-%20The%20Human%20Genome - PowerPoint PPT Presentation

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Title: -%20The%20Human%20Genome


1
Chapter 14
  • - The Human Genome

2
14-1 Human Heredity
  • The children in this family have some traits that
    are similar to their mothers and some that are
    similar to their fathers.

3
  • Can you predict chin shape?
  • Procedure
  • Two parents with cleft chins, both heterozygous
    for cleft chin (Cc), have three children with
    cleft chins. The parents are sure that their
    fourth child will not have a cleft chin. Draw a
    Punnett square to see if this is possible.
  • Determine the probability that the fourth child
    will have a cleft chin. _________



4
Human Heredity
  • Human Chromosomes
  • Make us who we are.
  • This is the genetic information (DNA) which is
    inside the human cell.

5
  • To look at these chromosomes, biologists,
    photograph cells in mitosis.
  • Mitosis is when the cell nucleus divides and the
    chromosomes are easier to see.
  • Biologists then take these photographs and group
    them together in pairs.
  • This picture of chromosomes arranged in this way
    is called a karyotype

6
Karyotype
7
  • The human body contains 46 chromosomes
  • 23 (sperm)
  • 23 (egg)
  • Together this forms a diploid zygote
  • 46 total chromosomes

8
Sex Chromosomes and Autosomes
  • Sex chromosomes
  • Only 2 of the 46
  • Determine if someone is male or female
  • Female XX
  • Male XY
  • Autosomes
  • Remaining 44 chromosomes

9
Human Traits
  • Human traits are inherited
  • Gregor Mendel
  • Pedigree chart
  • A pedigree shows a relationship within a family
  • A pedigree chart follows one specific trait in a
    family

10
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11
Cleopatras Pedigree Chart
12
Russian Royal Family Pedigree Chart
13
Polygenic
  • Some traits are actually polygenic
  • Controlled by two or more genes
  • Shape of your eyes
  • Shape of your ears
  • Eye color

14
Other Trait Influences
  • Environment
  • Nutrition
  • Exercise
  • Your parents might both be 6 feet tall, but if
    they dont feed you, you are unlikely to grow to
    be 6 feet tall.

15
Human Genes
  • Our complete set of genetic information is our
    genome
  • 30,000 genes
  • Blood Group Genes
  • Knowing a persons blood group is critical
    because using a wrong blood type could be life
    threatening
  • Rh
  • ABO
  • Are two genes that are part of your blood type

16
Rh
  • Rhesus Monkey
  • 2 alleles that determine blood type
  • Rh is dominant Rh- is recessive
  • A person with 2 positive alleles is Rh
  • A person with a positive and a negative allele is
    RH
  • A person with 2 negative alleles is Rh-

17
ABO
  • There are 3 alleles that determine blood type
  • IA, IB and i
  • Two of these alleles are codominant and one is
    recessive.
  • Blood type is dependant upon what the antigens
    are on the surface of the red blood cells
  • Type A blood lAlA, or IAi
  • Type B blood IBIB or IBi
  • Type AB blood IAIB
  • Type O blood ii

18
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19
  • Based on what you know of blood types which one
    of Mr. Mrs. Lopezs four kids must have been
    adopted? _____________

20
Recessive Alleles
  • Studying genetic disorders have helped us
    understand how human genes work
  • Many of these disorders are caused by recessive
    alleles

21
Phenylketonuria (PKU)
  • People with this disorder lack the enzyme needed
    to break down Phenylalanine
  • Causes
  • A build-up of phenylalanine in tissues
  • Mental retardation
  • Can be controlled by a special diet
  • All babies in US are tested for this at birth

22
Tay-Sachs Disease
  • Nervous system breakdown
  • Infant death

23
Albinism
  • Lack of pigment in skin, hair, and eyes

24
Cystic Fibrosis Galactosemia
  • Excess mucus in lungs, digestive tract, and liver
  • Susceptibility to infections
  • Death in early adulthood if not treated
  • Inability to digest the sugar galactose.
  • Causes mental retardation, eye and liver damage

