mitosis and meiosis

A human cell has 46 chromosomes. Following mitosis, the daughter cells would each have a total of _____ chromosomes. After meiosis I, the two daughter cells would have _____ chromosomes, and after meiosis II ______ chromosomes.

46 23 23

(meiosis 1) X (meiosis 2) What is the ploidy level of the cell in the red square? A) haploid B) diploid C) triploid

A

From prophase through metaphase of mitosis, each chromosome has ___________ DNA molecule(s), while from anaphase through telophase of mitosis, each chromosome has ____________ DNA molecule(s). A) two; one B) 2n; 1n C) homologous; nonhomologous D) condensed; decondensed E) nonsister chromatid; sister chromatid

A

One way to make seedless watermelons is to produce triploid seed. The triploid watermelons that grow from that seed cannot produce functional seeds and the fruit is seedless. Which phase of the cell cycle would you expect triploid cells to be unable to complete with the result that seeds don't form? A) meiosis I B) meiosis II C) S-phase D) G2

A

Oogenesis, the process that creates female gametes (eggs), is halted at prophase I until puberty. Which of the following describes the DNA content of a female's gametes during her childhood? A) 46 chromosomes, 92 chromatids B) 23 chromosomes, 23 chromatids C) 46 chromosomes, 46 chromatids D) 23 chromosomes, 46 chromatids

A

Oogenesis, the process that creates female gametes, is halted at prophase I until puberty in humans. Which of the following describes the DNA content of a human female's gametes during her childhood? A) 46 chromosomes, 92 chromatids B) 23 chromosomes, 23 chromatids C) 46 chromosomes, 46 chromatids D) 23 chromosomes, 46 chromatids

A

Tasmanian Devils have 14 chromosomes in their somatic cells. How many different chromosome combinations are created by independent assortment in these animals? A) 2^7 B) 2^14 C) 14^2 D) 7^2

A

Two sister chromatids are joined at the centromere prior to meiosis. Which statement is correct? A) Barring mutation, the two sister chromatids must be identical. B) These chromatids make up a diploid chromosome. C) The cell that contains these sister chromatids must be haploid.

A

When do homologous chromosomes pair? Select all that apply. A) During meiosis I B) During meiosis II C) During mitosis D) During interphase before meiosis E) During interphase between meiosis I and meiosis II

A

Which of the following is true of mitosis? A) Mitosis creates genetically identical daughter cells. B) Mitosis creates genetically distinct daughter cells. C) Mitosis is cell division for reproduction. D) Mitosis produces 4 daughter cells.

A

Which statement correctly describes a key difference between cells entering prophase of mitosis versus prophase I of meiosis? A) For cells entering mitosis, homologous chromosomes function independently; for cells entering meiosis, homologous chromosomes pair up. B) Cells entering meiosis contain twice as much DNA as cells entering mitosis, which is essential because meiosis involves two cell divisions. C) DNA replication before mitosis produces sister chromatids, whereas DNA replication before meiosis produces homologous chromosomes.

