BIO 101 1st Edition Exam 3 Study Guide Chapters 12 16 Lecture 16 October 29 The Cell Cycle Know the cell cycle phases interphase G1 S G2 and mitosis prophase prometaphase metaphase anaphase and telophase Which is the shortest interphase or mitosis Interphase approximately 90 of cell cycle is spent in interphase G1 cell grows and gets bigger S DNA replicates cell continues to grow G2 cell gets ready for mitosis and cytokinesis makes special proteins needed for that Mitosis division of the nucleus Prophase replicated chromosomes condense nuclei break down spindle apparatus is formed Prometaphase nuclear envelope breaks down spindle apparatus attaches to replicated chromosomes at the kinetochore Metaphase replicated chromosomes line up single file in the center of the cell Anaphase sister chromatids separated and are pulled to opposite poles of the cell once the sister chromatids separate they are bona fide chromosomes Telophase chromosomes decondense spindle apparatus disappears nuclear envelope reforms Terms to know genome chromatin nuclear envelope centromere kinetochore spindle replicated chromosome sister chromatid metaphase plate Genome a cell s total genetic information Chromatin mass of dispersed DNA plus proteins found in between periods of cell division Nuclear envelope breaks down during prometaphase and reforms during telophase Centromere where sister chromatids are connected Kinetochore protein complexes located at the centromere where the spindle apparatus attaches to replicated chromosomes Spindle serves to move chromosomes around disappears during telophase Replicated chromosome when the DNA molecules replicate an exact copy is made the 2 copies remain held together along the length by proteins called cohesins and take on a condensed form become shorter and thicker and can be seen more easily Sister chromatid each DNA molecule in a replicated chromosome Metaphase plate the place of the spindle approximately equal from the two poles along which the chromosomes line up What happens in each phase of the cell cycle Interphase approximately 90 of cell cycle is spent in interphase G1 cell grows and gets bigger S DNA replicates cell continues to grow BIO 101 1st Edition G2 cell gets ready for mitosis and cytokinesis makes special proteins needed for that Mitosis division of the nucleus Prophase replicated chromosomes condense nuclei break down spindle apparatus is formed Prometaphase nuclear envelope breaks down spindle apparatus attaches to replicated chromosomes at the kinetochore Metaphase replicated chromosomes line up single file in the center of the cell Anaphase sister chromatids separated and are pulled to opposite poles of the cell once the sister chromatids separate they are bona fide chromosomes Telophase chromosomes decondense spindle apparatus disappears nuclear envelope reforms Cytokinesis division of the cytoplasm BIO 101 1st Edition What is cytokinesis It is the division of the cytoplasm In animal cells the cells are pinched apart and a cleavage furrow forms between 2 newly formed nuclei Microfilaments form a ring at cleavage furrow and tighten to pinch 2 cells apart In plant cells vesicles from golgi meet and fuse in center of cell It forms 2 new membranes within single cell wall and a new cell wall forms between 2 new membranes How is the cell cycle controlled What is G0 What happens at the G1 S checkpoint There are cell cycle control points called checkpoints points in cycle where stop and go ahead signals are given Molecular sensors at checkpoints check to see if all the right things have happened Molecular brakes at checkpoints slow things down if something is wrong Apoptosis cell suicide if cell cycle controls don t result in correction of a problem the cell may kill itself G0 is a non dividing state the cell enters if it decides not to divide exits the cell cycle At the G1 S checkpoint the cell determines if it is going to divide or NOT at this checkpoint based on signals from environment and also on internal signals If the cell passes the G1 S checkpoint then it is committed to divide Be able to draw a pie chart showing the stages of the cell cycle and the order in which they occur as well as the location of checkpoints Show the point in the cycle where the cell exits the cell cycle to enter the non dividing state G0 BIO 101 1st Edition Be able to draw a cell in metaphase and label sister chromatids kinetochore and spindle Prometaphase Metaphase How do cancer cells differ from normal cells with regard to cell cycle control Cancer cells mostly ignore or don t perceive cell cycle controls to stop dividing If they do stop dividing they often don t stop at the right place stopping randomly not at G1 S checkpoint Results in cancer cells having the wrong amount of DNA if they stop in middle of S phase Lecture 17 October 31 Meiosis and Sexual Life Cycles What are the two major kinds of reproduction and how do they differ from each other with regard to the offspring produced Asexual reproduction is where a single individual is the sole parent and passes all of its genetic information to the offspring It occurs by cell division and the offspring are genetically identical to the parent and to all other offspring of that parent Sexual reproduction is where two parents give rise to offspring with a unique combination of genes Sexually produced offspring differ genetically from their parents and from other offspring Terms to know gamete zygote chromosome homologous chromosomes Gamete sex cells or eggs and sperm Zygote a new baby formed from a female egg and a male sperm in fertilization Chromosome DNA molecule with associated proteins to help maintain structure and control the activity of the gene Homologous chromosomes the pair of chromosomes in diploid cells also known as homologs Haploid vs Diploid There are twice as many chromosomes in diploid cells 2N body cells as in haploid 1N gamete cells This is because chromosomes in diploid cells come in pairs each chromosome has a partner What is meiosis What is the purpose of meiosis What kind of cell undergoes meiosis Meiosis is a special type of cell division that produces haploid 1N cells occurring in two stages meiosis I and meiosis II The purpose is to make gametes out of germline cells In humans germline cells are only found in the ovaries and the testes BIO 101 1st Edition Given the diploid 2N or haploid 1N number of an organism be able to draw a cell of that organism in metaphase of mitosis meiosis I and