Cell Cycle & Mitosis - Biological Concepts PDF

LESSON 2- CELLULAR REPRODUCTION (MITOSIS) Cell Division — process by which a cell divides into 2 new cells Why do cells need to divide? 1.Living things grow by producing more cells, NOT because each cell increases in size 2.Repair of damaged tissue 3.If cell gets too big, it canno...

LESSON 2- CELLULAR REPRODUCTION (MITOSIS) Cell Division — process by which a cell divides into 2 new cells Why do cells need to divide? 1.Living things grow by producing more cells, NOT because each cell increases in size 2.Repair of damaged tissue 3.If cell gets too big, it cannot get enough nutrients into the cell  https:// www.youtube.com/watch?v=7NM-UW FHG18&t=99s CELL CYCLE AND MITOSIS https:// www.youtube.com/watch?v=p0TfJaoT i9U&t=55s MEIOSIS  The original cell is called the parent cell; 2 new cells are called daughter cells Before cell division occurs , the cell replicates (copies) all of its DNA, so each daughter cell gets complete set of genetic information from parent cell Each daughter cell is exactly like the parent cell – same kind and number of chromosomes as the original cell 2 Daught er Cells Parent  Many organisms, especially unicellular organisms, reproduce by means of cell division – called asexual reproduction – Ex: bacteria DNA DNA is located in the nucleus and controls all cell activities including cell division Long and thread-like DNA in a non-dividing cell is called chromatin Doubled, coiled, short DNA in a dividing cell is called chromosome Consists of 2 parts: chromatid and centromere o 2 identical “sister” chromatids attached at an area in the middle called a centromere o When cells divide, “sister” chromatids separate and 1 goes to each new cell Chromatin to chromosomes illustration: Chromatin Coils up into Duplicat chromosomes es itself Why does DNA need to change from chromatin to More efficient division chromosome?  Every organism has its own specific number of chromosomes Examples: Human = 46 chromosomes or 23 pairs Dog = 78 chromosomes or 39 pairs Goldfish = 94 chromosomes or 47 pairs Lettuce = 18 chromosomes or 9 pairs  Examples: Human = 46 chromosomes Human skin cell = 46 chromosomes Human heart cell = 46 chromosomes Human muscle cell = 46 chromosomes Fruit fly = 8 chromosomes Fruit fly skin cell = 8 chromosomes Fruit fly heart cell = 8 chromosomes Fruit fly muscle cell The cell cycle is the series of events through which cells pass to divide and create two identical daughter cells. http://upload.wikimedia.org/wikipedia/commons/thumb/7/71/Diagram_of_mitosis.svg  THE CELL CYCLE (the life of a cell) 1.6.U4 Interphase is a very active phase of the cell cycle with many processes occurring in the nucleus and cytoplasm. Interphase consists of the parts of the cell cycle that don’t involve cell division. G1 (Gap 1) S Increase the volume of (Synthesis) cytoplasm DNA Organelles produced replicated Proteins synthesised n.b. cells can also be said to be in G0 (Gap 0). This is a ‘resting’ phase where G2 (Gap 2) the cell has left the Increase the volume cycle and has stopped dividing. Cells in G0 still of cytoplasm carry out all their normal Organelles produced functions. Proteins synthesised http://gardeningstudio.com/wp 1.6.U4 Interphase is a very active phase of the cell cycle with many processes occurring in the nucleus and cytoplasm. Interph Cells spend the majority of their time in interphase. It is a very active phase of the ase cycle. This when the cell carries out it’s normal functions Metabolic reactions (e.g. respiration to produce Mr ATP) are necessary for the life of the cell Protein synthesis - proteins and enzymes are P necessary to allow cell grow Organelles numbers are increased to first O support the enlarged cell DNA is replicated to ensure a second copy is D available to enable mitosis http://botit.botany.wisc.edu 1.6.U1 Mitosis is division of the nucleus into two genetically identical daughter nuclei. Get the terminology right centrioles organise spindle microtubules centromere is the part of a Spindle chromosome that microtubul links sister es (also chromatids referred to as spindle fibres) In animal cells two centrioles are held by a protein mass referred to as a centrosome Sister chromatids are It is easy to misuse the terms chromatid duplicated chromosomes and chromosome. It is even easier to attached by a centromere confuse the terms centromere, centriole After anaphase when the sister and centrosome due to their similar chromatids separate they should spelling. Keep the terms clear in your then be referred to as mind to avoid losing marks. chromosomes http://commons.wikimedia.org/wiki/File:Chromoso me.svg http://commons.wikimedia.org/wiki/Mitosis#mediaviewer/ STAGES OF THE CELL CYCLE: Remember: IPMATC MITOSIS is after Interphase… Mitosis is considered “Cell Division” Four Phases are a