Chapter 12 Flashcards
(163 cards)
1
Q
What are the key roles of cell division?
A
Cell division plays several important roles in life, including:
* Giving rise to new organisms in single-celled organisms
* Enabling embryonic development and growth in multicellular eukaryotes
* Functioning in renewal and repair in fully grown multicellular eukaryotes
Cell division is essential for both reproduction and maintenance of organisms.
2
Q
What constitutes a cell’s genome?
A
All the DNA in a cell constitutes the cell’s genome
The genome includes all genetic information necessary for the growth and functioning of the organism.
3
Q
What is the difference in the genome of prokaryotic and eukaryotic cells?
A
A genome can consist of:
* A single DNA molecule (common in prokaryotic cells)
* A number of DNA molecules (common in eukaryotic cells)
Prokaryotic cells typically have a simpler structure, while eukaryotic cells have more complex genomic organization.
4
Q
How is DNA organized within a cell?
A
DNA molecules in a cell are packaged into chromosomes
Chromosomes help in the efficient organization and segregation of DNA during cell division.
5
Q
What does the DNA molecule of a chromosome carry?
A
The DNA molecule of a chromosome carries several hundred to a few thousand genes
Genes are the basic units of heredity and contain the instructions for making proteins.
6
Q
What do eukaryotic chromosomes consist of?
A
Chromatin, a complex of DNA and protein that condenses during cell division
Chromatin plays a critical role in packaging DNA into a smaller volume to fit in the nucleus and protect the DNA structure and sequence.
7
Q
How many chromosomes do somatic cells have?
A
Two sets of chromosomes
Somatic cells are all body cells except for gametes.
8
Q
How many chromosomes do gametes have compared to somatic cells?
A
Half as many chromosomes as somatic cells
Gametes are reproductive cells, specifically sperm and eggs.
9
Q
What happens to DNA during preparation for cell division?
A
DNA is replicated and the chromosomes condense
This process is crucial for ensuring that each daughter cell receives an exact copy of the parent cell’s genetic material.
10
Q
What are sister chromatids?
A
Joined copies of the original chromosome
Sister chromatids are formed after DNA replication and are essential for accurate segregation during cell division.
11
Q
What is the function of cohesins in chromosomes?
A
They attach sister chromatids along their lengths
Cohesins ensure that sister chromatids remain together until they are ready to be separated during cell division.
12
Q
What is the centromere?
A
The narrow ‘waist’ of the duplicated chromosome
The centromere is crucial for the movement of chromosomes during cell division.
13
Q
What is the notation for the number of chromosomes in somatic cells?
A
2n
The notation ‘2n’ indicates that somatic cells are diploid, containing two sets of chromosomes.
14
Q
What is the value of n in the context of human chromosomes?
A
23
In humans, ‘n’ represents the number of chromosomes in a gamete, which is half the diploid number.
15
Q
Fill in the blank: Eukaryotic species have a characteristic number of chromosomes in each cell _______.
A
nucleus
This characteristic number is specific to each species and is crucial for proper development and function.
16
Q
What happens to sister chromatids during cell division?
A
They separate and move into two nuclei.
17
Q
What are sister chromatids called once they are separated?
A
Chromosomes.
18
Q
What are the components of a chromosome?
A
Chromosomal DNA molecules and centromere.
19
Q
What is the structure of a chromosome?
A
Chromosomal DNA is tightly wrapped with a centromere and chromosome arms.
20
Q
True or False: Chromatids are only called chromosomes before cell division.
A
False.
21
Q
Fill in the blank: During cell division, chromatids move into _______.
A
two nuclei.
22
Q
What are chromosomes primarily composed of?
A
Chromosomal DNA molecules
Chromosomes consist of DNA that is tightly coiled and organized.
23
Q
What is the function of the centromere in a chromosome?
A
It is the region where sister chromatids are joined.
The centromere plays a critical role during cell division.
24
Q
What are sister chromatids?
A
Identical copies of a chromosome that are created during chromosome duplication.
Sister chromatids are formed after DNA replication.
