Problem 6
Question
Nondisjunction at meiosis can result in _________. a. karyotyping b. crossing over c. duplications d. aneuploidy
Step-by-Step Solution
Verified Answer
Answer: d. aneuploidy.
1Step 1: Understand the Concept of Nondisjunction
Nondisjunction is an error in meiosis where homologous chromosomes or sister chromatids fail to separate properly during cell division. This can result in cells with an abnormal number of chromosomes.
2Step 2: Define Aneuploidy
Aneuploidy is a chromosomal condition where the number of chromosomes is not the typical set for an organism due to nondisjunction. This can lead to conditions like Down syndrome, which is caused by an extra copy of chromosome 21.
3Step 3: Analyze the Options
Look at each option to see if it matches the effects caused by nondisjunction:
- Karyotyping: A method to view the number and structure of chromosomes, not a result of nondisjunction.
- Crossing over: The exchange of genetic material between homologous chromosomes, which is a normal process different from nondisjunction.
- Duplications: Refers to a segment of the chromosome being duplicated, not directly related to nondisjunction.
- Aneuploidy: Results from nondisjunction as it causes an incorrect number of chromosomes.
4Step 4: Conclusion
Based on the analysis, the only option that matches the outcome of nondisjunction is aneuploidy. Nondisjunction at meiosis leads to cells with an abnormal chromosome number, which is defined as aneuploidy.
Key Concepts
AneuploidyMeiosisChromosomes
Aneuploidy
Aneuploidy refers to a situation where a cell has an abnormal number of chromosomes, deviating from what is typical for an organism. Typically, human cells contain 46 chromosomes. However, due to errors like nondisjunction during cell division, a cell might have more or fewer chromosomes than the usual count.
Aneuploidy often results in various genetic conditions. One of the most commonly known conditions is Down syndrome, which occurs when there is an extra copy of chromosome 21. Another example is Turner syndrome, which results from a missing X chromosome in females.
Individuals affected by aneuploidy may exhibit a range of physical and developmental characteristics depending on which chromosomes are involved. These variations depend on which chromosomes are missing or have additional copies.
Aneuploidy often results in various genetic conditions. One of the most commonly known conditions is Down syndrome, which occurs when there is an extra copy of chromosome 21. Another example is Turner syndrome, which results from a missing X chromosome in females.
Individuals affected by aneuploidy may exhibit a range of physical and developmental characteristics depending on which chromosomes are involved. These variations depend on which chromosomes are missing or have additional copies.
Meiosis
Meiosis is a specialized form of cell division that reduces the chromosome number by half, creating gametes (egg and sperm cells) necessary for sexual reproduction. This process ensures that when gametes unite during fertilization, the offspring have the correct number of chromosomes.
Meiosis involves two division stages:
The significance of meiosis lies in genetic diversity, achieved through mechanisms such as crossing over and independent assortment. These processes shuffle genetic information, contributing to genetic variation in populations.
Meiosis involves two division stages:
- Meiosis I: Homologous chromosomes are separated, reducing the chromosome number by half.
- Meiosis II: Similar to mitosis, it involves the separation of sister chromatids.
The significance of meiosis lies in genetic diversity, achieved through mechanisms such as crossing over and independent assortment. These processes shuffle genetic information, contributing to genetic variation in populations.
Chromosomes
Chromosomes are structures made of DNA and proteins. They carry genetic information necessary for the growth, development, and functioning of organisms. In humans, chromosomes reside in the cell nucleus and come in pairs.
Each species has a specific number of chromosomes. Humans, for instance, have 46 chromosomes in 23 pairs. One chromosome of each pair is inherited from the mother, and one from the father. The 23rd pair determines the sex of the individual and includes the X and Y chromosomes.
During cell division, particularly meiosis, it's crucial that chromosomes are distributed correctly to daughter cells. Any errors in this process can lead to nondisjunction, resulting in aneuploidy. Proper chromosome segregation ensures that each gamete, or sex cell, receives the correct number of chromosomes, which is vital for producing healthy offspring.
Each species has a specific number of chromosomes. Humans, for instance, have 46 chromosomes in 23 pairs. One chromosome of each pair is inherited from the mother, and one from the father. The 23rd pair determines the sex of the individual and includes the X and Y chromosomes.
During cell division, particularly meiosis, it's crucial that chromosomes are distributed correctly to daughter cells. Any errors in this process can lead to nondisjunction, resulting in aneuploidy. Proper chromosome segregation ensures that each gamete, or sex cell, receives the correct number of chromosomes, which is vital for producing healthy offspring.
Other exercises in this chapter
Problem 4
A recognized set of symptoms that characterize a specific disorder is a ________. a. syndrome b. disease c. pedigree
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Most genes for human traits are located on _________. a. the \(X\) chromosome b. the Y chromosome c. autosomes d. dominant chromosomes
View solution Problem 7
Turner syndrome (XO) is an example of _________. a. dominance b. polyploidy c. aneuploidy d. gene linkage
View solution Problem 8
Match the chromosome terms appropriately. $$ \text {________crossing over} \quad \quad\quad\quad\quad \text {a. number and defining features of an individual's
View solution