Cellular Division - AP Biology
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In a dihybrid cross of seed color and seed shape, Y (yellow) is dominant to y (green) and R (rounded) is dominant to r (wrinkled). An individual with genotype YyRr is crossed with an individual with genotype YYRr. The inheritance of the alleles for seed color does not affect inheritance of genes for seed shape. Which law supports this statement?
In a dihybrid cross of seed color and seed shape, Y (yellow) is dominant to y (green) and R (rounded) is dominant to r (wrinkled). An individual with genotype YyRr is crossed with an individual with genotype YYRr. The inheritance of the alleles for seed color does not affect inheritance of genes for seed shape. Which law supports this statement?
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The law of independent assortment states that inheritance of one gene does not influence inheritance of another gene. Thus, inheritance of seed color does not affect the inheritance of seed shape.
The law of independent assortment states that inheritance of one gene does not influence inheritance of another gene. Thus, inheritance of seed color does not affect the inheritance of seed shape.
Which law of inheritance is incorrectly matched to its explanation?
Which law of inheritance is incorrectly matched to its explanation?
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The laws of inheritance include the laws of segregation (each gamete receives only one copy of each gene from its parent), dominance (in a heterozygote individual, only the dominant allele will influence the phenotype), and independent assortment (inheritance of one gene does not influence inheritance of another gene)
The laws of inheritance include the laws of segregation (each gamete receives only one copy of each gene from its parent), dominance (in a heterozygote individual, only the dominant allele will influence the phenotype), and independent assortment (inheritance of one gene does not influence inheritance of another gene)
Which is not true during meiosis?
Which is not true during meiosis?
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According to the Law of Segregation, each gamete receives one allele for each gene from each parent. During Meiosis, each parent’s two copies of each allele are separated from each other, then the gamete receives one copy of each allele from each parent (for a total of two alleles).
According to the Law of Segregation, each gamete receives one allele for each gene from each parent. During Meiosis, each parent’s two copies of each allele are separated from each other, then the gamete receives one copy of each allele from each parent (for a total of two alleles).
The law of independent assortment states that .
The law of independent assortment states that .
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This is the definition of the law of independent assortment; during meiosis, the inheritance of one gene does not influence whether another, separate gene will also be inherited by that gamete.
This is the definition of the law of independent assortment; during meiosis, the inheritance of one gene does not influence whether another, separate gene will also be inherited by that gamete.
According to Mendel’s Law of Dominance, the phenotype of a heterozygote will be .
According to Mendel’s Law of Dominance, the phenotype of a heterozygote will be .
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According to the Law of Dominance, each individual has two alleles for each trait and only the dominant allele contributes to the phenotype.
According to the Law of Dominance, each individual has two alleles for each trait and only the dominant allele contributes to the phenotype.
During what process do homologous chromosomes segregate into different gametes?
During what process do homologous chromosomes segregate into different gametes?
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According to the Law of Segregation, during Meiosis, homologous chromosomes segregate into different gametes.
According to the Law of Segregation, during Meiosis, homologous chromosomes segregate into different gametes.
A scientist is interested in studying the event of crossing over (recombination) in mouse gametes. She wants to label some of the mouse DNA with fluorescent dyes to better visualize it. During what phase of the cell cycle should she look at these fluorescent DNA strands in order to most effectively study recombination?
A scientist is interested in studying the event of crossing over (recombination) in mouse gametes. She wants to label some of the mouse DNA with fluorescent dyes to better visualize it. During what phase of the cell cycle should she look at these fluorescent DNA strands in order to most effectively study recombination?
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Recombination or crossing over happens primarily in Prophase I. In anaphase and telophase, the DNA strands are separated and cannot recombine. In metaphase, homologous chromosomes line up with each other, but do not recombine.
Recombination or crossing over happens primarily in Prophase I. In anaphase and telophase, the DNA strands are separated and cannot recombine. In metaphase, homologous chromosomes line up with each other, but do not recombine.
Which of these statements is FALSE concerning mitosis and meiosis?
Which of these statements is FALSE concerning mitosis and meiosis?
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Mitosis and meiosis share many procedural similarities, however, it is important to remember that mitosis makes identical cells while meiosis allows genetic variability between cells.
Meiosis takes place in sex cells, which are capable of creating millions of different variations of offspring. Mitosis takes place in normal cells involved in growth and regeneration within a single, uniform organism.
Mitosis and meiosis share many procedural similarities, however, it is important to remember that mitosis makes identical cells while meiosis allows genetic variability between cells.
Meiosis takes place in sex cells, which are capable of creating millions of different variations of offspring. Mitosis takes place in normal cells involved in growth and regeneration within a single, uniform organism.
Which of the following highlights a key difference between meiosis and mitosis?