25
What process includes both chromosome duplication and condensation?
Mitosis
## Footnote
Mitosis involves the division of a mother cell into two daughter cells.
26
Fill in the blank: The _______ is the part of the chromosome where two sister chromatids are held together.
centromere
27
What happens during the separation of sister chromatids?
They are pulled apart to opposite sides of the cell.
## Footnote
This separation is crucial for ensuring each daughter cell receives an identical set of chromosomes.
28
What does chromosome duplication include?
DNA replication
## Footnote
This is the process by which a cell makes a copy of its chromosomes.
29
True or False: Chromosome arms are the sections of the chromosome that extend from the centromere.
True
## Footnote
Each chromosome has two arms, typically referred to as the short arm and the long arm.
30
What are the two main processes of eukaryotic cell division?
1. Mitosis: division of genetic material in the nucleus
2. Cytokinesis: division of the cytoplasm
## Footnote
These processes are essential for cell reproduction.
31
What type of cells are produced by meiosis?
Gametes
## Footnote
Meiosis yields nonidentical daughter cells with half the number of chromosomes.
32
What is the main purpose of mitosis?
For somatic cells
## Footnote
Mitosis is responsible for growth and repair in multicellular organisms.
33
What is the main purpose of meiosis?
For germ/gamete cells
## Footnote
Meiosis is crucial for sexual reproduction.
34
What are the two main phases of the cell cycle?
1. Mitotic (M) phase
2. Interphase
## Footnote
The M phase includes mitosis and cytokinesis, while interphase involves cell growth and chromosome copying.
35
What percentage of the cell cycle is interphase?
About 90%
## Footnote
Interphase is the longest phase, preparing the cell for division.
36
What are the three phases of interphase?
1. G1 phase (first gap)
2. S phase (synthesis)
3. G2 phase (second gap)
## Footnote
Each phase has distinct roles in cell growth and preparation for division.
37
During which phase of interphase does DNA replication occur?
S phase
## Footnote
This phase is critical for ensuring that each daughter cell receives an identical set of chromosomes.
38
Fill in the blank: The G1 phase is known as the _______.
first gap
## Footnote
This phase involves cell growth before DNA synthesis.
39
Fill in the blank: The G2 phase is known as the _______.
second gap
## Footnote
This phase involves further growth and preparation for mitosis.
40
What are the three phases of Interphase?
G1, S, G2
## Footnote
G1: Growth phase, S: DNA synthesis, G2: Preparation for cell division.
41
What occurs during the S phase of Interphase?
Metabolic activity, growth, and DNA synthesis
## Footnote
This phase is crucial for replicating the cell's genetic material.
42
What is the purpose of the Mitotic (M) Phase?
Distribution of chromosomes into two daughter nuclei and division of cytoplasm
## Footnote
Includes both mitosis and cytokinesis.
43
What are the two main processes that occur during the Mitotic (M) Phase?
Mitosis and Cytokinesis
## Footnote
Mitosis involves chromosome distribution while cytokinesis divides the cytoplasm.
44
List the five stages of Mitosis.
* Prophase
* Prometaphase
* Metaphase
* Anaphase
* Telophase
## Footnote
These stages represent the sequence of events in cell division.
45
What happens during Cytokinesis?
Division of cytoplasm, producing two daughter cells
## Footnote
Each daughter cell can start a new cell cycle.
46
What is the role of centrosomes during Prophase?
Organize microtubules for chromosome movement
## Footnote
Centrosomes play a crucial role in the formation of the mitotic spindle.
47
What structure holds sister chromatids together?
Centromere
## Footnote
The centromere is a region of the chromosome where sister chromatids are joined.
48
True or False: The nucleolus disappears during Prophase.
True
## Footnote
The nucleolus is involved in ribosome production and is no longer visible during mitosis.
49
Fill in the blank: The _______ phase is where chromosomes condense and become visible.
Prophase
## Footnote
This phase marks the beginning of mitosis.
50
What are nonkinetochore microtubules?
Microtubules that do not attach to chromosomes
## Footnote
They help in elongating the cell during mitosis.
