The Cell Cycle 2020 PDF

THE CELL CYCLE CELLS GROW, AND WE ARE GOING TO LEARN ABOUT THEIR GROWTH CYCLE THE CELL CYCLE – A CIRCULAR TIMELINE INTERPHASE – G1 PHASE, S PHASE, AND G2 PHASE ◼ Interphase ◼ Basically 75% of a cell’s lifetime is spent in interphase ◼ G1, S, G2 THE PHASES OF INTERPHASE G1, S, AND G2 G1 PHAS...

THE CELL CYCLE CELLS GROW, AND WE ARE GOING TO LEARN ABOUT THEIR GROWTH CYCLE THE CELL CYCLE – A CIRCULAR TIMELINE INTERPHASE – G1 PHASE, S PHASE, AND G2 PHASE ◼ Interphase ◼ Basically 75% of a cell’s lifetime is spent in interphase ◼ G1, S, G2 THE PHASES OF INTERPHASE G1, S, AND G2 G1 PHASE - THE BEGINNING OF A CELL’S LIFE (RIGHT AFTER DIVISION) ◼ G1 Phase ◼ G stands for “gap” or “growth” ◼ This is a young cell ◼ It is focused on growing, making organelles, normal cell functions, making proteins, increasing cell size ◼ G1 Checkpoint - checks for the following before moving on to S Phase (if failed, it will ender G0 (a resting state)) ◼ Nutrients ◼ Growth Factors ◼ DNA Damage S PHASE - DNA Replication ◼ A cell will only enter S Phase if it successfully passes the G1 Checkpoint ◼ (DNA Replication) S Phase ◼ S stands for “synthesis” ◼ Synthesis of DNA ◼ The cell’s DNA is doubled to prepare for cell division, later ◼ Human cells have 23 pairs of chromosomes (46 total). So in S Phase, the cell will now have two copies of all the 23 pairs (92 total) G2 PHASE ◼ G2 Phase ◼ G stands for “gap” or “growth” ◼ The cell is preparing for cell division ◼ The cell is making all the parts needed for cell division ◼ There is a G2 Checkpoint to make sure the cell is ready for division. It checks for: ◼ Cell size ◼ Proper DNA replication LET’S REVIEW INTERPHASE INTERPHASE – 75% OF A CELL’S LIFETIME ◼ G1 Phase ◼ Gap/growth where the cell is doing normal cell things: growing, making organelles and proteins, etc. ◼ Checkpoint! Has the cell grown enough? Is the DNA in good shape? If not, a cell will NOT go into S Phase, but instead go into a resting state, G0 ◼ S Phase ◼ The cell’s DNA is synthesized/replicated/duplicated/doubled in preparation for cell division (because if we make another cell, that cell will need its own copy of DNA) ◼ G2 Phase ◼ Final preparations before cell division ◼ Checkpoint! Is the cell big enough? Did the DNA replicate properly? If not, the cell is not allowed to divide READY TO DIVIDE!! DURING MITOSIS, THE DNA WILL CHANGE SHAPE ◼ DNA is usually in the form of chromatin – loose and stringy – so that it can be read ◼ During mitosis, it will be wound up like an extension cord into an X shape called chromosomes ◼ Chromosomes are easier to move around because they are condensed. Chromatin is like a bowl of spaghetti and that is hard to separate CHROMOSOMES ◼ Chromosomes are the shape of DNA during most of mitosis ◼ They have “parts” that we will be referring to ◼ Chromatids (sister chromatids) ◼ Each side of the “X” ◼ The sides are identical, because the DNA was copied during S Phase of Interphase (one side is a copy of the other side) so we call them “sisters” ◼ Centromere ◼ The very middle or “waist” of the X ◼ This is where the spindle fibers will attach to the chromosome to move them around M PHASE – CELL DIVISION ◼ M stands for “mitotic” ◼ First, the cell will divide its parts and DNA towards the two sides of the cell (mitosis) ◼ Then, the cell will split in half (cytokinesis) ◼ Creating two identical cells, each with their own copy of DNA! THE PHASES OF M PHASE MITOSIS AND CYTOKINESIS MITOSIS – NUCLEAR DIVISION ◼ Four phases – separates the doubled DNA and organelles ◼ Prophase ◼ (sometimes there is a fifth phase mentioned in between prophase and metaphase: prometaphase or late prophase) ◼ Metaphase P M A ◼ Anaphase ◼ Telophase MITOSIS – PROPHASE ◼ Prophase = Prepare ◼ The membrane around the nucleus dissolves, leaving the DNA exposed ◼ DNA is normally in the shape of chromatin (loose and stringy) but it condenses into chromosomes (the little X-shaped form) so that moving it around will be easier ◼ The cell parts needed to move the DNA around (the mitotic spindle) are made MITOSIS – METAPHASE ◼ Metaphase = Middle ◼ The DNA, in the shape of chromosomes, are lined up in the middle by the spindle fibers attached to their middles ◼ Checkpoint! The cell will not move onto Anaphase unless the DNA is correctly lined up in the