CHAPTER 14 THE HUMAN GENOME

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
(No Transcript)
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

5
(No Transcript)
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 X
X XX XX
Y XY 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

• http//www.zerobio.com/drag_gr11/pedigree/pedigree
  _overview.htm

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
Antigen on Red Blood Cell
Phenotype (Blood Type
Genotype
From
To
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
HUNTINGTONS 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
include
include
include
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

25
(No Transcript)
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 3000 BASE PAIRS
• LARGEST GENE 2.4 MILLION BASE PAIRS
  (Dystrophin-associated with Muscular Dystrophy)

27
HUMAN GENES AND CHROMOSOMES

• CHROMOSOME 21
• CONTAINS 225 GENES
• ALS LOU GEHRIGS 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
• http//www.toledo-bend.com/colorblind/Ishihara.htm
  l

30
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

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
34
(No Transcript)
35
CHROMOSOMAL DISORDERS

• DOWN SYNDROME TRISOMY 21 HAVING 3 COPIES OF
  CHROMOSOME 21 RESULTING IN MILD TO SEVERE MENTAL
  RETARDATION

36
(No Transcript)
37
SEX CHROMOSOME DISORDERS

• TURNERS SYNDROME - FEMALES WHO INHERIT 1 SEX
  CHROMOSOME (X)
• STERILE, SEX ORGANS DO NOT DEVELOP AT PUBERTY
• KLINEFELTERS 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

41
(No Transcript)
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