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14-1 HUMAN HEREDITY 14-2 HUMAN CHROMOSOMES 14-3 HUMAN MOLECULAR GENETICS

CH 14: THE HUMAN GENOME. 14-1 HUMAN HEREDITY 14-2 HUMAN CHROMOSOMES 14-3 HUMAN MOLECULAR GENETICS. CHAPTER 14 THE HUMAN GENOME. 14-1 - HUMAN CHROMOSOMES WHAT MAKES US HUMAN? – LOOK INSIDE CELLS – CHROMOSOMES ARE PRESENT CHROMOSOMES ARE PHOTOGRAPHED DURING MITOSIS

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14-1 HUMAN HEREDITY 14-2 HUMAN CHROMOSOMES 14-3 HUMAN MOLECULAR GENETICS

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  1. CH 14: THE HUMAN GENOME 14-1 HUMAN HEREDITY 14-2 HUMAN CHROMOSOMES 14-3 HUMAN MOLECULAR GENETICS

  2. CHAPTER 14THE HUMAN GENOME • 14-1 - HUMAN CHROMOSOMES • WHAT MAKES US HUMAN? – LOOK INSIDE CELLS – CHROMOSOMES ARE PRESENT • CHROMOSOMES ARE PHOTOGRAPHED DURING MITOSIS • A KARYOTYPE IS A PICTURE OF CHROMOSOMES ARRANGED INTO PAIRS

  3. HUMAN CHROMOSOMES • THERE ARE 46 CHROMOSOMES IN OUR BODY CELLS • THEY ARE ARRANGED INTO 23 PAIRS • THE 23RD PAIR IS CALLED THE SEX CHROMOSOMES • THE REMAINING 22 PAIRS ARE CALLED AUTOSOMES • FEMALE – 46XX AND MALE – 46XY

  4. HUMAN CHROMOSOMES • EACH EGG CELL CARRIES ONE X CHROMOSOME (23 X) • HALF THE SPERM CARRY AN X CHROMOSOME (23 X) AND HALF CARRY A Y CHROMOSOME (23 Y) • THEREFORE, MALES DETERMINE THE SEX OF THE CHILD

  5. HUMAN TRAITS • HUMAN TRAITS ARE INHERITED ACCORDING TO THE SAME PRINCIPLES THAT MENDEL DISCOVERED WITH HIS PEAS. • NOT ALL TRAITS ARE INHERITED; SOME ARE INFLUENCED BY THE ENVIRONMENT • TO DETERMINE IF INHERITED, ONE MUST STUDY HOW THE TRAIT IS PASSED ON FROM GENERATION TO GENERATION

  6. PEDIGREE CHARTS • A PEDIGREE CHART SHOWS RELATIONSHIPS WITHIN FAMILIES • GENETIC COUNSELORS USE THEM TO DETERMINE GENOTYPES OF FAMILY MEMBERS

  7. Figure 14-3 A Pedigree Section 14-1 A circle represents a female. A square represents a male. A horizontal line connecting a male and female represents a marriage. A vertical line and a bracket connect the parents to their children. A half-shaded circle or square indicates that a person is a carrier of the trait. A circle or square that is not shaded indicates that a person neither expresses the trait nor is a carrier of the trait. A completely shaded circle or square indicates that a person expresses the trait.

  8. Pedigree Practice • http://www.zerobio.com/drag_gr11/pedigree/pedigree_overview.htm

  9. GENES AND THE ENVIRONMENT • MANY GENES ARE STRONGLY INFLUENCED BY THE ENVIRONMENT • NUTRITION AND EXERCISE

  10. HUMAN GENES • OUR HUMAN GENOME – OUR COMPLETE SET OF GENETIC INFORMATION INCLUDES OVER TENS OF THOUSANDS OF GENES • ONE OF THE FIRST GENES TO BE IDENTIFIED WERE THOSE THAT CONTROL BLOOD TYPE

  11. BLOOD GROUP GENES • RECALL THAT THERE ARE 3 ALLELES THAT CONTROL BLOOD TYPE – A,B,O • A IS DOMINANT TO O • B IS DOMINANT TO O • O IS RECESSIVE • A AND B ARE CODOMINANT MEANING BLOOD TYPE AB