part of Mitosis: Prophase Metaphase Anaphase Telophase Cytokinesis is after Mitosis – division of the nucleus into 2 nuclei, each with the same number of chromosomes Mitosis occurs in all the somatic (body) cells So each new daughter cell has Why does mitosis occur? nucleus with a complete set of chromosomes  4 phases of nuclear division (mitosis), directed by the cell’s DNA (PMAT) Prophas Metaphase— e (Middle) Anaphase— (Apart) Anaphase— Telophase— (Apart) (Two)  1.6.U1 Mitosis is division of the nucleus into two genetically identical daughter nuclei. Propha DNA supercoils* chromatin condenses se and becomes sister chromatids, which are visible under a light microscope The centrosomes move to opposite poles of the cell and spindle fibres begin to form The between them nuclear membrane is broken down and disappears http://www.microscopy-uk.org.uk/mag/artnov04macro/ percoling is dealt with in more detail by 1.6.U2 jronionroot.html http://commons.wikimedia.org/wiki/Mitosis#mediaviewer/File:Mitosis_cells_sequence.svg 1.6.U1 Mitosis is division of the nucleus into two genetically identical daughter nuclei. Metaphas e Spindle fibers from each of the two centrosomes attach to the centromere of each pair of sister chromatids Contraction of the microtubule spindle fibres cause the sister chromatids to line up along the centre of the cell. http://www.microscopy-uk.org.uk/mag/artnov04macro/ jronionroot.html http://commons.wikimedia.org/wiki/Mitosis#mediaviewer/File:Mitosis_cells_sequence.svg 1.6.U1 Mitosis is division of the nucleus into two genetically identical daughter nuclei. Continued contraction of the Anaphase microtubule spindle fibres cause the separation of the sister chromatids The chromatids are now referred to as chromosomes Chromosomes move to the opposite poles of the cell http://www.microscopy-uk.org.uk/mag/artnov04macro/ jronionroot.html http://commons.wikimedia.org/wiki/Mitosis#mediaviewer/File:Mitosis_cells_sequence.svg 1.6.U1 Mitosis is division of the nucleus into two genetically identical daughter nuclei. The chromosomes uncoil Telophas de-condense to chromatin (and are no e Chromosomes longer visible under a light microscope). arrive at the poles. Microtubule spindle fibers disappear New nuclear membranes reform around each set of Now cytokinesis chromosomes begins! http://www.microscopy-uk.org.uk/mag/artnov04macro/ jronionroot.html http://commons.wikimedia.org/wiki/Mitosis#mediaviewer/File:Mitosis_cells_sequence.svg 1.6.U3 Cytokinesis occurs after mitosis and is different in plant and animal cells. Urrrmm, we have only divided the nucleus … what about the rest of the cell? http://www.haroldsmithlab.com/images/pg_HeLa_cell_division.jpg 1.6.U3 Cytokinesis occurs after mitosis and is different in plant and animal cells. mitosis is the division of the nucleus whereas cytokinesis is the division of the cytoplasm The division and hence of the thecell into two daughter cells cell (cytokinesis) occurs concurrently with telophase. Though mitosis is similar for animal and plant cells cytokinesis is very different. http://glencoe.mheducation.com http://www.haroldsmithlab.com/images/pg_HeLa_cell_division.jpg /sites/9834092339/student_view0/c hapter10/animation_-_ http://wwwprod.biochem.wisc.edu/biochem/faculty/bednarek/images/ figure_color.gif http://commons.wikimedia.org/wiki/Mitosis#mediaviewer/File:Mitosis_cells_sequence.svg cytokinesis.html 1.6.U3 Cytokinesis occurs after mitosis and is different in plant and animal cells. Animal cells Plant cells A ring of contractile protein During telophase, membrane-enclosed (microfilaments) immediately inside vesicles derived from the Golgi apparatus the plasma membrane at the equator migrate to the centre of the cell. pulls the plasma membrane inward. Vesicles fuse to form tubular structures. The inward pull on the plasma The tubular structures merge (with the membrane produces the addition of more vesicles) to form two layers characteristic cleavage furrow. of plasma membrane (i.e. the cell plate) When the cleavage furrow reaches The cell plate continues to develop until it the centre of the cells it is pinched connects with the existing cell’s plasma apart to form two daughter cells. membrane. This completes the division of the cytoplasm and the formation of two daughter cells. Vesicles deposit, by exocytosis, pectins and other substances in the lumen between the daughter cells to form the middle lamella (‘gluing’ the cells together) Both daughter cell secrete cellulose to form http://www.haroldsmithlab.com/images/pg_HeLa_cell_division.jpg their new adjoining cell walls. http://upload.wikimedia.org/wikibooks/en/thumb/9/98/Cyto.png/800px-Cyto.png Summary: Cell Cycle Interphase Mitosis (PMAT) Cytokinesis When cells become old or damaged, they die and are replaced with new 1.6.U5 Cyclins are involved in the control of