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Questions and Answers
What are the four main stages of the cell cycle?
What are the four main stages of the cell cycle?
Gap 1, Synthesis, Gap 2, and Mitosis
What is the role of the Gap 1 Checkpoint?
What is the role of the Gap 1 Checkpoint?
The Synthesis phase involves the division of the cell nucleus.
The Synthesis phase involves the division of the cell nucleus.
False
What happens during Mitosis?
What happens during Mitosis?
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What is the purpose of Telomeres?
What is the purpose of Telomeres?
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During Cytokinesis, the cytoplasm divides between _____ daughter cells.
During Cytokinesis, the cytoplasm divides between _____ daughter cells.
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What is Meiosis primarily associated with?
What is Meiosis primarily associated with?
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How many chromosomes do gametes have at the end of Meiosis II?
How many chromosomes do gametes have at the end of Meiosis II?
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Match the stages of Mitosis with their descriptions:
Match the stages of Mitosis with their descriptions:
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Study Notes
The Cell Cycle
- The cell cycle is a regular pattern of growth, DNA duplication, and cell division that occurs in eukaryotic cells
- Consist of four main stages: gap 1 (G1), synthesis (S), gap 2 (G2), and mitosis (M)
- G1, S, and G2 together make up interphase
Checkpoints
- Critical control points in the cell cycle where stop and go signals can regulate the cell cycle
Gap 1 Checkpoint
- Also known as the Restriction point
- Cell is large enough to divide and has enough nutrients to support the daughter cell
- If it receives a go signal, it will continue to the cell cycle
- If it receives a stop signal, it will exit the cell cycle
Gap 0 Checkpoint
- Cells in this state will not divide
Synthesis (S) Phase
- "Synthesis" means "combining of parts to make a whole"
- DNA is copied, resulting in two sets of DNA
Gap 2 Checkpoint
- Cells continue to carry out their normal functions, and additional growth occurs
- Checks whether the DNA is undamaged with adequate cell size before it proceeds with mitosis and cell division
Mitosis (M)
- Includes two processes: mitosis and cytokinesis
- Division of the cell nucleus
- During mitosis:
- The nuclear membrane dissolves
- Duplicated DNA condenses around proteins and separates
- Two new nuclei form
- Cytokinesis is the process that divides the cell cytoplasm.
- The result is two daughter cells that are genetically identical to the original cell
Chromosomes
- Essential for cell division
- Responsible for the replication, division, and creation of daughter cells with the correct sequences of DNA and proteins
Parts of a Chromosome
- Nucleotides : DNA is a double-stranded molecule made of four different subunits
- Chromosome : One long continuous thread of DNA that consists of numerous genes along with regulatory information. Human body cells have 46 chromosomes each.
- Histones: A group of proteins associated with the chromosomes. DNA wraps around histones at regular intervals, similar to beads on a string. Parts of the histones interact with each other, further compacting the DNA.
- Chromatin : Loose combination of DNA and proteins
- Chromatid : One half of the duplicated chromosome
- Sister chromatids : Two identical chromatids
- Centromere : Region of the condensed chromosome that looks pinched
- Telomere : Ends of DNA molecules
Stages of Mitosis
- Divides two new cells genetically identical with the parent cell
- Allows for splitting of the cell nucleus into two new sets of chromosomes
Prophase
- Duplicated chromosomes condense
- The nuclear envelope breaks down
- Centrioles begin to move to opposite poles and spindle fibers form
Metaphase
- Spindle fibers attach to each chromosome
- They align the chromosomes along the cell equator
Anaphase
- Chromatids separate to opposite sides of the cell
- Cytokinesis usually begins in late anaphase or telophase
Telophase
- Nuclear membranes start to form
- Chromosomes begin to uncoil
- Spindle fibers fall apart
Cytokinesis
- Divides cytoplasm between two daughter cells, each with a genetically identical nucleus
- The cells enter interphase and begin the cycle again
Meiosis
- Form of nuclear division that creates four haploid cells from one diploid cell
- Involves two rounds of cell division: meiosis I and meiosis II
- Each round of cell division has four phases, similar to those in mitosis
- Only occurs for sex cells
- At the end of meiosis II, each cell (i.e., gamete) would have half the original number of chromosomes (15)
Homologous Pairs
- Similar but not identical chromosome pairs an organism receives from its two parents
- Accomplished in meiosis using a two-step division process
- Homologous pairs separate during a first round of cell division.
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Description
Explore the stages of the cell cycle, focusing on G1, S, G2, and M phases. Learn about critical checkpoints that regulate cell division, including the gap 1 and gap 0 checkpoints. This quiz will enhance your understanding of eukaryotic cell growth and division.
