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/

DNA Genes are made of long sections of DNA (deoxyribonucleic acid) 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? To determine risk of a genetic disorder or the gender of the child. 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.

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.

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

one X only for chromosome 23 XXY for chromosome 23 Genetic Disorder Down'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 Triple X Syndrome Edward's Syndrome Patau Syndrome Trisomy 23 XXX for chromosome 23 3 copies of chromosome 18 3 copies of chromosome 13 XYY for chromosome 23 1 in 700 1 in 6,000 1 in 15,000 1 in 2,000 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/

one X only for chromosome 23 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

deleted part of chromosome 5 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/

female with normal intelligence and appearance, may be sterile 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/

male with low mental ability, normal in appearance 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