Biology Week 18Biology Week 18 Mendel, Heredity, and Mendel, Heredity, and GeneticsGenetics Chapter 10.1 Pg. 253Chapter 10.1 Pg. 253

Gregor Gregor MendelMendel(1822-1884)(1822-1884)

The Father of The Father of GeneticsGenetics

Explain why

• some brown eyed parents may have blue eyed children, while

• other brown eyed parents cannot

a characteristic a characteristic that can be that can be

inheritedinherited

Traits are coded for by Traits are coded for by sections of DNA called sections of DNA called genesgenes

Eye color is a Eye color is a traittrait – –

which make up chromosomes in the nucleus

Different forms of the same trait (gene) are called alleles.

What are two alleles for eye color?

HeredityHeredity

the branch of the branch of biology that biology that studies hereditystudies heredity

Genetics Genetics The passing on of The passing on of

characteristics from characteristics from parents to offspringparents to offspring

Write observations for each generation.

TraitTrait

Characteristics that are inheritedCharacteristics that are inherited

GameteGameteA male or female sex cell, A male or female sex cell, has 1 set of chromosomes, has 1 set of chromosomes,

half of the amount of a normal body cellhalf of the amount of a normal body cell

A human male gamete has

1 set of 23 chromosomes

+A human female

gamete has1 set of

23 chromosomes

=A human body

cell has2 sets of

23 chromosomes

for a total of 46 chromosomes

FertilizationFertilization

When the male gamete unites with the When the male gamete unites with the female gametefemale gamete

zygote

The first cell is called a

ZygoteZygote

The cell which results from the fusing The cell which results from the fusing of male and female gametes, which of male and female gametes, which will develop into a seedwill develop into a seed

Male gameteFemale gamete

PollinationPollination

The transfer of The transfer of pollen grains in a pollen grains in a plant from a male plant from a male reproductive reproductive organ to a female organ to a female reproductive reproductive organ organ

HybridHybrid

The offspring of parents that have The offspring of parents that have different forms of a trait, such as different forms of a trait, such as yellow or green – which below is a yellow or green – which below is a hybrid?hybrid?

AlleleAllele

Different gene forms, Different gene forms,

ex. for eye color B (brown) or b (blue)ex. for eye color B (brown) or b (blue)

DominantDominant traits that don’t traits that don’t

always appear, can always appear, can be masked by be masked by dominant alleles,dominant alleles,

lower caselower case

RecessiveRecessive Traits that Traits that

always appear, always appear, CAPITAL LETTERCAPITAL LETTER

Human Traits:  autosomalHuman Traits:  autosomal 1. Shape of face (probably polygenic) 1. Shape of face (probably polygenic) Oval dominantOval dominant, square recessive, square recessive 2. Cleft in chin2. Cleft in chin No cleft dominantNo cleft dominant, cleft recessive, cleft recessive 3. Hair curl (probably polygenic)3. Hair curl (probably polygenic)

    Assume incomplete dominance    Assume incomplete dominanceCurly:  homozygousCurly:  homozygousWavy:  heterozygousWavy:  heterozygousStraight: homozygousStraight: homozygous

4. Hairline 4. Hairline Widow peak dominantWidow peak dominant, straight hairline recessive, straight hairline recessive 5. Eyebrow size5. Eyebrow size Broad dominantBroad dominant, slender recessive, slender recessive 6. Eyebrow shape6. Eyebrow shape Separated dominantSeparated dominant, joined recessive, joined recessive 7. Eyelash length7. Eyelash length Long dominantLong dominant, short recessive, short recessive 8. Dimples8. Dimples Dimples dominantDimples dominant, no dimples recessive, no dimples recessive 9. Earlobes9. Earlobes Free lobe dominantFree lobe dominant, attached recessive, attached recessive 10. Eye shape 10. Eye shape  Almond dominantAlmond dominant, round recessive, round recessive 11. Freckles 11. Freckles  Freckles dominantFreckles dominant, no freckles recessive, no freckles recessive 12. Tongue rolling 12. Tongue rolling Roller dominantRoller dominant, nonroller recessive, nonroller recessive 13. Tongue folding13. Tongue folding Inability dominantInability dominant, ability recessive, ability recessive 14. Finger mid-digital hair  14. Finger mid-digital hair   Hair dominantHair dominant, no hair recessive, no hair recessive 15. Hitch-hiker's thumb15. Hitch-hiker's thumb Straight thumbStraight thumb dominant, hitch-hiker thumb recessive dominant, hitch-hiker thumb recessive 16. Bent little finger16. Bent little finger Bent dominantBent dominant, straight recessive, straight recessive 17. Interlaced fingers17. Interlaced fingers Left thumb over right dominantLeft thumb over right dominant, right over left , right over left

recessiverecessive 18. Hair on back of hand18. Hair on back of hand Hair dominantHair dominant, no hair recessive, no hair recessive 19. Tendons of Palmar 19. Tendons of Palmar MuscleTwo tendons dominantMuscleTwo tendons dominant, three tendons recessive, three tendons recessive

Law of SegregationLaw of Segregation

States that every individual has two States that every individual has two alleles of each gene (ex. TT, Tt, or tt) alleles of each gene (ex. TT, Tt, or tt) and when gametes are produced, each and when gametes are produced, each gamete receives one of these allelesgamete receives one of these alleles

PhenotypePhenotype

The way an The way an organism looks organism looks and behavesand behaves

Genotype Genotype

The alleles that The alleles that an organism hasan organism has

HomozygousHomozygous

An organism that has the same two An organism that has the same two alleles for a trait, like TT or ttalleles for a trait, like TT or tt

HeterozygousHeterozygous

An organism that has different alleles An organism that has different alleles for a trait, like Ttfor a trait, like Tt

Law of Independent AssortmentLaw of Independent Assortment

States that States that genes for genes for different traits different traits are inherited are inherited independently independently of each otherof each other

Punnett SquarePunnett Square

Predicts the proportion of genotypes in Predicts the proportion of genotypes in the offspring produced by a crossthe offspring produced by a cross

Aa

Aa

aa

aa

Monohybrid Monohybrid Cross Cross

(mono-, "one, (mono-, "one, single"): a cross single"): a cross involving one set of involving one set of alleles, alleles,

ex. Aa x Aaex. Aa x Aa

(di-, "two"): a cross (di-, "two"): a cross involving two involving two different alleles different alleles

RrYy x RrYyRrYy x RrYy

Dihybrid Dihybrid CrossCross

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