Which of the following highlights a key difference between meiosis and mitosis?
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Meiosis includes two divisions, resulting in two pairs of haploid cells, while mitosis only involves a single division.
Both meiotic and mitotic divisions share the same phases, though there are some differences in the activity of these phases. Mutation can, and does, occur in both mitosis and meiosis. Crossing over, however, is unique to meiosis.
Meiosis includes two divisions, resulting in two pairs of haploid cells, while mitosis only involves a single division.
Both meiotic and mitotic divisions share the same phases, though there are some differences in the activity of these phases. Mutation can, and does, occur in both mitosis and meiosis. Crossing over, however, is unique to meiosis.
Crossing over during prophase occurs during which cycle of division?
Crossing over during prophase occurs during which cycle of division?
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Crossing over ensures genetic variability as it results in daughter cells with different genetic material than their parent cells. This occurs during meiosis I, but is not seen in mitosis or meiosis II.
Crossing over ensures genetic variability as it results in daughter cells with different genetic material than their parent cells. This occurs during meiosis I, but is not seen in mitosis or meiosis II.
Human gametes are produced by the process of .
Human gametes are produced by the process of .
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Gametes are haploid cells that produced via meiosis. During meiosis, diploid cells divide into four nonidentical haploid daughter cells. Mitosis produces two identical diploid somatic cells from one parent cell.
Gametes are haploid cells that produced via meiosis. During meiosis, diploid cells divide into four nonidentical haploid daughter cells. Mitosis produces two identical diploid somatic cells from one parent cell.
Which of the following statements regarding mitosis and meiosis is correct?
Which of the following statements regarding mitosis and meiosis is correct?
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Both mitosis and meiosis occur in humans. Somatic cells (body cells) divide via mitosis, while gametes (sex cells) divide via meiosis. Because of actions such as crossing over, meiosis results in a higher genetic variability than mitosis.
Prokaryotes, such as bacteria, reproduce asexually, and are incapable of meiosis.
Both mitosis and meiosis occur in humans. Somatic cells (body cells) divide via mitosis, while gametes (sex cells) divide via meiosis. Because of actions such as crossing over, meiosis results in a higher genetic variability than mitosis.
Prokaryotes, such as bacteria, reproduce asexually, and are incapable of meiosis.
Which of the following chromosomal abnormalities is an example of monosomy?
Which of the following chromosomal abnormalities is an example of monosomy?
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Turner syndrome occurs when a person is missing one sex chromosome, and only has one X-chromosome. As a result, they will be female, and may suffer a variety of symptoms. This is an example of monosomy, in which a person only has one chromosome, when they should have two.
The other three choices are examples of trisomy. Klinefelter is an instance of sex-linked trisomy, with a karyotype of XXY. Down syndrome is cause by trisomy 21, and Edwards syndrome is caused by trisomy 18.
Turner syndrome occurs when a person is missing one sex chromosome, and only has one X-chromosome. As a result, they will be female, and may suffer a variety of symptoms. This is an example of monosomy, in which a person only has one chromosome, when they should have two.
The other three choices are examples of trisomy. Klinefelter is an instance of sex-linked trisomy, with a karyotype of XXY. Down syndrome is cause by trisomy 21, and Edwards syndrome is caused by trisomy 18.
Non-disjunction can result in which of the following?
Non-disjunction can result in which of the following?
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Non-disjunction occurs when sister chromatids fail to separate during meiosis, leading subsequent daughter cells to have an unequal number of chromosomes. This can result in a cell having one extra chromosome (trisomy), or missing one chromosome (monosomy).
The following shows non-disjuction occuring in metaphase II of meiosis. "X" represents a chromosome, "|" represents a cell membrane, and "\" and "/" represent chromatids. When a sperm cell fuses with the egg formed to the left of the membrane (|), it will result in trisomy. When a sperm fuses with the egg to the right of the membrane (|), it will result in monosomy.
Metaphase I: X X
Telophase I: X | X
Metaphase II: / \
Telophase II: / \ |
Non-disjunction occurs when sister chromatids fail to separate during meiosis, leading subsequent daughter cells to have an unequal number of chromosomes. This can result in a cell having one extra chromosome (trisomy), or missing one chromosome (monosomy).
The following shows non-disjuction occuring in metaphase II of meiosis. "X" represents a chromosome, "|" represents a cell membrane, and "\" and "/" represent chromatids. When a sperm cell fuses with the egg formed to the left of the membrane (|), it will result in trisomy. When a sperm fuses with the egg to the right of the membrane (|), it will result in monosomy.
Metaphase I: X X
Telophase I: X | X
Metaphase II: / \
Telophase II: / \ |
Which of the following statements is true concerning meiosis?
Which of the following statements is true concerning meiosis?
