Chapter 27 Human Genetics

Karyotype The arrangement of all the chromosomes found in a cell. Includes: 23 rd pair Female sex chromosomes X X Female = Male = Sex Chromosomes: chromosome pair 23 Autosomes: chromosome pairs 1-22 X X Y

FEMALE MALE Sex Chromosomes (they determine male or female) “Autosomes”

Amniocentesis A medical technique used to collect the chromosomes of a developing fetus. It is done by inserting a needle into the womb and gathering cells in the amniotic fluid.

Problems that may show up in a karyotype… 1. Turner’s syndrome: female missing an X chromosome…only 45 total chromosomes Underdeveloped female sex characteristics short stocky stature, underdeveloped breasts, late developer, possibly sterile. NO mental retardation May be aided by hormones Missing chromosome #23

2. Klinefelter’s Syndrome: Male with extra X on the 23 rd pair (sex chromosomes XXY) Symptoms may include more feminine characteristics such as high voice, lack of facial hair, breast development. Mental retardation is usually associated with Klinefelters. Extra X chromosome

3. Down Syndrome iosis%20I.htm Autosomal disorder found on the 21 st chromosome, and therefore can be male or female Extra chromosome #21….also called Trisomy 21. Symptoms include, overlapping skin at the eyes, round shaped head, straight thin hair, short and stocky, and may be sterile. Mental retardation is associated with Down Syndrome.

Statistics… Age of Mother Frequency of Down Syndrome Frequency of Any Chromosomal Disorder in in in in in in in in in in 82 1 in 63 1 in 49 1 in 38 1 in 30 1 in in in in in in in in 83 1 in 66 1 in 53 1 in 42 1 in 33 1 in 26 1 in 21

1. Color blindness genetic disorder found on the sex chromosome X known as a “sex-linked” because its found on chromosome 23 Sex-linked disorders found on the chromosomes… Sex 23 rd pair

XCXC XCXC XCXC Y XCXC XCXC XCXC XCXC XCXC XCXC YY Color blind Dad and Normal mother produces…. XCXC XCXC XCXC Y XCXC XCXC XCXC XCXC XCXC XCXC YY Normal Dad and Carrier mother produces…. What is the only way to get a color-blind daughter?? Two normal sons 2 “carrier” daughters (NOT color blind) 1 color blind son, 1 normal son 1 “carrier” daughter, 1 normal daughter

Color-blind people have trouble distinguishing certain colors (ex: red/green) They DO NOT just “see everything in black and white!!” Misconception:

2.Hemophilia Blood disorder found on the X chromosome (sex-linked) Blood does not clot correctly Known as the “royal genetic disorder” because it’s history is traced back to the European royal families. This is a _________________ showing the actual genetic inheritance of hemophilia in the European royal families… Compare the number of females that suffered to the number of males!! Females: _______ Males: _______ pedigree 0 10

1. Blood Type there are _________________________ 4 different blood types Blood TypeGenes Blood Type AA A or A O Blood Type BB B or B O Blood Type ABA B Blood Type OO

Which blood types are compatible for transfusion?? OB Yes or No ? BA AA B A O Yes No Yes

AA B B AO B O AB A B AB O O OO A O AO A O AB BO AOOO AAAB BB AO BO OO AA

Blood type statistics… If there are 100 people in the room: 39 will be O+ 7 will be O- 34 will be A+ 6 will be A- 9 will be B+ 2 will be B- 3 will be AB+ and only 1 in 200 will be AB- Note: The + and – is the presence (or absence) of a third antigen (Rh).

Sickle-cell anemia blood disorder where the blood cells are sickle-shaped rather than round. The disorder is found on chromosome 11 and is therefore not sex-linked. The Oxygen carrying hemoglobin can not carry oxygen as efficiently and the odd-shaped cells can easily clot and break. Fatigue, pain, and organ failure due to lack of oxygen supply are common symptoms of sickle cell anemia. It is common in the African community Normal RBCSickle-cell

R = round blood cell R’ = sickle cell R R’ = carrier RR R’ R R R R Actual blood cells R’ R R R’

Incomplete dominance Red White X Pink. There is a third color that exists in the heterozygous type. It’s a mixture between the two homozygous types.

Co-Dominance PINKWHITE PINK AND WHITE

Polygenic traits Many human traits are influenced by MORE than one gene!!