middle, along the metaphase plate MITOSIS – ANAPHASE ◼ Anaphase = Away/Apart ◼ The spindle fibers pull the sister chromatids apart from each other, towards opposite ends of the cell MITOSIS – TELOPHASE ◼ Telophase = Two ◼ A new nuclear membrane forms around the two groups of DNA ◼ We have finished moving the DNA, so we can unwind it back into the form of chromatin (no more chromosome form) ◼ The organelles have been separated on either side of the cell LET’S REVIEW MITOSIS PMAT CYTOKINESIS THE SECOND STAGE OF M PHASE CYTOKINESIS ◼ The two sides of the cell are split, forming two cells, each with their own nucleus and DNA ◼ The place where they are being pinched is called the “cleavage furrow” ◼ These two new cells are called “daughter cells” ◼ Then the daughter cells enter into Interphase (starting with G1) LET’S REVIEW M PHASE MITOSIS AND CYTOKINESIS M PHASE Mitosis Cytokinesis ◼ Prophase ◼ The cell is split into two daughter cells, ◼ DNA is condensed each with their own nucleus of DNA ◼ Mitotic spindle is formed ◼ These cells are identical ◼ Metaphase ◼ Chromosomes line up in the middle ◼ Anaphase ◼ Sister chromatids are pulled apart ◼ Telophase ◼ DNA unwinds and new nuclei form LET’S REVIEW THE CELL CYCLE INTERPHASE AND MITOTIC PHASE  Interphase Mitotic Phase Cytokinesi G1 S G2 Mitosis s Prophas Metapha Anaphas Telophas e se e e ORDER OF THE STAGES AFTER DIVISION: ◼ Interphase, Mitotic Phase ◼ Interphase, Mitosis, Cytokinesis ◼ Interphase, Prophase, Metaphase, Anaphase, Telophase, Cytokinesis ◼ G1, S, G2, Mitotic Phase ◼ G1, S, G2, Mitosis, Cytokinesis ◼ G1, S, G2, Prophase, Metaphase, Anaphase, Telophase, Cytokinesis ◼ All are correct! It just depends on what level of detail you describe. VOCAB TO REMEMBER (BESIDES ALL THE PHASES): ◼ Chromatin (loose form of DNA) ◼ Chromosome (compacted form of DNA) ◼ Centromere (the middle/waist of the chromosome) ◼ Chromatid (each side of the chromosome) ◼ Centrioles (on either end of the cell where the spindle fibers are attached; the mitotic spindle) ◼ Spindle Fibers (what connect to and move the chromosomes) ◼ Checkpoints (times during the cell’s life where it is checked before moving on) ◼ G0 (resting phase of a cell that will not divide) ◼ Cleavage Furrow (where the daughter cells are being pinched apart) THE CELL CYCLE INTERPHASE MITOTIC PHASE MITOTIC PHASE (MITOSIS AND CYTOKINESIS) THE CELL CYCLE REVIEW QUESTIONS IN WHAT STAGE OF THE CELL CYCLE IS THE DNA REPLICATED? ◼Mitosis ◼G0 ◼Prophase ◼S Phase PUT THE STAGES OF MITOSIS IN THIS EXAMPLE OF PLANT CELLS IN ORDER. WHAT STAGE IS MISSING? ◼ PQR; Anaphase ◼ RPQ; Prophase ◼ RPQ; Anaphase ◼ QRP; Prophase ◼ DNA normally exists in the form of chromatin, loose and messy. However, when ◼Helix preparing for cell division, ◼Gene the DNA is coiled many times and wrapped around small ◼Nucleotide proteins to organize it. Which term best describes the form ◼Chromosome of DNA that is neatly coiled and wrapped for processes like mitosis? WHAT MUST OCCUR DURING S PHASE OF THE CELL CYCLE SO THAT THE TWO RESULTING DAUGHTER CELLS CAN BE PRODUCED DURING THE MITOTIC PHASE? ◼The cell membrane must be expanded ◼The chromosomes must be joined ◼The DNA must be replicated ◼The cytoplasm must be separated LABEL THE CELL CYCLE E. iv. iii. D ii. 2 1 i. ◼ During which phase of the ◼Prophase cell cycle do the chromosomes line up in ◼Metaphase the equator, or middle, of ◼Anaphase the cell with each pair of chromatids attached at the ◼Telophase centromere by spindle fibers? ◼Cytokinesis ◼ During which stage of ◼Prophase Mitosis are the sister ◼Metaphase chromatids pulled away from each other by the ◼Anaphase spindle fibers, going ◼Telophase towards opposite ends of the cell? ◼Cytokinesis  ◼Prophase ◼ During which stage of Mitosis does the nuclear ◼Metaphase envelope begin to dissolve, ◼Anaphase spindle fibers form, and DNA is condensed into ◼Telophase chromosomes? ◼Cytokinesis ◼ During which stage of the ◼Prophase cell cycle is the cytoplasm ◼Metaphase and cell membrane/cell wall (depending on the ◼Anaphase type of cell) split ◼Telophase completely in half, forming two new cells? ◼Cytokinesis ADDITIONAL RESOURCES ◼Please always feel free to look up YouTube videos about the topics that we talk about in class! ◼There are several cell cycle and mitosis videos to watch that can help you!