Cell Cycle & Genetic Material

• Chromatin is a DNA and protein complex that forms chromosomes within a cell's nucleus.
• Chromatid refers to one of two identical halves of a copied chromosome, prepared for cell division.
• Centromere denotes the constricted region of a chromosome joining sister chromatids and facilitating DNA division.
• Diploid cells contain two complete sets of chromosomes, with each parent contributing one chromosome per pair.
• Haploid cells possess a single set of chromosomes.
• Homologous chromosomes are chromosome pairs, one from each parent, similar in size, shape, and gene location.
• Tetrads are structures formed during meiosis when homologous chromosomes pair up.
• Karyotype shows a visual representation of all cell chromosomes, often during the metaphase stage of mitosis.
• Binary fission is a division process in single-celled organisms, resulting in two identical daughter cells.
• Apoptosis is a programmed cell death process that halts the cell cycle.

Cell Cycle Control

• Regulatory proteins act as signals, determining when a cell progresses to the next life cycle stage.
• Cell growth and division rates vary.
• Cancer develops from uncontrolled cell growth due to loss of control mechanisms.
• Tumors form when cells mass together.
  • Benign tumors are non-cancerous.
  • Malignant tumors are cancerous.

Cell Cycle Phases

• Interphase involves cell growth and development.
  • G1 (gap 1) phase: cell grows.
  • S (synthesis) phase: DNA is copied.
  • G2 (gap 2) phase: cell grows and organelles prepare for M phase.
• Mitosis occurs after interphase.
  • Prophase: nuclear envelope dissolves, centrioles extend spindle fibers.
  • Metaphase: chromosomes line up along the metaphase plate, spindle fibers attach.
  • Anaphase: sister chromatids separate and move to opposite poles, now considered individual chromosomes.
  • Telophase: two forming cells, chromosomes reach poles, cytoplasm divides, new nuclear membrane forms.
• Nuclear membrane: surrounds the nucleus of a cell that breaks down during mitosis, allowing the chromosomes to separate, and then reforms around each set of chromosomes to create two new nuclei in the daughter cells at the end of mitosis
• Spindle fiber: A protein structure, made of microtubules that forms during cell division and acts like a rope to pull apart duplicated chromosomes, ensuring each new cell gets an equal set of genetic material
• Centriole: A small cylindrical organelle found in animal cells that plays a crucial role in cell division by helping to organize the microtubules that pull apart chromosomes during the process, ensuring each new cell gets the correct number of chromosomes
• Sister chromatids: Two identical copies of a chromosome that are attached together at the centromere, formed during DNA replication before cell division, and separate during anaphase to ensure each new cell gets a complete set of chromosomes
• Daughter cells: A new cell that is created when a single cell divides through the process of mitosis, resulting in two genetically identical copies of the original cell
• Metaphase plate: An imaginary line located at the center of a dividing cell where all the chromosomes line up and get ready to separate during the metaphase stage
• Centromere: The constricted area on a chromosomes where the two sister chromatids are attached to each other, acting as a point where spindle fibers connect during cell division to pull the chromatids apart and distribute them evenly to new daughter cells
• cleavage furrow: An indentation in the cell membrane that appears during cytokinesis
• Cytokinesis is the final cell cycle stage.
  • In animal cells, the cleavage furrow separates the cell into two.
  • In plant cells, the cell plate divides the cell, eventually forming the cell wall.

Explore genetic material: chromatin, chromatids, centromeres, diploid, and haploid cells. Understand homologous chromosomes, tetrads, karyotypes, binary fission, and apoptosis.