  12. Figure 14-4 Blood Groups Section 14-1 Safe Transfusions Antigen on Red Blood Cell Phenotype (Blood Type Genotype From To

  13. BLOOD GROUP GENES • Rh BLOOD GROUP – DETERMINED BY SINGLE GENE • CAN BE POSITIVE OR NEGATIVE • Rh+/Rh+ OR Rh+/Rh- ARE Rh POSITIVE INDIVIDUALS • Rh-/Rh- ARE Rh NEGATIVE INDIVIDUALS

  14. RECESSIVE ALLELES • MANY HUMAN GENES HAVE BECOME KNOWN THROUGH THE STUDY OF GENETIC DISORDERS • SOME EXAMPLES ARE:

  15. SOME AUTOSOMAL RECESSIVE DISORDERS IN HUMANS

  16. SOME AUTOSOMAL DOMINANT DISORDERS IN HUMANS

  17. AUTOSOMAL DISORDER CAUSED BY CODOMINANT ALLELES • SICKLE CELL DISEASE – SICKLE RED BLOOD CELLS; DAMAGE TO MANY TISSUES • SS = NORMAL • Ss = SOME CELLS SHAPED LIKE SICKLES • ss = SICKLE CELL ANEMIA

  18. Codominant alleles Recessive alleles Dominant alleles Tay-Sachs disease Huntington’s disease Sickle cell disease Galactosemia Albinism Cystic fibrosis Hypercholes- terolemia Phenylketonuria Achondroplasia Concept Map Section 14-1 Autosomol Disorders caused by include include include

  19. FROM GENE TO MOLECULE • A SMALL CHANGE IN THE DNA OF A SINGLE GENE AFFECTS THE STRUCTURE OF A PROTEIN CAUSING A SERIOUS GENETIC DISORDER • TWO EXAMPLES: TAY SACHS DISEASE AND SICKLE CELL DISEASE

  20. CYSTIC FIBROSIS • CAUSED BY RECESSIVE ALLELE ON CHROMOSOME 7 • THICK, HEAVY MUCUS THAT CLOGS LUNGS • MOST CASES CAUSED BY DELETION OF 3 BASES IN A PROTEIN

  21. SICKLE CELL DISEASE • COMMON GENETIC DISORDER FOUND IN AFRICAN AMERICANS • SICKLE CELLS GET STUCK IN THE BLOOD VESSELS CAUSING DAMAGE TO BRAIN, HEART, AND SPLEEN • PROTEIN HEMOGLOBIN IS ALTERED • ONE DNA BASED IS CHANGED CAUSINGAMINO ACID GLUTAMIC ACID TO SUBSTITUTE AMINO ACID VALINE

  22. 14-2 HUMAN CHROMOSOMES • FACTS ABOUT DNA AND CHROMOSOMES: • 1 CELL CONTAINS 6 BILLION BASE PAIRS • ONLY 2% OF YOUR DNA FUNCTIONS AS GENES • AVERAGE HUMAN GENE IS 3000 BASE PAIRS • LARGEST GENE – 2.4 MILLION BASE PAIRS (Dystrophin-associated with Muscular Dystrophy)

  23. HUMAN GENES AND CHROMOSOMES • CHROMOSOME #21: • CONTAINS 225 GENES • ALS – LOU GEHRIG’S DISEASE • CHROMOSOME #22: • CONTAINS 545 GENES • LEUKEMIA, AND TUMOR-CAUSING DISEASE

  24. SEX-LINKED GENES • SEX-LINKED GENES – GENES LOCATED ON SEX CHROMOSOMES • GENETIC DISORDERS FOUND ON THE X CHROMOSOME

  25. SEX-LINKED RECESSIVE DISORDERS • COLORBLINDNESS –UNABLE TO DISTINGUISH CERTAIN COLORS – MOSTLY RED-GREEN • XCXC = NORMAL FEMALE • XC Xc = CARRIER FEMALE • Xc Xc = COLORBLIND FEMALE • XCY = NORMAL MALE • XcY = COLORBLIND MALE • http://www.toledo-bend.com/colorblind/Ishihara.html

