•91. Cell Reproduction Notebook Check•92. Karyotype Lab (graded)•93. Intro to Genetics Reading Guide (stamped)•94. Genetics Notes•95. Punnett Squares•96. More Punnett Square Practice•97. Exceptions to Mendel’s Rules•98. Oompah Loompa’s•99. Progress Report #6•100. POP QUIZ!•101. Pedigrees (a & b)•102. Ugly Baby Lab•103. Genetic Disorders

• Finish Genetic Disorders #103• 3/29 & 3/30 Genetics Unit

TEST!

HOMEWORK!!

a medical procedure used to diagnose chromosomal disorders in a developing fetus. A small amount of amniotic fluid, which contains fetal

tissues, is extracted from the amniotic sac surrounding a

developing fetus, and the DNA is examined.

AMNIOCENTESIS

GENETICS #94• Gregor Mendel = father of heredity–Mid 1800s–Studied garden pea plants (because they

could produce purebred individuals)–Studied how traits were passed from one

generation to the next

–Mendel came up with several important concepts

1. Parents pass on genes2. For each trait, an organism has 2 genes (1

allele from Mom and 1 from Dad)3. Alleles can be dominant and recessive• Tall plants could equal TT or Tt, short = tt•Genotype = genetic make-up for trait (TT)• Phenotype = physical look of trait (tall)

Law of Dominance• If organisms contain two identical

alleles for a trait, it shows that trait.Curly hair = HHStraight hair = hh

• If organisms contain two different alleles for a trait, it shows the dominant trait.Curly hair = Hh

HOMOZYGOUS ALLELES

HETEROZYGOUS ALLELES

Punnett SquaresUsed to

predict the possible

combinations of dominant

and recessive alleles in the

offspring.Genotypic ratio = 1 RR : 2 Rr : 1 rrPhenotypic ratio = 3 pink : 1 yellow

• Dad = XY, some sperm have X, some have Y• Mom = XX, all eggs

have X because that’s all Mom has to donate• Who determines

gender of baby – Mom or Dad?

Determining Gender!

Law of Independent Assortment

The genes for traits found on different chromosomes separate independently

when gametes are made.

Test CrossA deliberate

genetic cross with a homozygous

recessive individual that can be used to

determine whether an organism is

homozygous or heterozygous dominant for a

trait.

?

Phenotype is a mix of geneticsand environment

MostlyEnvironment Mix

MostlyGenetic

Language Height Blood typeReligion Weight Eye color

Intelligence

Nature vs. Nurture Debate

1. Green pea plant (GG) X Green pea plant (Gg)2. Tall plant (TT) X short plant (tt)3. Two tall plants (Tt)4. Two white flowers (white = recessive)5. Homozygous red flower X white flower6. Homozygous dominant brown mouse X

heterozygous brown mouse (tan = recessive)7. Heterozygous white rabbit X black rabbit.8. Two heterozygous white rabbits. (black = rec)9. How would you figure out if a purple plant

(dominant) is heterozygous vs. homozygous?

#96 More Punnett Square Practice(make Punnett Squares & describe offspring using genotypic and phenotypic ratios)

GENOTYPIC RATIO

PHENOTYPIC RATIO

Sometimes genetics isn’t always as simple as Mendel’s

Law of Dominance

Exceptions to Mendel’s Rules

#97

• Heterozygote is a BLEND of the 2 homozygotes• RR = red flowers• rr = white flowers• Rr = PINK flowers• Cross two pink flowers.• Genotypic ratio 1:2:1• Phenotypic ratio

Incomplete Dominance

1 red: 2 pink: 1 white

Codominance• Heterozygote show BOTH traits• BB = black cows• WW = white cows• BW = black & white• BB X WW• All BW offspring• Genotypic ratio = 0:4:0• Phenotypic ratio = 0:4:0

Multiple Alleles• Traits that have more than two

alleles.• Blood types –

3 allelesA and B are co-dominantO is recessive to A and B

4 phenotypes1)Type A

blood contains “A” proteinsgenotype: AA or AO

2) Type Bblood contains “B” proteins (genotype: BB or BO)

3)Type ABblood contains both proteins genotype: AB

4) Type Oneither protein present in bloodGenotype: OO

• AB is an example of ________________.

Polygenic Inheritance• Several genes are inherited

from each parent for 1 trait.• Many possible phenotypes.• Examples: skin color, eye color,

height, weightABC, ABc, AbC, aBC = dark

abc, abC, Abc, aBc = light

ABC ABc AbC Abc aBC aBc abC abc

ABC 66 5 5 4 5 4 4 3ABc 5 4 4 3 4 3 3 2AbC 5 4 4 3 4 3 3 2Abc 4 3 3 2 3 2 2 1aBC 5 4 4 3 4 3 3 2aBc 4 3 3 2 3 2 2 1abC 4 3 3 2 3 2 2 1abc 3 2 2 1 2 1 1 0

• Located on X chromosome• Females are only carriers• Mostly males are affected• Colorblindness, hemophilia, baldness• XBXB = normal female• XBXb = carrier female• XbXb = colorblind female• XBY = normal male• XbY = colorblind male• Cross a carrier female with a normal male.

Explain the possible offspring.

Sex-Linked Traits

#98