Mitosis and Cancer (Chapter 6) PDF

Cell Division Do cells live forever? If not, how long do cells live for? If you were going to make a cell from another cell, what would...

Cell Division Do cells live forever? If not, how long do cells live for? If you were going to make a cell from another cell, what would you need to do? Mitosis and Cancer Chapter 6 Introduction to Cell Division Introduction to DNA Cells come from other cells Deoxyribonucleic acid (DNA): Growth primary information bearing Replacement molecule of life. Two chains of nucleotides linked together to form a double helix Three main steps 1. DNA replication Nucleotide: nitrogenous base attached to a five-carbon sugar 2. Mitosis: division of parent cell’s (ribose) and a phosphate molecule nucleus and chromosomes Complementary base pairs 3. Cytokinesis: division of cytoplasm Adenine and Thymine into two daughter cells Guanine and Cytosine  DNA and Chromosomes Chromosomes Gene: a specific section of Genome: complete collection of an DNA that contains information organism's genetic information necessary to produce a protein Histones Genome Karyotype: pictorial arrangement of Chromatin: linear strand of chromosomes DNA wrapped around histones Gene Histones: proteins that keep DNA Humans have 23 pairs of chromosomes from getting tangled or 46 total chromosomes. Would you expect a potato to have Chromosome: a compact greater or fewer chromosomes than strand of DNA humans? Comparison of Chromosome Number Variation in Genome Size Haploid: cells with a single copy of each chromosome Size of an organism’s Gametes: sex cell genome is not related Egg and sperm to the complexity of the organism Diploid: cells with two copies of each chromosome, one maternal and one paternal Somatic cells: cells forming the body of the organism Potato 24 78  Percentage of Coding DNA The Cell Cycle Many organisms have large portions of DNA that do not code for proteins and have no known purpose Only 2% of human DNA codes for proteins DNA Replication DNA Replication 1. DNA of unduplicated 1. DNA to be replicated chromosome unwinds 2. New DNA nucleotides join 2. Strands separate with each individual DNA strand to form a new double helix 3. Each strand now serves as a template for the synthesis of a separate DNA molecule as free nucleotides base-pair 3. Duplicated DNA results in with complementary nucleotides on the existing strands. duplicated chromosome Sister chromatids Order of bases encodes 4. This results in two Centromere Information for protein identical strands of DNA. production. Chromosomes Before and After Replication DNA Replication Helicase: enzyme that unwinds DNA separating it into two complementary strands DNA Polymerase: enzyme that creates the complementary strand by adding new DNA nucleotides to the template strand Check Your Understanding Check Your Understanding A section of DNA that codes for a specific protein is known as True or False: Gametes are the only cells within the human body ___________. that have two sets of chromosomes a. chromatin True or False: Most of the DNA found in humans codes for b. a genome proteins c. a chromosome d. a gene True or False: Cytosine always binds with Guanine e. a nucleotide  Check Your Understanding The Cell Cycle Which of the following are responsible for unwinding the DNA to form two complementary strands? a. Histones b. Helicase c. DNA polymerase d. Chromatin e. Ribosomes An Overview of Mitosis Mitosis and Cytokinesis Mitosis and Cytokinesis Interphase Daughter cells G1 S PHASE AND G2 contain the same complement of chromosomes as the parent cell. Prophase Metaphase Anaphase Telophase Cytokinesis Sister End of Beginning chromatids Interphase Parent cell: Parent cell: of 4 unreplicated 4 replicated Interphase chromosomes During mitosis, sister chromatids chromosomes separate. Two daughter cells are formed by cytokinesis.  