General Biology I - Cell Cycle and M Phases PDF

Britannica.com Britannica.com ScienceNotes.org ScienceNotes.org  OBJECTIVES: 1.Learn about the cell cycle. 2.Develop an understanding why cell cycle occurs. 3.Accomplish the 10-item evaluation (GRADED). 4.Complete given activity at the end of the slide. 1 ST CLASS...

Britannica.com Britannica.com ScienceNotes.org ScienceNotes.org  OBJECTIVES: 1.Learn about the cell cycle. 2.Develop an understanding why cell cycle occurs. 3.Accomplish the 10-item evaluation (GRADED). 4.Complete given activity at the end of the slide. 1 ST CLASS ACTIVITY  => WHAT IS THIS CALLED? ETYOGZ ABBY OEDLDTR EGTARENE 2 nd CLASS ACTIVITY What can you say about Dua Lipa’s hair? The root of the hair is made up of protein cells and is nourished by blood from nearby blood vessels. As more cells are created, the hair grows out of the skin and reaches the surface. Sebaceous glands near the hair follicles produce oil, which nourishes the hair and skin Alternation of Generation Alternation of generations is a type of life cycle found in terrestrial plants and some algae in which subsequent generations of individuals alternate between haploid and diploid organisms. In general, the generations alternate between the sporophytes capable of creating spores and the gametophytes, capable of creating gametes.  A repeating I tis made up of different sequence of cellular phases, each has its own growth and division unique process or event Inorder to ensure the cell cycle regulation, critical points called ‘checkpoints’ must also be identified.  CELL CYCLE includes two phases 1. INTERPHASE G1 Phase S Phase G2 Phase 2. MITOTIC PHASE The G0 phase, also known as the resting phase, is the phase of the cell cycle during which a cell is neither dividing nor preparing to divide.  G1 Phase cell grows by producing more organelles and increasing the volume of the cytoplasm cell is active at the biochemical level cell is accumulating the building block of chromosomal DNA, associated proteins, and enough energt reserves for the replication of DNA in the next phase. G1 Checkpoint (Restriction Point) determines wether all conditions are favorable for cell division point at which cell irreversibly commits to the cell division process cell not meeting growth requirements will not progress into S phase S Phase (Synthesis) DNA replication occurs formation of identical DNA molecules centrosome is duplicated G2 Phase cell replenishes its energy stores and synthesizes proteins for chromosome manipulation. some organelles are duplicated cytoskeleton is dismantled to provide resources for the mitotic phase completion of final preparations for the mitotic phase  G2 Checkpoint prevents entry into the mitotic phase if certain conditions are not met like: complete replication of DNA No damaged DNA If such problems are detected, the cell cycle halts and the cell attempts to complete DNA replication or repair damanged DNA  M Checkpoint “SPINDLE CHECKPOINT” determines whether all the sister chromatids are correctly attached to the spindle microtubules occurs near the end of metaphase stage  Sister Chromosome Chromosome Chromatid condensed form of DNA s Chromatids duplicated chromosomes Chromatin DNA + PROTEIN condenses to form chromosome  Diploid Cell 2n=46 chromosomes (23 pairs of chromosome) Cell Cycle Mitosis Meiosis n=92 individual chromatids 2 Diploid Cell 4 Haploid Cell Fertilization Diploid Cell  four phases namely: type of cell prophase, metaphase, division that anaphase, and produces two telophase; genetically which is the followed identical daughter by the division of the cells cytoplasm known as ‘cytokinesis.’ Prophase Chromosomes condense Nucleolus disappears Separation of centrosomes Formation of mitotic spindle (structure that separates the duplicated chromosomes) Prometaphase Nuclear membrane breaks down Polar microtubulues push against each other, moving centrosomes apart Microtubulues attached at the centromere, specifically at the kinetochore (protein) Metaphase Chromosomes line up along the metaphase plate (imaginary plane) The spindle fibres attach to the chromosomes (at the centromere, kinetochore) Anaphase centromere splits, allowing sister chromatids to separate The kinetochore spindle fibers shorten.  Telophase begins once the chromosomes have completed separating and reached the opposite poles of the cell remains of the network of spindle fibers is dismantled nuclear envelope begins to form and the daughter chromosomes begin to decondense CYTOKINESIS CLEAVAGE FURROW final stage of the cell cycle can occur anywhere from Anaphase into Telephase once the chromosomes have separated cytoplasm of the cell begins to split and divides evenly in half Produces TWO DAUGHTER CELLS  type of cell division involving the Itis divided into two production of gametes. major phases: A diploid Meiosis Ior the cell tends to divide Reduction phase and twice in order to Meiosis IIor the produce four haploid Replication phase daughter cells.  Prophase I homologous chromosomes line up side by side which is a process known as SYNAPSIS DNA is exchanged between two nonsister chromatids of a homologous pair of chromosomes Metaphase I the homologous pairs of chromosomes align on either side of the equatorial plate spindle apparatus forms from opposite ends of the cell and attaches to the chromosomes spindle fibers are only able to make contact with the kinetochore on the sister chromatid that is facing outward in each chromosome pair Anaphase I attachment of spindle fibres are complete. The homologous chromosomes are pulled apart and move towards opposite ends of the cell Telophase I The chromosomes are now at opposite ends of the cell and begin to form two distinct chromosome clusters Cytokinesis Nuclear division begins, and the parent cell is divided in half, forming 2 daughter cells Prophase II chromosomes begin to recondense and spindle fibers begin to form once again spindle fibres attach to the kinetochore (in the centromere) of the sister chromatids. Metaphase II Each of the 23 chromosomes line up along the center of the cell at the metaphase plate Anaphase II centromere splits, freeing the sister chromatids from each other spindle fibers begin to shorten, pulling the newly- separated sister chromatids towards opposite ends of the cell. Telophase II nucleus forms around the bundle of chromosones remains of the network of spindle fibers is dismantled Cytokinesis cell division begins again in each of the two daughter cells, creating 4 daughter cells (haploid).