Chromosomal Genetic Disorders

Skin Cell

Karyotype An organized profile/picture of a person's chromosomes. -In order from largest to smallest

Sex Chromosomes The last 2 of the pairs (#23). Female: XX Male: XY

SEX chromosomes (male)

Female (woman) Male (man)

Y Chromosome In male mammals, Y chromosomes determine gender Causes development of testes instead of ovaries

Autosomes The other 22 pairs of chromosomes all except sex chromosomes To describe # and sex scientists will write: 44XX or 44XY

Gametes(Sex Cells) Females gametes only carry 22X Male gametes carry 22X (50%) and 22Y (50%) So what is the probability of having a boy or a girl?

2 Types of Disorders Scientists can diagnose or predict genetic disorders by studying chromosomes. 1. Chromosomal disorders –abnormal # of chromosomes 2. Sex-linked disorders -Disorder found only on x or y chromosomes 3. Sex-linked genes –Genes found on x or y chromosomes

EVEN seats (seats 2,4) Explain to your shoulder partner where on a karyotype you’d find the autosomes. Pairs 1-22

ODD seats (Seats 1,3,5) Tell your partner how many autosomes (body chromosomes) are in every NON-SEX cell in your body 44 autosomes (every body cell) + 2 sex chromosomes = 46 TOTAL chromosomes

Explain to your face partner How is a chromosomal disorder different than a sex linked disorder?

Chromosomal Disorders Nondisjunction is when homologous chromosomes fail to separate during meiosis. R2oOkhttp:// R2oOk

NORMALNORMAL

AbnormalAbnormal

Predicting genetic disorders Normal (diploid) karyotype has 46 chromosomes: 44 AUTOSOMES and 2 sex chromosomes (in EVERY BODY cell) 23 rd pair –Male XY –Female XX

Down Syndrome People with Down Syndrome have 3 copies of chromosome 21. Trisomy 21 –For this reason, Down Syndrome is also called "Trisomy 21". Down Syndrome is a genetic disorder caused by extra genetic material can include mental retardation, eyes that slant upward, and heart defects.

Cri du chat Syndrome Cri du chat is a rare syndrome caused by a deletion on chromosome 5. The name of this syndrome is French for "cry of the cat," referring to the distinctive cry of children with this disorder. low birth weight and may have respiratory problems.

Sex-Linked Disorders Disorders ONLY on x or y chromosome. –X chromosome=X linked –Y chromosome= Y linked (RARE) –X is Much larger so there are MORE X linked traits

Sex Linked Genes (continued) Males have only one X chromosome They will ALWAYS inherit ANY genetic disorder found on the X chromosome even if it recessive. Female must get 2 recessive x linked alleles to have disorder.

Sex-Linked Genes(continued) Many genetic disorders are located on the x chromosome. –Ex. Colorblindness, hemophilia Females: XX Males: XY

Turner Syndrome Women and girls with Turner Syndrome have only one X chromosome. Girls with Turner Syndrome do not develop secondary sex characteristics

Klinefelter Syndrome Men and boys with Klinefelter Syndrome XXY Often tall and usually do not develop secondary sex characteristics –May develop breast tissue

XXX syndrome – female with three X chromosomes on the 23 rd pair. Symptoms: –have no signs –Increased space between the eyes –Small head –Speech and language delays and learning disabilitiesSpeech and language delayslearning disabilities –Delayed puberty –Infertility

Red Green Color Blind Test

C= Normal vision (dominant) c = colorblind vision (recessive) X C = Normal Vision X c = Colorblind Vision How Do we Write it?

X C X c X c X C X C Y X c Y Female with regular vision; carries recessive gene for colorblindness (CARRIER) Female colorblind, carries both recessive Female normal vision, not carrier Male, Normal vision Male, Colorblind

X H X h X h X H X H Y X h Y Female with regular blood clotting; carries recessive gene for hemophilia (CARRIER) Female hemophilia, carries both recessive Female normal blood clotting, not carrier Male, Normal blood clotting Male, hemophilia X Linked Disorder-hemophilia (recessive). H=normal clotting. h=hemophilia

Sex-linked traits X chromosomes carries a gene for colorblindness.

X-linked dominant Retinitis pigmentosa Rett syndrome X-linked recessive Adrenoleukodystrophy Androgen insensitivity syndrome Barth syndrome Becker's muscular dystrophy Color blindnessColor blindness: Red and green Duchenne muscular dystrophy Fragile X syndrome G6PD deficiency Haemophilia Kennedy disease Lesch-Nyhan syndrome Ornithine transcarbamylase deficiency Wiskott-Aldrich syndrome X-linked agammaglobulinemia X-linked ichthyosis X-linked form of centronuclear myopathy or myotubular myopathycentronuclear myopathymyotubular myopathy Y-linked SRY

Sample Problem - do in your notebook A Colorblind woman marries a man with normal vision. 1. What is the probability that a son will be colorblind? 2. What is the probability of a girl being colorblind? 3. What is the probability of a girl being a carrier?

Sample Problem - do in your notebook A woman that is a carrier for the colorblind gene marries a man with normal vision. 4. What is the probability that the sons will be colorblind? 5. What is the probability of a girl being colorblind? 6. What is the probability of a girl being a carrier?

Sample Problem - do in your notebook A woman that is a carrier for the colorblind gene marries a man that is colorblind. 7. What is the probability that the sons will be colorblind? 8. What is the probability of a girl being colorblind? 9. What is the probability of a girl being a carrier? 10.Of all the offspring, what percent are colorbind?

Other Examples of Sex- linked Traits Red-green colorblindness Male Pattern Baldness Hemophilia Duchenne Muscular Dystrophy

Videos Biologix Chromsosomal alterations 29Biologix Chromsosomal alterations Morgans theory of gene linkages Gene mapping Web Disorders Gene Therapy animation hatisgt/ hatisgt/