ANSWER KEY
KEYSTONE REVIEW PACKET ANCHOR 5: CELL GROWTH AND REPRODUCTION
LEARNING OBJECTIVES:
 Describe the there stages of the cell cycle: Interphase, Nuclear Division, and Cytokinesis
o Describe the events that occur during the cell cycle: interphase, nuclear division (ie. Mitosis
or meiosis), cytokinesis
o Compare the processes and outcomes of mitotic and meiotic nuclear divisions
 Explain how genetic information is inherited
o Describe how the process of DNA replication results in the transmission and/or conservation
of genetic information
o Explain the functional relationships between DNA, genes, alleles, and chromosomes and their
roles in inheritance
Vocabulary:
Anaphase
Allele
Cell cycle
Centromere
Chromosomes
Chromatids
Crossing over
Cytokinesis
DNA replication
Gamete
Gene
Homologous
Concepts To Know:
Main Idea #1: The Cell Cycle

The Cell cycle – period of time from the
beginning of one cell division to the beginning
of the next
o During the cell cycle, a cell grows,
prepares for division, and divides to
form two daughter cells, each of
which then begins the cell cycle again
(only in mitosis)
o
Consists of 3 phases:
1) INTERPHASE (longest)
 G1 – intense growth and activity
 S phase – copying of
chromosomes (DNA replication)
 G2 – intense growth and activity
2) NUCLEAR DIVISION – (mitosis or
meiosis– the division of the cell
nucleus
3) CYTOKINESIS – cytoplasmic division
Interphase
Gene recombination
Interphase
Meiosis
Metaphase
Mitosis
Nondisjunction
Prophase
Semiconservative replication
MITOSIS

Biologists divide the events of mitosis into 4 phases: prophase, metaphase, anaphase,
and telophase
1. Prophase – 1st and longest phase of mitosis (50-60% of total time)
o chromosomes become visible as pairs of identical sister chromatids, joined at
the centromere
o centrioles separate and take up positions on opposite sides of the nucleus
 chromosomes attach to spindle at the centromere
 plants do not have centrioles
 organize spindle from areas called centrosomes
o nucleolus disappears
o nuclear envelope breaks down
2. Metaphase – 2nd phase of mitosis
o chromosomes line up along center of the cell
o microtubules connect the centromere of each chromosome to the poles of the spindle
3. Anaphase – 3rd phase of mitosis
o centromeres that join the sister chromatids split
o chromatids separate and become individual daughter chromosomes
o chromatids get pulled apart, to the poles of the spindle
4. Telophase – 4th phase of mitosis
o chromosomes become loose and begin to disperse
o nuclear envelope reforms
o spindle breaks apart
o a nucleolus reappears
o cytokinesis begins during telophase
CYTOKINESIS – division of the cytoplasm


in animals, cell membrane pinches in at the middle
in plants, cell plate forms midway through the cell, eventually growing to become new wall
1. Match the correct term to the events being described:
___B__ Stage of Interphase where DNA is copied
A. G1 Phase
___H__ Stage of Mitosis where sister chromatids are pulled apart
B. S Phase
___E__ When cytoplasm divides and daughter cells are made
C. G2 Phase
___A__ Stage of Interphase when cell grows in size
D. Mitosis or Meiosis
___G__ Stage of Mitosis when chromosomes are lined up at equator of cell
E. Cytokinesis
___C__ Stage of Interphase when cell prepares for mitosis
F. Prophase
___D__ Nuclear division
G. Metaphase
___F__ Stage of Mitosis where sister chromatids condense and become visible
H. Anaphase
2. Use the following word bank to label the diagram below: (#’S NEXT TO TERMS REFER TO BOX #’S)
(3) spindle fibers
(1) centrioles
(2) chromatin (4 & 9) interphase (2X)
(5) prophase
(6) metaphase
(7) anaphase
(8) telophase
MEIOSIS




