AP Biology Flashcards: Cell Cycle

What this deck covers

This deck focuses on Cell Cycle, giving you a quick way to review the definitions, rules, and examples that matter most for AP Biology.

How to use these flashcards

Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: What is the main function of p$53$ in the cell cycle?

Answer: Halts cycle for DNA repair or triggers apoptosis. Guardian of genome responds to DNA damage signals.

Flashcard 2: Identify the structure that forms during plant cell cytokinesis to separate daughter cells.

Answer: Cell plate (from vesicles) that becomes new cell wall. Golgi vesicles fuse to create separating membrane wall.

Flashcard 3: What is the significance of telomeres in cell division?

Answer: Protect chromosome ends, limit cell division. Prevent chromosome degradation and count cell divisions.

Flashcard 4: What molecules directly drive cell-cycle transitions by phosphorylating target proteins?

Answer: Cyclin-dependent kinases (CDKs). Protein kinases that phosphorylate substrates when activated.

Flashcard 5: Which spindle microtubules attach directly to kinetochores?

Answer: Kinetochore microtubules. Direct connection between spindle apparatus and chromosomes.

Flashcard 6: Which enzyme is responsible for DNA replication?

Answer: DNA polymerase. The main enzyme that synthesizes new DNA strands.

Flashcard 7: Which checkpoint verifies DNA replication completion and damage repair before mitosis?

Answer: G$2$ checkpoint. Ensures genome integrity before nuclear division begins.

Flashcard 8: Identify the complex that promotes the G$2$  M transition in many eukaryotic cells.

Answer: MPF (M-phase promoting factor: cyclin BCDK$1$). Key regulatory complex controlling entry into mitosis.

Flashcard 9: Identify the term for uncontrolled cell division.

Answer: Cancer. Results from loss of cell cycle control mechanisms.

Flashcard 10: Identify the phase where crossing over occurs.

Answer: Prophase I of meiosis. Genetic recombination occurs between homologous chromosomes.

Flashcard 11: Identify the structure that forms the cleavage furrow in animal cell cytokinesis.

Answer: Actinmyosin contractile ring. Contractile proteins create constriction that divides cytoplasm.

Flashcard 12: What process follows telophase in the cell cycle?

Answer: Cytokinesis. The process that physically divides the cell into two.

Flashcard 13: What is a cell cycle checkpoint?

Answer: Control point where stop/go signals regulate cycle. Quality control mechanisms that monitor cell cycle progress.

Flashcard 14: What is the primary purpose of G$2$ phase?

Answer: Growth and preparation for mitosis; error checking. Ensures cell is ready and DNA is intact before division.

Flashcard 15: What is a key feature of the metaphase checkpoint?

Answer: Ensure chromosomes are aligned at metaphase plate. Prevents anaphase until all chromosomes are attached.

Flashcard 16: What is checked at the G₂ checkpoint?

Answer: DNA integrity, DNA replication completion. Ensures DNA is properly replicated before mitosis.

Flashcard 17: What is the primary event of S phase?

Answer: DNA replication (chromosomes are duplicated). Each chromosome is copied to form sister chromatids.

Flashcard 18: Which checkpoint ensures all chromosomes are attached to the spindle before anaphase?

Answer: M checkpoint (spindle assembly checkpoint). Prevents premature chromatid separation during mitosis.

Flashcard 19: Identify the checkpoint between G₁ and S phase.

Answer: G₁ checkpoint. The restriction point controlling entry into S phase.

Flashcard 20: What is the main purpose of the G₁ checkpoint?

Answer: Assess cell size, nutrients, DNA damage. Determines if the cell is ready for DNA replication.

Flashcard 21: What occurs during the S phase of the cell cycle?

Answer: DNA replication. The synthesis phase where chromosomes are duplicated.

Flashcard 22: What is the primary event that occurs in G₀ phase?

Answer: Cell cycle arrest. Non-dividing state where cells exit the active cycle.

Flashcard 23: What is anchorage dependence in animal cells?

Answer: Cells must attach to a substrate to divide. Cell adhesion requirement for normal cell division.

Flashcard 24: What is G$0$ phase?

Answer: Nondividing state outside the cell cycle. Quiescent cells exit cycle temporarily or permanently.

