AP Biology Chapter 9 Group Notes: The Cell Cycle and Cellular Reproduction PDF

AP Bio Chapter 09 Group Notes: The Cell Cycle and Cellular Reproduction LINK TO GOOGLE SLIDE PRESENTATION Team Members: HSR&T (Highly Suggested Reading and Thinking) 4.3, 4.4, 4.7 This is independent work that you can do as a (GSN) team/individually - either way, ALL members of the team should do...

AP Bio Chapter 09 Group Notes: The Cell Cycle and Cellular Reproduction LINK TO GOOGLE SLIDE PRESENTATION Team Members: HSR&T (Highly Suggested Reading and Thinking) 4.3, 4.4, 4.7 This is independent work that you can do as a (GSN) team/individually - either way, ALL members of the team should do the reading/thinking….you will be assessed over this information. Big Idea 3: Information Storage, Transmission, and Response ~ “The G1 Checkpoint” (p. 150) 1. Why do cells have to pass through the G1 checkpoint? ….What is evaluated?.... and what stage will they enter if they don’t? The G1 checkpoint ensures that conditions are right for making the commitment to divide by evaluating the meaning of growth signals and determining the availability of nutrients as well as assessing the integrity of DNA. 2. For Evaluating Growth Signals - (fill in the blanks and be sure to focus on the bigger picture of signal transduction) a. Signaling molecules like hormones may be sent from nearby cells or distant tissues to regulate the cell cycle and determine if the cell enters the G1 stage or S stage. b. Growth signals that promote cell division cause CDKs to add a phosphate group to the RB protein. c. The phosphorylated RB protein will then release its attached E2F protein which will then bind to DNA which activates certain genes whose products are needed to complete the cell cycle. d. Likewise, cells that are in the G0 phase can also be prompted to reenter the G1 stage and then S stage. 3. For Determining Nutrient Availability - how are the signals discussed above used to ensure cells do not move through the cell cycle if nutrients are not available? A cell ensures that nutrient levels are adequate before committing cell division. A phosphate group is removed from RB and does not release E2F, and the proteins needed to complete the cell cycle are not produced. 4. For Assessing DNA Integrity (fill in the blanks and be sure to focus on the bigger picture of verifying that information storage and transmission is accurate) a. In response to DNA damage, CDKs phosphorylate p53 which then will bind to DNA. Certain genes are then activated; and DNA repair proteins are produced. b. If the DNA damage can not be repaired, p53 levels continue to rise. If the damage is repaired the p53 levels fall and allow the cell to move forward in the cell cycle. 5. Describe two different benefits from researching the G1 checkpoint: It is currently an area of intense research because understanding this can hold many key possibilities of curing cancer and unleashing the power of normal, healthy cells to regenerate tissues. Nature of Science ~ “Reproductive and Therapeutic Cloning” (p. 157) 1. Differentiate between the objectives of reproductive and therapeutic cloning. Reproductive is cloning of adult animals and therapeutic cloning produces mature cells of various cell types rather than an individual organism. 2. Differentiate between the two types of therapeutic cloning. You can use adult stem cells or embryonic stem cells. 9.1 Cell Increase and Decrease 4.6-7 The Cell Cycle: from the moment the cell forms until its own - Cell cycle is lifetime of the cell division into two cells. - G0 is off-ramp: not dying, like retiring 1. Stages of Interphase (I): most of cell’s life spent in this - Cancer is cells going out of control stage, apx. 90% instead of going to G0 a. G1 - cell grows larger, organelles increase (G0 - Cells rely on communication & stage branches off here for muscles and control nerves, will no longer enter mitotic stage) - Paralysis is cells going to G0 early - S stage for synthesis (of DNA) b. S - DNA synthesis/duplication of chromosomes, 1. Unwind and unzip DNA = replication Separate into 2 chains of nucleotides c. G2 - proteins are synthesized 2. Complementary nucleotides =  AP Biology - Chapter 09 - Cell Cycle and Cellular Reproduction 2 Building sister chromatids 2. Mitotic Stage (M): - Semi-conservative a. Mitosis - nuclear division, two nuclei contain the replication exact same DNA as the parent cell 3. Twist up and join together by b. Cytokinesis - division of the cytoplasm, forming centromere two cells 3. Control of the Cell cycle: a. Basics