BIO 101 1st EditionExam #3 Study Guide Chapters 12-16Lecture 16 (October 29)The Cell CycleKnow the cell cycle phases: interphase (G1, S, G2), and mitosis (prophase, prometaphase, metaphase, anaphase, and telophase). Which is the shortest, interphaseor mitosis?Interphase- approximately 90% of cell cycle is spent in interphaseG1- cell grows and gets biggerS- DNA replicates, cell continues to growG2- cell gets ready for mitosis and cytokinesis- makes special proteins needed for that Mitosis- division of the nucleusProphase- 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 informationChromatin- mass of dispersed DNA plus proteins found in between periods of cell divisionNuclear envelope- breaks down during prometaphase, and reforms during telophaseCentromere- where sister chromatids are connectedKinetochore- protein complexes located at the centromere; where the spindle apparatus attaches to replicated chromosomesSpindle- serves to move chromosomes around; disappears during telophaseReplicated 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 easilySister chromatid- each DNA molecule in a replicated chromosomeMetaphase 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 interphaseG1- cell grows and gets biggerS- DNA replicates, cell continues to growBIO 101 1st EditionG2- cell gets ready for mitosis and cytokinesis- makes special proteins needed for that Mitosis- division of the nucleusProphase- 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 EditionWhat 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 andgo ahead signals are given. Molecular sensors at checkpoints- check to see if all the right things have happenedMolecular brakes at checkpoints- slow things down if something is wrongApoptosis- 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 EditionBe able to draw a cell in metaphase and label sister chromatids, kinetochore and spindle. Prometaphase MetaphaseHow 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, notat 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 CyclesWhat 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 geneHomologous chromosomes- the pair of chromosomes in diploid cells; also known as homologsHaploid 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