  26. SEX-LINKED RECESSIVE DISORDERS • HEMOPHILIA – A PROTEIN MISSING FOR NORMAL BLOOD CLOTTING • CAN BE TREATED WITH INJECTIONS OF NORMAL CLOTTING PROTEINS • http://www.ygyh.org/hemo/whatisit.htm

  27. SEX-LINKED RECESSIVE DISORDERS • DUCHENNE MUSCULAR DYSTROPHY –DISORDER THAT RESULTS IN WEAKENING AND LOSS OF SKELETAL MUSCLE • CAUSED BY A DEFECTIVE GENE THAT CODES FOR MUSCLE PROTEIN

  28. CHROMOSOMAL DISORDERS • DUE TO NONDISJUNCTION – AN ERROR IN MEIOSIS IN WHICH HOMOLOGOUS CHROMOSOMES FAIL TO SEPARATE • RESULTS IN ABNORMAL CHROMOSOME NUMBER

  29. NONDISJUNCTION IN DAUGHTER CELLS

  30. CHROMOSOMAL DISORDERS • DOWN SYNDROME – “TRISOMY 21” – HAVING 3 COPIES OF CHROMOSOME 21 RESULTING IN MILD TO SEVERE MENTAL RETARDATION

  31. SEX CHROMOSOME DISORDERS • TURNER’S SYNDROME - FEMALES WHO INHERIT 1 SEX CHROMOSOME (X) • STERILE, SEX ORGANS DO NOT DEVELOP AT PUBERTY • KLINEFELTER’S SYNDROME – MALES WHO INHERIT 3 SEX CHROMOSOMES (XXY) • CANNOT REPRODUCE

  32. 14-3 HUMAN MOLECULAR GENETICS • HUMAN DNA ANALYSIS • WAYS THAT BIOLOGISTS SEARCH THE HUMAN GENOME • TESTING FOR ALLELES – GENETIC TESTS THAT SCREEN FOR DIFFERENCES IN THE DNA CODE

  33. DNA FINGERPRINTING • NO TWO INDIVIDUALS (EXCEPT FOR IDENTICAL TWINS) HAVE THE SAME DNA • DNA FINGERPRINT – ANALYZES SECTIONS OF DNA THAT VARY FROM INDIVIDUAL TO INDIVIDUAL

  34. HOW A DNA FINGERPRINT WORKS • DNA IS CUT WITH RESTRICTION ENZYMES • DNA IS SEPARATED BYSIZE USING GEL ELECTROPHORESIS • VARIABLE REGIONS ARE DETECTED USING A DNA PROBE • DNA SAMPLES CAN BE OBTAINED THROUGH BLOOD, SPERM, HAIR

  35. HUMAN GENOME PROJECT • HGP – AN EFFORT TO ANALYZE THE HUMAN DNA SEQUENCE • OTHER ORGANISMS HAVE ALREADY BEEN SEQUENCED – E. coli, YEAST, AND THE FRUIT FLY. • IN JUNE 2000 – HGP WAS ESSENTIALLY COMPLETE

  36. HUMAN GENOME PROJECT • SEARCHING FOR GENES –HUMANS HAVE ABOUT 25,000 FUNCTIONING GENES • THE FRUIT FLY HAS 14,000 GENES AND A TINY WORM ABOUT 20,000 GENES

  37. HUMAN GENOME PROJECT • RESEARCH GROUPS AROUND THE WORLD ARE ANALYZING INFORMATION IN THE DNA SEQUENCE LOOKING FOR GENES THAT MAY PROVIDE CLUES TO THE PROPERTIES OF LIFE • UNDERSTANDING THEIR STRUCTURE MAY BE USEFUL IN DEVELOPING NEW DRUGS AND TREATMENTS FOR DISEASES

  38. GENE THERAPY • GENE THERAPY – WHEN AN ABSENT OR FAULTY GENE IS REPLACED BY A NORMAL FUNCTIONING GENE • FIRST USED IN 1990 • IN 1999, CELLS FROM A YOUNG GIRL WERE REMOVED, MODIFIED IN A LAB, AND INSERTED BACK IN THE BODY - CURED

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