A

The p53 protein, referred to as the "Guardian of the Genome," is a tumor suppressor that plays an important role in halting the division of cells (mitosis) that have sustained DNA damage. The p53 protein arrests the cell cycle at two different times: before DNA replication (between phases G1 and S) and before cell division (between phases G2 and M). Arresting the cell cycle at these points helps prevent the division of cells containing damaged DNA, which could become cancerous. The gene encoding p53 is often mutated in cancers. In fact, this gene is mutated more often than any of the other 20,000 human genes. A deeper understanding of the role of p53 in the cell cycle can therefore improve our understanding of cancers and perhaps lead to new forms of treatment. Caption: Alleles of the p53 gene were selectively disrupted in a line of human cells and then monitored after exposure to DNA-damaging gamma (γ) radiation to determine what proportion of the cells entered mitosis (cell division). The shaded squares represent cells with two normal alleles of the p53 gene. The half-shaded squares represent cells with one normal and one disrupted allele of the p53 gene (note that some of the half-shaded squares are covered by the shaded squares). The unshaded squares represent cells in which both alleles of the p53 gene were disrupted. The mitotic index is the proportion of cells undergoing mitosis at a given time. In this study, researchers investigated the role of p53 in cell cycle regulation at the checkpoint between the G2 and M phases. Most human cells contain two alleles of every gene, one allele inherited from the mother and the other from the father. Normally, an allele can be used to produce a protein, such as p53. However, researchers can use genetic engineering to "disrupt" an allele, making it unable to produce a properly functioning protein. In this case, the researchers genetically engineered a cell line to create two new cell lines, one in which a single allele of the p53 gene was disrupted and the other in which both alleles were disrupted. Next, they exposed all three cell lines to DNA-damaging gamma radiation and observed how this exposure impacted cell division. They measured the impact by determining the proportion of cells undergoing mitosis, called the mitotic index, for each cell line every 12 hours for four days. The mitotic index was measured by fixing or preserving a sample of the cells and then staining them with a DNA-specific fluorescent stain (Hoechst). Using microscopy, cells containing condensed, evenly stained chromosomes were identified and counted. Condensed chromosomes are an indication that the cells were undergoing mitosis at the time they were fixed. Use this information to answer the following X questions. Which cell line(s) have a properly functioning p53 protein? Select all that apply. A) Cell lines with 2 copies of the normal p53 allele. B) Cell lines with 1 normal copy of the p53 allele and one disrupted copy. C) Cell lines with 2 disrupted copies of the p53 allele.

A & B

The p53 protein, referred to as the "Guardian of the Genome," is a tumor suppressor that plays an important role in halting the division of cells (mitosis) that have sustained DNA damage. The p53 protein arrests the cell cycle at two different times: before DNA replication (between phases G1 and S) and before cell division (between phases G2 and M). Arresting the cell cycle at these points helps prevent the division of cells containing damaged DNA, which could become cancerous. The gene encoding p53 is often mutated in cancers. In fact, this gene is mutated more often than any of the other 20,000 human genes. A deeper understanding of the role of p53 in the cell cycle can therefore improve our understanding of cancers and perhaps lead to new forms of treatment. Caption: Alleles of the p53 gene were selectively disrupted in a line of human cells and then monitored after exposure to DNA-damaging gamma (γ) radiation to determine what proportion of the cells entered mitosis (cell division). The shaded squares represent cells with two normal alleles of the p53 gene. The half-shaded squares represent cells with one normal and one disrupted allele of the p53 gene (note that some of the half-shaded squares are covered by the shaded squares). The unshaded squares represent cells in which both alleles of the p53 gene were disrupted. The mitotic index is the proportion of cells undergoing mitosis at a given time. In this study, researchers investigated the role of p53 in cell cycle regulation at the checkpoint between the G2 and M phases. Most human cells contain two alleles of every gene, one allele inherited from the mother and the other from the father. Normally, an allele can be used to produce a protein, such as p53. However, researchers can use genetic engineering to "disrupt" an allele, making it unable to produce a properly functioning protein. In this case, the researchers genetically engineered a cell line to create two new cell lines, one in which a single allele of the p53 gene was disrupted and the other in which both alleles were disrupted. Next, they exposed all three cell lines to DNA-damaging gamma radiation and observed how this exposure impacted cell division. They measured the impact by determining the proportion of cells undergoing mitosis, called the mitotic index, for each cell line every 12 hours for four days. The mitotic index was measured by fixing or preserving a sample of the cells and then staining them with a DNA-specific fluorescent stain (Hoechst). Using microscopy, cells containing condensed, evenly stained chromosomes were identified and counted. Condensed chromosomes are an indication that the cells were undergoing mitosis at the time they were fixed. Use this information to answer the following X questions. According to this information, which of the following statements is accurate? Select all that apply. A) Cells with two normal alleles of p53 will not enter mitosis for at least 96 hours after exposure to DNA-damaging gamma radiation. B) Cells will not enter mitosis for 96 hours after exposure to DNA-damaging gamma radiation when they have at least one functioning allele of the p53 gene. C) Cells with two mutated copies of the p53 gene show a more protective response to the exposure to DNA-damaging effects of gamma radiation. D) p53 plays an important regulatory role in the cell cycle, preventing damaged cells from proliferating

A & B & D

(duplication of chromosomes) X X (meiosis 1) What is the ploidy level of the cell in the red square? A) haploid B) diploid C) triploid

B

If a species has 50 chromosomes in each of its gametes, then how many different chromosomal combinations are possible during gamete production? A) 2 x 50 B) 2^50 C) 2 x 25 D) 2^25 E) 25^2 F) 50^2

B

Tasmanian Devil populations are suffering an alarming decrease due to Devil Facial Tumor Disease (a transmissible form of cancer). Which of the following is likely to be a factor in this disease? A) They have too few chromosomes to protect against disease. B) They have low genetic diversity. C) They reproduce via mitosis rather than meiosis. D) They are carnivores and eat too much meat - this is bad for their health.

