BIOL 1100Exam # 3 Study Guide Chapters: 12-15Chapter 12-Two types of cell division-meiosis-mitosis-cytokinesis: the cytoplasm of the cell divides into two distinct daughter cells; occurs immediately after mitosis-in plants form a cell plate-in animals, fungi and slime mold forms a cleavage furrow-no cytokinesis in bacteria they divide via fission-the cell cycle-M phase-interphase (G1, S, G2, phases)-meiosis-gametes (eggs/sperm)-daughter cells have half the amount of genetic material as the parent cell-mitosis-somatic cells-daughter cells are genetically identical to the parent cell-Three key events in multicellular eukaryotes: growth, wound repair, asexual reproduction-the division of replicated chromosomes-formation of 2 daughter nuclei-identical chromosomes and genes-is complete when 2 independent nuclei have formed-mitosis (M phase)-prophase-prometaphase-metaphase-anaphase-telophase-a gene is a section of DNA that encodes a specific RNA and therefore a specific protein-chromosomes contain a single long double helix of DNA and are wrapped around proteins called histones-chromosome and replication-every species has a characteristic number of chromosomes (humans have 46)-how do chromosomes move during mitosis?-chromatin is DNA associated with histone proteins-Mitosis-promoting factor (MPF)-present in the cytoplasm of M-phase-induces mitosis in eukaryotes-subunits-kinase: Cdk, active only when bound to the cyclin subunit, at which 2 sites does Cdkbecome phosphorylated?-cyclin: concentration increases during interphase, when concentrations are high more MPF is active and proteins are phosphorylated initiating mitosis-Cell-cycle checkpoints-late in G1-p53-between the G2 and M phases-during M phase-Cancer: all cancers arise from cells in which cell-cycle checkpoints have failed-Two types of defects-tumor forms when one or more cells in a multicellular organism begin to divide in an uncontrolled fashion-benign tumors: noninvasive, noncancerous-malignant tumors: invasive, cancerous, spread throughout the body via blood or lymph-metastasis: when cancer cells detach from the original tumor and invade other tissues-social control; cells respond to signals from other cells. Based on growth factors; small proteins released by cells that stimulate division in other cells-Rb protein enforces the G1 checkpoint and excessive growth factors can override the inhibitory effects of RbChapter 13-during sexual reproduction a sperm and an egg unite to form a new individual, this process is called fertilization-meiosis is nuclear division that precedes the formation of gametes, usually accompanied by cytokinesis (division of cytoplasm into two distinct cells)-meiosis reduces chromosome number by half-in diploid organisms the products of meiosis are haploid gametes or daughter cells-before meiosis begins, each chromosome in the diploid parent cell is replicated, when replication is complete, each chromosome has two identical sister chromatids that are attached at the centromere-Meiosis I-Early prophase I-late prophase I-metaphase I-anaphase I-telophase I-Meiosis II-prophase II-metaphase II-anaphase II-telophase II-key difference between meiosis and mitosis is that homologs pair in mitosis-karyotype is the number and types of chromosomes present in an organism-sex chromosomes determine the sex of the individual, all other chromosomes are autosomes-humans have 46 chromosomes (1 pair of sex chromosomes, 22 pairs of autosomes)-chromosomes of the same type are called homologous chromosomes or homologs; homologs carry the same genes in the same locations but each one may contain different alleles- The haploid number, n, indicates the number of distinct types of chromosomes present; organisms with just one of each type of chromosome-diploid: organisms with two of each type of chromosome (2n); have one paternal chromosome and one maternal chromosome-polyploid: organisms with three or more versions of each type of chromosome-a cell’s ploidy indicates the number of each type of chromosome present-where does crossing over occur?-offspring produced during asexual reproduction are clones that are genetically identical to one another-offspring produced by sexual reproduction, the fusion of gametes, have a chromosome makeupdifferent from that of one another and from that of either parent-genetic variation in sexual reproduction results from: independent assortment, crossing over, and random combination of egg and sperm-in many sexually reproducing species gametes from different individuals combine to form offspring, a process called outcrossing-how do mistakes in meiosis occur?-nondisjunction-aneuploid zygotes, those with too few or too many chromosomes, typically do not survive to produce viable offspring-Two gametes that have an extra copy of a chromosome causes a condition called trisomy, ex. down syndrome (caused by an extra copy of chromosome 21)-sexual reproduction is common among multicellular organisms, organisms in most lineages of the tree of life undergoes asexual reproduction-asexually reproducing organisms should reproduce faster, they can outcompete similar organisms that invest in sexual reproduction; asexual reproduction is much more efficient than sexual reproduction because no males are produced-offspring that are genetically different from their parents (produced by sexual reproduction) are more likely to survive and produce offspring if the environment changes-offspring that are genetically identical to their parents (produced by asexual reproduction) are less likely to survive and produce offspring if the environment changesChapter 14-Gregor Mendel rules of inheritance experiments on garden peas-chromosome theory of inheritance: proposes that meiosis causes the patterns of inheritancethat Mendel observed-why offspring resemble their parents?-how transmission of traits occurs?Hypotheses-blending inheritance-inheritance of acquired characteristics-genetics is the branch of biology that focuses on inheritance-heredity: the transmission of traits from parents to their offspring-trait: any characteristic of an individual-self-fertilization: pollinating themselves, and cross-pollination: fertilize the female reproductive organs of flowers on different plants-an individual’s observable features comprise its phenotype-hybrids: mating two different pure lines that differed in one or more traits-parental generation-the offspring are the F1 (first filial) generation-offspring of F1 are the F2