Flashcard 25: What are the phases of the cell cycle?

Answer: G₁, S, G₂, M. The sequential order of the four main cell cycle phases.

Flashcard 26: What is the primary event of S phase?

Answer: DNA replication (chromosomes are duplicated). Each chromosome is copied to form sister chromatids.

Flashcard 27: What is the primary function of mitosis?

Answer: Generate two identical daughter cells. Nuclear division producing genetically identical offspring.

Flashcard 28: What protein complex is activated by cyclins?

Answer: Cyclin-dependent kinases (CDKs). Enzymes that phosphorylate target proteins when bound to cyclins.

Flashcard 29: What is an oncogene?

Answer: Mutated gene that promotes uncontrolled cell division. Drives excessive proliferation when growth controls fail.

Flashcard 30: What is a tumor suppressor gene?

Answer: Gene that restrains division; loss increases cancer risk. Normally prevents cancer by controlling cell division.

Flashcard 31: Identify the phase where the spindle fibers attach to kinetochores.

Answer: Prometaphase. Nuclear envelope breaks down and spindle attaches.

Flashcard 32: What is the role of cyclins in cell-cycle control?

Answer: They activate CDKs by binding; levels fluctuate. Regulatory proteins that rise and fall cyclically.

Flashcard 33: What occurs during anaphase of mitosis?

Answer: Sister chromatids separate. Spindle fibers pull sister chromatids to opposite poles.

Flashcard 34: What is the difference between mitosis and meiosis?

Answer: Mitosis produces identical cells; meiosis produces gametes. Mitosis maintains chromosome number; meiosis reduces it.

Flashcard 35: Which spindle microtubules push poles apart by overlapping at the cell center?

Answer: Nonkinetochore (polar) microtubules. Elongate spindle by sliding past each other.

Flashcard 36: What is the definition of cytokinesis?

Answer: Division of the cytoplasm to form two cells. Physical separation creating two distinct cells.

Flashcard 37: What is the term for programmed cell death?

Answer: Apoptosis. Controlled cell death to eliminate damaged cells.

Flashcard 38: Which option correctly states chromosome and chromatid counts at metaphase for a diploid cell with $2n=8$?

Answer: 8 chromosomes and 16 chromatids. Condensed duplicated chromosomes align before chromatid separation.

Flashcard 39: What is the primary purpose of M phase?

Answer: Mitosis and cytokinesis to form two daughter cells. Nuclear division followed by cytoplasmic division.

Flashcard 40: What is the primary purpose of G$1$ phase?

Answer: Cell growth and normal metabolic activity. Cell increases size and synthesizes proteins for normal functions.

Flashcard 41: What is the role of cohesin in chromosome structure?

Answer: Holds sister chromatids together until anaphase. Protein ring maintaining chromosome cohesion during replication.

Flashcard 42: What molecules directly drive cell-cycle transitions by phosphorylating target proteins?

Answer: Cyclin-dependent kinases (CDKs). Protein kinases that phosphorylate substrates when activated.

Flashcard 43: What key event defines anaphase?

Answer: Sister chromatids separate and move to opposite poles. Chromosome segregation ensures equal genetic distribution.

Flashcard 44: What key events define telophase?

Answer: Nuclei reform; chromosomes decondense; spindle disassembles. Mitosis concludes with nuclear reformation and chromosome relaxation.

Flashcard 45: What is the main function of the Rb (retinoblastoma) protein at the G$1$ checkpoint?

Answer: Inhibits S-phase entry until phosphorylated. Tumor suppressor blocking S-phase until growth signals arrive.

Flashcard 46: Identify the complex that promotes the G$2$  M transition in many eukaryotic cells.

Answer: MPF (M-phase promoting factor: cyclin BCDK$1$). Key regulatory complex controlling entry into mitosis.

Flashcard 47: What key event defines prometaphase?

Answer: Nuclear envelope breaks down; spindle attaches to kinetochores. Spindle captures chromosomes after nuclear envelope fragments.

Flashcard 48: What is the name of the process that reduces chromosome number by half?

Answer: Meiosis. Reduction division producing haploid gametes from diploid cells.

Flashcard 49: What structure forms during cytokinesis in plant cells?