25
Cystic Fibrosis
26
Dominant Alleles
  • Not all genetic disorders are caused by recessive
    alleles
  • If you have a dominant allele for a genetic
    disorder, it will be expressed even if you also
    have a normal recessive allele
  • Achondroplasia
  • Huntingtons disease
  • Hypercholesterolemia

27
Achondroplasia
  • Dwarfism

28
Huntingtons Disease
  • Mental deterioration and uncontrollable movements

Hypercholesterolemia
  • Excess cholesterol in blood
  • Heart disease

29
Gene Expression
  • In certain diseases, a small change in the DNA of
    a single gene affects the structure of a protein,
    causing a serious genetic disorder
  • Cystic fibrosis
  • Sickle cell anemia

30
Sickle Cell Anemia
  • Abnormal hemoglobin produced because of a single
    amino acid change in the hemoglobin protein
  • Causes the RBCs to deform which causes clogging
    in the capillaries

31
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32
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33
Sickle Cell Anemia
34
Sex-Linked Genes
14-2 Human Chromosomes
  • Because the X and Y chromosomes determine sex,
    genes located here are said to be sex-linked
    genes
  • More than 100 sex-linked genetic disorders have
    been mapped to the X chromosome
  • Males have just one X chromosome. Thus, all
    X-linked alleles are expressed in males, even if
    they are recessive

35
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36
Sex-Linked Genes
  • Genes that are found on the X or Y chromosome.
  • More genes are found on the X chromosome than the
    Y

37
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38
Colorblindness
  • Three genes associated with color vision are
    found on the X chromosome
  • Males are more often colorblind because they only
    have one X chromosome

39
Colorblindness Test
40
Colorblindness
  • All X-linked alleles are expressed in males even
    if they are recessive

41
Examples of X-linked Recessive Disorders
  • Hemophilia blood-clotting disorder
  • Duchenne Muscular Dystrophy
  • Ichtyosis scaly skin
  • Norrie Disease abnormal growth of retina
  • Rett Syndrome mental retardation

42
Hemophilia
43
Duchenne Muscular Dystrophy
44
X-Chromosome Inactivation
  • Females have 2 X chromosomes and males only one.
    What to do?
  • In all female cells, one X chromosome is randomly
    shut off.
  • This causes some interesting problems if one X
    chromosome has a mutated gene

45
Chromosomal Disorders
  • Get too many or too few copies of a chromosome
  • Caused by non-disjunction during meiosis
  • Exs. Downs Syndrome Trisomy 21
  • Turners Syndrome X_
  • Klinefelters Syndrome XXY

46
Downs Syndrome
47
Turner Syndrome
48
Kleinfelter Syndrome
49
14-3 Human Molecular Genetics
  • Human DNA Analysis
  • Genetic tests are now available for hundreds of
    disorders.
  • This can allow prospective parents to determine
    if they are carrying recessive alleles for a
    disorder.

50
DNA Fingerprinting
  • DNA is analyzed of by separating it into
    fragments
  • This reveals a series of DNA bands of various
    sizes
  • A pattern of bands is produced that can be
    distinguished from any other individual in the
    world (except for an identical twin).
  • DNA samples can be obtained from blood, sperm,
    and hair strands that have tissue at their base.

51
DNA Fingerprinting
52
The Human Genome Project
  • The Human Genome Project was an attempt to
    sequence all human DNA
  • In June 2000, scientists announced that the Human
    Genome was complete.
  • There is open availability of nearly all its
    data.
  • You can use the Internet to read the latest
    genome data.

53
Gene Therapy
  • Gene Therapy is the process of changing the gene
    that causes a genetic disorder
  • In gene therapy, an absent or faulty gene is
    replaced by a normal, working gene
  • This way, the body can make the correct protein
    or enzyme it needs, which eliminates the cause of
    the disorder

54
Gene Therapy
55
Ethical Issues
  • What will happen to the human species of we could
    design our bodies? What would be the
    consequences?
  • Society will have to develop a thoughtful and
    ethical consensus of what should and should not
    be done with the Human Genome.
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