B

What stage of mitosis is this? (linned up in middle) A) Prophase B) Metaphase C) Anaphase D) Telophase

B

Which one of the following statements about sex is true? A) All organisms have sexual reproduction. B) Sex is the exchange of genetic material. C) Sexual reproduction produces offspring that are genetically identical to their parents. D) Sex requires the formation of eggs and sperm. E) All of these are true of sex

B

II II II II II II How many chromosomes are in this cell? A) 3 B) 6 C) 12

B Yes! Each chromosome is comprised of two sister chromatids - but there are 6 centromeres so there are 6 chromosomes.

(cell split & chromo splitting) What stage of cell division is shown in this image? A) Anaphase B) Anaphase I C) Anaphase II D) Telophase I

C

A human kidney cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain? A) 23 B) 46 C) 92 D) 23 or 46, depending on the portion of prophase examined E) 46 or 92, depending on the portion of prophase examined

C

Asexual reproduction ________________________________________________. A) is limited to single-cell organisms B) leads to a loss of genetic material C) produces offspring genetically identical to the parent D) requires both meiosis and mitosis

C

How many different chromosome combinations are produced by independent assortment in a cell with 10 chromosomes (5 homologous pairs)? A) 5 B) 10 C) 2^5 D) 2^10

C

The bananas you purchase in the grocery store in the United States, are the product of asexual propagation methods. Which of these processes produces genetic variation in the bananas that you eat with your breakfast cereal? Select all that apply. A) Crossing-over B) Independent assortment C) Mutation

C

The image on the left is in the G1 phase of the cell cycle and image on the right is in G2 (notice that both G1 and G2 are part of interphase and a simple light microscope does not allow you to see the differences between the stages). Which of the following statements is most accurate? A) The G1 cell has double the amount of DNA as the G2 cell. B) The G2 cell has 4x as much DNA as the G1 cell. C) The G1 cell has half the amount of DNA as the G2 cell. D) The G1 and G2 cells have same amount of DNA.

C

What stage of mitosis is this? (pulling apart) A) Prophase B) Metaphase C) Anaphase D) Telophase

C

Which of the following statements is NOT true of meiosis in a diploid organism? A) Meiosis creates reproductive cells. B) Meiosis results in four haploid daughter cells. C) In meiosis, chromosomes do not exchange genetic material. D) In meiosis, homologous pairs of chromosomes are pulled apart. E) All the statements are true.

C

During what part of the cell cycle would you see a chromosome that looks like this? A) G1 B) G2 C) M D) S

C Yes! Chromosomes are only visible during the M-phase (either mitosis or meiosis).

Which of these cells is (are) haploid? Select all that apply. A (interphase) B (meiosis 1) C (meiosis 2) D

C & D

Some organisms are capable of asexual or sexual reproduction. Under favorable conditions, reproduction proceeds asexually. When conditions become more stressful reproduction switches to a sexual mode. Why? A) Sexual reproduction is simple and more rapid allowing larger numbers of offspring to be produced. B) Sexual reproduction requires 2 separate individuals, who can both provide nutrient support during stress. C) Asexual reproduction requires more energy. D) Sexual reproduction produces individuals with new combinations of chromosomes increasing diversity.

D

Which of the following statements about mitosis is INCORRECT? A) The daughter nuclei are genetically identical to the parent nucleus. B) It results in two daughter cells. C) Chromosome replication takes place during interphase. D) The process that divides the cytoplasm is called karyokinesis.

D

Which of the following statements about homologous chromosomes is accurate? Select all that apply. A) They are the same as sister chromatids. B) They are genetically identical. C) They pair during mitosis. D) They pair during meiosis. E) They are genetically similar.

