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Genetic Disorders. Genetic Disorders Can Result from. INHERITANCE. MUTATIONS. The inheritance of a dominant or recessive trait. The inheritance of a sex-linked trait. Exposure to outside factors. Mistakes during meiosis. Mutations. Changes in genes.

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slide2

Genetic Disorders Can Result from

INHERITANCE

MUTATIONS

The inheritance of a dominant or recessive trait

The inheritance of a sex-linked trait

Exposure to outside factors

Mistakes during meiosis

mutations
Mutations
  • Changes in genes.
  • Sometimes result in traits that are expressed differently.
  • Can be harmful or helpful.
environmental factors
Environmental Factors

UV-RAYS

X-RAYS

RADIOACTIVESUBSTANCES

CHEMICALS

slide5

On April 26, 1986 at the Chernobyl Nuclear Power Plant in the Ukraine a sudden power outage caused series of nuclear explosions. The worst nuclear power plant accident in history caused mutations in the population that have been passed down to the children of Chernobyl.

slide6

MUTATIONS

Exposure to outside factors

Mistakes during meiosis

X-rays

UV-rays

Chemicals

Radioactive Substances

Children of Chernobyl

chromosome disorders
Chromosome Disorders

MUTATIONS

  • Mistakes during meiosis can result in an organism having too many or too few chromosomes.
  • A change in the total number of human chromosomes is usually fatal to the unborn embryo or fetus, or the baby may die soon after birth.
  • Disorders occur when the incorrect number of chromosomes is inherited.
  • Example:
    • Down’s Syndrome- occurs when three copies of chromosome 21 are produced in the female egg.

Mistakes during meiosis

Too Many or Too Few Chromosomes

Example: Down’s Syndrome

down s syndrome
Down’s Syndrome
  • Shorter than average
  • Over-sized tongue
  • Poor muscle tone
  • Almond-shaped eyes
  • Exhibit learning disabilities
  • Have heart problems
  • Can live normal lives if they have no severe health complications.

3 copies of chromosome 21

dominant genetic disorders
Dominant Genetic Disorders

INHERITANCE

  • Only one mutated copy of a gene is necessary for a person to be affected by a dominant genetic disorder.
  • Examples include:
    • Huntington’s Disease (Hh or HH)
    • Marfan’s Syndrome (Mm or MM)
    • Ahondroplasia (Dwarfism) (Dd or DD)

Inheritance of a dominant or recessive trait

Dominant Genetic Disorders

Huntington’s

Disease

(Hh or HH)

Marfan’s Syndrome

(Mm or MM)

Dwarfism

(Dd or DD)

huntington s disease
Huntington’s Disease
  • A progressive brain disorder that causes involuntary, rapid, jerky movements and mental deterioration.
marfan s syndrome
Marfan’s Syndrome
  • A disorder of the body’s connective tissue.
  • Affected people often have extra long limbs and stooped shoulders. Their eyeballs have a blueish tint.
ahondroplasia dwarfism
Ahondroplasia (Dwarfism)
  • Body size is extremely smaller than normal.
  • Limbs are very short but the body’s trunk is almost normal in size.
  • Have normal intelligence and can lead healthy lives.
genetics problem 1
Genetics Problem 1

Dwarfism (D) is a dominant trait in humans. Suppose Snowhite(dd) mates with Grumpy(Dd). What is the probability that their child will have the disorder?

slide14

dd x Dd

d

d

50%

D

Dd

dd

d

Dd

dd

recessive genetic disorders
Recessive Genetic Disorders

INHERITANCE

  • Caused when both parents supply a recessive gene to an offspring.
  • Some tend to affect people of one particular ethnic background at a higher rate than the rest of the population.
  • Examples include:
    • Cystic Fibrosis (cc)
    • Tay-Sachs Syndrome (tt)
    • Sickle-Cell Anemia (ss)

