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Questions and Answers
At what age might a child with Down syndrome walk?
At what age might a child with Down syndrome walk?
About 2 years
What is the frequency of Klinefelter's syndrome?
What is the frequency of Klinefelter's syndrome?
1 in 500 male births
What physical characteristic is common in individuals with Turner's syndrome?
What physical characteristic is common in individuals with Turner's syndrome?
Short stature
What is the frequency of XXX syndrome?
What is the frequency of XXX syndrome?
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What is a common intellectual characteristic of individuals with XYY syndrome?
What is a common intellectual characteristic of individuals with XYY syndrome?
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What is a reproductive characteristic of individuals with Klinefelter's syndrome?
What is a reproductive characteristic of individuals with Klinefelter's syndrome?
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What is one of the emotions that parents may experience when expecting a child?
What is one of the emotions that parents may experience when expecting a child?
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What is the inherited condition that affects people of African heritage?
What is the inherited condition that affects people of African heritage?
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What is one of the functions of red blood cells?
What is one of the functions of red blood cells?
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Why is it especially worrisome for parents to find out their child has sickle-cell disease?
Why is it especially worrisome for parents to find out their child has sickle-cell disease?
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What is one of the reasons parents might be concerned about their baby's health?
What is one of the reasons parents might be concerned about their baby's health?
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Why is it important to understand the genetic bases of child development?
Why is it important to understand the genetic bases of child development?
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What is one of the reasons sickle-cell disease is painful?
What is one of the reasons sickle-cell disease is painful?
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What is the purpose of learning about genetic disorders like sickle-cell disease?
What is the purpose of learning about genetic disorders like sickle-cell disease?
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What is the characteristic of an individual with sickle-cell trait?
What is the characteristic of an individual with sickle-cell trait?
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What is endogamy, and what does it prefer?
What is endogamy, and what does it prefer?
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What is clinal variation, and where is it observed?
What is clinal variation, and where is it observed?
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What is the approximate frequency of sickle-cell disease in children of African heritage?
What is the approximate frequency of sickle-cell disease in children of African heritage?
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What is the unique benefit of having the sickle-cell allele?
What is the unique benefit of having the sickle-cell allele?
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What is the mode of transmission of malaria?
What is the mode of transmission of malaria?
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What is the relationship between the sickle-cell trait and malaria?
What is the relationship between the sickle-cell trait and malaria?
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What is a common genetic disorder that affects individuals of African heritage?
What is a common genetic disorder that affects individuals of African heritage?
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What is the abnormal shape of red blood cells in individuals with sickle-cell disease?
What is the abnormal shape of red blood cells in individuals with sickle-cell disease?
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What is the function of white blood cells in the body?
What is the function of white blood cells in the body?
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What is the thread-like structure inside the nucleus of every cell that comprises DNA?
What is the thread-like structure inside the nucleus of every cell that comprises DNA?
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What is the term for specific segments of DNA that have different functions?
What is the term for specific segments of DNA that have different functions?
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How many individual chromosomes are present in each egg or sperm cell?
How many individual chromosomes are present in each egg or sperm cell?
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What is the process by which egg and sperm cells are produced with half the amount of genetic material?
What is the process by which egg and sperm cells are produced with half the amount of genetic material?
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What would happen if an egg and sperm each had a full complement of genetic material (46 chromosomes)?
What would happen if an egg and sperm each had a full complement of genetic material (46 chromosomes)?
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Why is it important for each egg and sperm cell to contribute half the necessary genetic material for development?
Why is it important for each egg and sperm cell to contribute half the necessary genetic material for development?
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What is the primary effect of albinism on an individual's visual system?
What is the primary effect of albinism on an individual's visual system?
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What is the characteristic of cystic fibrosis that leads to lung infections?
What is the characteristic of cystic fibrosis that leads to lung infections?
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What is the effect of phenylalanine accumulation in individuals with PKU?
What is the effect of phenylalanine accumulation in individuals with PKU?
