mendel april 2014

7/24/2019 Mendel April 2014

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RETNO DWI WULANDARI

pril 2014


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Gregor Johann Mendel (1882-1884)

Biarawan Austrian1856 1863:membudidayakan dan

melakukan percobaan28,000 kacang polong (Pisumsativum)Pola pewarisan sifat pada

tanaman tsb : tanaman anakmewarisi sifat tanamaninduk

copyright cmassengale

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The laws of inheritance


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Gregor Johann Mendel (Father of Genetics)

Mendel : sifat yg diwariskan particles

particles were actually Chromosomes & DNA

Mendel's work was not recognized until the

turn of the 20th century


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Istilah-istilah penting :

Sifat (Trait)karakter yang diwariskan dariorang tua ke anak

Hereditas (Heredity)pewarisan sifat dariorang tua anak

Genetikamempelajari hereditas


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Percobaan Mendel dengan Kacang Polong


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Cross 2 P:

Pure Plants

(Tall x short)

F1:

Results in all

(tall) Hybrids

Cross 2 Hybrids

get F2:

3 Tall & 1 Short

Tall dominant trait


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copyright cmassengale6

Eight Pea Plant Traits


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Mendels Experimental Results


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Istilah penting

Alel (allele) dua bentuk gen (dominan &resesif)

Dominan gen yg lebih kuat , berekspresi

pada hybrid; ditulis huruf besar (R) Resesif (Recessive)gene that shows up less

often in a cross; ditulis huruf kecil (r) Genotip (Genotype) kombinasi gen untuk

suatu sifat (mis. RR, Rr, rr) Fenotip (Phenotype) - tampilan fisik dari

suatu genotip (mis. Bunga warna red, white)



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Homosigot (Homozygous)genotype

kombinasi gen yang terdiri dari 2 gen dominan

atau 2 gen resesif(mis. DDordd)

pure

Heterosigot (Heterozygous)genotype

kombinasi gen : 1 alel dominant & 1 recessive

(Dd) hybrid



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Types of Genetic Crosses

Monohybrid cross perkawinan (cross ) yg

melibatkan 1 sifat (single trait),mis. Warna bunga

Dihybrid cross-melibatkan 2 sifat , mis. flower

color plant height


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Alleles: A

Round a

Wrinkled

Cross: Roundseeds x Wrinkled seeds

AA x aa

A

A

aa

Aa

AaAa

Aa

Genotype:Aa

Phenotype:Round

Genotypic

Ratio: All alike (100 )

Phenotypic

Ratio:All alike (100 )

Seed Shape cross (homozygous)

b d k


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F1Mono ybrid Cross untuk genotipheterozygote


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Trait: Seed Shape

Alleles: ARound aWrinkled

Cross: Roundseeds x Round seeds

Aa x Aa

A

a

aA

AA

aaAa

Aa

Genotype:AA, Aa, aa

Phenotype:Round &

wrinkled

Ratio genotip : 1:2:1

Ratio fenotip : 3:1


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Monohybrid Cross


Trait: Seed colour Alleles: BBrown bWhite Cross: Brownseeds x Brown seeds BB x Bb

B

B

bB

BB

BbBB

Bb

Genotype:BB, Bb

Phenotype:Brown

GenotypicRatio: 1:1

PhenotypicRatio:All alike

b d


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Mono ybrid Cross(heterosigot x homosigot)

copyrightcmassengale

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Trait: Seed Shape

Alleles: R

Round r

Wrinkled

Cross: Wrinkledseeds x Round seeds

rr x Rr

r

r

rR

Rr

rrRr

rr

Genotype:Rr, rr

Phenotype:Round &

Wrinkled

Genotype Ratio: 1:1

PhenotypeRatio:1:1


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Mendels Principles (laws) of inheritance

1.

Law of segregation or purity of gametes.

At formation of gametes, the two chromosomes ofeach pair separate (segregate) into two different cell

which form the gametes.

Each gamete receives one member of a pair offactors and the gametes are pure.


