Mastering Bio Chap. 8 Homework

Did doctors ask Henrietta Lacks' permission to take her cells, and was she paid for them?

She was never told that her cells were being taken, and neither she nor her family has been compensated.

A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.

16 is half of 32.

Normal human gametes carry _____ chromosomes.

23

On average, what percentage of infants born to 45-year-old mothers have Down syndrome?

3%

What is IGF-II?

A chemical that stimulates growth in pancreatic tumors.

Polyploidy is involved in which of the following examples?

A normal watermelon has 22 chromosomes but seedless watermelons have 33 chromosomes.

According to this research, a pancreatic cancer patient with which of the following would likely fair the best?

A patient with a large number of cheater cells.

Which of these cells is (are) haploid?

After Meiosis I and Meiosis II (C &D)

What is the difference between a benign tumor and a malignant tumor?

Benign tumors do not metastasize; malignant tumors do.

In the laboratory, cancer cells fail to show density-dependent inhibition of growth in cell culture. What is one explanation that could account for this?

Cancer cells continuously secrete growth factors into the cell culture medium.

How did doctors harvest and culture cells from Henrietta Lacks?

Cells were taken while she was being treated for cancer many years ago, and these cells have been cultured in the lab ever since.

Trisomy for most autosomes is fatal, yet trisomy or even tetrasomy (four copies) of the X chromosome is not. What is the explanation for this difference?

Only one copy of the X chromosome is functional within any given cell, regardless of the total number of X chromosomes.

You are an oncologist doing research that confirmed what was known about producer/cheater relationships in pancreatic tumors. What did you find out?

Producers get nothing from cheaters.

What property of Henrietta Lacks' cells was most unusual when they were grown in the laboratory?

They continue to divide and multiply after decades of culture.

Which of the following is a hallmark of cancer cells?

They multiply quickly.

Although in humans there are 22 pairs of autosomal chromosomes, only three different chromosomal trisomies are commonly seen in newborns. Of the remaining 19 autosomes, many trisomies have not been seen in newborns. Why not?

Trisomy for the other autosomal chromosomes is often lethal, and the affected embryos are miscarried.

In theory, when a nondisjunction for chromosome 18 occurs during meiosis I, four gametes can be produced. If these gametes are fertilized with unaffected gametes from the second parent, what observations would you make concerning the resulting embryos?

Two of the embryos will be trisomic for chromosome 18, and two will contain a single copy of chromosome 18.

What is given to this process?

asexual reproduction

Meiosis differs from mitosis in that _____ only occurs in meiosis.

crossing over

A cell is treated with a drug that prevents the formation of vesicles. Which of the following processes depends on the formation of vesicles and would therefore be blocked?

cytokinesis in a plant cell

Consider the photograph shown below. You can determine this is a plant cell rather than an animal cell because it has __________.

formed a cell plate

Meiosis starts with a single diploid cell and produces

four haploid cells

During anaphase I, __________.

homologous chromosomes separate and migrate toward opposite poles

During prophase I of meiosis,

homologous chromosomes stick together in pairs.

Chromatids are _____.

identical copies of each other if they are part of the same chromosome

A cell preparing to undergo meiosis duplicates its chromosomes during

interphase

One version of a gene may encode __________, whereas a different version of the same gene may encode __________.

red eyes; white eyes

During anaphase II, __________.

sister chromatids separate and migrate toward opposite poles

When cells were first taken from Henrietta Lacks, she was _____.

suffering from cervical cancer

When examining cells in the laboratory, you notice that a particular cell has half as much DNA as the surrounding cells. This observation can be explained if this cell's cell cycle halted at checkpoint _____.

G1

Immune system cells enter a resting phase after undergoing mitosis. When activated—for example, by an infection—they can reenter the sequence of events in the cell cycle that leads to cell division. What would be the correct cell cycle sequence of events for these reactivated cells?

G1, S, G2, M

You suspect that a serious developmental disorder is due to a chromosome abnormality and prepare a karyotype from an affected individual. In analyzing the karyotype, how could you distinguish trisomy from a chromosome structural defect such as a duplication?

In trisomy there would be one extra chromosome; in a duplication, the number of chromosomes would be normal, but one chromosome would have two copies of a portion of the chromosome.

During binary fission, each copy of the duplicating chromosome moves to opposite ends of the cell. What does this achieve?

It ensures that each daughter cell receives one copy of the chromosome.

If this research holds true, which of the following would happen in treatment?

Non-producing cells would cause the destruction of a tumor.

When we say that an organism is haploid, we mean that _____.

its cells each have one set of chromosomes

Gametes are produced by _____.

meiosis

Cells taken from Henrietta Lacks have been used for experiments leading to _____.

new treatments for cancer,tests of the effects of atomic radiation on life, the development of a polio vaccine

In the telophase of mitosis, the mitotic spindle breaks down and the chromatin uncoils. This is essentially the opposite of what happens in _____.

prophase

The correct order of events during meiosis is

prophase I, metaphase I, anaphase I, telophase I, cytokinesis, meiosis II.

During meiosis, segments of nonsister chromatids can trade places. This recombination of maternal and paternal genetic material is a key feature of meiosis. During what phase of meiosis does recombination occur?

prophase I.