Chapter 14: The Human Genome What makes you, you?

14-1: Human Heredity What is a karyotype? Picture of chromosomes arranged in homologous pairs Homo means what? A typical human being has 46 chromosomes 2 are sex chromosomes Male: XY Female: XX 44 are autosomes See Figure 14-1 page 341 Analyze this karyotype and identify the person’s sex

50:50 chance of being male or female X X See the Punnett square on page 342 XX XY X Y

Pedigree Charts Tool used to show the relationships within a family Can show how a trait or genetic diseases is passed through generations See Figure 14-3 on page 342 Who does a circle represent? What about a square? What does shading represent?

Human Genes The human genome is our complete set of genetic information Includes tens of thousands of genes Sequence of DNA determines characteristics like eye color, blood type, structure of proteins (just to name a few) Sequence completed in 2000

Genetic Disorders Recessive alleles Dominant alleles Co-dominant alleles See pg. 345 Table 14-6 Can you list a few genetic disorders?

14-2 Human Chromosomes Sometimes, things go wrong with the chromosomes Sex linked genes Chromosomal disorders X-chromosome inactivation

Sex-linked genes There is a special pattern of inheritance for genes located on the X and Y chromosomes Sex linked = genes located on the sex chromosomes X chromosome is larger than the Y chromosome More genes on the X chromosome

Sex-linked genes (cont.) Why is this important? Boys are at a disadvantage!! Sex linked disorders include: Color blindness, hemophilia, Duchenne muscular dystrophy Males have 1 X chromosome (meaning, they only have to inherit one bad gene to get the disease) Women have 2 X chromosomes (it’s like a back up) They will be a carrier, but not affected

Chromosomal Disorders Most of the time, the mechanisms that separate chromosomes in meiosis works very well. But, things can go wrong Common error: non-disjunction not coming apart Non-disjunction = abnormal # of chromosomes See Figure 14-15 page 352

Common Chromosomal Disorders Down’s Syndrome Autosomal Trisomy 21 Take a look at Figure 14-16 (pg. 353) … what do you notice? Sex chromosome disorders Extra or too few sex chromosome Turners (female: XO) Klinefelter (male: XXY, XXXY,)

Human Molecular Genetics Gene therapy An absent or faulty gene is replaced by a normal, working gene Sequencing the human genome Ethical issues?