Podcast
Questions and Answers
During which phase of the cell cycle does DNA replication occur?
During which phase of the cell cycle does DNA replication occur?
What is the primary function of tumor suppressor genes in a healthy cell?
What is the primary function of tumor suppressor genes in a healthy cell?
What is the consequence of DNA damage in the G₁ phase that is not repaired?
What is the consequence of DNA damage in the G₁ phase that is not repaired?
Which of the following best describes the relationship between proto-oncogenes and oncogenes?
Which of the following best describes the relationship between proto-oncogenes and oncogenes?
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Which stage of mitosis involves the separation of sister chromatids?
Which stage of mitosis involves the separation of sister chromatids?
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Why are villi in the small intestine important for nutrient absorption ?
Why are villi in the small intestine important for nutrient absorption ?
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Which of the following is NOT a key structural component of DNA?
Which of the following is NOT a key structural component of DNA?
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What type of stem cells are found in a blastocyst?
What type of stem cells are found in a blastocyst?
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Study Notes
Cell Cycle & Mitosis
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Cell Cycle Phases:
- G₁ (Gap 1): Cell growth, normal functions, DNA replication preparation.
- S (Synthesis): DNA replication, chromosome duplication.
- G₂ (Gap 2): Cell growth, resource production for mitosis.
- M (Mitosis): Nucleus division.
- Cytokinesis: Cytoplasm division, two daughter cells.
- Longest Phase: G₁
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DNA Structure & Replication:
- Base Pairing: A-T, C-G
- Backbone: Phosphate and sugar molecules.
- Ends: 5' and 3' indicate DNA strand direction.
- Bonds: Phosphodiester (sugar-phosphate), hydrogen (base pairs).
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Cell Cycle Checkpoints:
- Cyclins and checkpoint proteins regulate cell progression.
- DNA damage and cell readiness are checked.
- Checkpoint failure leads to uncontrolled cell division (cancer).
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Cancer and Genetic Mutations:
- Proto-oncogenes: Mutated to oncogenes, promote uncontrolled division.
- Tumor Suppressor Genes: Prevent uncontrolled growth; mutations disable them.
Cancer Risk Factors
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General Risks:
- Genetic predisposition (family history).
- Environmental factors (radiation, smoking, toxins).
DNA Damage & Consequences
- G₁ Phase Damage: Unfixed damage leads to accumulated mutations, potentially causing cancer.
Stem Cells
- Stem Cell Types: Pluripotent stem cells (differentiate into any cell type).
- Location: Embryonic stem cells in blastocysts.
Villi in the Small Intestine
- Function: Increase surface area for nutrient absorption.
- Structure: Contain microvilli for further nutrient uptake.
Surface Area & Cell Exchange
- Optimal Shape: Small, cube-shaped cells have a larger surface area-to-volume ratio for efficient exchange.
Mitosis Stages
- Prophase: Chromosomes condense, spindle fibers form, nuclear membrane breaks down.
- Metaphase: Chromosomes align at the cell center.
- Anaphase: Sister chromatids separate to opposite poles.
- Telophase: Nuclear membranes reform around chromosomes.
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Cytokinesis: Cytoplasm divides into two daughter cells
- Chromosome Count: Without DNA replication, daughter cells have half the normal number of chromosomes.
Chromosome Structures
- Unreplicated Chromosomes: Single-stranded DNA.
- Chromatin: Loose, uncoiled DNA during interphase.
- Replicated Chromosomes: Two sister chromatids connected at a centromere.
DNA Replication
- Leading Strand: Continuous synthesis.
- Lagging Strand: Synthesis in short fragments (Okazaki).
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Key Enzymes:
- Helicase: Unwinds DNA.
- DNA Polymerase: Adds nucleotides.
- Ligase: Seals gaps in the lagging strand.
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Description
Explore the key phases of the cell cycle, including G₁, S, G₂, M, and cytokinesis. Understand DNA structure and replication processes, as well as the significance of cell cycle checkpoints and their relation to cancer development. This quiz covers fundamental concepts in cell biology and genetics.