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Applying the Law of Segregation


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Applying the Law of Segregation


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2. Law of Independent Assortment


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Alleles for differenttraits are distributedto sex cells (& offspring) independently of

one another.Alel untuk sifat berbeda didistribusikan ke sel seks (gamet)secara indpendent satu dengan yang lain

This law can be illustrated using dihybrid

crosses.


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Dihybrid Cross

Traits: Seed shape & Seed color

Alleles: R round

r wrinkled

Y yellow

y green

RrYy x RrYy

RY Ry rY ry

RY Ry rY ry


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Dihybrid Cross (RrYy x RrYy)


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RY Ry rY ry

RY

Ry

rY

ry

RRYY RRYy RrYY

RrYyRrYY

rryyrrYyRryyRrYy

RRYy RRyy RrYy Rryy

RrYy

rrYyrrYY

Alleles: R round

r wrinkled

Y yellow

y green


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3. Law of dominance

Hybrid offspring have visibly the character of onlyone parent or the other, though they transmit

those of both parents.

Sepasang gen yang mengendalikan karakter /sifatyang sama (misal warna bunga), tetapi kontras(bunga merah-MM atau bunga putih-mm), makaperkawinan MM x mm akan menghasilkanketurunan bunga warna merah-Mm. Bunga merah(Mm) seolah-olah hanya memiliki sifat dari salahsatu induk, meskipun mewarisi gen dari keduainduknya


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Dominant & Recessive Alleles

Dominant: produces the same phenotypewhether it is paired with same or different allele

R is dominant to r therefore RR or Rr has the

same phenotype (exp. Red flower)

Recessive: produces the same phenotype only ifit is paired with the same allele

rr code for white flower


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Dominant & Recessive Alleles

f


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Summary of Mendels laws


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LAWPARENTCROSS

OFFSPRING

DOMINANCE TT x tttall x short

100% Tttall

SEGREGATIONTt x Tttall x tall

75% tall25% short

INDEPENDENTASSORTMENT

RrGg x RrGg

round & greenxround & green

9/16 round seeds & greenpods3/16 round seeds & yellow

pods3/16 wrinkled seeds & greenpods1/16 wrinkled seeds & yellowpods


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genetic pedigree

Unaffected female:Affected female:Unaffected male:

Affected male:

1 2

1 2 3 4 5

1 2 3 4 5

I

II

III


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Autosomal dominant pedigree

Trait is found in every generation Affected individuals transmit the trait to ~1/2 of their

children (regardless of sex) Affected children have at least one affected parent Two affected parents can produce an unaffected child


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Autosomal dominant traits

There are few

autosomal dominanthuman diseases (why?),but some rare traitshave this inheritance

pattern

ex. achondroplasia (a sketelaldisorder causing dwarfism)


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Dominant Recessive

dimples no dimples

unattached ear lobes attached ear lobes

Roman nose straight nose

rolling tongue into a U non-rolling tonguecurved thumb straight thumb

curly hair straight hair

right handed left handed

hair on fingers hairless fingers


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Autosomal recessiveAutosomal recessive

1. Affected childrencan have unaffectedparents

2. Both males andfemales are affectedwith equal frequency

3. Heterozygotes havea normal phenotype

4. Two affected parentswill always haveaffected children


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Autosomal recessive

Albinism (a) : Lack of pigment in skin, hair, and eyes

Cystic Fibrosis (CF) :

Caused by recessive allele on chromosome 7


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Variations on Mendels Principles

Codominance, multiple alleles Incomplete dominance Pleiotropy Polygenic traits Sex-linked genes

Environmental effects


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Codominance

and

Incomplete dominance


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Bl d h b th M lti l All l


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Blood has both Multiple Allelesand is CoDominant

Codominant:

when neither of two alleles dominate the other

blood type: A is dominant over O

B is dominant over O

therefore, O is recessive

A and B are codominant


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Codominant

Examples of Blood type crosses


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Multiple Alleles

Blood type in humans is an example of this

inheritance pattern.