Meiosis is a process of reduction division in which the number of chromosomes per cell is cut in half and
homologous chromosomes in a diploid cell are separated
o Involves two distinct stages: meiosis I and meiosis II
o One diploid (full # of chromosomes) cell becomes 4 haploid (half # of chromosomes) cells
Homologous chromosomes – pairs of chromosomes (one from mom and one from dad) with genes for same
traits on them
o Body Cells have both sets of chromosomes = DIPLOID (2n)
 2 complete sets of chromosomes (so have 2 complete sets of genes)
o Gametes (egg and sperm) have only one set of chromosomes = HAPLOID (n)
 contain only one set of genes
Meiosis I – prior to meiosis I, each chromosome is replicated
o Chromosomes line-up similar to mitosis, except the homologous
chromosomes form a tetrad (4 chromatids)
 Occurs during prophase I
 Crossing over may occur – results in the exchange of alleles
between homologous chromosomes and produces new
combinations of alleles
o Homologous chromosomes separate and two new cells are formed
Meiosis II – cells from meiosis I enter meiosis II
o Cell does not undergo chromosome replication before Meiosis II
o Anaphase II – chromatids separate instead of homologous pairs
o
Each resulting sex cell (gamete) has one copy of each gene
3. Label the stages of Meiosis Below. Indicate where you see crossing over occur.
ANAPHASE I
METAPHASE I
PROPHASE II
ANAPHASE II
METAPHASE II
CROSSING OVER
I
PROPHASE I
TELOPHASE I
TELOPHASE II
Main Concept #2: Compare the processes of mitotic and meiotic nuclear division
4. In the table provided, place a check in the column that is true for the description in the left column.
(note: you may have checks in both columns if the statement relates to both Mitosis and Meiosis)
Description / Event
Mitosis
Meiosis
Nuclear membrane breaks down
X
X
Creates Gametes (egg & sperm)
X
Daughter cells are identical to parent
X
Body cells result
X
Is used for growth and repair
X
Final chromosome # is the same as the parent cell
X
Diploid (2n) cells result at end
X
Homologous chromosomes join, forming Tetrads
DNA is replicated before it begins
X
X
X
Haploid (n) Cells Result
X
Crossing over happens
X
Errors in Mitosis and Meiosis

Cancer – Uncontrolled cell division; cells continue to divide, creating a tumor. Results from a
mutation(s) in genes that control the cell cycle.

Nondisjunction - failure of homologous
chromosomes to separate during meiosis. If
nondisjunction occurs, abnormal numbers of
chromosomes may find their way into gametes, and
a chromosome disorder may result (e.g. Down
Syndrome, 3 chromosomes at 21st pair)
Main Concept #3: Describe how the process of
DNA replication results in the transmission and/or
conservation of genetic information.
Structure of DNA: DNA is a double helix (two strands that
coil around each other) and resembles a twisted ladder. Each
chain is a polymer made of nucleotides (monomer unit of nucleic acids). One
nucleotide contains three parts:



