Human Genetics Human Chromosomes Karyotype picture of chromosomes

Human Genetics

Human Chromosomes ●Karyotype = picture of chromosomes arranged in pairs & organized by size ●Humans have 46 chromosomes ● 2 of these are sex chromosomes XX = female XY = male ●The other 44 chromosomes are known as autosomes

Down Syndrome Trisomy 21

Edward Syndrome - caused by an extra chromosome 18 (trisomy 18) Median life expectancy is 4 days. However, about 5 -10% survive beyond one year

NONDISJUNCTION Failure of chromosomes to separate in meiosis – results in an egg (sperm) with too many or too few ●Down Syndrome (extra #21) ●Klinefelter Syndrome (XXY) ●Turner Syndrome (XO) ●Supermale (XYY)

Trisomy – 3 chromosomes Monosomy – 1 chromosome

1. A picture of a person's chromosomes is called a _____. 2. In this pictures, chromosomes are arranged in pairs according to their ______. 3. Humans have ______ pairs of chromosomes. 4. The last set of chromosomes is the _____ chromosomes. 5. Males have what sex chromosomes? ______ 6. A person who has an extra chromosome #21 has what disorder? _____ 7. If a person has XXY for sex chromosomes, he has what disorder? _________ 8. As a woman gets _______, her risk for having a child with down syndrome increases. 9. A human has 2 sex chromosomes, the other 44 chromosomes are called _______. 10. When chromosomes fail to separate during meiosis, ______ has occurred.

Human Traits ●To study inheritance, biologists use pedigree charts o. Shows relationships within a family

Not all Human Traits can be traced back to a single gene Many traits are strongly influenced by environmental factors (ex: height, weight, personality)

Human Genome ●Our complete set of genetic info ●Includes thousands of genes ●Base sequences of many genes identified

BLOOD TYPES Genes controlling blood types were 1 st genes to be identified ABO & Rh blood groups ( + and - )

ABO Blood Group Multiple Allele Trait ●Controlled by 3 alleles: A, B, O ●A and B are codominant ●O is recessive to both A and B ●The blood type is the phenotype

Genotype Blood Type AA, AO Type A BB, BO Type B AB codominant Type AB (universal recipient) OO recessive Type O (universal donor)

Blood Types Practice Mom has type A blood (genotype AO), dad has type AB blood. What blood types are possible among their children? Mom has type B blood (genotype BO), dad has type O blood. What blood types are possible among their children?

Human Genetic Disorders Phenylketonuria (PKU) Tay – Sachs disease Albinism * all recessive

Other animals can be albino too. .

Sickle-Cell Disease codominant (AA, Aa, aa ) heterozygous is resistant to malaria

Achondroplasia (dwarfism) Huntington’s disease * Both dominant

1. Achondroplasia is another name for ______ 2. What are the four possible blood types? _______ 3. Is albinism dominant or recessive? _____ 4. If two people are both heterozygous for sickle cell trait, what is the chance they will have a child with sickle cell disease? 5. If a person with type A blood is married to person with type O blood, what blood types are possible in their children? 6. The human _______ describes all the genes found in humans. 7. What type of chart is used to study a trait in a family? __