Mitosis Mitosis and Cytokinesis Separation: Sister chromatids are Exit from mitosis: moved to opposite poles in Chromosomes unravel; One cell becomes two: the cell, each chromatid nuclear envelopes form The cell membrane pinches These two cells now enter now becoming a Cleavage furrow together completely full-fledged chromosome. the G1 phase of interphase. begins to form. Interphase Mitosis: Prophase Interphase (three parts) Chromatin condenses to form G1 (gap 1 phase) = growth and chromosomes normal functions Nuclear membrane and Nucleolus S (synthesis phase) = DNA disappear (chromosome) replication Chromosomes G2 (gap 2 phase) = growth and Two chromatids with centromere normal functions continue Centrosomes develop Mitotic spindles form Microtubules  Mitosis: Metaphase Mitosis: Anaphase Centrosomes at opposite poles Duplicated chromosomes (sister chromatids) are pulled apart by spindle fibers Microtubules attach to sister chromatids One full set of chromosomes goes to one end of the cell and one set Chromosomes line up on metaphase goes to the other end plate Mitosis: Telophase and Cytokinesis Cell Division in Plants Reverse of Prophase Nuclear envelopes reform around chromosomes Cytokinesis Animal cells Cleavage Furrow Plant cells 1. Membrane-lined vesicles 2.Vesicles fuse together, 3.The newly formed plasma membrane accumulate near the metaphase forming a cell plate that and cell wall fuse with the parent Cell Plate plate.The vesicles contain grows toward the parent plasma membrane and cell wall, precursors to the cell wall. cell wall. forming two distinct daughter cells.  Check Your Understanding Check Your Understanding DNA replication and cell growth occurs during ____________. The separation of sister chromatids occurs during __________. a. Prophase a. Prophase b. Metaphase b. Telophase c. Anaphase c. Anaphase d. Cytokinesis d. Metaphase e. Interphase e. Cytokinesis Cancer Cells Cancer Cells Proto-oncogenes: Cancer = out of control cell ○ Genes that promote cell division, "gas pedal." Mutations can cause them to stay "on," leading to multiplication, which invade uncontrolled division. nearby tissues or other parts Tumor suppressor genes: of the body, destroying ○ Genes inhibit abnormal growth. A mutated gene like P53 can stop working, allowing unchecked working tissues division. Multiple mutations: ○ At least two mutations are usually needed for a cell to become cancerous.  Characteristics of Cancer Cells Characteristics of Cancer Cells No contact inhibition Indefinite cell division Disorganized arrangement Cancer cells can divide an unlimited number of times and they divide faster than most other cells in body Characteristics of Cancer Cells Characteristics of Cancer Cells T-cell deactivation Membrane proteins Cancer cells have membrane have reduced adhesive Cancer cell proteins that turn off some properties immune system cells called T-cells, Malignant tumors which prevents the T-cells from Cancer membrane protein Antigen finding and killing the cancer cells T-cell receptor T-cell receptor T-cell  Cancerous Tumors Cancer Treatments Benign Malignant If cancer cells are your own cells that have gone rogue, then Malignant tumor cells Normal cells divide and spread to how can cancer treatments target just the cancerous cells? adjacent tissues and to distant tissues through lymphatic vessels and blood vessels Work with the people around you to think of ways that Lymph vessel scientists can use the characteristics of cancer cells to fight Blood vessel cancer. Benign tumor cells may continue to divide, but are not New tumor that has invasive (they do not formed in distant spread from tumor) tissue by metastasis Cancer Treatments Cancer Treatments Chemotherapy: treatment using Radiation therapy: ionizing drugs that either kill cancer cells radiation used to damaged the DNA or keep cancer cells from dividing of cancer cells which prevents them Drugs designed to attack fast from replicating. dividing cell Ionizing radiation is radiation caused by Prevent DNA replication high energy particles that cause Prevent transcription electrons to detach from atoms or Inhibit microtubule formation molecules. Radiation can be administer externally or Alter mitochondrial DNA internally replication and transcription  Cancer Treatments Cancer Treatments Surgery: surgeons remove Immunotherapy: drugs that cancerous cells or tumors from contain protein inhibitors that the body. prevent the cancer proteins from Cryosurgery: extreme cold used to binding with the t-cell receptors, destroy cancerous tissue which allows t-cells to destroy Hyperthermia: extreme heat used cancer cells Protein inhibitors to damage and kill cancerous cells Lasers: precision lasers used to cut through cancerous tissue T-cell receptor Photo from National Geographic T-cell Cancer in our World