[BIO 110 LEC] 2.1 Cell Division.pdf

UNIT II. Cell Division LU1 BIO 110 LEC – DE VERA – AY 2024-2025 EUCHROMATIN The portion of chromosome TOPIC OVERVIEW that is extended except...

UNIT II. Cell Division LU1 BIO 110 LEC – DE VERA – AY 2024-2025 EUCHROMATIN The portion of chromosome TOPIC OVERVIEW that is extended except during cell division. These A. THE CELL CYCLE are transcribed into RNA a. Interphase b. M-Phase HETERO- The portion of chromatin i. Mitosis CHROMATIN that is permanently ii. Cytokinesis condensed. It is not B. MEIOSIS transcribed into RNA. Most a. Meiosis 1 centromere regions are heterochromatic HOMOLOGUES Homologous VOCABULARY OF CELL DIVISION chromosomes. One of a pair of chromosomes that BINARY A form of asexual carry the same genes FISSION reproduction where an organism duplicates its KINETOCHORE Protein bound to the genetic material and then centromere and attached divides into two parts, with to microtubules during each new organism having mitosis. It links each one copy of DNA. It is the chromatid to the spindle main method of apparatus reproduction for prokaryotic organisms MICROTUBULE A hollow cylinder composed of tubulin CENTROMERE The region of a subunits that assists in cell chromosome composed of shape, cell movement. It about 220 nucleotides of also helps separate highly repeating DNA chromosomes during sequences called satellite mitosis DNA. This part joins two sister chromatids during MITOSIS Form of nuclear division mitosis and is where that results in the forming kinetochores attach of two genetically identical daughter nuclei CHROMATID One of the two copies of chromosome NUCLEOSOME A subunit of the chromatin where the DNA is wound CHROMATIN A mixture of DNA and around a cluster of histone proteins that compose proteins eukaryotic chromosomes CHROMOSOME The structure in cells that contain genes. For eukaryotes, it consists of a linear DNA molecule CYTOKINESIS The division of cytoplasm after nuclear division PAGE 1 UPCM CLASS OF 2031 BIO 110 LEC TRANS TEAM; PENULLAR, ROSARIO  UNIT II. Cell Division LU1 BIO 110 LEC – DE VERA – AY 2024-2025 A THE CELL CYCLE nucleus with nucleoli; forms two centrosomes; The process of cell growth and division Importance: Duration of the Cell Cycle ○ Growth of the organism A particular human cell might More cells = growth undergo one division in 24 hours. ○ Asexual Reproduction for unicellular organisms G1 5-6 hours; S phase 10-12 hours; G2 4-6 hours; M ○ Regeneration and repair phase < 1 hour A2 M-PHASE Shortest phase in the cell cycle Mitosis and cytokinesis are separate phases, but may happen simultaneously at some phase in mitosis MITOSIS DOES NOT INCLUDE CYTOKINESIS A2.1 MITOSIS PROPHASE Nuclear membrane disintegrates Nucleolus disappears Coiling of chromatin fibers → condensing of chromosomes → visible chromosomes A1 INTERPHASE Mitotic spindle forms between centrioles Kinetochore matures and attaches to Accounts for about 90% of the cycle spindle Cell growth by producing proteins and cytoplasmic organelles ○ e.g., mitochondria & endoplasmic reticulum Chromosomes are NOT VISIBLE even in G2 phase PHASES OF INTERPHASE G1 PHASE Cell Growth S PHASE Duplication of chromosomes G2 PHASE Continued cell growth in preparation for cell division (nuclear envelope encloses PAGE 2 UPCM CLASS OF 2031 BIO 110 LEC TRANS TEAM; PENULLAR, ROSARIO  UNIT II. Cell Division LU1 BIO 110 LEC – DE VERA – AY 2024-2025 PROMETAPHASE The nuclear envelope fragments. Microtubules from centrosome invade the nuclear area. More condensation of chromosomes Formation of kinetochore at the centromere of each chromatid. Some microtubules attach to the kinetochores → “kinetochore microtubules,”. Nonkinetochore microtubules lengthens the cell. ANAPHASE Shortest stage of mitosis Begins when the cohesin proteins are cleaved → separates sister chromatids The two new daughter chromosomes move to the opposite ends of the cell as kinetochore microtubules shorten. ○ Yields complete and identical sets of chromosomes The cell elongates as the nonkinetochore microtubules lengthen for cytokinesis METAPHASE The centrosomes are at opposite poles of the cell. The chromosomes, specifically their centromeres, are aligned at the metaphase plate. The kinetochores of the sister chromatids are attached to kinetochore microtubules from opposite poles. TELOPHASE Formation of nuclei in the daughter cells from the nuclear fragments of the parent cell Nucleoli reappear. PAGE 3 UPCM CLASS OF 2031 BIO 110 LEC TRANS TEAM; PENULLAR, ROSARIO  UNIT II. Cell Division LU1 BIO 110 LEC – DE VERA – AY 2024-2025 The chromosomes become less condensed. Any remaining spindle microtubules are depolymerized. PLANT CELLS Formation of cell plate → separates the plant cells in two B MEIOSIS Reduces chromosome number from diploid to haploid Each haploid product has a complete set of chromosomes Promotes genetic diversity A2.2 CYTOKINESIS Examples (if necessary) Occurs by a process known as cleavage B1 MEIOSIS 1 Period of Cytokinesis PROPHASE 1 The division of the cytoplasm is usually Nuclear envelope disintegrates well under way by late telophase, so Chromosomes condense the two daughter cells appear shortly Spindle fibers appear after the end of mitosis. PROMETAPHASE 1 Nuclear envelope disintegrates Chromosomes condense CYTOKINESIS Spindle fibers appear ANIMAL CELLS Formation of cleavage Additional Information furrow* → pinches cell in Include any extra details in this section, two such as additional instructions or *shallow groove in the cell surface insights provided by your professor, near the old metaphase plate along with any other relevant information that may enhance your notes. PAGE 4 UPCM CLASS OF 2031 BIO 110 LEC TRANS TEAM; PENULLAR, ROSARIO