Cell Division
Section 8-1 Chromosomes
1. What molecule in cells stores the genetic information?
DNA
2. DNA is built of billions of subunits called __________________________.
nucleotides
3. What are chromosomes, & when can they be seen?
Condensed DNA (supercoiled), canbe seen during cell division (mitosis and
meiosis)
4. What is the shape of chromosomes, & what 2 things are they made of?
Linear (or X when replicated), made of centromere and chromatids
5. Each chromosome is a single ________________ molecule with
____________________.
6. What is the purpose of histones? Histones act as a spool: DNA is wrapped
around them to avoid breaking and they help organize coiling
7. What is the purpose of nonhistone proteins? Forget nonhistones
8. Chromosomes consist of two identical _____________________ called
_________________. Arms, chromatids
9. What is a centromere? The middle of the chromosomes, where spindle
fibers attach
10. Draw and label the parts of a chromosome.
11. Chromatids _________separate______________ during cell division so the
two new cells will each
receive _____one____________ chromatid.
12. How does DNA appear in a cell between cell divisions? You can’t see it
clearly, looks like a solid nucleus
13. What is chromatin & when does it exist in cells? Chromatin: unraveled
(uncoiled) DNA plus histones, exists between cell division (interphase)
14. How many chromosomes do prokaryotes have? one
15. How many chromosomes do each of these organisms have:
a. humans? 46
b. dog? dunno
c. fruit fly? 8
16. What are the two categories of chromosomes? Autosomes, sex
17. Give 2 functions of the sex chromosomes. Determine gender, carry genes
18. Name the 2 sex chromosomes & tell what combination determines a male
and a female organism. XY male, XX female
19. What are autosomes & how many autosomes are in human cells?
Autosomes are non-sex chromosomes, 44 in human cells
20. What are homologous chromosomes & how do they compare to each other?
Chromosomes with the same shape and size, but may carry different genes for
the same traits. You get one from you mom, and the other from your dad
21. What is a karyotype? A picture of all the chromosomes found in a cell. we
use it to find chromosomal abnormalities
22. In a human karyotype, where would each of these be found:
a. sex chromosomes? 23rd pair
b. longest homologs? 1st pair
c. autosomes? Pairs 1-22
23. What is the main difference between diploid & haploid cells? Haploid cells
have half the normal number of chromosomes (n), and diploid cells have the
normal number of chromosomes (2n)
24. What type of cells in human would be diploid? Haploid? Sex cells=haploid
all other cells=diploid
25. How are diploid cells abbreviated? Haploid cells? Diploid (2n) haploid (n)
26. When a haploid (1n) ____sex__________________ cell combines with a
haploid
______sex_________________ cell, the new cell will be
___________diploid___________
or ______2n______________________.
Section 8-2 Cell Division
27. All cells are derived from __________other
cells_________________________.
28. What is cell division? The splitting of a cell into two new cells
29. Define binary fission. The asexual division of bacteria
30. Describe the stages in binary fission of a prokaryote. 1. Replication of
DNA 2. Movement to opposite sides of the cell 3. Pinching of cell membrane
and cell wall
31. How do the two new cells compare to each other after binary fission? How
do they compare to the original cell? they are all identical
32. What two main cellular parts must be divided in eukaryotic cell division?
Nucleus and cytoplasm
33. Name the 2 types of cell division in eukaryotes. Mitosis, meiosis
34. Define mitosis. Division of the nucleus
35. What type of cell uses mitosis? Body cells, all cells that replicate, but do
not become sex cells
36. What effect does meiosis have on the chromosome number of a cell? it
divides the normal number of chromosomes by half
37. How do the cells produced by meiosis reestablish a complete set of
chromosomes? By combining with another sex cell (ex: sperm + egg  2n)
38. What is the cell cycle? The time between cell division: from the birth of a
cell, to the point right after cytokinesis
39. Draw & label all parts of the cell cycle. (Figure 8-5, page 149)
40. What is the time between divisions in the life of a cell called? interphase
41. How many phases is interphase divided into? Cell division? 3 interphase, 2
cell division (mitosis and cytokinesis)
42. Name the 2 parts of cell division. Mitosis and cytokinesis
43. What happens to the cell in each of these two parts of cell division? Mitosis
is the division of the nucleus, cytokinesis is the division of the cytoplasm
44. In what stage do cells spend most of their time? interphase
45. What is the size of cells immediately following cell division?
Small?
