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Questions and Answers
A typical human has 48 chromosomes.
A typical human has 48 chromosomes.
False
Chromosomes in a karyotype are arranged from largest to smallest.
Chromosomes in a karyotype are arranged from largest to smallest.
True
A karyotype helps identify chromosomal abnormalities.
A karyotype helps identify chromosomal abnormalities.
True
There are 44 sex chromosomes in a typical human.
There are 44 sex chromosomes in a typical human.
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Gregor Mendel is associated with traits that can be predicted using probability and Punnett squares.
Gregor Mendel is associated with traits that can be predicted using probability and Punnett squares.
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A hypotonic solution causes white blood cells to shrink.
A hypotonic solution causes white blood cells to shrink.
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Nondisjunction refers to the proper separation of chromosomes during meiosis.
Nondisjunction refers to the proper separation of chromosomes during meiosis.
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All egg cells carry a single X chromosome.
All egg cells carry a single X chromosome.
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In a karyotype, males have two X chromosomes.
In a karyotype, males have two X chromosomes.
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In humans, both parents contribute 22 chromosomes to their offspring.
In humans, both parents contribute 22 chromosomes to their offspring.
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The process of centrifugation is used to separate blood cells from the culture fluid.
The process of centrifugation is used to separate blood cells from the culture fluid.
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Trisomy refers to having 2 copies of a chromosome instead of 3.
Trisomy refers to having 2 copies of a chromosome instead of 3.
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Down Syndrome is caused by a trisomy of chromosome 21.
Down Syndrome is caused by a trisomy of chromosome 21.
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Sister chromatids are the same as homologous chromosomes.
Sister chromatids are the same as homologous chromosomes.
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Down syndrome is a type of chromosomal disorder.
Down syndrome is a type of chromosomal disorder.
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Turner's Syndrome results in a female with two X chromosomes.
Turner's Syndrome results in a female with two X chromosomes.
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Klinefelter’s Syndrome typically results in a male who is often fertile.
Klinefelter’s Syndrome typically results in a male who is often fertile.
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Nondisjunction can occur during meiosis I or meiosis II.
Nondisjunction can occur during meiosis I or meiosis II.
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Patau Syndrome is also known as Trisomy 18.
Patau Syndrome is also known as Trisomy 18.
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The Y chromosome is unaffected by mutations from father to son.
The Y chromosome is unaffected by mutations from father to son.
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Approximately 1 in 800 babies is born with Down Syndrome.
Approximately 1 in 800 babies is born with Down Syndrome.
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What is the primary purpose of a karyotype?
What is the primary purpose of a karyotype?
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A typical human karyotype displays chromosomes only in pairs of sex chromosomes.
A typical human karyotype displays chromosomes only in pairs of sex chromosomes.
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How many autosomes does a typical human have?
How many autosomes does a typical human have?
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The process of _______ is used to photograph chromosomes during mitosis for karyotyping.
The process of _______ is used to photograph chromosomes during mitosis for karyotyping.
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Match the following genetic terms with their definitions:
Match the following genetic terms with their definitions:
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What is the result of mixing white blood cells with a hypotonic solution?
What is the result of mixing white blood cells with a hypotonic solution?
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Nondisjunction is when chromosomes separate normally during meiosis.
Nondisjunction is when chromosomes separate normally during meiosis.
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What is the chromosomal configuration of a typical female?
What is the chromosomal configuration of a typical female?
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In a karyotype, males typically have the chromosomal makeup of ______.
In a karyotype, males typically have the chromosomal makeup of ______.
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Match the following disorders with their associated chromosome abnormalities:
Match the following disorders with their associated chromosome abnormalities:
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Which of the following describes the role of centrifugation in blood culture?
Which of the following describes the role of centrifugation in blood culture?
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All sperm carry either an X or a Y chromosome.
All sperm carry either an X or a Y chromosome.
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What term describes when chromatids fail to separate normally during meiosis?
What term describes when chromatids fail to separate normally during meiosis?
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Which syndrome is associated with having three copies of chromosome 21?
Which syndrome is associated with having three copies of chromosome 21?
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Klinefelter’s Syndrome occurs in females who have one X chromosome.
Klinefelter’s Syndrome occurs in females who have one X chromosome.
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What is the general effect of Down Syndrome on individuals?
What is the general effect of Down Syndrome on individuals?
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Trisomy 18 is also known as __________ Syndrome.
Trisomy 18 is also known as __________ Syndrome.
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Match the following conditions with their corresponding chromosome abnormalities:
Match the following conditions with their corresponding chromosome abnormalities:
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What is a common characteristic of Turner’s Syndrome?