The ______different

blood groups:

A, B, O, and AB

Are produced

by ______different

alleles:

A, B, and O

Phenotype Genotype

A AA or AO

B BB or BO

AB AB only

O OO only

four

three


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Multiple Alleles

Examples of Blood type crosses


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Incomplete dominance

an offsprings

phenotype isintermediatebetween thephenotypes of itsparents

P GENERATION

F1GENERATION

F2GENERATION

RedRR

Gametes R r

Whiterr

PinkRr

R r

R R

r r

1/21/2

1/2

1/21/2

1/2SpermEggs

PinkRr

PinkrR

Whiter r

RedRR

Figure 9.12A


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Incomplete dominance in human hypercholesterolemia

Figure 9.12B

GENOTYPES:

HH

Homozygous

for ability to make

LDL receptors

Hh

Heterozygous

hh

Homozygous

for inability to

make

LDL receptors

PHENOTYPES:

LDL

LDL

receptor

Cell

Normal Mild disease Severe disease

A singl g n ma aff t man ph n t p s


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A single gene may affect many phenotypes:

pleiotropy


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Polygenic Traits

Traits controlled by two or more genes

Show a widerange ofphenotypes

The phenotype

is produced by

the interaction

of more than

________

of genes.

1 pair


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Polygenic Traits

These are called ___________ traits, which means

having _______ genes

In humans, _____ color,

_____ color,

polygenic

many

skin

eye


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Polygenic Traits




_____ color,

and _____ color

polygenic

many

skin

eye

hair
http://custombeautyproducts.com/wp-content/uploads/2007/08/082107-hair-color-examples.jpghttp://custombeautyproducts.com/wp-content/uploads/2007/08/082107-hair-color-examples.jpghttp://custombeautyproducts.com/wp-content/uploads/2007/08/082107-hair-color-examples.jpghttp://custombeautyproducts.com/wp-content/uploads/2007/08/082107-hair-color-examples.jpghttp://custombeautyproducts.com/wp-content/uploads/2007/08/082107-hair-color-examples.jpg


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Polygenic Traits




_____ color,

and _____ color

are just a few of

the many traits

__________ by

many genes.

polygenic

many

skin

controlled

eye

hair
http://custombeautyproducts.com/wp-content/uploads/2007/08/082107-hair-color-examples.jpghttp://custombeautyproducts.com/wp-content/uploads/2007/08/082107-hair-color-examples.jpghttp://custombeautyproducts.com/wp-content/uploads/2007/08/082107-hair-color-examples.jpg


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Polygenic Traits

Sometimes the combination of the different genes

results in continuous__________of these traits.

The combined size of all

the______parts fromhead to foot, determines

the_______of the person.

variation

body

height

James Bond Height Chart


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What is Sex Linkage?

Selain menetukan jenis kelamin, kromosom seksmemiliki gen-gen untuk beberapa karakter.

Gen-gen yang terletak pada kromosom seks dsebut: sex linked genes.

X-linked characters: gen terletak pada kromosom X Seorang ayah mewariskan X-linked alleles ke anak2

perempuan, tetapi tidak pada anak laki2

Seorang ibu dapat mewariskan

sex-linked alleles

ke

anak laki2 maupun perempuan.


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X-linked Recessive alleles

If a sex linked trait is due to a recessive allele: A female will express the phenotype only if she is

homozygous recessive. If a male receives the recessive allele from his mother he

will express the phenotype.

Far more males have disorders that are inherited assex linked recessives than females.

Examples: Colour blindnessHaemophilia

X-linkedrecessive

traits ditulis dengan Xa


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X-linkedDominantInheritance

Sifat X-linked dominant disebabkan adanya aleldominan pada kromosom X.

Tidak seperti X-linked recessive traits, female dan

male keduanya membutuhkan SATU alel dominanuntuk mengekspresikan sifat tsb.

X-linked dominanttraits ditulis dengan XA


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X linked dominantpedigree

male affected

female

affected

l h


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X-linked Dominant Inheritance

Example: Faulty Tooth Enamel and DentalDiscoloration

Individuals who have an X chromosome thatcarries a dominant allele for this trait will havedental discoloration.

l


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Y-linked pedigree

l h


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Y-linked Inheritance

All of the sons of an affected male will display thisY-linked trait.

Hairy ears


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mendel april 2014

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