Podcast
Questions and Answers
A cell in G0 phase is best described as being in what type of state?
A cell in G0 phase is best described as being in what type of state?
- Making final preparations for cell division.
- A dormant, non-dividing state. (correct)
- Undergoing rapid growth and consuming high amounts of energy.
- Actively replicating its DNA.
Which of the following statements accurately compares cell division in prokaryotes and eukaryotes?
Which of the following statements accurately compares cell division in prokaryotes and eukaryotes?
- Both prokaryotes and eukaryotes undergo meiosis for cell division.
- Both prokaryotes and eukaryotes reproduce sexually through mitosis.
- Prokaryotes reproduce asexually through binary fission, and eukaryotes divide through mitosis or meiosis. (correct)
- Prokaryotes divide through mitosis, while eukaryotes use binary fission.
What is the primary purpose of the checkpoints present at the end of G1 and G2 phases in the cell cycle?
What is the primary purpose of the checkpoints present at the end of G1 and G2 phases in the cell cycle?
- To allow cancer cells to accumulate mutations.
- To initiate DNA replication.
- To ensure the cell divides as quickly as possible.
- To assess whether the cell is ready to proceed to the next phase and prevent errors. (correct)
How does the duration of the cell cycle typically differ between healthy human cells and cancer cells, and why?
How does the duration of the cell cycle typically differ between healthy human cells and cancer cells, and why?
What is the significance of 'crossing over' during meiosis?
What is the significance of 'crossing over' during meiosis?
Why is it essential for chromosomes to be tightly packed during cell division?
Why is it essential for chromosomes to be tightly packed during cell division?
During which phase of mitosis do sister chromatids line up in the middle of the cell?
During which phase of mitosis do sister chromatids line up in the middle of the cell?
How many chromosomes are present in each human egg or sperm cell?
How many chromosomes are present in each human egg or sperm cell?
What is the end result of mitosis?
What is the end result of mitosis?
Which of the following is a primary reason for cell division in multicellular organisms?
Which of the following is a primary reason for cell division in multicellular organisms?
Flashcards
Interphase
Interphase
The longest stage of the cell cycle, accounting for approximately 90% of the cycle. Includes G1, S, and G2 phases.
G0 Phase
G0 Phase
A dormant, non-dividing state of the cell cycle where cells don't spend much energy, sometimes referred to as 'hibernation'.
Binary Fission
Binary Fission
A type of asexual reproduction in prokaryotes, where one loop of DNA is replicated and the cell divides.
Mitosis
Mitosis
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Metaphase
Metaphase
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Anaphase
Anaphase
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Cytokinesis
Cytokinesis
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Diploid
Diploid
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Haploid
Haploid
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Crossing Over
Crossing Over
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Study Notes
- The cell cycle consists of two phases: interphase and mitosis
- Human cells take about 30 hours to complete the cell cycle
- Cancer cells complete the cycle in roughly 10 hours by skipping phases/checkpoints, leading to increased mutations
- Older cells are more likely to accumulate mutations
Interphase
- Interphase is the longest stage of the cell cycle, accounting for 90% of the duration
- Interphase includes G1, S, and G2 phases
- G1 phase involves cell growth, preparing the cell for DNA replication
- G0 phase is a dormant, non-dividing state outside of the cell cycle where the cell expends minimal energy, cells can re-enter from G0
- S phase is where DNA replication occurs
- G2 phase involves further growth, checkpoints, and final preparations for cell division
- Checkpoints exist at the end of G1 and G2 phases
Cell Division (Mitosis)
- Cell division accounts for 10% of the cell cycle
- During cell division, a replicated copy of DNA is delivered to each of the two daughter cells
- Cell division in Eukaryotes occurs through mitosis
- Binary fission happens in prokaryotes such as bacteria, involving one loop of DNA and asexual reproduction
- Prokaryotic DNA is loosely packed
- Eukaryotic cells undergo two types of division: mitosis and meiosis
- Mitosis is asexual reproduction (one parent)
- Meisosis is sexual reproduction, producing sperm and egg cells
- 46 chromosomes are involved in mitosis
Meiosis (Sexual)
- Meiosis occurs in eukaryotic cells and involves sexual reproduction
- Meiosis results in egg and sperm cells
- These cells contain 23 chromosomes
- Prophase: Sister chromatids form (one chromosome after S phase becomes two identical chromosomes) which connect to sister chromatids centromeres with Mitotic spindles. The nuclear envelope breaks down during this stage
- Metaphase: All sister chromatids align in the middle connected by mitotic spindle
- Anaphase: Chromosomes within sister chromatids are pulled apart by contraction of the mitotic spindles
- Telophase: Two new daughter cells form, with chromosomes at opposite poles, and the nuclear envelope reforms
Cytokinesis
- Cytokinesis involves the creation of new cells, completing the cell cycle
Cell Division
- Cell division happens for two main reasons: to produce more cells, and to grow and repair areas of injury
- Chromosomes need to be tightly packed for cell division
Differences in Energy Expenditure
- Different processes in the cell are affected by varying energy expenditure
Binary Fission, Mitosis, Meiosis
Meiosis
- Meiosis produces gametes, which are haploid cells
Haploid Cells
- Haploid cells include egg and sperm cells, each containing 23 chromosomes
- Two haploid cells combine to form a zygote
- The zygote uses mitosis to grow
Diploid
- Diploid cells (or nuclei) contain two complete sets of chromosomes, one from each parent
Haploid Cell
- A haploid cell contains a single set of chromosomes
Meiosis Stages
- Meiosis occurs in two stages after interphase: Meiosis I and Meiosis II
- Each stage involves one round of cell division followed by cytokinesis, totaling two cell divisions
Meiosis
- In homologous chromosomes, one chromosome comes from each parent
- Crossing over is the physical exchange between nonsister chromatids in each duplicated homologous pair
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