Answer: Cell plate. Plant-specific structure that divides the cytoplasm.

Flashcard 50: In which phase does cytokinesis begin?

Answer: Telophase. Cytoplasm division overlaps with the final mitotic phase.

Flashcard 51: Identify the term for uncontrolled cell division.

Answer: Cancer. Results from loss of cell cycle control mechanisms.

Flashcard 52: Identify the final phase of mitosis.

Answer: Telophase. Nuclear envelopes reform and chromosomes begin to decondense.

Flashcard 53: In which phase do nuclear envelopes reform?

Answer: Telophase. Nuclear membranes reassemble around each set of chromosomes.

Flashcard 54: What is a key feature of the metaphase checkpoint?

Answer: Ensure chromosomes are aligned at metaphase plate. Prevents anaphase until all chromosomes are attached.

Flashcard 55: Which phase of the cell cycle is the longest?

Answer: Interphase. Includes $G_1$, S, and $G_2$ phases for cell growth.

Flashcard 56: What is a kinetochore?

Answer: Protein structure on centromere where spindle attaches. Specialized protein complex linking chromosomes to spindle fibers.

Flashcard 57: Which checkpoint verifies DNA replication completion and damage repair before mitosis?

Answer: G$2$ checkpoint. Ensures genome integrity before nuclear division begins.

Flashcard 58: What is the function of the p53 protein?

Answer: Regulates cell cycle and apoptosis. Tumor suppressor protein that monitors DNA damage.

Flashcard 59: What is the immediate effect of MPF activation on the cell?

Answer: Triggers mitosis, including nuclear envelope breakdown. Phosphorylates nuclear proteins to start chromosome condensation.

Flashcard 60: What phase follows prophase in mitosis?

Answer: Metaphase. Chromosomes align at the cell center after condensing.

Flashcard 61: What does G₁ stand for in the cell cycle?

Answer: Gap 1 phase. The first gap phase between mitosis and DNA synthesis.

Flashcard 62: What is density-dependent inhibition?

Answer: Crowding stops division due to reduced growth signaling. Contact inhibition limits proliferation at high cell density.

Flashcard 63: What key event defines prometaphase?

Answer: Nuclear envelope breaks down; spindle attaches to kinetochores. Spindle captures chromosomes after nuclear envelope fragments.

Flashcard 64: What key event defines anaphase?

Answer: Sister chromatids separate and move to opposite poles. Chromosome segregation ensures equal genetic distribution.

Flashcard 65: What is the immediate effect of MPF activation on the cell?

Answer: Triggers mitosis, including nuclear envelope breakdown. Phosphorylates nuclear proteins to start chromosome condensation.

Flashcard 66: What is the primary purpose of G$1$ phase?

Answer: Cell growth and normal metabolic activity. Cell increases size and synthesizes proteins for normal functions.

Flashcard 67: What structure forms during cytokinesis in plant cells?

Answer: Cell plate. Plant-specific structure that divides the cytoplasm.

Flashcard 68: What is the significance of telomeres in cell division?

Answer: Protect chromosome ends, limit cell division. Prevent chromosome degradation and count cell divisions.

Flashcard 69: Identify the checkpoint between G₁ and S phase.

Answer: G₁ checkpoint. The restriction point controlling entry into S phase.

Flashcard 70: What is a proto-oncogene?

Answer: Normal gene that can become an oncogene if mutated. Codes for growth-promoting proteins in normal cells.

Flashcard 71: Identify the structure that forms the cleavage furrow in animal cell cytokinesis.

Answer: Actinmyosin contractile ring. Contractile proteins create constriction that divides cytoplasm.

Flashcard 72: Which checkpoint ensures all chromosomes are attached to the spindle before anaphase?

Answer: M checkpoint (spindle assembly checkpoint). Prevents premature chromatid separation during mitosis.

Flashcard 73: What is the role of the Rb protein in the cell cycle?

Answer: Inhibits cell cycle progression. Tumor suppressor that blocks $G_1$ to S transition.

Flashcard 74: What is the purpose of the cell cycle control system?

Answer: Regulate timing of cell cycle events. Checkpoints and molecular machinery coordinate cell division.

Flashcard 75: What is the main purpose of the G₁ checkpoint?