46. Name the 1st stage of interphase & tell what happens to the cell. G1: the
cell grows
47. What stage of interphase do cells enter once they become mature? S
48. What happens to a cell during the S phase of interphase? DNA is replicated
49. What is the last stage of interphase called & what is happening to the cell?
G2, it’s getting ready for mitosis
50. What is the Go phase and what type of human cells are in this phase? Cells
that are not growing, nerve cells
51. Name the 4 stages of mitosis in order. Prophase, metaphase, anaphase,
telophase
52. What cellular part actually divides during mitosis? nucleus
53. Describe everything that happens to a cell during prophase. Chromosomes
condense, nuclear envelope breaks down, centrioles migrate to opposite poles
of the cell, spindle begins to form and attach to centromeres of chromosomes
54. Sketch and label a picture of a cell in prophase.
55. What are centrosomes & when do they appear? Main microtubule
organizing region
*56. What type of cell has centrosomes? eukaryotic
*57. What is found inside centrosomes? centrioles
58. Are centrioles found in both plant & animal cells? Explain. Centrioles are
only found in animals. *Plant cell walls and enzymes within the cell membrane
organize much of a plant’s cytoskeleton
59. What forms from centrioles & what is their function? Spindle fibers: to
attach to centromere of chromosomes, pull apart chromosomes, and elongate
the cell during anaphase
*60. Name the 2 types of fibers that make up the mitotic spindle & describe
each one. Microtubules and microfilaments
61. Describe everything that happens to a cell during metaphase.
Chromosomes line up in the middle of the cell
62. Sketch & label a cell during metaphase.
63. Describe everything that happens to a cell during anaphase. Chromosomes
are pulled apart at the centromere,
64. Sketch and label a cell during anaphase.
65. Describe everything that happens to a cell during telophase. Opposite of
prophase
66. Sketch & label an animal cell during telophase.
67. Mitosis is division of the ___nucleus____________________, while
_____cytokinesis___________________
is the division of the cytoplasm.
68. Define cytokinesis. Division of the cytoplasm and its contents
69. Describe how cytokinesis occurs in animal cells & include a drawing
(figure 8-7, page 151)
70. The _____cleavage furrow_______________ pinches a dividing animal
cell into two new cells by the action
of ___invagination___________________________.
*71. How does the cell plate from during cytokinesis of a plant cell? this
process is not entirely known. We know that extensions from the cell wall, as
well as enzymatic organization and generation of microtubules form a structure
called the phragmoplast, which serves as a template for the formation of the
new cell wall. The incomplete cell wall is then called a cell plate
72. Sketch and label a plant cell during cytokinesis (figure 8-8, page 151)
73. How do the new cells formed after mitosis & cytokinesis compare in size &
chromosome number to each other and the original cell that divided? The new
cells are smaller, and have the 2n number of chromosomes after mitosis,
whereas right before mitosis they had the 4n number of chromosomes
74. The original cell that divides is called the
___parent____________________ cell, while the
two new cells are called _____daughter_______________ cells. (from
lecture)
Section 8-3 Meiosis
75. What is meiosis? Cell division that produces gametes
76. What type of cell undergoes meiosis? Cells that generate gametes
77. Meiosis produces _______4____________ reproductive cells called
_____________gametes_______.
78. Name the 2 human gametes & tell their chromosome number. Sperm and
egg (23 chromosomes each)
79. What is the chromosome number for humans? 46
80. The fusion of a ______sperm___________ and an ___egg__________
produces a
______zygote*__________ with 46 (2n) chromosome number.
81. Cells starting mitosis & meiosis begin with a ____4n________________
set of chromosomes.