51
What is the role of the mitotic spindle during mitosis?
Controls chromosome movement during mitosis
## Footnote
The mitotic spindle is composed of microtubules.
52
Where does the assembly of spindle microtubules begin in animal cells?
In the centrosome
## Footnote
The centrosome acts as a microtubule-organizing center.
53
What happens to the centrosome during interphase?
It replicates, forming two centrosomes
## Footnote
These centrosomes migrate to opposite ends of the cell during prophase and prometaphase.
54
Fill in the blank: The _______ is a structure made of microtubules that controls chromosome movement during mitosis.
mitotic spindle
55
What is formed during the process of cytokinesis?
Cleavage furrow
## Footnote
This is a structure that forms to separate the daughter cells.
56
What is the significance of the daughter chromosomes during mitosis?
They are the result of chromosome separation
## Footnote
Each daughter chromosome is identical to the original chromosome.
57
What structure forms around the chromosomes during telophase?
Nuclear envelope
## Footnote
This marks the re-establishment of the nucleus in daughter cells.
58
True or False: The mitotic spindle is only involved during anaphase.
False
## Footnote
The mitotic spindle is involved throughout the entire process of mitosis.
59
What is the difference between mitosis and cytokinesis?
Mitosis refers to nuclear division, while cytokinesis refers to cytoplasmic division
## Footnote
These processes occur sequentially during cell division.
60
What is the relationship between the mitotic spindle and chromosome condensation?
The mitotic spindle condenses the chromosomes
## Footnote
This is crucial for the proper alignment and separation of chromosomes.
61
What happens to the centrosomes by the end of prometaphase?
The two centrosomes are at opposite ends of the cell
## Footnote
This positioning is crucial for proper chromosome alignment and separation during cell division.
62
What is an aster?
A radial array of short microtubules extending from each centrosome
## Footnote
Asters play a role in anchoring the spindle apparatus during cell division.
63
What components make up the spindle?
The spindle includes:
* Centrosomes
* Spindle microtubules
* Asters
## Footnote
The spindle is essential for the separation of sister chromatids during mitosis.
64
What is a kinetochore?
A protein complex associated with centromeres
## Footnote
Kinetochores are critical for the attachment of spindle fibers to chromosomes.
65
What type of microtubules attach to kinetochores during prometaphase?
Kinetochore microtubules
## Footnote
These attachments are vital for the movement of chromosomes during cell division.
66
Where are chromosomes lined up during metaphase?
At the metaphase plate, an imaginary plane midway between the spindle's two poles
## Footnote
This alignment is important for ensuring that each daughter cell receives an equal set of chromosomes.
67
What are sister chromatids?
Identical copies of a chromosome connected at the centromere
## Footnote
Sister chromatids are separated during anaphase to ensure proper distribution to daughter cells.
68
What is the function of nonkinetochore microtubules?
They overlap and help maintain the structure of the spindle
## Footnote
Nonkinetochore microtubules contribute to the elongation of the cell during division.
69
Fill in the blank: During prometaphase, some spindle microtubules attach to the _______.
kinetochores
## Footnote
This attachment is crucial for the movement of chromosomes toward the metaphase plate.
70
What is a kinetochore?
A protein structure on chromosomes where the microtubules attach during cell division
## Footnote
Kinetochore plays a crucial role in chromosome movement during mitosis.
71
What is the role of spindle poles in chromosome movement?
Spindle poles are sites where motor proteins 'reeled in' chromosomes during anaphase
## Footnote
Motor proteins facilitate the movement of chromosomes towards the poles.
72
What happens to microtubules after they pass motor proteins at the spindle poles?
Microtubules depolymerize after passing motor proteins at the poles
## Footnote
This depolymerization is essential for the movement of chromosomes.
73
True or False: Only one mechanism is responsible for chromosome movement during anaphase.
False
## Footnote
The consensus is that both the 'reeled in' mechanism and the depolymerization mechanism are used.
74
What occurs between nonkinetochore microtubules during cell division?
Nonkinetochore microtubules from opposite poles overlap and push against each other, elongating the cell
## Footnote
This action helps in the physical separation of the two daughter cells.
