Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Cellular Reproduction The Cell Cycle & Mitosis 9- Ch.9 – Cellular Reproduction 9.1 – Cellular Growth 9- Ch.9 – Cellular Reproduction Genetic Material Some key terms… Genome – All of the cell’s DNA/inheritable traits Chromosomes – Smaller packages of DNA molecules Somatic Cells – Body cells which have a full set of chromosomes (2n) Gametes – Reproductive cells which have ½ the number of chromosomes (n) Chromatin – DNA and protein molecules (histones) 9.1 – Cellular Growth 9- Ch.9 – Cellular Reproduction 9.1 – Cellular Growth Cells duplicate their genetic material before they divide, ensuring that each daughter cell receives an exact copy of DNA 9- Ch.9 – Cellular Reproduction 9.1 – Cellular Growth Cell Cycle (The life cycle of a cell) Broken into 2 parts Interphase Mitosis Period when the cell grows, carries out its cellular functions and replicates DNA in preparation for cellular division Period when the nucleus & nuclear material divides. Cytokinesis occurs near the end of mitosis. It is the dividing of the cytoplasm. 9- Ch.9 – Cellular Reproduction 9.1 – Cellular Growth Cell Cycle (The life cycle of a cell) Broken into 2 parts Interphase Mitosis Period when the cell grows, carries out its cellular functions and replicates DNA in preparation for cellular division Period when the nucleus & nuclear material divides. Cytokinesis occurs near the end of mitosis. It is the dividing of the cytoplasm. 9- Ch.9 – Cellular Reproduction Interphase G1 (1st Gap) Phase – Growth & normal cell function 9.1 – Cellular Growth S (Synthesis) Phase – DNA is copied G2 (2nd Gap) Phase – Cell prepares for division of its nucleus •Protein for microtubules is synthesized •Additional cell growth •Cell “checks” the DNA to be sure that it was copied correctly so that mitosis can begin Mitosis Can be broken Division of the down into 5 nuclear phases material Mitosis Rap 9- Ch.9 – Cellular Reproduction 9.2 – Mitosis & Cytokinesis PROPHASE •Chromatin condenses •Nucleolus disappears •Spindle fibers begin to form •Centrioles separate 9- Ch.9 – Cellular Reproduction 9.2 – Mitosis & Cytokinesis PROMETAPHASE •Nuclear envelope fragments •Centrioles near the poles •Chromosomes begin to attach to the spindle fibers at the kinectochore (a protein located at the centromere) 9- Ch.9 – Cellular Reproduction 9.2 – Mitosis & Cytokinesis METAPHASE •Longest stage of mitosis (~20min.) •Duplicated chromosomes align at the metaphase plate (equator of the cell) 9- Ch.9 – Cellular Reproduction 9.2 – Mitosis & Cytokinesis ANAPHASE •Shortest stage of mitosis (~2min.) •Sister chromatids are separated and are pulled to the poles •The cell elongates •By the end of anaphase each pole has one copy of each chromosome 9- Ch.9 – Cellular Reproduction 9.2 – Mitosis & Cytokinesis TELOPHASE •Nuclear membranes form •Nucleoli reappear •The chromosomes become less condensed (unwind) 9- Ch.9 – Cellular Reproduction 9.2 – Mitosis & Cytokinesis Mitosis Rap Mitosis in Plant Cells 9- Ch.9 – Cellular Reproduction CYTOKINESIS 9.2 – Mitosis & Cytokinesis Starts during telophase Mitosis Rap 9- Ch.9 – Cellular Reproduction 9.3 – Cell Cycle Regulation Cell Cycle Regulation G1 checkpoint •Ensures… •Enough nutrients •Large enough to divide •If “go” signal is given cell will divide •If go signal is not given cell will enter the G0 (nondividing) phase M checkpoint •Ensures… •All sister chromatids are connected properly at the kinetochore Checkpoint Animation G2 checkpoint •Ensures… •DNA was copied correctly in the S-phase 9- Ch.9 – Cellular Reproduction 9.3 – Cell Cycle Regulation The Cell Cycle Clock Controlled by cyclins and cyclin-dependent kinases Proteins that build up and then degrade at certain points in the cell cycle (Cdk) Enzymes the cyclins bind to in order to initiate the next the next phase in the cell cycle 9- Ch.9 – Cellular Reproduction 9.3 – Cell Cycle Regulation The Cell Cycle Clock Internal and external factors trigger cell division Internal Growth factors - proteins released by certain cells that stimulate other cells to divide. (Growth hormones in mammals) Cell reproduction stimulation animation External Space and available nutrients An anchor point (for most animal cells) 9- Ch.9 – Cellular Reproduction 9.3 – Cell Cycle Regulation What happens when cells lose the ability to control the cell cycle? Cancer… Cells can become cancerous when a mutation occurs spontaneously or from an outside factor (carcinogen) As cells multiply a predictable series of genetic changes occur 9- Ch.9 – Cellular Reproduction 9.3 – Cell Cycle Regulation These changes ultimately lead to the mutation of two types of genes that control the cell cycle… Oncogenes and tumor-suppressor genes 10 billion to 100 billion cells. Usually takes decades to cause a problem in humans Benign Tumor – does not invade surrounding tissue Malignant Tumor – invades surrounding tissue and spreads via circulatory or lymph system