11. Cell Division

Interphase

Mitosis and Cytokinesis

Lignin and cellulose provide rigidity to the cell walls of plants. But in most fungi, chitin performs this role. Why is it logical that most fungi don’t have lignin or cellulose in their cell walls?

The phase between DNA replication and the M phase.

The phase in which DNA is being replicated.

The first phase in the cell cycle (G1) corresponds to ___________.

 No. Chromatids are not found within chromosomes. 

 No. Centrioles are associated in animal cells with the centrosomes. 

 the bacterial equivalent of eukaryotic chromosomes 

 No. Most bacterial cells have a single, circular chromosome, but chromatids are found only in eukaryotic cells. 

 No. Chromatids are composed of DNA and protein. 

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

Sister chromatids separate during mitosis.

Chromatids are __________.

Which of the following occurs during S phase?
(A) condensation of the chromosomes
(B) replication of the DNA
(C) separation of sister chromatids
(D) spindle formation

If a cell at G1 contains four picograms of DNA, how many picograms of DNA will it contain at the end of the S phase of the cell cycle?
a. 0;
b. 2;
c. 4;
d. 8

 No. DNA is replicated before prophase begins. 

 No. You need to review the stages of the cell cycle. 

 No. Cytokinesis is the state in which a single cell completes its division into two daughter cells. 

Consider the phases of interphase.

DNA replication occurs in __________.

What is the role of the spindle fibers during mitosis?

Cells spend the majority of their time in which one of the following phases of the cell cycle?

Centrosomes & Mitotic Spindles

What is the name of the microtubule-organizing center found in animal cells as an identifiable structure present during all phases of the cell cycle?a) Spindle.b) Centromere.c) Centrosome.d) Kinetochore.

 No. This period is characterized by fragmentation of the nuclear envelope, condensation of chromosomes, and their alignment on the metaphase plate. 

 No. Duplicated chromosomes are separated from each other during the M phase. 

between the G2 phase and prophase

 No. During this time period, the chromosomes begin to condense and the nucleoli disappear. 

 No. During this time period, sister chromatids are separated to the opposite poles of the cell and reorganized into new nuclei. 

between the G1 and G2 phases

Consider when the S phase occurs.

A biochemist measured the amount of DNA in cells growing in the laboratory and found that the quantity of DNA in the cells doubled __________.

No. G1 occurs prior to the duplication of the genetic material.

 No. Although DNA synthesis is indeed taking place during the S phase, it is not until this phase is complete that the cell has the maximum amount of DNA. 

No. Cells in G0 are no longer actively dividing and have not replicated their DNA.

Consider the events of each of the phases of the cell cycle.

During what phase in the cell cycle would you find the most DNA per cell?

Which pair includes a phase of the cell cycle and a cellular process that occurs during that phase?

 No. Each human somatic cell has a total of 46 chromosomes. Only half are maternal chromosomes. 

 No. Human somatic cells have a total of 46 chromosomes. Only half are maternal chromosomes. 

 None of the listed responses is correct. 

 No. One of the other choices is correct. 

Maternal chromosomes are those inherited from the mother.

How many maternal chromosomes are present in a somatic human cell when it is not engaged in cell division?

Cell A has half as much DNA as cells B, C, and D in a mitotically active tissue. Cell A is most likely in
a. G1.
b. G2.
c. prophase.
d. metaphase.

Lawns are sometimes fertilized with nitrate that can be washed into neighboring woodlots by rain. If the trees in that woodlot are associated with EMF, what effect might the excess nitrate have on the fungi and/or trees?
a. Fungal growth may be stimulated, causing the trees to transport more nitrogen to the fungi.
b. The fungi may secrete more peptidases to break down the nitrate.
c. The trees may take up the nitrate directly into their roots and rely less on the fungi.
d. The excess nitrate may stimulate the fungi to transport more sugar to the trees.

 dispersed in the cytoplasm as long strands of chromatin 

 No. Consider the location of the genetic material during interphase. 

 condensed and the chromosomes are often visible under the light microscope 

 No. Compare the events of interphase and early mitosis. 

 No. This attachment occurs during prophase. 

 No. RNA and proteins are transported through the nuclear pores. 

 dispersed in the nucleus as long strands of chromatin 

Review interphase.

During interphase, the genetic material of a typical eukaryotic cell is __________.

 No. Sister chromatids remain paired until anaphase of mitosis. 

 No. Consider the number of chromosomes in a human somatic cell and review what takes place during the S phase. 

 No. This is the number of chromosomes in human somatic cells. 

 There is insufficient information to answer the question. 

 No. This chapter contains all the information you need to answer the question. 

Review the relationship between chromosomes and chromatids.

If a human somatic cell is just about to divide, it has __________ chromatids.

 No. Fifty units would be the quantity of DNA following meiosis. 

 No. Cell division is very exact. The amount of DNA would never be indicated by a range. 

No. Remember, G2 immediately precedes mitosis; DNA replication has already occurred.

No. The 200 units of DNA in the sister chromatids of cells in G2 will be divided equally during the M phase, resulting in daughter cells each containing 100 units of DNA.

What happens to the chromosomes between the S phase and cytokinesis?

A cell biologist carefully measured the quantity of DNA in grasshopper cells growing in cell culture. Cells examined during the G2 phase of the cell cycle contained 200 units of DNA. What would be the amount of DNA at G1 of the cell cycle in one of the grasshopper daughter cells?

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