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Meiosis allows for the creation of genetically different haploid cells from one original germ cell. Following anaphase I, homologous chromosomes are separated from one another, resulting in a halving of the genetic material (haploid). As a result, the two cells are haploid following meiosis I. The separation of genetic material in anaphase II involves the splitting of chromatids, not homologous chromosomes. This does not affect the number of chromosomes in each cell, meaning all cells remain haploid.
Parent: diploid (XX)
Meiosis I: haploid, full chromosome (X)(X)
Meiosis II: haploid, single chromatid (/)(\)(/)(\)
Note that crossing over can only occur when the cell is diploid in meiosis I, specifically during prophase I.
Meiosis allows for the creation of genetically different haploid cells from one original germ cell. Following anaphase I, homologous chromosomes are separated from one another, resulting in a halving of the genetic material (haploid). As a result, the two cells are haploid following meiosis I. The separation of genetic material in anaphase II involves the splitting of chromatids, not homologous chromosomes. This does not affect the number of chromosomes in each cell, meaning all cells remain haploid.
Parent: diploid (XX)
Meiosis I: haploid, full chromosome (X)(X)
Meiosis II: haploid, single chromatid (/)(\)(/)(\)
Note that crossing over can only occur when the cell is diploid in meiosis I, specifically during prophase I.
Which of the following would result in a cell with an abnormal number of chromosomes after meiosis?
Which of the following would result in a cell with an abnormal number of chromosomes after meiosis?
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Crossing over, or recombination, is a process that takes place in the earlier stages of meiosis and promotes genetic diversity. During recombination, genetic material is exchanged between two homologous chromosomes. The chromosomes ultimately contain the same amount of genetic material after recombination, and are properly separated during subsequent divisions.
The cleavage of the protein securin is actually what allows the sister chromatids to separate, a process that is essential to maintaining the correct number of chromosomes in each daughter cell.
Nondisjunction is the name given to the phenomenon in which separation of genetic material fails to occur. Either homologous chromosomes fail to separate properly in meiosis I, or sister chromatids fail to separate properly during meiosis II. The result of these nondisjunction events is one cell with an abnormally high number of chromosomes (for example trisomy) and one cell with an abnormally low number of chromosomes (for example monosomy).
Crossing over, or recombination, is a process that takes place in the earlier stages of meiosis and promotes genetic diversity. During recombination, genetic material is exchanged between two homologous chromosomes. The chromosomes ultimately contain the same amount of genetic material after recombination, and are properly separated during subsequent divisions.
The cleavage of the protein securin is actually what allows the sister chromatids to separate, a process that is essential to maintaining the correct number of chromosomes in each daughter cell.
Nondisjunction is the name given to the phenomenon in which separation of genetic material fails to occur. Either homologous chromosomes fail to separate properly in meiosis I, or sister chromatids fail to separate properly during meiosis II. The result of these nondisjunction events is one cell with an abnormally high number of chromosomes (for example trisomy) and one cell with an abnormally low number of chromosomes (for example monosomy).
Crossing over is an event that contributes to the non-identical nature of gametes. Which of the following is true regarding crossing over?
I. It occurs during prophase I
II. It involves exchange of genetic material between sister chromatids
III. It involves exchange of genetic material between homologous chromosomes
Crossing over is an event that contributes to the non-identical nature of gametes. Which of the following is true regarding crossing over?
I. It occurs during prophase I
II. It involves exchange of genetic material between sister chromatids
III. It involves exchange of genetic material between homologous chromosomes
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Crossing over occurs during prophase of meiosis I (prophase I). This process requires tetrad formation, where the homologous chromosomes (with their sister chromatids) pair with each other. Following tetrad formation, the genetic material from one homologous chromosome can be exchanged with that of the other. This exchange of genetic material leads to genetic recombination and results in production of non-identical gametes. Crossing over occurs only between homologous chromosomes. Sister chromatids are situated to form a single chromosome; crossing over does not include recombination of genetic material within a single chromosome.
Remember that crossing over is not a mutation and is a completely natural process for every sexually reproducing organism.
Crossing over occurs during prophase of meiosis I (prophase I). This process requires tetrad formation, where the homologous chromosomes (with their sister chromatids) pair with each other. Following tetrad formation, the genetic material from one homologous chromosome can be exchanged with that of the other. This exchange of genetic material leads to genetic recombination and results in production of non-identical gametes. Crossing over occurs only between homologous chromosomes. Sister chromatids are situated to form a single chromosome; crossing over does not include recombination of genetic material within a single chromosome.
Remember that crossing over is not a mutation and is a completely natural process for every sexually reproducing organism.
How many chromosomes does a human germ cell contain during metaphase I and telophase II, respectively?
How many chromosomes does a human germ cell contain during metaphase I and telophase II, respectively?