Answer: Assess cell size, nutrients, DNA damage. Determines if the cell is ready for DNA replication.

Flashcard 76: What is interphase in the cell cycle?

Answer: G$1$, S, and G$2$; growth and DNA replication prep. Three phases between cell divisions preparing for next division.

Flashcard 77: Identify the phase where crossing over occurs.

Answer: Prophase I of meiosis. Genetic recombination occurs between homologous chromosomes.

Flashcard 78: Which spindle microtubules anchor the spindle to the cell cortex?

Answer: Astral microtubules. Position and orient spindle within the cell.

Flashcard 79: What is the role of cohesin in chromosome structure?

Answer: Holds sister chromatids together until anaphase. Protein ring maintaining chromosome cohesion during replication.

Flashcard 80: What is anchorage dependence in animal cells?

Answer: Cells must attach to a substrate to divide. Cell adhesion requirement for normal cell division.

Flashcard 81: What is the role of the enzyme telomerase?

Answer: Extends telomeres in germ cells and cancer cells. Maintains telomere length in stem and cancer cells.

Flashcard 82: What is the definition of mitosis?

Answer: Division of the nucleus into two genetically identical nuclei. Ensures equal genetic distribution to daughter cells.

Flashcard 83: What protein complex is activated by cyclins?

Answer: Cyclin-dependent kinases (CDKs). Enzymes that phosphorylate target proteins when bound to cyclins.

Flashcard 84: What is the definition of cytokinesis?

Answer: Division of the cytoplasm to form two cells. Physical separation creating two distinct cells.

Flashcard 85: What does G₁ stand for in the cell cycle?

Answer: Gap 1 phase. The first gap phase between mitosis and DNA synthesis.

Flashcard 86: Identify the phase where chromosomes line up at the cell equator.

Answer: Metaphase. Chromosomes align at the metaphase plate before separation.

Flashcard 87: What structure is responsible for separating chromosomes during mitosis?

Answer: Mitotic spindle. The protein structure that pulls chromosomes apart.

Flashcard 88: What is the correct order of the eukaryotic cell cycle phases (including interphase and M phase)?

Answer: G$1$  S  G$2$  M. Standard sequence: Gap1, Synthesis, Gap2, Mitosis phases.

Flashcard 89: What is the role of growth factors in the cell cycle?

Answer: Stimulate cell division. External signals that promote cell cycle progression.

Flashcard 90: What is G$0$ phase?

Answer: Nondividing state outside the cell cycle. Quiescent cells exit cycle temporarily or permanently.

Flashcard 91: Which option correctly states chromosome and chromatid counts at metaphase for a diploid cell with $2n=8$?

Answer: 8 chromosomes and 16 chromatids. Condensed duplicated chromosomes align before chromatid separation.

Flashcard 92: What is the definition of mitosis?

Answer: Division of the nucleus into two genetically identical nuclei. Ensures equal genetic distribution to daughter cells.

Flashcard 93: What is the primary purpose of M phase?

Answer: Mitosis and cytokinesis to form two daughter cells. Nuclear division followed by cytoplasmic division.

Flashcard 94: Identify the final phase of mitosis.

Answer: Telophase. Nuclear envelopes reform and chromosomes begin to decondense.

Flashcard 95: What enzyme complex triggers sister chromatid separation at anaphase?

Answer: APC/C activates separase to cleave cohesin. Controls anaphase onset by removing chromatid cohesion.

Flashcard 96: What enzyme complex triggers sister chromatid separation at anaphase?

Answer: APC/C activates separase to cleave cohesin. Controls anaphase onset by removing chromatid cohesion.

Flashcard 97: What phase follows prophase in mitosis?

Answer: Metaphase. Chromosomes align at the cell center after condensing.

Flashcard 98: What occurs during the M phase of the cell cycle?

Answer: Mitosis and cytokinesis. Nuclear division followed by cytoplasm division.

Flashcard 99: Which spindle microtubules push poles apart by overlapping at the cell center?

Answer: Nonkinetochore (polar) microtubules. Elongate spindle by sliding past each other.

Flashcard 100: What process follows telophase in the cell cycle?

Answer: Cytokinesis. The process that physically divides the cell into two.