75
What begins during anaphase or telophase?
Cytokinesis begins during anaphase or telophase
## Footnote
Cytokinesis is the process where the cell divides its cytoplasm, resulting in two daughter cells.
76
What happens to the spindle after cytokinesis?
The spindle eventually disassembles
## Footnote
This disassembly is part of the completion of cell division.
77
What is the significance of the study by G. J. Gorbsky, P. J. Sammak, and G. G. Borisy?
It provided data showing that chromosomes move poleward in anaphase along stationary microtubules that disassemble from their kinetochore ends
## Footnote
This research contributed to the understanding of the mechanisms of chromosome movement.
78
Fill in the blank: Chromosomes are 'reeled in' by _______ at the spindle poles.
[motor proteins]
79
What are the 'little feet' referred to in the context of microtubules?
Motor proteins that facilitate movement along microtubules
## Footnote
These 'little feet' are responsible for the active transport of chromosomes.
80
What is the overall conclusion regarding chromosome movement during anaphase?
Both 'reeled in' by motor proteins and depolymerization of microtubules are mechanisms used for chromosome movement
## Footnote
This dual mechanism enhances the efficiency of chromosome segregation.
81
What is cytokinesis?
The process of cell division that occurs after mitosis
82
What is the process of cytokinesis in animal cells called?
Cleavage
83
What is the first sign of cleavage in animal cells?
The appearance of a cleavage furrow
84
Where does the cleavage furrow appear in animal cells?
Near the old metaphase plate
85
What forms during cytokinesis in plant cells?
A cell plate
86
What is a cleavage furrow?
A shallow groove in the cell surface during cytokinesis in animal cells
87
What structure is involved in the formation of the cleavage furrow?
Contractile ring of microfilaments
88
Fill in the blank: In plant cells, during cytokinesis, a _______ forms.
cell plate
89
True or False: Cytokinesis occurs the same way in both animal and plant cells.
False
90
What are the end products of cytokinesis?
Daughter cells
91
What type of microscopy is used to visualize the cleavage of an animal cell?
Scanning Electron Microscopy (SEM)
92
What type of microscopy is used to visualize cell plate formation in a plant cell?
Transmission Electron Microscopy (TEM)
93
What type of cell division do prokaryotes use to reproduce?
Binary fission
## Footnote
Prokaryotes include bacteria and archaea.
94
What is the first step in binary fission?
Chromosome replicates at the origin of replication
## Footnote
This marks the beginning of the binary fission process.
95
What happens to the daughter chromosomes during binary fission?
They actively move apart
## Footnote
This movement is crucial for the successful division of the cell.
96
How is the bacterial cell divided during binary fission?
The plasma membrane pinches inward
## Footnote
This process results in the formation of two separate cells.
97
What are active areas of research regarding bacterial chromosomes?
How bacterial chromosomes move and their location established
## Footnote
Understanding these mechanisms can provide insights into bacterial reproduction.
98
What evolutionary relationship exists between binary fission and mitosis?
Mitosis probably evolved from binary fission
## Footnote
This suggests a common ancestry in cell division mechanisms.
99
What do certain unicellular eukaryotes exhibit in terms of cell division?
Types of cell division that seem intermediate between binary fission and mitosis
## Footnote
This indicates evolutionary links in the mechanisms of cell division.
100
Fill in the blank: The plasma membrane _______ inward during binary fission.
pinches
## Footnote
This action is critical for cell division.
101
True or False: Binary fission is a method of cell division used by eukaryotes.
False
## Footnote
Binary fission is specific to prokaryotes.
102
Fill in the blank: In binary fission, two daughter cells result from _______.
cell division
## Footnote
This is the final outcome of the binary fission process.
103
What regulates the eukaryotic cell cycle?
A molecular control system
## Footnote
This system includes both internal and external controls.
104
How does the frequency of cell division vary?
It varies with the type of cell
## Footnote
Differences in cell division frequency result from regulation at the molecular level.
105
What do cancer cells do in relation to the cell cycle?
