Chapter 14 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

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 Shows relationships within a family

Many traits are strongly influenced by environmental factors 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 1st genes to be identified ABO & Rh blood groups ( + and - )

ABO Blood GroupMultiple 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

(universal recipient) 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 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? __