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Questions and Answers
What is the main purpose of the S phase during interphase?
What is the main purpose of the S phase during interphase?
Which phase of interphase is known as the 'first gap'?
Which phase of interphase is known as the 'first gap'?
How long does interphase typically last in the cell cycle?
How long does interphase typically last in the cell cycle?
What occurs during the G2 phase of interphase?
What occurs during the G2 phase of interphase?
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Which of the following correctly identifies what mitosis involves?
Which of the following correctly identifies what mitosis involves?
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In which phase does cytokinesis occur?
In which phase does cytokinesis occur?
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What are the components that assist in the mitotic phase according to the visual description?
What are the components that assist in the mitotic phase according to the visual description?
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What is the significance of the G2 phase in preparing for mitosis?
What is the significance of the G2 phase in preparing for mitosis?
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What is the primary result of most cell division processes?
What is the primary result of most cell division processes?
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How many sets of chromosomes do somatic cells have?
How many sets of chromosomes do somatic cells have?
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Which of the following is a distinct characteristic of gametes?
Which of the following is a distinct characteristic of gametes?
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What happens to the sister chromatids during mitosis?
What happens to the sister chromatids during mitosis?
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What structure is referred to as the 'waist' of the duplicated chromosome?
What structure is referred to as the 'waist' of the duplicated chromosome?
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What occurs to DNA prior to cell division?
What occurs to DNA prior to cell division?
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Which type of cell division produces sperm and egg cells?
Which type of cell division produces sperm and egg cells?
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What constitutes a genome in a eukaryotic cell?
What constitutes a genome in a eukaryotic cell?
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What is the main function of the mitotic spindle during mitosis?
What is the main function of the mitotic spindle during mitosis?
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What structures make up the mitotic spindle?
What structures make up the mitotic spindle?
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During which phase do spindle microtubules attach to kinetochores?
During which phase do spindle microtubules attach to kinetochores?
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What happens to the sister chromatids during anaphase?
What happens to the sister chromatids during anaphase?
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What is the role of nonkinetochore microtubules during anaphase?
What is the role of nonkinetochore microtubules during anaphase?
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What occurs during telophase in the context of the mitotic spindle?
What occurs during telophase in the context of the mitotic spindle?
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What is the primary component of the centrosome?
What is the primary component of the centrosome?
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What occurs to the mitotic spindle during cytokinesis?
What occurs to the mitotic spindle during cytokinesis?
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What structure forms during cytokinesis in plant cells?
What structure forms during cytokinesis in plant cells?
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Which process is responsible for cytokinesis in animal cells?
Which process is responsible for cytokinesis in animal cells?
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Which of the following is NOT a characteristic of binary fission in prokaryotes?
Which of the following is NOT a characteristic of binary fission in prokaryotes?
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What role do growth factors play in the cell cycle?
What role do growth factors play in the cell cycle?
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What is the primary function of the cell cycle control system?
What is the primary function of the cell cycle control system?
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Which statement correctly describes the process of binary fission?
Which statement correctly describes the process of binary fission?
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What molecule typically regulates the cell cycle?
What molecule typically regulates the cell cycle?
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What is the first step in the binary fission process in prokaryotes?
What is the first step in the binary fission process in prokaryotes?
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What is the primary role of the G1 checkpoint in the cell cycle?
What is the primary role of the G1 checkpoint in the cell cycle?
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What happens to a cell that does not receive a go-ahead signal at the G1 checkpoint?
What happens to a cell that does not receive a go-ahead signal at the G1 checkpoint?
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Which of the following statements about cancer cells is true?
Which of the following statements about cancer cells is true?
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What distinguishes malignant tumors from benign tumors?
What distinguishes malignant tumors from benign tumors?
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What is the consequence of a nonfunctional p53 gene in cancer cells?
What is the consequence of a nonfunctional p53 gene in cancer cells?
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Which type of tumors arise from epithelial tissues?
Which type of tumors arise from epithelial tissues?
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Which phase of the cell cycle is associated with DNA synthesis?
Which phase of the cell cycle is associated with DNA synthesis?
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Where are most adult cancers observed in individuals over age 45 derived from?
Where are most adult cancers observed in individuals over age 45 derived from?
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Study Notes
Cell Cycle
- Continuity of life depends on cell reproduction (cell division)
- Unicellular organisms reproduce the entire organism through cell division
- Multicellular organisms depend on cell division for development (from a fertilized cell), growth, and repair
- A video titled "Cell Division & Cell Cycle" is available online
- The video runs for 5:34 minutes
Genetic Identical Daughter Cells
- Most cell division results in genetically identical daughter cells (Mitosis)
- Meiosis is an exception, it produces sperm and egg cells.