i. controlled by external (growth factor) and internal signals (DNA damage) ii. Signals: a molecule that either stimulates or inhibits a metabolic event b. Checkpoints: three, G1, G2 and M i. G1 checkpoint appears to be the most critical, the cell will remain in G0 if it does not receive the signal to move onto the S stage. ii. Cell checked to see if DNA is damaged - Cyclins = Tickets or can’t be repaired or chromosomes 1. G1 Checkpoint not lining up correctly - Critical iii. apoptosis if they don’t pass one of the - Cell stays in G0 if it doesn’t get the checkpoints signal to move onto S c. Cyclins: proteins that control the cell cycle - - Cell is checked for DNA damage, must be present (build up) to move into the S inability to be repaired, or for and M stages chromosomes not lining up correctly d. Kinases (enzymes): Activated by cyclins (called Cdks - cyclin dependent kinases), when cyclins - CHECK THAT MITOSIS WAS DONE deteriorate, kinases become inactive CORRECTLY e. Example: cyclin binds to kinase producing - G2 = Check that DNA was replicated / enough of the product MPF (mitosis promoting synthesized properly factor or maturation promoting factor) which will - Checking for damage that can’t be push the cell through the G2 phase and into the repaired M phase. Later in the M phase, cyclins begin to - Check the cell can move onto mitosis be destroyed to stop the M phase. - M = Check that chromosomes are properly aligned - Ras is like stepping on the gas - Signal transduction pathway - Ras stuck on = Keep growing = Cancer Apoptosis: - P53 = Tumor suppressor genes  AP Biology - Chapter 09 - Cell Cycle and Cellular Reproduction 3 1. Defined: programmed cell death 2. A balance between mitosis and apoptosis helps maintain the normal cell level of somatic cells - prevents tumor from developing 3. Death caused by: a. enzymes called caspases that are normally kept in check by inhibitors b. internal or external signals can deactivate inhibitors 9.2 The Eukaryotic Chromosome 4.6, 6.1 Basics: 1. Chromosome Structure: a. Following S and G2 stages of interphase, cells prepare for mitosis b. Chromatin (DNA and proteins) start to coil up into two rod shapes joined by a centromere (two copies of the DNA, one for each cell) c. Organization: DNA winds around histone protein spools that form a nucleosome. The nucleosomes then begin coiling until condensed into a chromosome 2. Chromosome Appearance: a. During Interphase: solid nucleus, DNA unwound, replicates during S stage but no noticeable shape under microscope b. Mitotic Stage: chromosomes form and appear as doubled, sister chromatids, held together by a centromere 9.3 Mitosis and Cytokinesis 4.6 Basics: - Diploid = 2 1. Numbers: - Haploid = Half a. Diploid number, 2n, when you have 2 full sets of chromosomes - one set from each parent, as found in somatic cells b. Haploid number, n, when you have only one set of chromosomes - a mixture of parental chromosomes. Sperm or egg - called gametes Mitosis: generates two identical cells - Stage 1: chromosomes are 1. Prophase: condensing (prophase)  AP Biology - Chapter 09 - Cell Cycle and Cellular Reproduction 4 a. chromosomes (consisting of two sister - Prep chromatids) become visible - Stage 2: getting organized meeting b. nuclear envelope and nucleolus disappear in the middle (metaphase) c. centrosomes with spindle fibers move to poles, - Stage 3: separate / away microtubules extend from the centrosomes (anaphase) forming an aster - Stage 4: to two nuclei to form two cells (telophase) 2. Metaphase: - Example of mitosis = baby growing a. chromosomes meet in the middle into toddler b. Microtubule complex is referred to as the - When cells replicate, they make spindle copies of the parent cells 3. Anaphase: a. sister chromatids pulled/pushed apart, motor molecules, kinesin and dynein assist in this sliding process. b. Cells begin the process that leads to the destruction of cyclin which inactivates the Cdk molecules thus bringing an end to mitosis. 