the cell cycle. Cyclins are a family of proteins that control the progression of cells through the cell cycle 1 Cells cannot progress to the 2 next stage of the cell cycle Cyclins bind to enzymes unless the specific cyclin called cyclin-dependent reaches it threshold. kinases 3 These kinases then become active and attach phosphate groups to other proteins in the cell. 4 The attachment of phosphate triggers the other proteins to become active and carry out tasks (specific to one of the phases of the cell cycle). http://upload.wikimedia.org/wikipedia 1.6.U5 Cyclins are involved in the control of the cell cycle. Progression through parts of the cell cycle are affected in various ways by specific cyclins prepares the activates DNA promotes the cell for DNA replication assembly of the replication in inside the mitotic spindle and Triggers cells S phase. nucleus in S other tasks in the to move from phase. cytoplasm to G0 to G1 and prepare for from G1 into S mitosis. phase. http://upload.wikimedia.org/wikipedia 1.6.U6 Mutagens, oncogenes and metastasis are involved in the development of primary and secondary tumours. Tumours are abnormal growth of tissue that develop at any stage of life in any part of the body. A cancer is a malignant tumour and is named after the part of the body where the cancer (primary tumour) first develops. Use the links to find out: most common types of cancer what causes cancer and associated risk factors how cancer can be treated http://youtu.be/8BJ8_5Gyhg8 http://www.e-learningforkids.org /health/lesson/cancer/ What causes cancer? http://www.cancerresearchuk.org/cancer-info/ cancerandresearch /all-about-cancer/what-is-cancer/ http://www.cancer.gov/cancertopics /types/commoncancers 1.6.U6 Mutagens, oncogenes and metastasis are involved in the development of primary and secondary tumours. A mutation is a change in an organisms genetic code. A mutation/change in the base sequence of a certain genes can result in cancer. Mutagens are agents that cause gene mutations. Not all mutations result in cancers, but anything that causes a mutation has the potential to cause a cancer. Mutagens can be: chemicals that cause mutations are referred to as carcinogens high energy radiation such as X-rays short-wave ultraviolet light http://en.wikipedia.org/wiki/Oncogene#mediaviewer/ 1.6.U6 Mutagens, oncogenes and metastasis are involved in the development of primary and secondary tumours. If a mutation occurs in an oncogenes it can become cancerous. In normal cells oncogenes control of the cell cycle and cell division. mutation in a oncogene malfunction in the control of the cell cycle uncontrolled cell division tumour formation http://en.wikipedia.org/wiki/Oncogene#mediaviewer/ 1.6.U6 Mutagens, oncogenes and metastasis are involved in the development of primary and secondary tumours. Several mutations must occur in the same cell for it to become a tumour causing cell. The probability of this happening in a single cell is extremely small. Factors (other than exposure to mutagens) that increase the probability of tumour development include: The vast number of cells in a human body – the greater the number of cells the greater the chance of a mutation. The longer a life span the greater the chance of a mutation. http://en.wikipedia.org/wiki/Oncogene#mediaviewer/ 1.6.U6 Mutagens, oncogenes and metastasis are involved in the development of primary and secondary tumours. The development of a primary tumours (cancers) have been outlined. Below is how a primary tumor can become a secondary tumour. A primary tumor is a malignant tumor growing at the site where the abnormal growth first occurred. Cancerous cells can detach from the primary tumour. Metastasis is the movement of cells from a primary tumour to set up secondary tumours in other parts of the body. Some cancerous cells gain the ability to penetrate the walls of lymph or blood vessels and hence circulate around the The circulating cancerous cells body invade tissues at a different locations and develop, by uncontrolled cell division, into a secondary tumours. http://en.wikipedia.org/wiki/Neoplasm#mediaviewer  Cancer is not just one disease, but many diseases – over 100 different types of cancers  Chromosome Important Phase Appearance & Events Location DNA replication, cell DNA copies itself; grows and replicates Interphase chromatin organelles Nuclear envelope Chromosomes coil up disappears, spindle Prophase fibers form Chromosomes line up Spindle fibers Metaphase in the middle connect to chromosomes Chromosome copies Spindle fibers pull divide and move chromosome copies Anaphase apart apart to opposite Nuclear poles envelopes Chromosomes uncoil reform, 2 new nuclei Telophase back into chromatin are formed, spindle fibers disappear Division of the rest of Chromat the cell: cytoplasm Cytokinesis in and organelles