52 Questions
What happens during the G1 phase of interphase?
Metabolic activity and growth
Which phase of the cell cycle involves the duplication of chromosomes?
S phase
What is the main function of the mitotic phase in the cell cycle?
Equal distribution of duplicated genetic material into daughter cells
What is the key feature of eukaryotic cell cycle regulation?
Molecular control system
Which phase is the most variable in length in different types of cells?
G1 phase
During which phase does duplication of chromosomes occur?
S phase
What is the main function of the G1 phase?
Growth and metabolic activity
Which phase involves intense metabolic activity and growth despite its misnaming?
G1 phase
What is the last stage of the cell cycle?
Cytokinesis
Which phase involves the formation of a mitotic spindle and condensation of chromosomes?
Prophase
What occurs during anaphase?
Separation of sister chromatids
What is the main function of the S phase?
DNA synthesis
What is the function of the M phase?
Actual cell division
During which phase do the centrosomes move away from each other?
Prophase
Which phase involves the movement of centrosomes and extension of microtubules into the nuclear area?
Prophase
What is the phase for preparation for cell division?
G2 phase
What is the function of cell division in multicellular eukaryotes?
Enables development from a single cell and facilitates renewal and repair
What is the typical number of chromosomes in human somatic cells?
46 chromosomes
What is the structure of eukaryotic chromosomes?
Consists of a long, linear DNA molecule associated with many proteins
What is the primary reason for packaging DNA into chromosomes?
To enable the replication and distribution of DNA
What is the characteristic number of chromosomes in human reproductive cells?
23 chromosomes
What is the role of chromosomes during cell division?
Behave differently with highly condensed duplicated chromosomes and the distribution of sister chromatids
What is the purpose of eukaryotic cell division?
Involves the distribution of identical genetic material to daughter cells
What is the accuracy of DNA passage during cell division?
Remarkable
What is the length of DNA in a typical human cell?
About 2 meters
What is the number of genes carried by a eukaryotic chromosome?
Several hundred to a few thousand genes
What is the variation in the number of chromosomes in eukaryotic somatic cells among species?
Varies widely
What is the distribution of identical genetic material to daughter cells during cell division?
A crucial function of most cell divisions
During cell division, what happens to sister chromatids?
They become individual chromosomes after separation
What is the result of mitosis followed by cytokinesis?
Two genetically equivalent cells
When is DNA replication followed by the condensation of chromosomes?
Before cell division
What do duplicated chromosomes consist of?
Two sister chromatids connected by sister chromatid cohesion
What is the portion of a chromatid to either side of the centromere referred to as?
An arm of the chromatid
What separates the sister chromatids into two chromosomes and distributes them to daughter cells?
Molecular and mechanical processes
Which phase of the cell cycle includes metabolic activity and growth?
Interphase
What reduces the chromosome number from 46 to 23 in gametes?
Meiosis
What is the result of mitosis?
Two genetically equivalent cells
What is the form of chromosomes when a cell is not dividing?
Long, thin chromatin fibers
What is the role of sister chromatid cohesion?
To keep the sister chromatids together
What is the part of the cell cycle that includes G1, S, and G2 phases?
Interphase
What is responsible for the poleward movement of chromosomes during anaphase?
Motor proteins on the kinetochores
During which phase do cohesins holding together sister chromatids get cleaved by an enzyme called separase?
Anaphase
Where does the assembly of spindle microtubules start in animal cells?
Centrosome
What is the role of the mitotic spindle in mitosis events?
Plays a crucial role
What happens to the cell during cytokinesis in animal cells?
It forms a cleavage furrow that pinches the cell in two
What is the function of nonkinetochore microtubules during mitosis?
They elongate as the cell elongates
When does the cell elongate as nonkinetochore microtubules lengthen?
During mitosis
What occurs during prophase and prometaphase in animal cells?
The two centrosomes move apart
What organizes the cell’s microtubules?
Centrosome
What is the role of kinetochores during prometaphase?
Some spindle microtubules attach to the kinetochores
What happens to spindle microtubules during mitosis?
They elongate and shorten through polymerization and depolymerization
What is the region containing material that organizes the cell’s microtubules?
Centrosome
Study Notes
Mitotic Spindle and Chromosome Movement in Cell Division
- Mitosis, the division of one nucleus into two genetically identical nuclei, is completed with the cell elongating as nonkinetochore microtubules lengthen
- Cytokinesis in animal cells involves the formation of a cleavage furrow that pinches the cell in two
- The mitotic spindle, consisting of microtubules and associated proteins, plays a crucial role in mitosis events
- Spindle microtubules elongate and shorten through polymerization and depolymerization, respectively
- In animal cells, the assembly of spindle microtubules starts at the centrosome, a region containing material that organizes the cell’s microtubules
- During interphase in animal cells, the single centrosome duplicates, forming two centrosomes, which move apart during prophase and prometaphase
- Each sister chromatid of a duplicated chromosome has a kinetochore, and during prometaphase, some spindle microtubules attach to the kinetochores
- At metaphase, the centromeres of all the duplicated chromosomes are on the metaphase plate, with microtubules overlapping and interacting
- Anaphase begins when cohesins holding together sister chromatids are cleaved by an enzyme called separase, allowing the chromatids to move toward opposite ends of the cell
- Mechanisms involving motor proteins on the kinetochores are responsible for the poleward movement of chromosomes during anaphase
- One mechanism suggests that motor proteins on the kinetochores "walk" the chromosomes along the microtubules, which depolymerize at their kinetochore ends
- Other research has shown that chromosomes are "reeled in" by motor proteins at the.
Test your understanding of mitotic spindle and chromosome movement in cell division with this quiz. Explore the key events of mitosis, including spindle assembly, kinetochore attachment, metaphase alignment, anaphase separation, and cytokinesis in animal cells.
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