4. Telophase: a. nuclear membranes with a nucleolus reform, sister chromatids (now called chromosomes) unwind Cytokinesis: division of cell, forming 2 cells 1. In animal cells: cleavage furrow indents the plasma membrane 2. In plant cells: cell walls do not permit furrowing, instead cell plate forms which will become cell wall. Function: - Somatic is a body cell 1. Mitosis by somatic cells is for growth and repair. Stem cells, red bone marrow, can continue to replicate and form new cells 2. Meristematic tissue in plants can always do mitosis  AP Biology - Chapter 09 - Cell Cycle and Cellular Reproduction 5 - Heterochromatin shows dark staining because the DNA is being condensed since it is not active 9.4 The Cell Cycle and Cancer 4.7 Introduction: 1. Normal cell division: a. Density-dependent inhibition (contact inhibition): the phenomenon in which crowded cells stop dividing b. Anchorage dependency: normal cells must be attached to a substratum, like the extracellular matrix of a tissue, to divide 2. Neoplasm: abnormal growth of cells: a. Tumor: mass of abnormal cells within otherwise normal tissue b. Benign tumor: not cancerous, encapsulated, has not invaded adjacent tissue c. Malignant tumor: has or has the ability to spread d. Metastasis: cells separate from a malignant tumor and enter blood or lymph vessels and travel to other parts of the body 3. Cancer: a. cellular growth disorder that results from the mutations of genes that regulate the cell cycle b. loss of control 4. Carcinogenesis: development of cancer which is usually gradual and can take decades  AP Biology - Chapter 09 - Cell Cycle and Cellular Reproduction 6 Characteristics of Cancer Cells: 1. Lack differentiation - not specialized, seem immortal 2. Abnormal nuclei - enlarged, or abnormal number or deleted or duplicated portions of chromosomes (gene amplification) 3. Do not undergo apoptosis - even though abnormal cells or aged DNA. Normally cells enter the cell cycle about 50 times 4. Form tumors: do not display density-dependent inhibition 5. Undergo metastasis and angiogenesis: a. metastasis: new tumors form which are distance from the primary tumor b. angiogenesis: when tumor cells acquire additional mutations that allow them to direct the growth of new blood vessels into the tumor Origin of Cancer: usually due to mutations 1. Proto-oncogenes code for proteins that PROMOTE the cells cycle and prevent apoptosis -like a gas pedal on a car a. stimulatory pathway, when they mutate they become oncogenes or cancer-causing genes b. over 40 potential oncogenes. Examples are: i. ras gene family: associated with lung, colon, pancreatic cancers, leukemia/lymphoma and thyroid cancers. Approximately 30% of all cancers ii. Other examples of proto-oncogenes include WNT, MYC, ERK, and TRK. (do not memorize these, just a list) 2. Tumor suppressor genes: code for proteins that INHIBIT the cell cycle and promote apoptosis - like brakes on a car a. prevent the cell cycle when DNA is damaged or promote apoptosis b. Estimated that there are over 1000 TSG: i. RB: stops the cell from dividing too fast 1. involved in retinoblastoma, breast, prostate, bladder and small-cell lung carcinoma. 2. Deletion of the RB1 gene occurs in 91%–100% of small cell lung cancer (SCLC), 72.2% of  AP Biology - Chapter 09 - Cell Cycle and Cellular Reproduction 7 basal-like and 61.5% of luminal B breast cancers, 63% of osteosarcomas, 30% of non–small cell lung cancer (NSCLC), and 17%–33% of castration-resistant prostate cancer (do not memorize, just here to share the significance of this gene) ii. P53: makes a protein that checks for damage in the Cells DNA 1. Estimated that over ½ human cancers due to abnormal or deleted p53 gene 2. p53: suppresses cancer in 4 different ways: (do not memorize) a. Activates p21 gene that binds with Cdks giving time for DNA repair b. Activates a group of miRNAs (microRNA) which inhibit the cell cycle. c. Turns on genes directly involved in DNA repair d. Activates “suicide genes”/caspases to stimulate apoptosis iii. BRCA1 and BRCA2 are tumor suppressor genes 3. Other origins: a. DNA repair systems fail b. Telomeres, ends of chromosomes, not shortening with each replication due to telomerase, an enzyme that keeps the chromosomes at a constant length. Cells with short chromosomes tend to stop dividing so these do not stop. 9.5 Prokaryote Cell Division 4.6, 6.1 Prokaryotic Chromosome: 1. A single circular chromosome located in nucleoid region with just a few associated proteins - 1000x the length of the cell 2. Asexual reproduction: offspring are genetically identical to the parent Binary Fission: chromosome replicates first, then cell  AP Biology - Chapter 09 - Cell Cycle and Cellular Reproduction 8 elongates and builds a cell membrane and wall between the two identical chromosomes. Comparing Prokaryotes and Eukaryotes: Organism Cell Division Function Prokaryotes: bacteria and Binary Fission Asexual reproduction archaea Eukaryotes: Protists and some Mitosis and cytokinesis Asexual reproduction fungi Eukaryotes: other fungi, plants, Mitosis and cytokinesis Development, growth and repair and animals