CH 14: THE HUMAN GENOME
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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. 14-1 - HUMAN CHROMOSOMES WHAT MAKES US HUMAN? – LOOK INSIDE CELLS – CHROMOSOMES ARE PRESENT CHROMOSOMES ARE PHOTOGRAPHED DURING MITOSIS

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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
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


Human chromosomes
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


Human chromosomes1
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


Human traits
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


Pedigree charts
PEDIGREE CHARTS

  • A PEDIGREE CHART SHOWS RELATIONSHIPS WITHIN FAMILIES

  • GENETIC COUNSELORS USE THEM TO DETERMINE GENOTYPES OF FAMILY MEMBERS


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.


Pedigree practice
Pedigree Practice

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


Genes and the environment
GENES AND THE ENVIRONMENT

  • MANY GENES ARE STRONGLY INFLUENCED BY THE ENVIRONMENT

    • NUTRITION AND EXERCISE


Human genes
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


Blood group genes
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


Figure 14-4 Blood Groups

Section 14-1

Safe Transfusions

Antigen on

Red Blood Cell

Phenotype

(Blood Type

Genotype

From

To


Blood group genes1
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


Recessive alleles
RECESSIVE ALLELES

  • MANY HUMAN GENES HAVE BECOME KNOWN THROUGH THE STUDY OF GENETIC DISORDERS

  • SOME EXAMPLES ARE:




Autosomal disorder caused by codominant alleles
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


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


From gene to molecule
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


Cystic fibrosis
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


Sickle cell disease
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


14 2 human chromosomes
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)


Human genes and chromosomes
HUMAN GENES AND CHROMOSOMES

  • CHROMOSOME #21:

  • CONTAINS 225 GENES

  • ALS – LOU GEHRIG’S DISEASE

  • CHROMOSOME #22:

  • CONTAINS 545 GENES

  • LEUKEMIA, AND TUMOR-CAUSING DISEASE


Sex linked genes
SEX-LINKED GENES

  • SEX-LINKED GENES – GENES LOCATED ON SEX CHROMOSOMES

  • GENETIC DISORDERS FOUND ON THE X CHROMOSOME


Sex linked recessive disorders
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


Sex linked recessive disorders1
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


Sex linked recessive disorders2
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


Chromosomal disorders
CHROMOSOMAL DISORDERS

  • DUE TO NONDISJUNCTION – AN ERROR IN MEIOSIS IN WHICH HOMOLOGOUS CHROMOSOMES FAIL TO SEPARATE

  • RESULTS IN ABNORMAL CHROMOSOME NUMBER



Chromosomal disorders1
CHROMOSOMAL DISORDERS

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


Sex chromosome disorders
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


  • 14 3 human molecular genetics
    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


  • Dna fingerprinting
    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


    How a dna fingerprint works
    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


    Human genome project
    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


    Human genome project1
    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


    Human genome project2
    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


    Gene therapy
    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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