Escape the usual controls on the cell cycle
## Footnote
This leads to rapid and uncontrollable division.
106
What drives the cell cycle?
Specific signaling molecules present in the cytoplasm
## Footnote
These molecules are crucial for the regulation of the cell cycle.
107
What experiment provided evidence for the cell cycle control system?
Fusing cultured mammalian cells at different phases of the cell cycle
## Footnote
This resulted in both nuclei entering the same phase of the cell cycle.
108
What directs the sequential events of the cell cycle?
A distinct cell cycle control system
## Footnote
This control system is essential for proper cell cycle progression.
109
What are the specific checkpoints in the cell cycle control system?
Points where the cell cycle stops until a go-ahead signal is received
## Footnote
These checkpoints ensure that the cell cycle proceeds only when conditions are favorable.
110
Fill in the blank: The cell cycle control system is regulated by both _______ and external controls.
internal
## Footnote
Internal controls refer to mechanisms within the cell that regulate the cycle.
111
What are the two types of regulatory proteins involved in cell cycle control?
Cyclins and cyclin-dependent kinases (Cdks)
## Footnote
These proteins play crucial roles in regulating the progression of the cell cycle.
112
Why are cyclins named so?
They are named for their cyclically fluctuating concentrations in the cell
## Footnote
Cyclins are integral in regulating the cell cycle phases.
113
What must Cdks be attached to in order to be active?
A cyclin
## Footnote
The binding of cyclin activates the Cdk for its regulatory functions.
114
What does MPF stand for?
Maturation-promoting factor
## Footnote
MPF is a key regulator that facilitates the transition from G phase to M phase.
115
What triggers a cell's passage past the G checkpoint into the M phase?
MPF (maturation-promoting factor)
## Footnote
MPF is crucial for initiating mitosis.
116
How does MPF activity correlate with cyclin concentration?
Peaks of MPF activity correspond to the peaks of cyclin concentration
## Footnote
This relationship is essential for the timing of cell cycle events.
117
What dual role does MPF play in the cell cycle?
Acts both as a kinase and indirectly through activating other kinases
## Footnote
This multifunctionality is important for the regulation of various processes during the cell cycle.
118
What is cyclin's role in the cell cycle?
Cyclin is involved in regulating the cell cycle by fluctuating in concentration and activity.
119
What does MPF stand for in the context of the cell cycle?
MPF stands for Maturation Promoting Factor.
120
During which phases are the three important checkpoints located?
The checkpoints are located in the G1, G2, and M phases.
121
What happens if a cell receives a go-ahead signal at the G1 checkpoint?
The cell will usually complete the S, G2, and M phases and divide.
122
What occurs if a cell does not receive the go-ahead signal at the G1 checkpoint?
The cell will exit the cycle and switch into a nondividing state called the Go phase.
123
What types of signals are registered at checkpoints?
Signals from cellular surveillance mechanisms within the cell and signals from outside the cell.
124
True or False: The G1 checkpoint is the least important checkpoint for many cells.
False.
125
Fill in the blank: If a cell does not receive the go-ahead signal, it enters the _______.
Go phase.
126
What is the significance of checkpoints in the cell cycle?
Checkpoints help regulate the cell cycle by ensuring that conditions are favorable for progression.
127
What is the role of internal signals in cell division?
Cells will not begin anaphase until all chromosomes are properly attached to the spindle at the metaphase plate.
## Footnote
This mechanism ensures that daughter cells have the correct number of chromosomes.
128
What are external factors that influence cell division?
Both chemical and physical factors influence cell division.
129
What are growth factors?
Substances released by certain cells that stimulate other cells to divide.
130
What is the significance of Platelet-derived growth factor (PDGF)?
PDGF is required for the division of cultured fibroblasts.
131
What type of cells produce PDGF?
Blood cell fragments called platelets.
132
Fill in the blank: An example of an internal signal is that cells will not begin anaphase until all chromosomes are properly attached to the _______.
spindle at the metaphase plate.
133
True or False: External factors are the only influences on cell division.
False.