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For this question you have to carefully track the chromosomes through meiosis. A human cell in metaphase I will have formed the tetrads and would have aligned the genetic material along the metaphase plate. The sister chromatids are still attached to one another, so they only count as one chromosome per pair of chromatids. There are a total of 46 chromosomes in metaphase I, each comprised of two sister chromatids. There are 23 homologous pairs, each containing two complete chromosomes.
During telophase II, the cell is in a haploid state. The homologous pairs have been separated during anaphase I, such that each cell contains 23 complete chromosomes. Each chromosome is then broken into its chromatids, such that the total number of chromosomes represented during anaphase II is 46, with each chromatid representing a chromosome. If each of the chromosomes still had its sister chromatid, then the total number of chromosomes would be 23. Telophase II follows anaphase II. The 46 chromatids are sequestered to opposite sides of the cell, but the cell has not yet divided. A cell in telophase II is haploid, containing only one copy of each homologous chromosome, but contains two chromatids for each copy. The total number of chromosomes in a telophase II cell is thus 46. As soon as the cell completes cytokinesis, and two daughter cells are formed, they become haploid cells with 23 chromosomes each.
For this question you have to carefully track the chromosomes through meiosis. A human cell in metaphase I will have formed the tetrads and would have aligned the genetic material along the metaphase plate. The sister chromatids are still attached to one another, so they only count as one chromosome per pair of chromatids. There are a total of 46 chromosomes in metaphase I, each comprised of two sister chromatids. There are 23 homologous pairs, each containing two complete chromosomes.
During telophase II, the cell is in a haploid state. The homologous pairs have been separated during anaphase I, such that each cell contains 23 complete chromosomes. Each chromosome is then broken into its chromatids, such that the total number of chromosomes represented during anaphase II is 46, with each chromatid representing a chromosome. If each of the chromosomes still had its sister chromatid, then the total number of chromosomes would be 23. Telophase II follows anaphase II. The 46 chromatids are sequestered to opposite sides of the cell, but the cell has not yet divided. A cell in telophase II is haploid, containing only one copy of each homologous chromosome, but contains two chromatids for each copy. The total number of chromosomes in a telophase II cell is thus 46. As soon as the cell completes cytokinesis, and two daughter cells are formed, they become haploid cells with 23 chromosomes each.
Cells containing only one homologue of each chromosome would be produced following which of the following processes?
Cells containing only one homologue of each chromosome would be produced following which of the following processes?
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For this question, remember that a cell containing only one homologue is a haploid cell. Cells containing two homologous chromosomes are considered diploid.
Following the S phase and mitosis, the cells are diploid because they contain pairs of homologous chromosomes.
Following meiosis I, however, the daughter cells are haploid because they contain only one homologue. These homologues still consist of two identical sister chromatids, which will be separated following meiosis II, but the halving of genetic material during meiosis I still generates haploid daughter cells.
For this question, remember that a cell containing only one homologue is a haploid cell. Cells containing two homologous chromosomes are considered diploid.
Following the S phase and mitosis, the cells are diploid because they contain pairs of homologous chromosomes.
Following meiosis I, however, the daughter cells are haploid because they contain only one homologue. These homologues still consist of two identical sister chromatids, which will be separated following meiosis II, but the halving of genetic material during meiosis I still generates haploid daughter cells.
Independent assortment of traits on different chromosomes is due to the random alignment of different pairs of homologues. This alignment occurs during which of the given phases?
Independent assortment of traits on different chromosomes is due to the random alignment of different pairs of homologues. This alignment occurs during which of the given phases?
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Remember that the law of independent assortment states that genes on different chromosomes are passed independently of one another to offspring. This phenomenon results from the random alignment of the chromosomes along the metaphase plate. This random alignment allows genes to be segregated independently, and occurs during metaphase I.
Metaphase II involves the alignment of single chromosomes along the metaphase plate for segregation of identical sister chromatids. Remember that independent assortment is only valid for genes on different chromosomes. Genes on the same chromosomes are not passed independently of one another from parent to offspring.
Independent assortment can, thus, only occur during metaphase I, since this phase involves alignment of independent, non-identical chromosomes.
Remember that the law of independent assortment states that genes on different chromosomes are passed independently of one another to offspring. This phenomenon results from the random alignment of the chromosomes along the metaphase plate. This random alignment allows genes to be segregated independently, and occurs during metaphase I.
Metaphase II involves the alignment of single chromosomes along the metaphase plate for segregation of identical sister chromatids. Remember that independent assortment is only valid for genes on different chromosomes. Genes on the same chromosomes are not passed independently of one another from parent to offspring.
Independent assortment can, thus, only occur during metaphase I, since this phase involves alignment of independent, non-identical chromosomes.