Inheritance of a dominant or recessive trait

Recessive Genetic Disorders

Cystic Fibrosis

(cc)

Tay –Sachs

(tt)

Sickle- Cell

Anemia

(ss)

cystic fibrosis
Cystic Fibrosis
  • Most common recessive disorder.
  • 5% of Caucasians are carriers of the disease.
  • Causes excessive secretion of unusually thick mucus that clogs the lungs.
  • People with the disease usually die before the age of 20.
sickle cell anemia
Sickle-Cell Anemia
  • A blood disorder that affects hemoglobin, the protein found in red blood cells, that helps carry oxygen throughout the body.
  • Characterized by “sickle-shaped” red blood cells.
  • Symptoms include: jaundice, fatigue, and severe pain throughout body parts.
tay sachs syndrome
Tay-Sachs Syndrome
  • A fatal disorder in which harmful quantities of a fatty substance build up in the brain.
  • Infants appear to develop normally for the first months of life.
  • As nerve tissues are destroyed, the baby becomes blind, deaf, and unable to swallow. Thereafter, the infant becomes paralyzed and dies within 4 years.
genetics problem 2
Genetics Problem 2

Popeye and Olive Oil have a baby who develops TaySach’s Syndrome at the age of 2 months. If the baby has a genotype of (tt) for the disorder, what are the genotypes of the parents?

slide20

Both parents are heterozygous

Mother: Tt Father: Tt

sex linked genetic disorders
Sex-Linked Genetic Disorders

INHERITANCE

  • Inherited through one of the sex chromosomes – X or Y.
  • Females carry the disorder if it is on one X chromosome and they are affected by the disorder if it is on both X chromosomes.
  • If a male has the disorder on his X or Y chromosome, he is affected by the disorder.
  • Examples of sex-linked genetic disorders:
    • Y-chromosome Infertility (XYi)
    • Hemophilia (XhXh or XhY)
    • Colorblindness (XcXc or XcY)

The inheritance of a sex-linked trait

X-chromosome Genetic Disorders

Y-chromosome Genetic Disorders

Hemophilia

Affected:

(XhXh or XhY)

Carrier:

XhX

Y- Chromosome Infertility

(XYi)

Colorblindness

Affected:

(XcXc or XcY)

Carrier:

XcX

y chromosome infertility
Y Chromosome Infertility
  • Caused by deletions that occur on the Y chromosome.
  • Affects the production of sperm, making it difficult or impossible for a male to father children.
  • The mutation will be inherited on the y chromosome of any son that an affected male fathers.
hemophilia
Hemophilia
  • An inherited bleeding disorder in which blood does not clot normally.
  • The defective gene is found on the x chromosome and is recessive.
  • Women may have the disease or carry the disease.
  • If the defective gene is found on a man’s x chromosome, he will have the disorder.

Queen Victoria’s

“Curse”

colorblindness
Colorblindness
  • Inability to perceive difference between some colors.
  • The defective gene is found on the x chromosome and is recessive.
  • Women may have the disease or carry the disease.
    • XX- normal female
    • XcX- carrier female
    • XcXc- colorblind female
  • If the defective gene is found on a man’s x chromosome, he will have the disorder.
    • XY- normal male
    • XcY-colorblind male
genetics problem 3
Genetics Problem 3

Wilma is colorblind(xcxc) and Fred is normal (xy). What is the probability that Pebbles is colorblind?

slide29

XcXc x XY

xc

xc

x

xcx

xcx

y

xcy

xcy

O%

Females would be carriers

genetics problem 4
Genetics Problem 4

Queen Victoria is a carrier for hemophilia (xhx). She married Prince Albert (xy).The royal couple’s eighth child, Leopold, had hemophilia and suffered from frequent hemorrhages. What is the probability that Leopald’s sister was a hemophiliac?

slide31

XhX x XY

xh

x

x

xhx

xx

O%

Females would be carriers or normal

y

xhy

xy