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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 doinant


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Parents

Gamet es

A>ected A>ected %na>ect

ofspring


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 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.


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 recessive


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•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


•! 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

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