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Cell bio > Chapter 13 > Flashcards

Chapter 13 Flashcards

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1
Q

What is the significance of crossing over during meiosis?

A

Crossing over during prophase I of meiosis increases genetic diversity by exchanging segments of chromatids between homologous chromosomes, creating recombinant chromosomes.

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2
Q

How does independent assortment contribute to genetic variation?

A

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.

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3
Q

What is the role of random fertilization in genetic variation?

A

Random fertilization further increases genetic diversity by combining the genetic material from two different gametes, resulting in a vast number of possible zygote combinations.

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4
Q

How many possible diploid combinations can result from independent assortment alone in humans?

A

Independent assortment alone can result in approximately 70 trillion (70 × 10^12) different diploid combinations in humans.

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5
Q

What is the average number of crossover events per chromosome pair in humans?

A

The average number of crossover events per chromosome pair in humans is one to three.

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6
Q

How does crossing over affect the genetic diversity of daughter cells?

A

Crossing over generates combinations of genes that are different from those present in the original chromosomes, enhancing the genetic diversity of daughter cells.

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7
Q

What is the significance of genetic variation for evolution?

A

Genetic variation provides the raw material for natural selection, shaping adaptation and survival in changing environments.

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8
Q

How do mutations contribute to genetic diversity?

A

Mutations introduce new alleles into a population, increasing genetic diversity and providing new traits that may be beneficial for survival.

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9
Q

What is the role of sexual reproduction in generating genetic diversity?

A

Sexual reproduction generates genetic diversity through meiosis (independent assortment and crossing over) and random fertilization, creating unique combinations of alleles in offspring.

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10
Q

How does the bdelloid rotifer generate genetic variation without sexual reproduction?

A

The bdelloid rotifer generates genetic variation by incorporating DNA from different species during dry spells when the organisms are in a dormant state.

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11
Q

What is the significance of cytogenetic maps in genetic research?

A

Cytogenetic maps provide a visual representation of chromosomal features observed under a microscope, aiding in the study of genetic variation and chromosomal abnormalities.

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12
Q

How does whole-genome sequencing contribute to genetic research?

A

Whole-genome sequencing provides nucleotide-level details, confirming the linear order of genes from linkage maps and offering accurate physical distances between genes.

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13
Q

What are the limitations of linkage maps in genetic research?

A

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.

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14
Q

How does genetic variation arise in sexually reproducing organisms?

A

Genetic variation arises primarily due to meiosis (independent assortment and crossing over) and random fertilization, with mutations also contributing to diversity.

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15
Q

What is the significance of independent assortment in genetic diversity?

A

Independent assortment increases genetic diversity by ensuring that each pair of homologous chromosomes segregates independently during meiosis I.

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16
Q

How does the process of crossing over differ from independent assortment?

A

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.

17
Q

What is the impact of random fertilization on genetic diversity?

A

Random fertilization amplifies genetic diversity by combining the genetic material from two different gametes, resulting in unique combinations of alleles in offspring.

18
Q

How does the number of chromosome pairs affect genetic variation in offspring?

A

A higher number of chromosome pairs offers more combinations of chromosomes in gametes, resulting in greater genetic variety in offspring.

19
Q

What is the role of genetic variation in natural selection?

A

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.

20
Q

What are homologous chromosomes?

A

Homologous chromosomes are pairs of chromosomes that have the same structure and gene sequence but may carry different alleles.

21
Q

What is synapsis and when does it occur?

A

Synapsis is the pairing of homologous chromosomes during prophase I of meiosis, allowing crossing over to occur.

22
Q

What is the significance of the chiasmata in meiosis?

A

Chiasmata are the points where crossing over occurs between homologous chromosomes, leading to genetic recombination.

23
Q

How does meiosis I differ from meiosis II?

A

Meiosis I separates homologous chromosomes, reducing the chromosome number by half, while meiosis II separates sister chromatids, similar to mitosis.

24
Q

What is the outcome of meiosis in terms of chromosome number and genetic diversity?

A

Meiosis results in four genetically diverse haploid cells, each with half the chromosome number of the original diploid cell.

25
Q

What is the role of the spindle apparatus in meiosis?

A

The spindle apparatus helps segregate chromosomes during meiosis by attaching to kinetochores and pulling chromosomes apart.

26
Q

What is the difference between a diploid and a haploid cell?

A

A diploid cell has two sets of chromosomes (one from each parent), while a haploid cell has only one set of chromosomes.

27
Q

What is the significance of the reduction division in meiosis?

A

The reduction division (meiosis I) ensures that gametes have half the chromosome number of somatic cells, maintaining genetic stability across generations.

28
Q

How does fertilization restore the diploid chromosome number?

A

Fertilization combines two haploid gametes (sperm and egg) to form a diploid zygote, restoring the diploid chromosome number.

29
Q

What is the role of genetic recombination in evolution?

A

Genetic recombination creates new combinations of alleles, providing genetic diversity that can be acted upon by natural selection.

30
Q

How does the environment influence genetic variation?

A

Environmental factors can affect mutation rates, selection pressures, and the expression of genetic traits, influencing genetic variation in populations.

31
Q

What is the importance of genetic linkage maps?

A

Genetic linkage maps help identify the relative positions of genes on chromosomes, aiding in the study of inheritance patterns and genetic disorders.

32
Q

How do cytogenetic maps differ from genetic linkage maps?

A

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.

33
Q

What is the significance of whole-genome sequencing in genetics?

A

Whole-genome sequencing provides detailed information about the entire genetic makeup of an organism, enabling the study of genetic variation and disease.

34
Q

How do mutations contribute to genetic disorders?

A

Mutations can alter the function of genes, leading to genetic disorders if they disrupt normal biological processes.

35
Q

What is the role of genetic counseling in managing genetic disorders?

A

Genetic counseling provides information and support to individuals and families affected by genetic disorders, helping them understand their risks and options.

36
Q

How does genetic variation affect population dynamics?

A

Genetic variation influences the adaptability and survival of populations, affecting their ability to respond to environmental changes and evolutionary pressures.

37
Q

What is the impact of genetic drift on small populations?

A

Genetic drift can lead to significant changes in allele frequencies in small populations, potentially reducing genetic diversity and increasing the risk of inbreeding.

38
Q

How do gene flow and migration affect genetic variation?

A

Gene flow and migration introduce new alleles into populations, increasing genetic diversity and reducing differences between populations.

Cell bio (18 decks)

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