Chapter 13 Flashcards
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What is the significance of crossing over during meiosis?
Crossing over during prophase I of meiosis increases genetic diversity by exchanging segments of chromatids between homologous chromosomes, creating recombinant chromosomes.
How does independent assortment contribute to genetic variation?
Independent assortment during meiosis I ensures that each pair of homologous chromosomes segregates independently, leading to a variety of possible combinations of maternal and paternal chromosomes in gametes.
What is the role of random fertilization in genetic variation?
Random fertilization further increases genetic diversity by combining the genetic material from two different gametes, resulting in a vast number of possible zygote combinations.
How many possible diploid combinations can result from independent assortment alone in humans?
Independent assortment alone can result in approximately 70 trillion (70 × 10^12) different diploid combinations in humans.
What is the average number of crossover events per chromosome pair in humans?
The average number of crossover events per chromosome pair in humans is one to three.
How does crossing over affect the genetic diversity of daughter cells?
Crossing over generates combinations of genes that are different from those present in the original chromosomes, enhancing the genetic diversity of daughter cells.
What is the significance of genetic variation for evolution?
Genetic variation provides the raw material for natural selection, shaping adaptation and survival in changing environments.
How do mutations contribute to genetic diversity?
Mutations introduce new alleles into a population, increasing genetic diversity and providing new traits that may be beneficial for survival.
What is the role of sexual reproduction in generating genetic diversity?
Sexual reproduction generates genetic diversity through meiosis (independent assortment and crossing over) and random fertilization, creating unique combinations of alleles in offspring.
How does the bdelloid rotifer generate genetic variation without sexual reproduction?
The bdelloid rotifer generates genetic variation by incorporating DNA from different species during dry spells when the organisms are in a dormant state.
What is the significance of cytogenetic maps in genetic research?
Cytogenetic maps provide a visual representation of chromosomal features observed under a microscope, aiding in the study of genetic variation and chromosomal abnormalities.
How does whole-genome sequencing contribute to genetic research?
Whole-genome sequencing provides nucleotide-level details, confirming the linear order of genes from linkage maps and offering accurate physical distances between genes.
What are the limitations of linkage maps in genetic research?
Linkage maps may not always correspond directly to physical distances due to variation in crossing over frequency along chromosomes and genetic unlinking for genes far apart.
How does genetic variation arise in sexually reproducing organisms?
Genetic variation arises primarily due to meiosis (independent assortment and crossing over) and random fertilization, with mutations also contributing to diversity.
What is the significance of independent assortment in genetic diversity?
Independent assortment increases genetic diversity by ensuring that each pair of homologous chromosomes segregates independently during meiosis I.
How does the process of crossing over differ from independent assortment?
Crossing over involves the exchange of genetic material between homologous chromosomes, while independent assortment refers to the random segregation of chromosome pairs during meiosis I.
What is the impact of random fertilization on genetic diversity?
Random fertilization amplifies genetic diversity by combining the genetic material from two different gametes, resulting in unique combinations of alleles in offspring.
How does the number of chromosome pairs affect genetic variation in offspring?
A higher number of chromosome pairs offers more combinations of chromosomes in gametes, resulting in greater genetic variety in offspring.
What is the role of genetic variation in natural selection?
Genetic variation increases the chances that some individuals in a population will have traits beneficial for survival in changing environments, driving natural selection and evolution.
What are homologous chromosomes?
Homologous chromosomes are pairs of chromosomes that have the same structure and gene sequence but may carry different alleles.
What is synapsis and when does it occur?
Synapsis is the pairing of homologous chromosomes during prophase I of meiosis, allowing crossing over to occur.
What is the significance of the chiasmata in meiosis?
Chiasmata are the points where crossing over occurs between homologous chromosomes, leading to genetic recombination.
How does meiosis I differ from meiosis II?
Meiosis I separates homologous chromosomes, reducing the chromosome number by half, while meiosis II separates sister chromatids, similar to mitosis.
What is the outcome of meiosis in terms of chromosome number and genetic diversity?
Meiosis results in four genetically diverse haploid cells, each with half the chromosome number of the original diploid cell.
What is the role of the spindle apparatus in meiosis?
The spindle apparatus helps segregate chromosomes during meiosis by attaching to kinetochores and pulling chromosomes apart.
What is the difference between a diploid and a haploid cell?
A diploid cell has two sets of chromosomes (one from each parent), while a haploid cell has only one set of chromosomes.
What is the significance of the reduction division in meiosis?
The reduction division (meiosis I) ensures that gametes have half the chromosome number of somatic cells, maintaining genetic stability across generations.
How does fertilization restore the diploid chromosome number?
Fertilization combines two haploid gametes (sperm and egg) to form a diploid zygote, restoring the diploid chromosome number.
What is the role of genetic recombination in evolution?
Genetic recombination creates new combinations of alleles, providing genetic diversity that can be acted upon by natural selection.
How does the environment influence genetic variation?
Environmental factors can affect mutation rates, selection pressures, and the expression of genetic traits, influencing genetic variation in populations.
What is the importance of genetic linkage maps?
Genetic linkage maps help identify the relative positions of genes on chromosomes, aiding in the study of inheritance patterns and genetic disorders.
How do cytogenetic maps differ from genetic linkage maps?
Cytogenetic maps provide a visual representation of chromosomal features observed under a microscope, while genetic linkage maps show the relative positions of genes based on recombination frequencies.
What is the significance of whole-genome sequencing in genetics?
Whole-genome sequencing provides detailed information about the entire genetic makeup of an organism, enabling the study of genetic variation and disease.
How do mutations contribute to genetic disorders?
Mutations can alter the function of genes, leading to genetic disorders if they disrupt normal biological processes.
What is the role of genetic counseling in managing genetic disorders?
Genetic counseling provides information and support to individuals and families affected by genetic disorders, helping them understand their risks and options.
How does genetic variation affect population dynamics?
Genetic variation influences the adaptability and survival of populations, affecting their ability to respond to environmental changes and evolutionary pressures.
What is the impact of genetic drift on small populations?
Genetic drift can lead to significant changes in allele frequencies in small populations, potentially reducing genetic diversity and increasing the risk of inbreeding.
How do gene flow and migration affect genetic variation?
Gene flow and migration introduce new alleles into populations, increasing genetic diversity and reducing differences between populations.
