Biology April 6, 2015 Copy and answer the following EQ into your spiral notebook. EQ: What does a karyotype show us? A karyotype is an actual photograph of the chromosomes from one cell.

Word of the Day Genetic Disorder A genetic problem caused by one or more abnormalities in the genome, especially a condition that is present from birth (congenital).

Modern Genetics Monosomy, Trisomy, Addition & Deletion Disorders

How are Karyotypes made? A picture of all chromosomes is made. They are arranged by size. The last pair is always the sex chromosomes.

Normal Karyotype of Humans

Monosomy & Trisomy Monosomy occurs when nondisjunction occurs during meiosis and a chromosome is missing from a pair. Trisomy occurs when nondisjunction occurs during meiosis and a chromosome is added to a chromosome pair.

Addition & Deletion Addition occurs when nondisjunction during meiosis causes a chromosome to become fragmented and be added to a pair. Deletion occurs when nondisjunction during meiosis causes a chromosome to fragment and be lost from a pair.

Nondisjunction

Examples of Nondisjunction

Trisomy 21 – Downs Syndrome Occurs 1 in births Most common non-lethal trisomy 95% due to maternal nondisjunction Affected children have tongue protrusion, small head, flattened occiput, flat nasal bridge, epicanthal folds with up-slanting, loose skin around neck, short, stubby fingers, single palmer crease, and low IQ’s

Trisomy 21 – Downs Syndrome

Turner’s & Klinefelter’s Syndrome

Turner’s Syndrome – Monosomy 23 Occurs in approximately 1 in 5000 births. Common abnormalities include infertility, short stature, broad chest with widely spaced nipples, puffy fingers and toes, low hairline, and webbed posterior neck % have major cardiac malformations Most have normal IQ’s 99% of XO conceptions spontaneously abort.

Turner’s Syndrome – Monosomy 23

Kleinfelters Syndrome – Trisomy 23 Occurs in approximately 1 in 850 births. Common abnormalities include small testes, long arms and legs, often small genitals, high-voiced, not very hairy, and rarely go bald. Many Klinefelter men are sterile and their average IQ is lower than “normal”.

Kleinfelters Syndrome – Trisomy 23

Turner’s Syndrome – Monosomy 23

Kleinfelters Syndrome – Trisomy 23

Patau Syndrome – Trisomy 13 Occurs in approximately 1 in 20,000. Common abnormalities include cardiac disorders. Other abnormalities include microcephaly (tiny head), cleft lip, cleft palate, abnormal ears, punched out appearing scalp and polydactyl. Median survival rate of 3 days, 90% die in first month. Surviving infants are severely mentally disabled.

Patau syndrome – Trisomy 13

Cyclops Syndrome - Trisomy 13

Trisomy 18 - Edward Syndrome Occurs in 1 in 8000 births Most die within first week of life 45% die within one year of life. 95% have cardiac abnormalities Features include prominent occiput, malformed auricles, small mouth, rocker-bottom feet. Surviving children are severely mentally disabled. These fetuses commonly have heart rate abnormalities during labor.

Trisomy 18

Trisomy 18 - Edward syndrome

Cru de Chat Deletion Chromosome 5 Occurs 1 in 50,000 births. Common abnormalities include severe mental challenges with severe behavioral problems, low birth weight and may have respiratory problems. Some people with this disorder have a shortened lifespan, but most have a normal life expectancy.

Cru de Chat Syndrome

Metamale – XYY Syndrome Occurs in 1 in 1000 births. Common abnormalities include increased height, problematic acne, higher than average testosterone, allegedly average slightly lower IQ's, wiry rather than bulky, and tend to be poorly coordinated.

Metamale – XYY Syndrome These are twin brothers. The brother on the left is “normal” the brother on the right has two Y chromosomes.

MetaFemale – Multiple X Syndrome Occurs in 1 in 1000 births. Females have three or more X- chromosomes. Most XXX women are normal, though supposedly they are a bit slower than “normal”. XXXX woman are usually mildly retarded, and XXXXX produces severe disability.

Letter to the Parents Now that you have finished the karyotype that was given to you, you will write a letter to the parents of the unborn baby. It should have information which includes the gender and any abnormality the child might possess. Inform the parent about the prognosis and characteristics to be expected. Be kind and professional in your message. Dear Mr. and Mrs …… Sincerely, Dr.

Post Lab Questions 1. Define Karyotype. 2. What can karyotypes be used to determine? 3. How many chromosomes do normal humans have? 4. How did you know if 2 chromosomes were a homologous pair? (What made you pair 2 chromosomes together)? 5. What does the 23rd pair of chromosomes determine? 6. The first 22 pairs of chromosomes are homologous in a normal person. Is that "always true for the 23rd pair of chromosomes? Explain your answer.