BIOL 1107 1nd EditionExam # 4 Study Guide Lectures: 25-30Each section below includes material from the lecture, homework and textbook.Chapter 12: The Cell Cycle (12.1 and 12.2)Unicellular organisms- division of one cell reproduces entire organismMulticellular organism- depend on cell division for: development from fertilized cell, growth andrepair- Cell division is an integral part of cell cycle, life of a cell from formation to its own divisionCell division- Ability of organisms to produce more of their own kind best distinguishes living things from nonliving matter- Continuity of life is based on reproduction of cells, or cell division- Most cell division results in daughter cells with identical genetic info, DNA- Exception is meiosis, a special type of division that can produce sperm and egg cellsCellular Organization of Genetic Material- All DNA in cell constitutes cell’s genome- a genome can consist of a single DNA molecule (common in prokaryotic cells) or a numberof DNA molecules (common in eukaryotic cells)- DNA molecules in a cell are packages into chromosomes Eukaryotic Cell Division - In preparation for cell division, DNA is replicated and chromosomes condense - Each duplicated chromosome has two sister chromatids (joined copies of the original chromosome), which separate during cell division - Centromere- narrow “waist” of the duplicated chromosome, where the two chromatids are most closely attached - Eukaryotic chromosomes consist of chromatin, a complex of DNA and protein that condenses during cell division - Every eukaryotic species has a characteristic number of chromosomes in each cell nucleus - Somatic cells- (nonreproductive cells) have two sets of chromosomes - Gametes- (reproductive cells: sperm and eggs) have half as many chromosomes as somatic cells - During cell division, two sister chromatids of each duplicated chromosomes separate and move into nuclei- Once separate, the chromatids are called chromosomesCell Cycle- It consists of: mitotic phase (M-phase) and interphaseo Mitotic (M) phase- mitosis and cytokinesiso Interphase- cell growth and copying of chromosomes in preparation for cell division- Eukaryotic cell division consists ofo Mitosis- division of genetic material in nucleuso Cytokinesis- division of cytoplasm- Gametes are produced by a variation of cell division called meiosis- Meiosis yields nonidentical daughter cells that have only one set of chromosomes, half as many as the parent cell - Interphase (90% of cell cycle) can be divided into subphases: G1 phase (“first gap”), S phase (“synthesis”), G2 phase (“second gap”)- Cell grows during all three phases, but chromosomes are duplicated only during S phaseMitotic Phase- 1882- German anatomist Walther Flemming developed dyes to observe chromosomes during mitosis and cytokinesis - Five phases of mitosis: prophase, Prometaphase, metaphase, anaphase, telophase - Cytokinesis overlaps the latter stages of mitosis- Mitotic spindle- a structure made of microtubules that controls chromosome movement during mitosis- In animal cells, assembly of spindle microtubules begins in the centromere, the microtubule organizing center - The centrosome replicates during interphase, forming two centrosomes that migrate to opposite ends of the cell during prophase and prometaphase - Aster- a radial array of short microtubules; it extends from each centrosome - The spindle includes centrosomes, the spindle microtubules and the asters - During prometaphase, some spindle microtubules attach to kinetochores of chromosomes and begin to move the chromosomes - Kinetochores- protein complexes associated w/ centromeres - At metaphase, the chromosome are all lined up at the metaphase plate, an imaginary structure at the midway point between the spindle’s two poles - In anaphase, sister chromatids separate and move along the kinetochore microtubules toward opposite ends of the cell - The microtubules shorten by depolymerizing at their kinetochore ends- Nonkinetochore microtubules from opposite poles overlap and push against each other, elongating the cell- In telophase, genetically identical daughter nuclei form at opposite ends of the cell- Cytokinesis begins during anaphase or telophase and the spindle eventually disassembles - In animal cells, cytokinesis occurs by a process known as cleavage, forming a cleavage furrow - In plant cells, a cell plate forms during cytokinesisEvolution of Mitosis- Since prokaryotes evolved before eukaryotes, mitosis probably evolved from binary fission- Certain protists exhibit types of cell division that seem intermediate between binary fission and mitosis - Prokaryotes (bacteria and archaea) reproduce by a type of cell division called binary fission- In binary fission, chromosome replicates (beginning at origin of replication) and the two daughter chromosomes actively move apart - Plasma membrane pinches inward, diving the cell into twoChapter 13: Meiosis and Sexual Life Cycles Living organisms are distinguished by their ability to reproduce their own kindSome Definitions- Genetics- scientific study of heredity and variation- Heredity- transmission of traits from one generation to the next - Variation- demonstrated by the differences in appearance that offspring show from parents and siblings - Genes- units of heredity; made up of segments of DNAo They are passed to next generation via reproductive cells called gametes (sperm and eggs) o Each gene has a specific location called a locus on a certain chromosomeo Most DNA is packaged into chromosomesAsexual v. Sexual Reproduction- Asexual reproduction- a single individual passes genes to its offspring without the fusion of gametes - Clone- group of genetically identical individuals from the same parent- Sexual reproduction- two parents give rise to offspring that have unique combinations of genes inherited from the two parents - Offspring acquire genes from parents by inheriting chromosomes - In a literal sense, children do not inherit particular physical traits from their parents- It is genes that are actually inherited - Life cycle- generation-to-generation sequence of stages in the reproductive history of an organism- Sex chromosomes- determine the sex of the individual, are called X and Yo Human females have a homologous pair of X chromosomes (XX)o Human males have one X and one Y chromosome - Remaining 22 pairs of chromosomes are called autosomes Sets of Chromosomes in Human Cells- human somatic cells (any cell other