DNA, Genes, Chromosomes, and Cells

• Your body is made of trillions of cells, each one with a nucleus.

• Inside each nucleus are 46 chromosomes.

You got 23 from mom, 23 from dad

• Chromosomes are made of many genes

http://www.connectmydna.com/the-science/

• Genes are made of long sections of DNA (deoxyribonucleic acid)

DNA

http://abcnews.go.com/blogs/business/2013/04/letter-on-dna-structure-sells-for-record-5-3-million/

• Some of the genes you inherit are dominant, some of the them are recessive.

• Scientists can look at these genes on your chromosomes and use them to help diagnose disease or provide better treatment.

http://cpmc.coriell.org/

You may soon go to your doctor with a picture of your chromosomes

Karyotype

Normal babies have cells with 46 chromosomes

Normal sperm and egg cells each have 23 chromosomes

A picture of a cell’s chromosomes is called a karyotype.

Chromosomes are paired up and lined up according to their patterns

and size.

We use “cartoon” versions of chromosomes to make our task

easier.

The different patterns on

chromosomes are different

genes for traits

A karyotype can be used to diagnose a disease or determine

gender

Boys are XY, girls are XX for chromosome #23

Sometimes there are extra or missing chromosomes

Turner’s Syndrome (one X)

Klinefelter’s Syndrome (XXY)

Cri du Chat Syndrome (deleted part of chromosome 5)

Down Syndrome (3 copies of #21)

Karyotypes can be made for a fully formed human or for a developing

fetus.

Why would a parent want to know a child’s karyotype?

Early testing can help parents prepare physically and

emotionally for the birth of their child. They can be better

prepared to meet the needs of their child with early

intervention and care.

To determine risk of a genetic disorder or the gender of the child.

Even plants can have a karyotype made of their chromosomes for

identification purposes

Genetic testing can now be used to search for potential diseases

• Breast/ovarian cancer (#17 and 13)

• Alzheimer’s (#19)

• Cystic Fibrosis (#7)

• Autism (#15 is different if the person has this disease-not yet known why this happens)

Genetic testing can also be used to determine gender, especially in

cases of elite athletes.

http://www.hhmi.org/biointeractive/gendertest/gendertest.html

http://www.nytimes.com/2010/04/08/sports/08sportsbriefs-semenya.html

http://news.bbc.co.uk/2/hi/programmes/newsnight/9373209.stm

Your task:

• You will receive a sample of chromosomes from a developing fetus.

• You must arrange the chromosomes according to size and pattern into a karyotype.

• You will then determine the gender and disease this child may have (if any).

• Conclusion questions and karyotype are due on Thursday.

Instructions:1. Carefully cut apart the chromosomes, do NOT lose any!

2. Using the “Normal Karyotype” as your guide, arrange the patient’s chromosomes according to the same pattern.

3. Glue/Tape the chromosomes into place on the attached paper.4. Compare your patient’s karyotype to the normal karyotype and the disease

chart to determine, what disease, if any, the child has.

Genetic DisorderDown's Syndrome Turner's Syndrome Klinefelter Syndrome Cri du Chat Syndrome

karyotype change 3 copies of chromosome 21

one X only for chromosome 23

XXY for chromosome 23 deleted part of chromosome 5

How often does it occur? 1 in 800 1 in 2000 1 in 750 1 in 50,000

Physical Symptoms

mental retardation, eyes slant upwards, prone to heart defects and respiratory problems.

normal female in childhood, normal intelligence, fails to fully undergo

puberty and will remain infertile

male, normal in appearance and intelligence, sterile, may show some female characteristics (breast development, feminine

body shape)

distinctive cat-like cry in babies, respiratory

problems, shortened life

span is possible

Genetic DisorderTriple X Syndrome Edward's Syndrome Patau Syndrome Trisomy 23

karyotype change XXX for chromosome 23 3 copies of chromosome 18 3 copies of chromosome 13 XYY for chromosome 23

How often does it occur? 1 in 700 1 in 6,000 1 in 15,000 1 in 2,000

Physical Symptoms

female with normal intelligence and

appearance, may be sterile

feeding and breathing difficulties,

developmental delays, deformation of head

and face, cardiac defects, often results

in early death

mental retardation, cleft palate, extra fingers and

toes, incomplete development of internal organs, often results in

early death

male with low mental ability, normal in

appearance

Genetic Disorder Down Syndrome

karyotype change

3 copies of chromosome 21

How often does it occur?

1 in 800

Physical Symptoms

mental retardation, eyes slant upwards, prone to heart defects and respiratory problems.

http://www.ndss.org/

Genetic disorder

Turner Syndrome

karyotype change

one X only for chromosome 23

How often does it occur?

1 in 2000

Physical Symptoms

normal female in childhood,

normal intelligence, fails to fully

undergo puberty and will remain infertile

http://www.turnersyndrome.org/welcome-turner-syndrome-society-us

Genetic disorder

Klinefelter Syndrome

karyotype change

XXY for chromosome 23

How often does it occur?

1 in 750

Physical Symptoms

male, normal in appearance and

intelligence, sterile, may show

some female characteristics

(breast development, feminine body

shape)

http://ghr.nlm.nih.gov/condition/klinefelter-syndrome

Genetic disorder

Cri du Chat Syndrome

karyotype change

deleted part of chromosome 5

How often does it occur?

1 in 50,000

Physical Symptoms

distinctive cat-like cry in babies,

respiratory problems,

shortened life span is possible

http://www.fivepminus.org/

Genetic disorder

Triple X Syndrome

karyotype change

XXX for chromosome 23

How often does it occur?

1 in 700

Physical Symptoms

female with normal

intelligence and appearance,

may be sterile http://www.mayoclinic.com/health/triple-x-syndrome/DS01090

Genetic disorder

Edwards Syndrome

karyotype change

3 copies of chromosome 18

How often does it occur?

1 in 6,000

Physical Symptoms

feeding and breathing difficulties,

developmental delays,

deformation of head and face, cardiac defects, often results in

early death (fewer than 10% live for a

year)

http://www.trisomy18.org/site/PageServer?pagename=parents_whatisT18

Genetic Disorder

Patau Syndrome

karyotype change

3 copies of chromosome 13

How often does it occur?

1 in 15,000

Physical Symptoms

mental retardation, cleft

palate, extra fingers and toes,

incomplete development of internal organs, often results in

early death http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002625/

Genetic Disorder

Trisomy 23

karyotype change

XYY for chromosome 23

How often does it occur?

1 in 2,000

Physical Symptoms

male with low mental ability,

normal in appearance

http://ghr.nlm.nih.gov/condition/47xyy-syndrome