CH 14: THE HUMAN GENOME
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14-1 HUMAN HEREDITY 14-2 HUMAN CHROMOSOMES 14-3 HUMAN MOLECULAR GENETICS PowerPoint PPT Presentation


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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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14-1 HUMAN HEREDITY 14-2 HUMAN CHROMOSOMES 14-3 HUMAN MOLECULAR GENETICS

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14 1 human heredity 14 2 human chromosomes 14 3 human molecular genetics

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


14 1 human heredity 14 2 human chromosomes 14 3 human molecular genetics

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


14 1 human heredity 14 2 human chromosomes 14 3 human molecular genetics

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:


Some autosomal recessive disorders in humans

SOME AUTOSOMAL RECESSIVE DISORDERS IN HUMANS


Some autosomal dominant disorders in humans

SOME AUTOSOMAL DOMINANT DISORDERS IN HUMANS


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


14 1 human heredity 14 2 human chromosomes 14 3 human molecular genetics

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


Nondisjunction in daughter cells

NONDISJUNCTION IN DAUGHTER CELLS


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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