelian way of Autosoalrecessive inheritance
5ome other type isinherited by autosomaldominant way
$ystic 1
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y -
+ne out of every 7,B>> whites of #uropean descent but ismuch rarer in other groups.
+ne out of 7B whites /E 0 is a carrier
Gene codes for a membrane protein thatfunctions in chloride ion transportbetween certain cells and thee$tracellular
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5ay?Sachs disease ; (Autosoalrecessive
•fatal genetic disorder! mostly in children•aused by a dysfunctional &ital en$yme called he-osaminidase?A
("e-?A! fails to brea down brain ner&e cells lipids (called GM)
ganglioside of a certain class.
!icEle cell disease -Autosoal recessive
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!icEle/cell disease # -Autosoal recessive5ic"le)cell disease is caused by the substitution of a single amino
acid substitution in the hemoglobin protein of red blood cellsGene mutation aects ; out of E>> !frican !mericans.
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* lined inheritance
%n * lined inheritance the gene ispresented only * or 0 chromosome
F lnked nhertan%e
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X-linked recessive
Males with an altered gene on the0/chroosoe are always a>ected
Male
•5he males ha&e only one * chromosome! therefore they are
hemi$ygous•'emales can be hetero$ygous/careers
F lnked nhertan%e
Male
X-linked dominant
Males
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0/linEed recessive inheritance
)ne copy of an alteredgene on the 0chroosoe causes thedisease in a ale.
Male
An altered copy on oneof the 0 chroosoepair causes carrierstatus in a feale.
0 00 *
3eale
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F l k d h t
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F-lnked re%esse nhertan%e
pedgree
!e= LinEed "isorders in 'uans
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+=aples of 0/LinEed 7ecessive$onditionsA 1aemophilia
A 3uchenne muscular dystrophy /3M30 /ec"er M30
Aragile H syndromeA abry disease
A etinitis pigmentosa
A !lport syndrome
A 1unter syndrome
A +cular albinism+cular albinism
A !drenoleucodystrophy.!drenoleucodystrophy.
!e=/LinEed "isorders in 'uans
0/LinEed recessive inheritance
"uchenne uscular dystrophy
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y p y
•aects about one out of every 9,B>> males
•-eople with 3uchenne muscular dystrophy rarely livepast their early 7>s.
• *he disease is characteri@ed by a progressivewea"ening of the muscles and loss of coordination.
•-eople with syndrome have an absence of a "eymuscle protein called dystrophin and have trac"ed thegene for this protein to a speci'c locus on the Hchromosome.
Posture changes during progression of
Duchenne muscular dystrophy.
'eophilia
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+>ects of haeophilia-a 2leeding around el>>8;>,>>> male births.
aemophilia /factor IH de'ciency0 occurs in around ; in about7>,>>>89E,>>> male births
"emophilia
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$olor 2lindness In 'uans
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4umbers *hat Kou 5hould 5ee If Kou !re In +ne +f *he ollowingour Categories
*?Lined 5raits+
. @ormal olor =ision+
A+ )! ,+ 9B! + ??! D+ ):
). 1ed?Green olor?,lind+ A+ C! ,+ ??! + B! D+ ??
8. 1ed olor?blind+
A+ C! ,+ ??! + B! D+ :
9. Green olor?,lind+
A+ C! ,+ ??! + B! D+ )
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,aldness
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=aldness s an autosomal trat and s apparently n'luen%ed by sex hormones a'ter
people rea%h *4 years o' age or older.
?n men the gene s domnant" whle n women t s re%esse. A man needs only one
allele @= 'or the baldness trat to be expressed" whle a bald woman must be
homo#ygous 'or the trat @==.
6hat are the probabilities for the children for a bald man and
woman with no history of baldness in the family3
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/-lnked nhertan%e
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*/linEed inheritance shows a patters of transission of theutant phenotype fro father to son and it never appearsin faales.
*/linEed phenotypic trait is hairy ears.
1ett Syndrome
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1ett Syndrome
• 1ett syndrome s a rare x-lnked domnant seere bran dsorder
that mostly a''e%ts to 'emales. =e%ause t s lethal n hem#ygousmales.
– ,he males who sures wth ths syndrome usually hae two F-%romosomewth 6HFF/ Ilne'elter.
• A''e%ted about one n 4"444 to 9"444 'emales
Syndrome %aused by spontaneous
mutaton n F-lnked gene 2B>P).
?tJs beleed that the sngle gene
may n'luen%e many other genes
noled n deelopment.
Mosaicism
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Mosaicism
•Mosaicism is the presence in an indi&idual or a
tissue that contains at least two cell lines with
genetically different from whole body
It occurs when in the tissue one or two cell
lines undergo mutation and alter genetically
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Kse'ul lnks
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Kse'ul lnks
• http:$$anthro.palomar.edu$mendel$mendelL.htm
• http:$$www.nature.%om$s%table$top%page$mendelan-genet%s-patterns-o'-nhertan%e-and-sngle-388