D & E

(lined up in the middle) What stage of meiosis is shown in the above image? A) Prophase I B) Metaphase I C) Anaphase I D) Telophase I E) Prophase II F) Metaphase II G) Anaphase II H) Telophase II

F

The graph above represents the change in the DNA content of a cell during interphase. Which cell cycle phase represents the S-phase? I (beginning flat line) II (middle increasing line) III (ending flat line) IV (very end line)

II

This graph shows the amount of DNA in a nucleus as a cell is dividing. What numbered part of the graph correlates to the S-phase? What numbered part of the graph correlates with anaphase?

II IV

This is a picture of a spider plant and plantlet "baby" plants. For each of the statements below, indicate true or false. All of the plantlets are identical to the parent plant. All of the plantlets are identical to each other. This represents asexual reproduction. There is genetic variation among the plantlets. Each plantlet is a clone of the parent plant. The process of producing the plantlets involves gametes.

True True True False True False

Chromosome pairs of the same length and centromere location are called ____________________. Replicated forms of a chromosome are called ______________________ . Crossing over occurs between the ______________________ of homologous chromosomes early in meiosis I. Chromosomes that differ in length and centromere location are called ____________________________ .

homologous chromosomes sister chromatids nonsister chromatids nonhomologous chromosomes

The p53 protein, referred to as the "Guardian of the Genome," is a tumor suppressor that plays an important role in halting the division of cells (mitosis) that have sustained DNA damage. The p53 protein arrests the cell cycle at two different times: before DNA replication (between phases G1 and S) and before cell division (between phases G2 and M). Arresting the cell cycle at these points helps prevent the division of cells containing damaged DNA, which could become cancerous. The gene encoding p53 is often mutated in cancers. In fact, this gene is mutated more often than any of the other 20,000 human genes. A deeper understanding of the role of p53 in the cell cycle can therefore improve our understanding of cancers and perhaps lead to new forms of treatment. Caption: Alleles of the p53 gene were selectively disrupted in a line of human cells and then monitored after exposure to DNA-damaging gamma (γ) radiation to determine what proportion of the cells entered mitosis (cell division). The shaded squares represent cells with two normal alleles of the p53 gene. The half-shaded squares represent cells with one normal and one disrupted allele of the p53 gene (note that some of the half-shaded squares are covered by the shaded squares). The unshaded squares represent cells in which both alleles of the p53 gene were disrupted. The mitotic index is the proportion of cells undergoing mitosis at a given time. In this study, researchers investigated the role of p53 in cell cycle regulation at the checkpoint between the G2 and M phases. Most human cells contain two alleles of every gene, one allele inherited from the mother and the other from the father. Normally, an allele can be used to produce a protein, such as p53. However, researchers can use genetic engineering to "disrupt" an allele, making it unable to produce a properly functioning protein. In this case, the researchers genetically engineered a cell line to create two new cell lines, one in which a single allele of the p53 gene was disrupted and the other in which both alleles were disrupted. Next, they exposed all three cell lines to DNA-damaging gamma radiation and observed how this exposure impacted cell division. They measured the impact by determining the proportion of cells undergoing mitosis, called the mitotic index, for each cell line every 12 hours for four days. The mitotic index was measured by fixing or preserving a sample of the cells and then staining them with a DNA-specific fluorescent stain (Hoechst). Using microscopy, cells containing condensed, evenly stained chromosomes were identified and counted. Condensed chromosomes are an indication that the cells were undergoing mitosis at the time they were fixed. Use this information to answer the following X questions. This is an example of a ______________ . The x-axis shows ___________________, while the y-axis shows __________________________________.

line graph Number of hours after cells were exposed to gamma radiation Mitotic index (the proportion of cells undergoing mitosis)

(sample 1: highest amount of DNA sample 2: lowest amount of DNA sample 3: middle amount of DNA) A researcher studying the cell cycle has collected some data regarding the amount of DNA in three of his select cellular samples. Which sample is a diploid cell immediately following S-phase? Which sample is a cell immediately following meiosis? Which sample is a diploid cell in G1?

sample 1 sample 2 sample 3