27 Questions
What is the narrow 'waist' of the duplicated chromosome where the two chromatids are most closely attached?
Centromere
What is the term for a complex of DNA and protein that condenses into chromosomes during cell division?
Chromatin
What is the characteristic number of chromosomes in each cell nucleus for every eukaryotic species?
Varies widely among species
What is the term for nonreproductive cells with two sets of chromosomes?
Somatic cells
In which phase of the cell cycle does DNA replicate and chromosomes condense in preparation for cell division?
S phase
What is the term for the structure that connects sister chromatids at the centromere?
Cohesin
What are reproductive cells with half as many chromosomes as somatic cells called?
Gametes
What is the term for the life of a cell from formation to its own division?
Cell cycle
What is the term for the region of a chromosome where microtubules of the spindle attach during cell division?
Kinetochore
Which type of organisms depend on cell division for growth, development, and repair?
Multicellular organisms only
What is the correct order of the phases in the cell cycle?
G1, S, G2, mitotic phase
During which phase of the cell cycle does DNA replication occur?
S phase
What happens during anaphase of mitosis?
Sister chromatids are separated and pulled towards opposite poles of the cell
Which type of cell division results in two identical daughter cells?
Mitosis
What is the main function of mitosis?
Embryonic development, tissue growth, and cell proliferation
Which phase marks the beginning of mitosis?
Prophase
What is cytokinesis?
The division of the cytoplasm resulting in two separate cells
What happens during telophase?
New nuclear envelopes form and chromatids uncoil into chromatin
What are defects in proteins like cohesins associated with?
Errors in chromosome segregation
Which statement about cancer cells is true?
They do not exhibit density-dependent inhibition or anchorage dependence, allowing them to divide uncontrollably.
What is the function of MPF (maturation-promoting factor) in the cell cycle?
Triggers a cell’s passage past the G$_2$ checkpoint into the M phase
What is the role of cyclin B in the regulation of the cell cycle?
Acts as a regulatory subunit required for catalytic activity of the Cdk1 protein kinase
Which of the following statements about cancer cells is true?
Cancer cells may not need growth factors to grow and divide
What is the function of density-dependent inhibition in normal mammalian cells?
It inhibits cell division when cells are crowded together
What happens if a cell does not receive a go-ahead signal at the G$_1$ checkpoint?
It will exit the cycle and switch into a nondividing state called G$_0$ phase
What regulates MPF (maturation-promoting factor) activity during the cell cycle?
Phosphorylation and dephosphorylation of Cdk1
What role do internal signals play in regulating the cell cycle?
They can delay anaphase by sending molecular signals
Study Notes
- Chromosomes are duplicated during interphase, which makes up about 90% of the cell cycle
- Mitosis is a type of cell division that results in two identical daughter cells
- Mitosis is composed of interphase, mitotic phase (mitosis and cytokinesis), and cell division in animal and plant cells
- Interphase is further divided into G1, S, and G2 phases
- During interphase, DNA is replicated during S phase
- Mitosis begins with prophase, where chromosomes condense and the spindle starts forming
- In metaphase, chromosomes align on the metaphase plate
- During anaphase, sister chromatids are separated and pulled towards opposite poles of the cell
- In telophase, new nuclear envelopes form and chromatids uncoil into chromatin
- Cytokinesis is the division of the cytoplasm and results in two separate cells
- Mitosis is important for embryonic development, tissue growth, and cell proliferation
- Mitosis and meiosis are the two main types of cell division
- Defects in proteins like cohesins can lead to errors in chromosome segregation
- Cancer cells do not exhibit density-dependent inhibition or anchorage dependence, allowing them to divide uncontrollably.
Test your knowledge on how a cell's chromosomes change during cell division and learn about the differences between mitosis and meiosis. Explore the concept of check points and MPF in the cell cycle.
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