Chapter 8 - Genetic Recombination Flashcards by Vicki schenk

The process of ________ allows for the amplification of genetic diversity and is at the heart of the eukaryotic process of _________ , which is an essential component of sexual reproduction.

The process of RECOMBINATION allows for the amplification of genetic diversity and is at the heart of the eukaryotic process of MEIOSIS, which is an essential component of sexual reproduction.

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Genetic recombination requires two DNA molecules that ________ from each other in at least two places, a mechanism for bringing the two molecules into close proximity, and enzymes to cut the ________ bonds of the DNA backbones, ________ the ends, and _________ the DNA molecules back together.

Genetic recombination requires two DNA molecules that DIFFER from each other in at least two places, a mechanism for bringing the two molecules into close proximity, and enzymes to cut the COVALENT bonds of the DNA backbones, EXCHANGE the ends, and PASTE the DNA molecules back together.

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Most recombination events occur between _________ regions of DNA, that is, regions that are very similar. This similarity allows the two molecules to ____________ precisely.

Most recombination events occur between HOMOLOGOUS regions of DNA, that is, regions that are very similar. This similarity allows the two molecules to LINE UP precisely.

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In genetic recombination, enzymes cut each _________ of both molecules, the free ends are ____________ , and enzymes then attach the free ends by making a total of ____________ new covalent bonds.

In genetic recombination, enzymes cut each BACKBONE of both molecules, the free ends are EXHCHANGED, and enzymes then attach the free ends by making a total of FOUR new covalent bonds.

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In genetic recombination, despite the fact that four bonds are cut and reformed, this process leads to a(n) ____________ recombination event. If two DNA molecules were involved in a single recombination event, as is the case between various bacterial DNA molecules, the result would be the ____________ into a single larger molecule.

In genetic recombination, despite the fact that four bonds are cut and reformed, this process leads to a(n) SINGLE recombination event. If two DNA molecules were involved in a single recombination event, as is the case between various bacterial DNA molecules, the result would be the FUSING into a single larger molecule.

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What is genetic recombination?

Development of new combinations of genetic information to generate genetic variability.

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What is asexual reproduction?

A reproductive process that generates two identical daughter cells from a parental cell.

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What is evolution?

A process by which populations undergo change through the natural selection of certain individuals in the population based on heritable traits.

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What is homologous mean?

Similar

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What are alleles?

One of two or more versions of a gene.

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What is recombinant?

Phenotype with a different combination of traits from those of the original parents.

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What is sexual reproduction?

The mode of reproduction in which male and female parents produce offspring through the union of egg and sperm generated by meiosis.

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What are gametes?

A haploid cell; an egg or sperm. Haploid cells fuse during sexual reproduction to form a diploid zygote.

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What is meiosis?

The division of diploid cells to haploid progeny, consisting of two sequential rounds of nuclear and cellular division.

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What are somatic cells?

Any of the cells of an organism’s body other than reproductive cells.

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What is fertilization?

The fusion of the nuclei of an egg and sperm cell, which initiates development of a new individual.

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What is a zygote?

A fertilized egg.

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What is a paternal chromosome?

The chromosome derived from the male parent of an organism.

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What is a maternal chomosome?

The chromosome derived from the female parent of an organism.

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What are meiocytes?

A cell that is destined to divide by meiosis.

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What is interkenesis?

A brief interphase separating the two meiotic divisions.

What is a synapsis?

Process in meiosis in which homologous chromosomes come together and pair. Also known as pairing.

What are tetrads?

Homologous pair consisting of four chromatids.

What is the synaptonemal complex?

A protein framework that tightly holds together homologous chromosomes as they pair.

What are crossovers?

Site of recombination during meiosis. Also referred to as a chiasmata.

What is crossing over?

The recombination process in meiosis, in which chromatids exchange segments.

What is the metaphase plate?

During cell division, chromosomes are located to a position at the spindle midpoint prior to them separating during anaphase.

What are sex chromosomes?

Chromosomes that are different in male and female individuals of the same species.

What is the Y chromosome?

Sex chromosome that is paired with an X chromosome in male cells.

If chromosomes A and B are homologous, which of the following describes them? a. They have the same alleles, at different locations, but not necessarily the same genes. b. They have the same genes, at different locations, but not necessarily the same alleles. c. They have the same genes, at the same locations, but not necessarily the same alleles. d. They have the same alleles, at the same locations, but not necessarily the same genes.

c. They have the same genes, at the same locations, but not necessarily the same alleles.

