Download Genetic Processes Unit Review

Unit2 – Genetic Processes Review Questions
Part 1: Cell Division
1. Draw and label the cell cycle.
2. What is the overall purpose of mitotic cell division?
The overall purpose of Mitosis is to:



Ensure Growth
Repair of body tissue
Allow for genetic continuity
3. Draw a diagram of a chromosome. Label the centromere and sister
chromatids.
4. What is meant by the term “diploid”? What is the diploid number for human
cells?
The term “Diploid” refers to twice the number of chromosomes in a gamete. Every
cell of the body, with the exceptions of sex cells, contains a diploid chromosome
number.
5. State all the events that occur during prophase, metaphase, anaphase and
telophase of mitosis.
Interphase

The stage between nuclear divisions divided into three periods. The
division of centrioles is a process that last throughout these three
phases:
G1 phase - A rapid period of growth and metabolic activity.
Longest phase of cell cycle
S phase - DNA is replicated and Chromosome become
double stranded (46 duplicated chromosomes)
G2 Phase - A phase of growth (chromatin begin to condense to
form chromosomes) and final preparations for
cell division
Early Prophase

Chromosomes shorten but have now become quite thicker.

The divided centrioles migrate to opposite poles of the dividing cell.

Spindle fibres begin to form in the cell

Spindle fibres attach to the centrioles and to the chromosomes

Nuclear membrane (envelope) begins to disappear (dissolve)

Spindle fibres begin to place the chromosomes composed of sister
chromatids at the center of the cell (equatorial plate).

The centromere is now aligned across the equator of the cell

The chromosmes appear to be very dark, thick structures
Late Prophase
Metaphase
Anaphase

The centromeres divide, and the sister chromatids, now known as
chromosomes move to opposite poles of the cell

In theory, the same number of chromosomes should be founds at the
poles of the cell

Once reaching the opposite poles of the cell, the chromosomes begin to
unwind.

Spindle fibres dissolve

Nuclear membrane forms around the chromosome
Telophase
6. What is the overall purpose of meiosis?
The overall purpose of meiosis is to:
 Ensure genetic continuity by reducing the number of chromosomes to half. This
allows a constant number for the human species.
 Allow for variation
7. How many cells are potentially produced in meiotic cell division from one
diploid cell?
4 unique gametes are potentially produced in meiotic cell division
8. Answer the following regarding crossing over in meiosis?
a. When does it occur?
Early prophase
b. What kind of chromosomes are involved?
Homogulous chromosomes
c. What is the end result and why is this so significant to the overall purpose
of meiosis?
The end result is 4 unique gametes (sex cells), either sperm or egg that contain a haploid
number of chromosomes. Because these sex cells contain a haploid number of cells, they
can fertilize with a gamete of another sex to produce a zygote with a diploid number of
cells
9. What is non-disjunction, and what role does it play in Down syndrome?
Non-disjunction refers to the failure of homologous chromosomes to move to opposite
poles of the cell during meiosis. The result is that one that one of the gametes will have
an extra chromosome, while the other will be missing a chromosome. These two types of
cells, either with 22 or 24 chromosomes, are not able to function normally.
10. Compare and contrast the stage of metaphase for mitosis and metaphase I and II.
Draw diagrams to illustrate your answer.
Metaphase for Mitosis
Metaphase I
Metaphase II
Replicated chromosomes line up
at the equatorial plate.
Chromosomes are in one
straight line.
Homologous Chromosomes
(paired chromosomes) line
up in pairs at the equatorial
plate.
Replicated chromosomes line up
at the equatorial plate of both
cells. Chromosomes are in one
straight line.
11. What is a Karyotype?
A picture of chromosomes that have been arranged according to number, size, shape, or
some other characteristic is called a KARYOTYPE.