LH. Biology Heredity

Benchmark 1

Explain how characteristics of living things arepassed on from generation to generation.

Being Able to Curl up both sides of the Tongue is under the control of a dominant allele at one gene locus.

RRRrrr

Homozygous recessiveHomozygous recessive

Homozygous DominantHomozygous Dominant

HeterozygousHeterozygous

Inheritance for Tongue Rolling and Non-tongue Rolling

Susan’s mom is a tongue roller. Her father is a Susan’s mom is a tongue roller. Her father is a non-tongue roller. Susan has three oldernon-tongue roller. Susan has three olderbrothers and one younger sister. Her threebrothers and one younger sister. Her threebrothers are all tongue rollers. Her sister is brothers are all tongue rollers. Her sister is a non-roller.a non-roller. What are the genotypes of eachWhat are the genotypes of eachmember of Susan’s family?member of Susan’s family?

R = allele for ability to roll the tongueR = allele for ability to roll the tongue

r = allele for non-rollerr = allele for non-roller

What are Susan’s Family Tongue Rolling Genotypes?

Dad = rrDad = rr (non-roller, (non-roller, recessiverecessive trait expressed) trait expressed)

Sister = rrSister = rr (non-roller, (non-roller, recessiverecessive expressed) expressed)

Mom = RrMom = Rr ( (heterozygousheterozygous, mom had to donate, mom had to donatethe the “r” allele“r” allele to Susan’s sister and since mom is to Susan’s sister and since mom isa roller she must have the a roller she must have the “R” allele“R” allele))

Susan and her brothers = RrSusan and her brothers = Rr ( (heterozygousheterozygous, each, eachchild inherits an child inherits an “r” allele“r” allele from dad and because from dad and becausethey can roll they each inherited an they can roll they each inherited an “R” allele“R” allele from mom)from mom)

Mark marries Susan. . .

Mark’s momMark’s mom is a is a non-rollernon-roller and his and his daddad is a is arollerroller. Mark’s two. Mark’s two brothers brothers are are rollers rollers..

Mark and Susan are planning a family. What isMark and Susan are planning a family. What isthe probability that Susan will deliver a the probability that Susan will deliver a roller, a non-roller?roller, a non-roller?

What is What is Mark’s genotypeMark’s genotype for ability to for ability toroll the tongue?roll the tongue? RrRr

Punnett SquarePunnett SquareMarkMark

SSuussaann

RR rr

RR

rr

RR RR

rr rr

RR

RR

rr

rr

Genotypic Ratio 1:2:1Genotypic Ratio 1:2:1

Phenotypic Ratio 3:1Phenotypic Ratio 3:1

RollerRoller RollerRoller

RollerRoller Non RollerNon Roller

After fourteen years of marriage...After fourteen years of marriage...

MarkMarkSusanSusan

JessicaJessica AshleyAshley

……are all happy ROLLERS !!!are all happy ROLLERS !!!

Baby Peas Don’t Go

Baby Peas Don’t Go

Gregor Mendel Father of Heredity

Watson

Crick

Look, the Structureof DNA!

DNA Model1953

r rRr

r r

R r

If Mary and Peterare both Rollers, whatare the chances forAnne to be roller,a non-roller ?

TraitsDominantRecessive

Genetic materialgene pairgene combinationgene sorting

Key Concepts

Common contextsInheritance of a human genetic disease/disorder, such as sickle cell anemia

A family tree focused on certain traits

Examining animal or plant pedigrees.

Real-world contexts

Sickle Cell Anemia

http://www.bio.miami.edu/dana/250/25002_4print.html

a. no because both parents have only genes for being brown

b. yes, because offspring color does not depend on the genes of the parents

c. yes, because both parents have and pass on the gene for being white

d. no, because the parents can only pass on the dominant gene to their offspring.

A particular species of bird can be brown or white. The white color is a recessive trait,

while the brown color is a dominant trait. When two brown birds mate,

is it possible for them to have white offspring?

a. no because both parents have only genes for being brown

Incorrect: You don’t know for sure if both parents have two genes for being brown (BB). They could have a Brown gene and a white gene (Bb) and still have the phenotype (what they look like) of white color

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b. yes, because offspring color does not depend on the genes of the parents

Incorrect: The color does depend on their genes. This is an inherited trait.

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c. yes, because both parents have and pass on the gene for being white

Correct: You don’t know for sure if both parents have two genes for being brown (BB). They could have a Brown gene and a white gene (Bb) and still have the phenotype (what they look like) of white color

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d. no, because the parents can only pass on the dominant gene to their offspring.

Incorrect: They have an equal

chance of passing on the dominant and recessive gene if the contain both. The term dominant means that when an individual has two different genes for a trait the dominant is the one that shows up in the phenotype (appearance)

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