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

2. CHAPTER 14 THE HUMAN GENOME
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

4. 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

6. 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

7. X XX Y XY

8. 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

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

10. 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.

11. Pedigree Practice

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

13. 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

14. 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

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

16. 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

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

18. SOME AUTOSOMAL RECESSIVE DISORDERS IN HUMANS
ALBINISM
LACK OF PIGMENT IN SKIN, HAIR, AND EYES
CYSTIC FIBROSIS
EXCESS MUCUS IN LUNGS, AND DIGESTIVE TRACT
GALACTOSEMIA
BUILD UP OF GALACTOSE (SUGAR) IN TISSUES; MENTAL RETARDATION AND LIVER DAMAGE
PHENYLKETONURIA
BUILD UP OF PHENYLALANINE IN TISSUES; MENTAL RETARDATION
TAY-SACHS
LIPID BUILD UP IN BRAIN; DEATH IN EARLY CHILDHOOD

19. SOME AUTOSOMAL DOMINANT DISORDERS IN HUMANS
ACHONDROPLASIA
DWARFISM
HUNTINGTON’S DISEASE
MENTAL DETERIORATION AND UNCONTROLLABLE MOVEMENTS: ONSET OVER AGE 35
HYPERCHOLESTEROLEMIA
EXCESS CHOLESTEROL IN BLOOD: HEART DISEASE

20. 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

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

22. 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

23. 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

24. 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 CAUSING AMINO ACID GLUTAMIC ACID TO SUBSTITUTE AMINO ACID VALINE

26. 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 BASE PAIRS
LARGEST GENE – 2.4 MILLION BASE PAIRS (Dystrophin-associated with Muscular Dystrophy)

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

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

29. 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

30. SEX-LINKED RECESSIVE DISORDERS
HEMOPHILIA – A PROTEIN MISSING FOR NORMAL BLOOD CLOTTING
CAN BE TREATED WITH INJECTIONS OF NORMAL CLOTTING PROTEINS

31. 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

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

33. NONDISJUNCTION IN DAUGHTER CELLS

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

37. 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

38. 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

39. 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

40. 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

42. 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

43. 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

44. 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

45. 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