A Family Tree

To understand how traits are passed on , a pedigree diagram showing the family relationships, is used. In a pedigree, a circle =‘s a female, a square =‘s a male. A filled-in circle or square shows that the individual has the trait. The horizontal line that connects a circle and a square =‘s a marriage. The vertical line(s) and brackets below are the child(ren) of that couple.

1. This pedigree shows the inheritance of attached ear lobes. Which parent has attached ear lobes?2. How many children do the parents have? Which child has attached ear lobes?3. Which child is married? Does this child’s spouse have attached ear lobes? Do any of this child’s children have attached ear lobes?

14–1 Human Heredity

A.Human Chromosomes1. Karyotype a. autosomes b. sex chromo- somes

Making a Karyotype activity

http://learn.genetics.utah.edu/units/disorders/karyotype/karyotype.cfm

B. Human Traits- Click to see pedigree chartC. Human Genes

1. Blood Group Genes Click to see slide2. Recessive Alleles3. Dominant Alleles4. Codominant Alleles

D. From Gene to Molecule1. Cystic Fibrosis Click here for slide2. Sickle Cell Disease Click here for slide

Click here for concept map of these 3 alleles

Click button if you want to go directly to the next section

A square represents a male.

A horizontal line connecting a male and female represents a marriage.

A vertical line and a bracket connect the parents to their children.A half-shaded

circle or square indicates that a person is a carrier of the trait.

A completely shaded circle or square indicates that a person expresses the trait.

A circle or square that is not shaded indicates that a person neither expresses the trait nor is a carrier of the trait.

A circle represents a female.

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Phenotype(Blood Type Genotype

Antigen on Red Blood Cell

Safe Transfusions

To From

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caused by

Concept MapAutosomalDisorders

Recessive alleles Dominant alleles Codominant alleles

AlbinismGalacto-

semia

Tay-Sachs

disease

Huntington’s Sickle cell

Cystic fibrosis

Phenylketo-nuria

Achondro-

plasiaHyper-choles-

terolemia

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Chromosome # 7

The most common allele that causes cystic fibrosis is missing 3 DNA bases. As a result, the amino acid phenylalanine is missing from the CFTR protein.

Normal CFTR is a chloride ion channel in cell membranes. Abnormal CFTR cannot be transported to the cell membrane.

The cells in the person’s airways are unable to transport chloride ions. As a result, the airways become clogged with a thick mucus.

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20% of African Americans are carriers for sickle cell disease. Children who receive a recessive gene from each parent can become blind. Arms and legs can become paralyzed or even die. Strokes and heart attacks are common.

Treatments are available to decrease the complications of this disease but there is no cure.

Many African Americans will ask to be tested to see if they have one of these genes in their chromosomes.

Button takes you to next section.

Gender Benders

You may remember that in humans, the sperm cells may carry an X chromosome or a Y chromosome, while egg cells have only X chromosomes. Sometimes, errors during meiosis in one of the parents produce offspring with an abnormal number of sex chromosomes.

1. On a sheet of paper, construct a Punnett square for the following cross: XX x XY.

Fill in the Punnett square. What does the Punnett square represent? According to the Punnett square, what percentage of the offspring from this genetic cross will be males? What percentage will be females?

2. On a sheet of paper, construct a Punnett square for the following cross:

XXX x XY.

Fill in the Punnett square. How is this Punnett square different from the first one you constructed? What might have caused this difference?

3. How do the offspring in the two Punnett squares differ?

14–2 Human ChromosomesA. Human Genes and Chromosomes

Click for nondisjunction slideB. Sex-Linked Genes

1. Colorblindness Click for punnett square slide2. Hemophilia

http://www.ygyh.org/hemo/whatisit.htm 3. Duchene Muscular Dystrophy

http://www.ygyh.org/dmd/whatisit.htm

C. X-Chromosome Inactivation

The coloration of tortoiseshell cats is a visible manifestation of X-inactivation. The "black" and "orange" alleles of a fur coloration gene reside on the X chromosome. For any given patch of fur, the inactivation of an X chromosome that carries one gene results in the fur color of the other, active gene.

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D. Chromosomal Disorders

1. Down Syndrome- site has interactive slide show of how this syndrome occurshttp://learn.genetics.utah.edu/units/disorders/karyotype/downsyndrome.cfm

2. Sex Chromosome DisordersA. Turner’s site has interactive slide

show of how this syndrome occurshttp://learn.genetics.utah.edu/units/disorders/karyotype/turnersyndrome.cfm

B. Kleinfelter’s site has interactive slide show of how this syndrome occurshttp://learn.genetics.utah.edu/units/disorders/karyotype/klinefelter.cfm

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Homologous chromosomes fail

to separate

Homologous chromosomes fail

to separate

Meiosis I:Nondisjunction

Homologous chromosomes fail

to separate

Meiosis I:Nondisjunction

Meiosis II

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Daughter(normal vision)

Father(normal vision)

Colorblind

Normal vision

Mother (carrier)

Male

Female

Father(normal vision)

Colorblind

Normal vision

Mother (carrier)

Male

Female

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14–3-Human Molecular GeneticsA. Human DNA Analysis

1. Testing for Alleleshttp://www.accessexcellence.org/AE/AEPC/NIH/gene09.html Different types of genetic

tests are used to hunt for abnormalities in whole chromosomes, in short stretches of DNA within or near genes, and in the protein products of genes.

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2. DNA Fingerprinting-an on line interactive lab (takes 45 minutes, may wish to assign for home)

http://www.pbs.org/wgbh/nova/sheppard/analyze.html

DNA Game- quick look at how DNA fingerprinting can solve a crimehttp://library.thinkquest.org/C0125833/english/whodunit.php

Click to go to next slide

B. The Human Genome Project-This link is to the HGP home pagehttp://www.ornl.gov/sci/techresources/Human_Genome/home.shtml

1. Rapid Sequencing 2. Searching for Genes Click to go

to slide

3. A Breakthrough for Everyone –public knowledge and access. See above link. Click to continue outline

Sequences can locate genes.

Promoter

Intron

Insulin gene

Start codonStop codon

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C. Gene Therapy

Gene therapy using a virus. A new gene is inserted into a virus, which is used to introduce the modified DNA into a human cell. If the treatment is successful, the new gene will make a functional protein.

Who owns and controls genetic information?

Do healthcare

personnel

properly

counsel

parents about

the risks and

limitations of

genetic

technology?

Who should have access to personal

genetic information, and how will it be

used?

How will

genetic tests be

evaluated and

regulated for

accuracy,

reliability, and

utility?

D. Ethical Issues in Human Genetics

How does personal genetic information affect an individual and society's perceptions of that individual? How reliable and useful is fetal genetic testing?

How do we

prepare the

public to make

informed

choices?

How does genomic information affect members of minority communities?