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What is the genetic cause of Tay-Sachs disease?
What is the genetic cause of Tay-Sachs disease?
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What is the typical consequence of having an extra, missing, or damaged chromosome?
What is the typical consequence of having an extra, missing, or damaged chromosome?
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What is the chromosomal cause of Down syndrome?
What is the chromosomal cause of Down syndrome?
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What is a characteristic of babies with Down syndrome during the first several months?
What is a characteristic of babies with Down syndrome during the first several months?
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What is a common developmental challenge experienced by individuals with Down syndrome?
What is a common developmental challenge experienced by individuals with Down syndrome?
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Study Notes
Genetic Disorders
- A child with Down syndrome may develop at a slower pace, sitting up without help at around 1 year, walking at 2, and talking at 3, which is behind children without Down syndrome.
Chromosomal Disorders
- Klinefelter's syndrome: XXY, occurs in 1 in 500 male births, characterized by tall stature, small testicles, sterility, and below-average intelligence.
- XYY syndrome: XYY, occurs in 1 in 1000 male births, characterized by tall stature, and below-average intelligence in some cases.
- Turner's syndrome: X, occurs in 1 in 2500-5000 female births, characterized by short stature, limited development of secondary sex characteristics, and problems with spatial relations.
- XXX syndrome: XXX, occurs in 1 in 500-1200 female births, characterized by normal stature, but delayed motor and language development.
Sickle-Cell Disease
- Sickle-cell disease is an inherited condition that affects many people, particularly those of African heritage, and can be life-threatening.
- Red blood cells in sickle-cell disease patients are long and curved, stiff, and misshapen, blocking oxygen flow and the body's natural defense against bacteria.
- Inherited through a combination of genes, sickle-cell disease is more common in people of African heritage due to the protective effect of the sickle-cell allele against malaria.
Heredity and Chromosomes
- Chromosomes are thread-like structures containing DNA, present in every cell's nucleus, and carry genetic material.
- Each chromosome contains many genes, which instruct cells on how to make proteins.
- Gametes (eggs or sperm) contain 23 individual chromosomes, and when they combine, they form 23 pairs of chromosomes, necessary for human development.
- Meiosis is the process by which egg and sperm cells are produced, containing half the genetic material, to ensure a full complement of 46 chromosomes in the resulting person.
Inherited Traits
- Sickle-cell trait: a characteristic of individuals with one dominant and one recessive allele, resulting in partial expression of sickle-cell anemia.
- Endogamy: a preference for mating with people from one's own social or cultural group.
- Clinal variation: continuous genetic variation observed between geographic regions.
Single Gene Traits
- Examples of dominant and recessive phenotypes include:
- Curly hair vs. straight hair
- Dark hair vs. blond hair
- Thick lips vs. thin lips
- Cheek dimples vs. no dimples
- Normal hearing vs. deafness
- Normal vision vs. near-sightedness
- Normal color vision vs. red-green color blindness
- Type A blood vs. Type O blood
Global Perspective
- Sickle-cell disease affects about 1 in 400 children of African heritage, but is rare in children of Western or Eastern European heritage.
- The sickle-cell allele provides protection against malaria, which is common in warm climates, including many parts of Africa.
Other Genetic Disorders
- Albinism: affects 1 in 10,000 to 1 in 20,000 births, characterized by skin lacking melanin, causing visual problems and sensitivity to light.
- Cystic fibrosis: affects 1 in 2500 births among European North Americans, characterized by excess mucus clogging digestive and respiratory tracts.
- Phenylketonuria (PKU): affects 1 in 10,000 births, characterized by the accumulation of phenylalanine, an amino acid, causing cognitive delay.
- Tay-Sachs disease: affects 1 in 3000 births among Jews of European descent, characterized by the degeneration of the nervous system, causing deafness, blindness, cognitive delay, and death.
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Description
This quiz covers developmental milestones in children with Down syndrome and characteristics of Klinefelter's syndrome. Explore the genetic differences and their effects on physical and cognitive development.
