Exam 2: Chromosomes and Cellular Reproduction

The centromere divides a chromosome into two sections or "arms." A chromosome is found to have two arms of equal lengths. Such a chromosome can be BEST described as:

A diploid somatic cell from a rat has a total of 42 chromosomes (2n = 42). As in humans, sex chromosomes determine sex: XX in females and XY in males. What is the total number of chromosomes in a polar body cell from a rat?

In order to be functional, a eukaryotic chromosome requires all of the following EXCEPT:

Suppose that a diploid cell contains 8 chromosomes (2n = 8). How many different combinations in the gametes are possible?

Which of the following statements is FALSE?

A diploid, eukaryotic cell in interphase has these two pairs of homologous chromosomes with the indicated arrangement of alleles: Draw the chromosomes at the end of telophase of (a) mitosis and (b) meiosis II. Indicate placement of alleles on the chromosomes.

Why is mitosis important within the cell cycle?

In a typical flowering plant, a pollen grain that lands on a stigma grows a pollen tube to deliver _____ (how many?) sperm to the ovary. Fusion of a sperm with an egg produces a _____ n cell called a _____.

The highly organized internal scaffolding of the nucleus is called the:

Humans have 23 pairs of chromosomes. Rarely, an egg is produced with 46 chromosomes instead of 23. How might such an egg have originated?

Why are viruses considered to be neither prokaryotic nor eukaryotic?

In tissue from the intestinal epithelium of a frog, the following proportions of cells were found at each stage of the cell cycle: Stage Prop ortion of Cells Interphase 0.90 Prophase 0.04 Prometaphase 0.02 Metaphase 0.01 Anaphase 0.02 Telophase 0.01 If the entire cell cycle in frog epithelium cells requires 20 hours for completion, what is the average duration of each stage?

(a) Compare and contrast spermatogenesis and oogenesis in animals. For each process, be sure to include information about division of the nucleus, allocation of chromosomes to the various products, and division of the cytoplasm. (b) Why is the difference in cytoplasmic division between spermatogenesis and oogenesis important to reproduction, considering the different roles of sperm and eggs in reproduction?

List and briefly describe three major cell cycle checkpoints. For each checkpoint, predict the consequences if the checkpoint fails to work properly.

Describe what is happening to chromosomes during the five substages of prophase I.

Diploid cells are cells with _____ chromosomes.

A dividing eukaryotic cell is treated with a drug that inhibits the molecular motors associated with kinetochores. At which cell cycle stage would it stop?

Assume that cells that are about to undergo meiosis are treated with a chemical that blocks crossing over but does not affect the cells in any other way, and four viable cells are produced by the two divisions of meiosis. What will be the consequence of such a treatment?

Which of the following statements is TRUE?

Which of the following occurs during prometaphase?