Deoxyribose sugar
Phophate Group
Nitrogen-containing Base (Adenine, Guanine, Cytosine, or Thymine)
The sides of the ladder are alternating deoxyribose sugar molecules and phosphate
groups. A nitrogen-containing base is connected to each sugar molecule.
5. On the diagram below, label each deoxyribose sugar with a “D”, each phosphate group with a “P”,
and indicate the correct missing bases.
P
T
D
P
P
P
D
D
D
G
C
D
D
P
P
P
D
A
P
D
6. Using the diagram to the right, explain the
relationship between the bases of DNA
(nucleotides), genes, and chromosomes.
CHROMOSOMES ARE A COLLECTION OF DIFFERENT GENES, WHICH
ARE SEQUENCES OF DNA NUCLEOTIDES
 DNA Replication – copying of DNA
o Ensures that each resulting cell will have a
complete set of DNA molecules
o During DNA replication, the DNA molecule
separates into two strands, then produces
two new complementary strands following
the rules of base pairing. Adenine (A) pairs
with Thymine (T) and Cytosine (C) pairs with
Guanine (G)
o Each strand of the double helix of DNA serves
as a template against which the new strand is
made  called semiconservative replication
7. On the diagram
to the right,
color the original
parent DNA
strands red, and
the new DNA
strands blue.
8. Looking at the diagram you colored above, explain what the statement “DNA replication is
semi-conservative” means.
DURING DNA REPLICATION, EACH SIDE OF THE PARENT DNA MOLECULE IS USED AS A TEPMPLATE TO BUILD A
NEW COMPLIMENTARY STRAND. THEREFORE, THE DAUGHTER DNA MOLECULES CONSIST OF ONE STRAND
(SEMI) FROM THE ORIGINAL PARENT MOLECULE (CONSERVATIVE) AND ONE NEWLY BUILT STRAND.
9. Why is DNA replication a vital step in the cell cycle (S Phase)? What would happen if this
phase did not occur?
IF NO DNA REPLICATION OCCURRED DURING THE CELL CYCLE, THE ORIGINAL CHROMOSOMES OF THE PARENT CELL
WOULD NOT BE COPIED. WHEN CELL DIVISION OCCURRED, THERE WOULD NOT BE ENOUGH CHROMOSOMES FOR
THE TWO DAUGHTER CELLS.
10. Using base-pairing rules, list the correct nucleotides that would be complimentary to the
sequence listed below:
Side #1:
A T C G T C A G T A C G C A T T A C G A C G
Side #2:
Practice Questions:
T A G C A G T C A T G C G T A A T G C A G C
1. Which statement best describes the phase of the cell cycle shown?
A. The cell is in prophase of mitosis because the number of chromosomes has doubled.
B. The cell is in prophase I of meiosis because the number of chromosomes has doubled.
C. The cell is in telophase of mitosis because the cell is separating and contains two copies of each
chromosome. (BODY CELLS ARE DIPLOID)
D. The cell is in telophase of meiosis because the cell is separating and contains two copies of each
chromosome.
2. Mitosis and meiosis are processes by which animal and plant cells divide. Which statement best describes a
difference between mitosis and meiosis?
A. Meiosis is a multi-step process.
B. Mitosis occurs only in eukaryotic cells.
C. Meiosis is used in the repair of an organism.
D. Mitosis produces genetically identical daughter cells. (MEIOSIS PRODUCES GENETICALLY DIFFERENT
CELLS)
3. Which of the following statements is true?
A. Mitosis results in the formation of two haploid gametes which can then combine to form a diploid
daughter cell.
B. During the process of meiosis, haploid cells are formed. After fertilization, the diploid number of
chromosomes is restored.
C. The process of meiosis forms daughter cells which are genetically identical to their parent cells.
D. The daughter cells formed during mitosis are genetically similar to, though not identical to, their parent
cell.
4. Which of the following best describes the way that genes, chromosomes, and DNA are related?
A. Chromosomes contain several genes, which are made up of sequences of DNA.
B. Genes contain several chromosomes, which are made up of sequences of DNA.
C. Genes contain several sequences of DNA, which are made up of chromosomes.
D. Sequences of DNA contain several genes, which are made up of chromosomes.
5. If a cat has 38 chromosomes in each of its body cells, how many chromosomes will be in each daughter cell
after mitosis?
A. 19
C. 11
B. 76
D. 38
6. A cell in the process of cell division contains the normal chromosome number. Each chromosome consists of
two identical sister chromatids. During which stages and processes can such a cell exist?
A. telophase of mitosis, but no stage of meiosis
B. metaphase of mitosis, but no stage of meiosis
C. anaphase I of meiosis and anaphase of mitosis
D. prophase I of meiosis and prophase of mitosis
7. Sometimes an error called non-disjunction occurs during meiosis. What is the result of this error?
A. Cytokinesis fails to happen
B. Daughter cells do not get created
C. Daughter cells with an incorrect number of chromosomes are formed
D. Meiosis stops early