What is a common characteristic of Turner’s Syndrome?
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Nondisjunction can occur during both meiosis I and meiosis II.
Nondisjunction can occur during both meiosis I and meiosis II.
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What percentage of males in central Asia are believed to share a common ancestor linked to Genghis Khan?
What percentage of males in central Asia are believed to share a common ancestor linked to Genghis Khan?
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Study Notes
Human Genes and Chromosomes
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A typical human has 46 chromosomes, including 2 sex chromosomes and 44 autosomes.
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A karyotype is an organized display of an individual's chromosomes arranged in pairs, photographed during mitosis, and arranged by size.
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Karyotypes help identify chromosomal abnormalities causing genetic disorders.
Karyotype cont’d
- Down Syndrome is a trisomy of chromosome 21 (3 chromosomes instead of 2).
- Down Syndrome affects one in 800 babies and causes mild to severe mental learning disabilities, increased susceptibility to diseases, and other birth defects.
Is it a boy or a girl?
- Egg cells carry a single X chromosome.
- Sperm cells carry either an X or a Y chromosome.
- Women have XX chromosomes, while males have XY chromosomes.
Chromosomal Disorders
- Nondisjunction occurs when chromosomes or chromatids fail to separate normally in meiosis.
- Trisomy refers to having three copies of a chromosome instead of two.
- Other Trisomy Disorders include Patau Syndrome (Trisomy 13) and Edward’s Syndrome (Trisomy 18).
Sex Chromosome Disorders
- Turner's Syndrome affects females with one X chromosome and results in sterility.
- Klinefelter's Syndrome affects males with multiple X and one Y chromosome, usually resulting in sterility.
- XYY can also occur, and there are no documented cases of individuals born without an X chromosome.
Evolution Connection
- The Y chromosome provides clues about human male evolution because it is passed intact from father to son and mutations can reveal recent shared ancestry.
- Geneticists have discovered that about 8% of males in central Asia share striking Y chromosome similarity, tracing their genetic heritage to a single man living about 1,000 years ago.
- This evidence has helped historians link Genghis Khan to nearly 16 million men living today.
Human Genes and Chromosomes
- Humans have 46 chromosomes, with 2 being sex chromosomes and 44 being autosomes.
- A karyotype is an organized display of magnified images of an individual's chromosomes, aiding the identification of chromosomal abnormalities.
- A karyotype is created via the following steps:
- A blood culture is centrifuged to separate the blood cells.
- The cells are then placed in a hypotonic solution to allow the chromosomes to spread out.
- The cells are separated, preserved, placed on a slide, and stained.
- The two sex chromosomes are X and Y.
- Women have two X chromosomes, while men have one X and one Y chromosome.
Karyotype in Detail
- Down syndrome is a chromosomal disorder where a person has three copies of chromosome 21 (trisomy 21).
Chromosomal Disorders
- Meiosis usually works correctly, but sometimes errors occur in chromosome separation, leading to nondisjunction.
- Nondisjunction is a failure of chromosome separation, resulting in a gain or loss of chromosomes.
- Trisomy is the condition of having three copies of a chromosome instead of two.
- Examples of trisomy include Down syndrome.
Down Syndrome
- Down syndrome occurs due to trisomy of chromosome 21.
- Individuals with Down syndrome have three copies of chromosome 21.
- This affects approximately one in every 800 babies, leading to mild to severe intellectual disabilities and increased susceptibility to other diseases and birth defects.
Other Trisomy Disorders
- Other trisomy disorders include:
- Patau syndrome (trisomy 13)
- Edwards syndrome (trisomy 18)
Sex Chromosome Disorders
- Turner's syndrome:
- Occurs in females
- Characterized by having only one X chromosome
- Individuals are usually sterile
- Klinefelter's syndrome:
- Occurs in males
- Characterized by having multiple X chromosomes (at least two) and one Y chromosome
- Individuals are usually sterile
Y Chromosome Evolution
- The Y chromosome provides clues about human male evolution because it is passed intact from father to son.
- Mutations in the Y chromosome can reveal data about recent shared ancestry.
- Studies have shown that about 8% of males in central Asia share a very similar Y chromosome, tracing back to a single man who lived approximately 1,000 years ago, possibly Genghis Khan.
- This discovery links nearly 16 million men living today to a common ancestor, helping historians in their research.
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Description
Test your knowledge of human chromosomes and genetic disorders with this quiz. Explore topics such as karyotypes, Down Syndrome, and chromosomal abnormalities. Discover how sex chromosomes determine biological sex and the implications of nondisjunction in genetic disorders.