## Footnote
Both internal and external factors influence cell division.
134
What is the result of digesting the extracellular matrix in connective tissue?
A suspension of free fibroblasts
## Footnote
This process allows for the study and culture of fibroblasts in vitro.
135
What is added to halt cell growth in culture vessels?
PDGE
## Footnote
PDGE stands for platelet-derived growth factor, which is used to control cell division.
136
What is density-dependent inhibition?
Crowded cells will stop dividing
## Footnote
This mechanism ensures that cell growth does not exceed the available space.
137
What is anchorage dependence in cell division?
Cells must be attached to a substratum to divide
## Footnote
This characteristic is crucial for the normal growth of most animal cells.
138
What do most animal cells exhibit to check their growth?
Density-dependent inhibition and anchorage dependence
## Footnote
These mechanisms help maintain optimal cell density and attachment for healthy growth.
139
Do cancer cells exhibit density-dependent inhibition or anchorage dependence?
Neither
## Footnote
Cancer cells can grow uncontrollably regardless of density or attachment.
140
Fill in the blank: Cells form a single layer in _______.
Density-dependent inhibition
## Footnote
This phenomenon occurs when cells are in optimal conditions for growth.
141
Fill in the blank: Normal mammalian cells divide to fill a gap and then stop, while _______ do not exhibit this regulation.
Cancer cells
## Footnote
This distinction is critical in understanding tumor growth.
142
What do cancer cells not heed?
Normal signals that regulate the cell cycle
143
What happens to cancer cells when growth factors are depleted?
They do not stop dividing
144
Do cancer cells need growth factors to grow and divide?
No
145
How may cancer cells grow without external growth factors?
They may make their own growth factor or convey a growth factor's signal without the presence of the growth factor or have an abnormal cell cycle control system
146
What does it mean when cells acquire the ability to divide indefinitely?
They have undergone transformation
147
What forms when cancer cells are not eliminated by the immune system?
Tumors
148
What is a benign tumor?
A lump of abnormal cells that remains only at the original site
149
Do most benign tumors cause serious problems?
No, depending on their location
150
What is a malignant tumor?
A tumor that invades surrounding tissues and can undergo metastasis
151
What is metastasis?
The spread of cancer cells to other parts of the body
152
What can happen when localized tumors are treated?
They may be treated with high-energy radiation
153
What does high-energy radiation do to cancer cells?
It damages the DNA in the cancer cells
154
What ability have the majority of cancer cells lost?
The ability to repair DNA damage
155
What is the origin of a tumor?
A tumor grows from a single cancer cell.
## Footnote
Tumors can be benign or malignant, with malignant tumors being cancerous.
156
How do cancer cells spread to other parts of the body?
Cancer cells spread through lymph and blood vessels.
## Footnote
This process is known as metastasis.
157
What are metastatic tumors treated with?
Metastatic tumors are treated with chemotherapeutic drugs that target the cell cycle.
## Footnote
These drugs aim to inhibit cancer cell division.
158
What causes the side effects of chemotherapy?
The side effects of chemotherapy are due to the effects of the drugs on normal cells that divide frequently.
## Footnote
Common side effects include hair loss and gastrointestinal issues.
159
What is the current research focus regarding cancer treatment?
Researchers are producing a flood of information about cell-signaling pathways and their relationship to cancer.
## Footnote
Understanding these pathways can lead to more effective treatments.
160
How are cancer treatments becoming more personalized?
Treatments for cancer are becoming more personalized to a particular patient's tumor.
## Footnote
This approach is facilitated by new molecular techniques.
161
Name the phases of mitosis.
* Prophase
* Prometaphase
* Metaphase
* Anaphase
* Telophase
* Cytokinesis
## Footnote
Each phase plays a crucial role in cell division.
162
Fill in the blank: A small percentage of cancer cells may _______ to other parts of the body.
[metastasize].
## Footnote
Metastasis is a critical aspect of cancer progression.
163
True or False: Chemotherapeutic drugs only affect cancer cells.
False.
## Footnote
Chemotherapy also affects normal cells that divide frequently.
