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CH 14: THE HUMAN GENOME
14-1 HUMAN HEREDITY
14-2 HUMAN CHROMOSOMES
14-3 HUMAN MOLECULAR
GENETICS
CHAPTER 14
THE HUMAN GENOME
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14-1 - HUMAN
Heredity
WHAT MAKES
US HUMAN? –
LOOK INSIDE
CELLS –
CHROMOSOMES
ARE PRESENT
CHAPTER 14
THE HUMAN GENOME
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14-1 - HUMAN Heredity
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A KARYOTYPE IS A PICTURE OF
CHROMOSOMES ARRANGED INTO
PAIRS
HUMAN CHROMOSOMES
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THERE ARE 46 CHROMOSOMES IN
OUR BODY CELLS
THEY ARE ARRANGED INTO 23
PAIRS
HUMAN CHROMOSOMES
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THE 23RD PAIR IS CALLED THE SEX
CHROMOSOMES
THE REMAINING 22 PAIRS ARE
CALLED AUTOSOMES
HUMAN CHROMOSOMES
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FEMALE – 46XX AND MALE – 46XY
HUMAN CHROMOSOMES
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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)
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THEREFORE, MALES DETERMINE THE SEX OF
THE CHILD
X
X
X
XX
XX
Y
XY
XY
HUMAN TRAITS
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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
PEDIGREE CHARTS
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A PEDIGREE CHART SHOWS
RELATIONSHIPS WITHIN
FAMILIES
GENETIC COUNSELORS USE THEM
TO DETERMINE TRAITS IN FAMILY
MEMBERS
Figure 14-3 A Pedigree
Section 14-1
A circle represents
a female.
A horizontal line connecting
a male and female
represents a marriage.
A half-shaded circle
or square indicates
that a person is a
carrier of the trait.
A completely
shaded circle or
square indicates
that a person
expresses the
trait.
A square represents
a male.
A vertical line and a
bracket connect the
parents to their children.
A circle or square
that is not shaded
indicates that a
person neither
expresses the trait
nor is a carrier of
the trait.
Pedigree Practice
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http://www.zerobio.com/drag_gr11/pedigre
e/pedigree_overview.htm
BLOOD GROUP GENES
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THERE ARE 3 ALLELES THAT
CONTROL BLOOD TYPE – A,B,O
A IS DOMINANT
B IS DOMINANT
O IS RECESSIVE
BLOOD GROUP GENES
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THERE ARE 3 ALLELES THAT
CONTROL BLOOD TYPE – A,B,O
A AND B ARE CODOMINANT
MEANING BLOOD TYPE AB
Figure 14-4 Blood Groups
Section 14-1
BLOOD GROUP GENES
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Rh BLOOD GROUP – DETERMINED
BY SINGLE GENE
CAN BE POSITIVE OR NEGATIVE
Rh+ DOMINANT
Rh- RECESSIVE
BLOOD GROUP GENES
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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
RECESSIVE ALLELES
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MANY HUMAN GENES HAVE BECOME
KNOWN THROUGH THE STUDY OF GENETIC
DISORDERS
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SOME EXAMPLES ARE:
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
SOME AUTOSOMAL DOMINANT
DISORDERS IN HUMANS
ACHONDROPLASIA
HUNTINGTON’S
DISEASE
HYPERCHOLESTEROLEMIA
DWARFISM
MENTAL DETERIORATION AND
UNCONTROLLABLE MOVEMENTS:
ONSET OVER AGE 35
EXCESS CHOLESTEROL IN
BLOOD: HEART DISEASE
CYSTIC FIBROSIS
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CAUSED BY RECESSIVE ALLELE ON
CHROMOSOME 7
THICK, HEAVY MUCUS THAT CLOGS LUNGS
SICKLE CELL DISEASE
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GENETIC DISORDER
SICKLE CELLS GET STUCK IN THE BLOOD VESSELS CAUSING
DAMAGE TO BRAIN, HEART, AND SPLEEN
ONE DNA BASE IS CHANGED CAUSING AMINO ACID TO
SUBSTITUTE ANOTHER
Text book questions
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Page 348
Q1,2,4
14-2 HUMAN CHROMOSOMES
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FACTS ABOUT DNA AND CHROMOSOMES:
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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)
HUMAN GENES AND
CHROMOSOMES
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CHROMOSOME #21:
CONTAINS 225 GENES
ALS – LOU GEHRIG’S DISEASE
CHROMOSOME #22:
CONTAINS 545 GENES
LEUKEMIA, AND TUMORCAUSING DISEASE
SEX-LINKED GENES
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SEX-LINKED GENES – GENES LOCATED ON SEX
CHROMOSOMES
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GENETIC DISORDERS FOUND ON THE X
CHROMOSOME
SEX-LINKED RECESSIVE
DISORDERS
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COLORBLINDNESS – UNABLE TO DISTINGUISH
CERTAIN COLORS – MOSTLY RED-GREEN
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X CX C
XC Xc
Xc Xc
X CY
XcY
= NORMAL FEMALE
= CARRIER FEMALE
= COLORBLIND FEMALE
= NORMAL MALE
= COLORBLIND MALE
http://www.toledobend.com/colorblind/Ishihara.html
SEX-LINKED RECESSIVE
DISORDERS
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HEMOPHILIA – A PROTEIN MISSING FOR
NORMAL BLOOD CLOTTING
CAN BE TREATED WITH INJECTIONS OF
NORMAL CLOTTING PROTEINS
http://www.ygyh.org/hemo/whatisit.htm
CHROMOSOMAL DISORDERS
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Normal sperm
and egg cells
have 23
chromosomes
CHROMOSOMAL DISORDERS
Non disjunction –
error in sperm or
egg production
that results in
different number
of chromosomes
CHROMOSOMAL DISORDERS
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DOWN SYNDROME –
“TRISOMY 21” –
HAVING 3 COPIES OF
CHROMOSOME 21
RESULTING IN MILD TO
SEVERE MENTAL
RETARDATION
SEX CHROMOSOME
DISORDERS
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TURNER’S SYNDROME FEMALES WHO
INHERIT 1 SEX
CHROMOSOME (X)
SEX CHROMOSOME
DISORDERS
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KLINEFELTER’S
SYNDROME– MALES
WHO INHERIT 3 SEX
CHROMOSOMES (XXY)
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CANNOT REPRODUCE
14-3 HUMAN MOLECULAR GENETICS
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TESTING FOR ALLELES – GENETIC TESTS THAT
SCREEN FOR DIFFERENCES IN THE DNA CODE
HUMAN GENOME PROJECT
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HGP – AN EFFORT TO ANALYZE THE HUMAN
DNA SEQUENCE
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OTHER ORGANISMS HAVE ALREADY BEEN
SEQUENCED – E. coli, YEAST, AND THE FRUIT
FLY.
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IN JUNE 2000 – HGP WAS ESSENTIALLY
COMPLETE
HUMAN GENOME PROJECT
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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
HUMAN GENOME PROJECT
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RESEARCH GROUPS AROUND THE WORLD ARE
ANALYZING INFORMATION IN THE DNA SEQUENCE
LOOKING FOR GENES THAT MAY PROVIDE CLUES TO
THE PROPERTIES OF LIFE
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UNDERSTANDING THEIR STRUCTURE MAY BE
USEFUL IN DEVELOPING NEW DRUGS AND
TREATMENTS FOR DISEASES
GENE THERAPY
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GENE THERAPY – WHEN AN ABSENT OR
FAULTY GENE IS REPLACED BY A NORMAL
FUNCTIONING GENE
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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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