Human Genetics Biology

Human Chromosomes Karyotype Picture of chromosomes arranged in pairs Autosomes – 44 chromosomes that everyone has no matter what sex they are Sex chromosomes – 2 chromosomes that determine sex Females = XX, Males = XY

How is sex determined? Meiotic division Eggs = 22 autosomes, 1 sex chromosome (X) Sperm = 22 autosomes, 1 sex chromosome (X or Y) Human genetic disorders can exist within the autosomes (chromosome pairs 1-22) or the sex chromosomes (chromosome pair 23) Meiotic division

Human Genetic Disorders Changes in autosomal chromosomes

Ways genetic disorders happen: Changes can happen in a DNA sequence within an individual chromosome -substitution: one nucleotide base is substituted for another -insertion: an extra base pair not normally present is added to the code. -deletion: a base pair is subtracted from the normal code http://www.cancer.gov/cancertopics/understandingcancer/cancergenomics/AllPages

Example: Sickle Cell Anemia Recessive gene on chromosome 11 Results in mutated hemoglobin (protein that allows red blood cells to carry oxygen) Red blood cells are misshapen (like sickles) Common in African Americans

Changes can happen to a whole chromosome multiple/missing chromosomes: caused by possession of too many or not enough chromosomes nondisjunction: failure of chromosome pairs to separate properly during cell division translocation: small parts of chromosomes break and rejoin other chromosomes http://www.knowledgene.com/public/view.php3?db=gene_school&uid=62

Example: Trisomy 18 Edward’s Syndrome 99 Balloons: Most die before birth; those born die within 2 months Heart abnormalities Difficulty breathing Small in size 99 Balloons: http://www.youtube.com/watch?v=th6Njr-qkq0&safety_mode=true&persist_safety_mode=1

Human Genetic Disorders Changes in sex chromosomes

Sex Chromosome Abnormalities X-linked (previously covered in class) Chromosomal abnormalities on the 23rd pair of chromosomes Jacob’s Syndrome

Male Sex Chromosome Abnormalities Klinefelter Syndrome Males with 2 X chromosomes (XXY) Tend to be overweight, tall Some feminine traits (breasts, higher pitched voice) Sperm count is low Hormone injections can help

The Human Genome Project Sequence all the DNA in a human cell Find out what protein that DNA codes for Better understand human genetics and how our DNA works Cure diseases?

Gene Therapy With Human Genome Project, we understand what our genes do With gene therapy, we can try to fix them Cure genetic diseases Replace faulty genes with the correct one Cells begin to produce the proper protein and disease is cured!