Bio 1500 Exam 3 Questions And Answers
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Overview: The Key Roles of Cell Divisions
1. What is the cell cycle? - Answer✔the life of a cell from its formation to its own division
2. What are three important functions of cell division? - Answer✔(a) Reproduction
(b) Growth and
development
(c) Tissue renewal
Concept 9.1: Most cell division results in genetically identical daughter cells
3. Cellular Organization of the Genetic Material
a. What is a genome? - Answer✔All the DNA in a cell constitutes the cell's genome
b. How does a prokaryotic genome differ from a eukaryotic genome? - Answer✔A genome can
consist of a single DNA molecule (common in prokaryotic cells) or a number of DNA molecules
(common in eukaryotic cells)
c. Before cell division, what must occur to the cellular genome? - Answer✔Before the cell can
divide to form genetically identical daughter cells, all of this DNA must be copied, or replicated,
and then the two copies must be separated so that each daughter cell ends up with a complete
genome.
d. What is the shape of a eukaryotic chromosome? - Answer✔Each eukaryotic chromosome
consists of one very long, linear DNA molecule associated with many proteins
e. What is chromatin? - Answer✔Together, the entire complex of DNA and proteins that is the
building material of chromosomes
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f. What is the difference between a somatic cell and a gamete? - Answer✔Somatic cells
(nonreproductive cells) have two sets of chromosomes
Gametes (reproductive cells: sperm and eggs) have one set of chromosomes
g. How many chromosomes are found in the genome of a human somatic cell? - Answer✔46
chromosomes
h. How many chromosomes are found in a human gamete? - Answer✔23 chromosomes
4. Distribution of Chromosomes During Eukaryotic Cell Division
a. How does the appearance of chromosomes differ during different stages of the cell cycle? -
Answer✔When a cell is not dividing, and even as it replicates its DNA in preparation for cell
division, each chromosome is in the form of a long, thin chromatin fiber. After DNA replication,
however, the chromosomes condense as a part of cell divi- sion: Each chromatin fiber becomes
densely coiled and folded, making the chromosomes much shorter and so thick that we can see
them with a light microscope.
b. Why is it important that chromosomes replicate prior to cell division? - Answer✔so that an
entire copy of the DNA that is in each sister chromatid is transferred to the daughter cells.
c. When a chromosome duplicates prior to cell division, it consists of 2 attached sister
chromatids (see figure 9.4).
i. How are the sister chromatids attached to each other? - Answer✔attached by the centromere
ii. What is the centromere? What is its function? - Answer✔a region of the chromosomal DNA
where the chromatid is attached most closely to its sister chromatid.
iii. Once sister chromatids separate, what are they called? - Answer✔individual chromosomes
d. In eukaryotic division, two processes must occur, mitosis and cytokinesis. What occurs in
each process? - Answer✔Mitosis, the division of the genetic material in the nucleus, is usually
followed immediately by cytokinesis, the division of the cytoplasm.
e. Why is mitotic cell division necessary in a multicellular eukaryotic organism? Which type of
cell is produced by mitotic cell division? - Answer✔From a fertilized egg, mitosis and cytoki-
nesis produced the 200 trillion somatic cells that now make up your body, and the same
processes continue to generate new cells to replace dead and damaged ones.
f. Which cellular process results in the production of gametes? - Answer✔meiosis
g. Gametes have half the number of chromosomes (haploid) of a somatic cell (diploid). Why is
this important? - Answer✔to allow fertilization to fuse two gametes together (sperm and egg)
to create 46 chromosomes again
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Concept 9.2: The mitotic phase alternates with interphase in the cell cycle
5. Phases of the Cell Cycle. The cell cycle is divided into three main phases, interphase, mitosis,
and cytokinesis.
a. The majority of the cell cycle is spent in Interphase. Interphase can be subdivided into 3
subphases. What happens in each of these subphases:
i. G1 - Answer✔growth
ii. S - Answer✔continues to grow as it copies its chromosomes
iii. G2 - Answer✔grows more as it completes preparations for cell division
b. At the end of S phase, how many chromosomes will be present in the nucleus of a human
somatic cell? - Answer✔92(?)
c. At the end of S phase, how many chromatids will be present in the nucleus of a human
somatic cell? - Answer✔92(?)
6. The Mitotic Spindle: A Closer Look
a. Which type of protein fiber comprises the mitotic spindle? - Answer✔fibers made of
microtubules and associated proteins.
b. What is a centrosome? - Answer✔a subcellular region containing material that functions
throughout the cell cycle to organize the cell's microtubules.
c. What is the function of centrioles? - Answer✔A pair of centrioles is located at the center of
the centrosome, but they are not essential for cell division: If the centrioles are destroyed with
a laser microbeam, a spindle nevertheless forms during mitosis.
d. What is the function of the mitotic spindles? - Answer✔The spindle is necessary to equally
divide the chromosomes in a parental cell into two daughter cells during both types of nuclear
division: mitosis and meiosis
e. What is the function of the kinetochore? Where is it located? - Answer✔the kinetochore acts
as a coupling device that attaches the motor of the spindle to the cargo that it moves—the
chromosome.
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