82. How many times do cells divide during meiosis? 2
83. What are the stages of meiosis called? Meiosis 1 and meiosis 2
84. Explain what happens during Meiosis I to each of these structures:
a. chromosomes? They condense
b. spindle? Begins to form and attach to centromeres
c. nucleus? Envelope begins to disintegrate
d. nucleolus? disappears
85. What is synapsis & when does it occur? When homologous chromosomes
migrate towards one another
86. What is a tetrad? After synapsis, the structure formed when the replicated
homologous chromosomes are would together
87. How are genes aligned on homologous chromosomes? They are in the
same location
88. Explain what happens during crossing-over? Homologous chromosomes
exchange parts, or genes, with each other. This exchange can be as small as a
single gene, or as large as an entire arm. This exchange increases genetic
variation
89. Sketch and color a picture of chromosomes during crossing-over. (Figure 810, page 154)
90. What type of material is exchanged during crossing-over? Chromosome
parts
91. Crossing over results in genetic __________variation_____________.
92. Draw a cell during anaphase I and explain what is occurring.
93. What is independent assortment & what result does it produce?
Independent assortment states that genes are not associated with each other
when forming gametes. Each gamete can receive a unique combination of
genes. This is actually a false statement, even though it used to be called a law.
There are factors that cause genes to be passed into groups to the gametes, but
for this class, assume that all genes have an independent chance to get into the
gametes.
94. Name 2 things that occur during telophase I. nuclear envelope starts to
reform, chromosomes begin to unravel. Then in Prophase I the opposite
happens. Fun fact: some cells that undergo rapid meiosis do not uncondensed
chromosomes or reform nucleus
95. How many cells are formed at the end of Meiosis I & how many copies of
chromosomes does each cell have? 2, 2n
96. Is DNA copied before Meiosis II? no
97. How many cells form at the end of Meiosis II and how many chromosomes
do they contain? 4, n
98. In humans, meiosis occurs in the ____testes_______________ and in the
____________ovaries______
producing cells called _______gametes, or sperm and
egg_________________.
99. Define spermatogenesis & tell where it occurs. The making of sperm,
happens in testes of male
*100. Sketch spermatogenesis (Figure 8-12a, page 155).
*101. What are spermatids & how many form from meiosis?
102. Define oogenesis & tell where it occurs. Making of egg cells, ovaries of
female
103. Sketch oogenesis (Figure 8-12B, Page 155).
104. Mature egg cells are called ________egg___________.
105. Explain how only one egg cell is formed instead of four from meiosis. Of
the four gametes produced in oogenesis, three become polar bodies. These
polar bodies give valuable nutrients to the main egg cell
106. What are the 3 other products of meiosis called? Polar bodies
107. Define asexual reproduction. Reproduction without exchange of DNA
108. Name 2 types of asexual reproduction. Binary fission, *budding
109. Name a type of asexual reproduction in unicellular organisms. Binary
fission
110. How do the offspring of asexual reproduction compare to their parents?
The offspring are identical
111. Define sexual reproduction. Reproduction with the exchange of DNA
112. How do offspring from sexual reproduction compare to their parents?
They have the genes of the parents, but in a different combination
113. Is there ever a case in sexual reproduction where offspring can be
genetically alike? Explain. Not really, there are so many egg/sperm
combinations, both in what each cell gets and which egg and sperm combine
with each other.
114. What is the evolutionary advantage of sexual reproduction? It diversifies
the gene combinations, thereby leading to varied offspring, thereby increasing
chances for survival and adaptation during times of change. It also allows for
favorable gene combinations to become more dominant in the population, since
the most desirable gene combinations will survive and mate