- All DNA in a cell comprises the genome
- The genome is made up of a single DNA molecule in prokaryotic cells, or several DNA molecules in eukaryotic cells
- DNA molecules are packaged into chromosomes
- Each eukaryotic species has a specific number of chromosomes per cell nucleus
- Somatic cells (non-reproductive cells) have two sets of chromosomes
- Gametes (reproductive cells, sperm/eggs) have half as many chromosomes as somatic cells – one set
Distribution of Chromosomes
- Before cell division, DNA is replicated and chromosomes condense
- Each duplicated chromosome has two sister chromatids joined together
- The centromere is the narrow region of a duplicated chromosome, where the two chromatids are most closely attached
During Cell Division
- During mitosis, the two sister chromatids of each duplicated chromosome separate and move into two nuclei
- Once separated, the sister chromatids are called chromosomes
The Cell Cycle
- The cell cycle consists of Interphase and Mitotic (M) Phase
- Interphase, which takes up about 90% of the cell cycle, includes three subphases:
- G1 phase ("first gap")
- S phase ("synthesis") – DNA replication
- G2 phase ("second gap")
- The cell grows throughout all phases of Interphase, but DNA is only duplicated during S phase
- The mitotic (M) phase includes Mitosis and Cytokinesis
Eukaryotic Cell Division
- Eukaryotic cell division includes Mitosis (division of the genetic material in the nucleus) and Cytokinesis (division of the cytoplasm).
- Mitosis is divided into five phases.
- The stages of mitosis are; Prophase, Prometaphase, Metaphase, Anaphase, Telophase.
P²MAT
- A mnemonic device for the five stages of mitosis: Prophase, Metaphase, Anaphase, Telophase. Each stage has distinct characteristics. A video demonstrating the five stages of mitosis is available (title and details provided in the provided text)
Mitosis in Animal Cells
- The nuclear envelope breaks down before metaphase and re-forms during telophase
- Centrosomes and the mitotic spindle are stained yellow
- DNA is stained blue/purple
The Mitotic Spindle
- The spindle is a microtubule structure that controls chromosome movement during mitosis
- Mitotic Spindle is composed of centrosomes, spindle microtubules, and asters (radial arrays of short microtubules from the centrosome).
- The centrosome replicates during interphase, forming two centrosomes.
- Two centrosomes migrate to opposite ends of the cell.
- Some spindle microtubules attach to the kinetochores, protein complexes associated with centromeres, of chromosomes.
- During prometaphase, the chromosomes begin to move.
- Each centrosome consists of two centrioles, each being an array of 9 microtubules
Mitosis Continued
- In anaphase, sister chromatids separate and move along the kinetochore microtubules to opposite ends of the cell.
- Nonkinetochore microtubules overlap and push against each other, elongating the cell.
- In telophase, genetically identical daughter nuclei form at opposite ends of the cell
- Cytokinesis begins during anaphase or telophase.
- The spindle disassembles.
Cytokinesis
- In animal cells, cytokinesis occurs by cleavage, forming a cleavage furrow.
- In plant cells, a cell plate forms during cytokinesis.
BIO 1300 Schedule
- This section contains a schedule for a BIO 1300 course. The dates and activities are provided in the image.
Binary Fission in Bacteria
- Prokaryotes (bacteria and archaea) reproduce asexually by binary fission - a cell division.
- Chromosome replicates at the origin of replication
- Two daughter chromosomes migrate apart.
- The plasma membrane pinches inward, dividing the cell into two.
Eukaryotic Cell Cycle Control
- Eukaryotic cell cycle frequency varies by cell type (e.g., frequency is different for neurons vs. skin cells).
- Cell cycle is driven by specific chemical signals present in the cytoplasm.
- The cell cycle is regulated by both internal and external controls
- Signals such as growth factors can trigger these controls
- A cell cycle control system is like a cell's clock, including checkpoints where the cycle pauses until a go-ahead signal is received
- G1 checkpoint is the most important for many cells.
Control of Cell Cycle
- If a cell receives a go-ahead signal at the G1 checkpoint, the cell continues the cycle (S, G2 and M phases) to divide.
- If the cell does not get a go-ahead signal the cell cycle stops and enters G0 phase. A non-dividing state.
Loss of Cell Cycle Controls in Cancer Cells
- Cancer cells escape normal cell cycle controls
- Cancer cells don't need growth factors, sometimes creating their own
- Normal cells can be converted to cancerous cells through a process called transformation.
- Cancer cells that aren't eliminated form tumors (masses of abnormal cells).
- Benign tumors remain at the original site. Malignant tumors invade surrounding tissues and can metastasize (moving to other body parts).
Cancerous Cells
- Often have variations in size and shape.
- Have nuclei larger and darker than normal
- Abnormal chromosome numbers in a disorganized pattern.
p53 Gene
- The p53 gene is a tumor suppressor gene.
- In cancer cells, p53 is nonfunctional.
- Cancer cells undergo repeated cell division without stopping at the G1 checkpoint.
- Normal p53 functions to monitor DNA, destroy cells with irreparable DNA damage
- Abnormal p53 leads to uncontrolled cell division leading to cancerous growth
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Description
This quiz covers key concepts related to the cell cycle and mitosis, focusing on interphase stages such as G1, S, and G2, as well as the process of mitosis itself. Test your knowledge on cell division processes and the significance of each phase. Perfect for students learning about cellular biology.
