Meiosis Basics
How does meiosis contribute to maintaining a consistent number of chromosomes in offspring?
Meiosis reduces the chromosome number by half, forming haploid gametes.
What are homologous chromosomes, and how do they contribute to genetic diversity?
Homologous chromosomes are paired chromosomes with genes for the same trait. They contribute to genetic diversity through genetic recombination during crossing-over.
What happens during prophase I of meiosis?
Homologous chromosomes pair up to form tetrads, and crossing-over occurs.
How does genetic recombination (crossing-over) contribute to genetic diversity?
Crossing-over exchanges genetic material between homologous chromosomes, creating new combinations of alleles and increasing genetic diversity.
List three similarities between mitosis and meiosis.
Both involve nuclear envelope disappearance, DNA coiling into chromosomes, and the use of fibers to separate chromosomes.
What is the term for a cell with two of each kind of chromosome?
Diploid (2n) cell.
Explain the significance of crossing-over during meiosis.
Crossing-over results in the exchange of genetic material between non-sister chromatids, creating new combinations of alleles and increasing genetic diversity.
Contrast metaphase I in meiosis with metaphase in mitosis.
In metaphase I, homologous chromosomes line up in pairs, while in mitosis, chromosomes line up independently.
How can the frequency of genetic recombination be used to estimate gene distances on the same chromosome?
Genes farther apart will have a higher recombination frequency, while closer genes will have a lower recombination frequency.
What is the main difference between the outcomes of mitosis and meiosis?
Mitosis results in two genetically identical diploid daughter cells, while meiosis produces four genetically different haploid gametes.
Define haploid cells and provide an example.
Haploid cells have one of each kind of chromosome. Example: Gametes (sperm or eggs)
Provide the diploid and haploid chromosome numbers for humans.
Diploid: 46 chromosomes; Haploid: 23 chromosomes.
Describe the events of telophase II in meiosis.
Nuclei reform, spindle fibers disappear, and cytoplasm divides, resulting in four haploid cells.
What are translocations, and how can they affect genetic diversity?
Translocations are genetic events where genetic material is exchanged between nonhomologous chromosomes. They can generate new combinations but may result in unfavorable phenotypes if they occur within a gene.
Explain how genetic diversity is generated during metaphase I of meiosis.
Homologous pairs assort independently during metaphase I, resulting in different combinations of genetic material being passed on to the offspring.
Explain the significance of the haploid number of chromosomes in gametes during fertilization.
The haploid number ensures that when a haploid egg is fertilized by a haploid sperm, the resulting zygote has the correct diploid number of chromosomes.
What is the role of homologous chromosomes in meiosis, and how do they differ from each other?
Homologous chromosomes have genes for the same trait but may have different alleles. They pair up during meiosis, allowing genetic recombination.
What is the significance of the spindle fibers in meiosis, specifically during metaphase I and II?
Spindle fibers help align and separate chromosomes during metaphase I and II, ensuring the proper distribution of genetic material.
Explain how genetic diversity can be generated during metaphase I of meiosis.
Homologous pairs assort independently during metaphase I, resulting in different combinations of genetic material being passed on to the offspring.
What is the significance of the two rounds of cell division in meiosis compared to mitosis?
Meiosis has two rounds to reduce chromosome number by half and create haploid gametes, ensuring genetic diversity. Mitosis has one round, producing genetically identical diploid cells.
What is the difference between a diploid cell and a haploid cell in terms of chromosome number and genetic diversity?
A diploid cell has two sets of chromosomes, one from each parent, contributing to genetic diversity. In contrast, a haploid cell has one set of chromosomes, promoting genetic diversity through recombination.
Define allele and explain its significance in the context of homologous chromosomes.
An allele is a gene form for each variation of a trait. Homologous chromosomes may have different alleles, contributing to genetic diversity during meiosis.
Explain why meiosis has two rounds of cell division (meiosis I and meiosis II) while mitosis has only one round.
Meiosis has two rounds to reduce chromosome number by half, creating haploid gametes—mitosis results in genetically identical diploid cells.
How do meiosis and fertilization work together to ensure consistency in the number of chromosomes from one generation to the next?
Meiosis reduces chromosome number, and fertilization combines haploid gametes, resulting in a diploid zygote, maintaining the correct chromosome number.
Describe one potential consequence of genetic recombination between nonhomologous chromosomes during meiosis.
Genetic recombination between nonhomologous chromosomes can lead to translocations, creating new combinations of genetic material. If translocations occur within a gene, they may result in an unfavorable phenotype.