Which of the following is NOT required for genetic recombination to occur? a. homologous regions of DNA b. cutting and pasting of the DNA backbone c. enzymes that separate hydrogen bonds between DNA strands d. separation of the cytoplasm

d. separation of the cytoplasm

If a diploid organism normally has 16 chromosomes in somatic cells, how many chromosomes are from maternal origin and how many are from paternal origin? a. 32 from maternal origin; 32 from paternal b. 8 from maternal origin; 8 from paternal c. 4 from maternal origin; 4 from paternal d. 16 from maternal origin; 16 from paternal

b. 8 from maternal origin; 8 from paternal

Which statement is consistent with the alleles on a pair of homologous chromosomes? a. They are always the same. b. They are always different. c. They may or may not be the same.

c. They may or may not be the same.

In the process of meiosis, how many times does DNA replication occur? a. never b. once c. twice d. three times

a. never

During which phase do homologous pairs separate? a. anaphase I b. anaphase II c. telophase I d. prophase II

a. anaphase I

Suppose that the diploid number for an organism is six, and one homologous pair underwent nondisjunction during meiosis I. How many chromosomes would be present in the daughter cells at the end of meiosis I? a. Both daughter cells would have three chromosomes. b. One daughter cell would have two chromosomes and the other would have three. c. One daughter cell would have one chromosome and the other would have five. d. One daughter cell would have two chromosomes and the other would have four.

d. One daughter cell would have two chromosomes and the other would have four.

With respect to the sex chromosomes in humans, females and males will produce gametes with which possible sex chromosomes? a. Females will produce only X; males will produce only Y. b. Females will produce only X; males will produce both X and Y. c. Females will produce both X and Y; males will produce only Y. d. Females will produce both X and Y; males will produce both X and Y.

b. Females will produce only X; males will produce both X and Y.

Suppose that the diploid number for an organism is x, and that a crossover occurred during prophase I. What will be the amount of DNA in each cell at the end of meiosis I? a. 0.5x b. 0.75x c. x d. 2x

a. 0.5x

Which life cycle pattern would not give rise to genetic variability? a. diploid dominant b. haploid dominant c. diploid-haploid alternate d. asexual reproduction

d. asexual reproduction

Regardless of the life cycle pattern, which statement about gametes produced by meiosis is true? a. They are only different from each other. b. They are identical to each other but different from the parental cell. c. They are different from each other and from the parental cell.

c. They are different from each other and from the parental cell.

In which stage of meiosis are there events that promote genetic diversity among cells? a. prophase I b. anaphase I c. anaphase II d. all of the above

d. all of the above

If meiosis creates cells with haploid number of chromosomes in them, which of these processes restores the diploid number of chromosomes in adult diploid organisms? a. cell regulation b. mitosis c. binary fission d. fertilization

d. fertilization

Which of the following does meiosis accomplish? a. reduction of the number of chromosomes to half in the daughter cells b. reduction of the number of chromosomes to a third in the daughter cells c. doubling of the number of chromosomes in the daughter cells d. tripling of the number of chromosomes in the daughter cells

a. reduction of the number of chromosomes to half in the daughter cells

What is shared by both mitosis and meiosis II? a. production of two daughter cells with diploid number of chromosomes in each b. production of four daughter cells with haploid number of chromosomes in each c. separation of homologous chromosomes d. separation of sister chromatids

d. separation of sister chromatids

Which of the following best describes meiosis? a. It changes just the DNA sequence. b. It changes just the chromosome number. c. It changes both chromosome number and DNA sequence. d. It changes both chromosome number and RNA sequence.

c. It changes both chromosome number and DNA sequence.

Suppose you are observing a cell's division and you notice the step when the homologous chromosomes are separated in their respectful cells, but still duplicated. Which phase of the division has most likely finished? a. meiosis I b. meiosis II c. the whole meiosis d. mitosis

a. meiosis I

Which of these statements applies to tetrads? a. They form during mitosis. b. They form during meiosis I. c. They form during meiosis II. d. They form during fertilization.

b. They form during meiosis I.

Suppose a cell produced one gamete with extra chromosomes. What does this tell you about the cell? a. Its mitosis failed to separate chromosomes properly. b. Its meiosis failed to separate chromosomes properly. c. Its growth pattern was damaged. d. Its feeding pattern was compromised.

b. Its meiosis failed to separate chromosomes properly.

Suppose crossing-over happens between two non-homologous pairs. Which of these options would be the consequence of this? a. Gametes will not form at all. b. Gametes will all be genetically identical. c. Genetic mutation will occur in gametes. d. Gametes will still be normal.

c. Genetic mutation will occur in gametes.

Which of the following are the most important factors contributing to genetic diversity? a. genetic recombination, systematic segregation, alternative combinations at meiosis II, and random fertilization b. genetic recombination, random duplication, alternative combinations at meiosis II, and random fertilization c. genetic recombination, random segregation, alternative combinations at meiosis I, and random fertilization d. genetic recombination, random segregation, alternative combinations at meiosis II, and random fertilization

d. genetic recombination, random segregation, alternative combinations at meiosis II, and random fertilization