BIOL 1140 1st Edition Lecture 9Outline of Last LectureI. Discovering the Structure of DNAII. Watson and Crick: The Double HelixIII. Structure of DNAIV. Transcription and Translation OverviewV. RNA StructureVI. 3 Types of RNAVII. Transcription ContinuedVIII. Editing of mRNAIX. Genetic CodeOutline of Current Lecture I. The Cell CycleII. InterphaseIII. Mitotic PhaseIV. ReplicationV. Sister ChromatidsVI. Homologous Chromosomes VII. Cell ReproductionVIII. MitosisCurrent LectureI. The Cell Cyclea. Body cells have a life cycle called cell cycle. Lasts 18-24 hoursb. Consists ofi. Interphase1. Long period when cells do not divide (95%)ii. Mitotic Phase1. Short period when cells divide (5%)c. Some cells divide indefinitely, but slow as we aged. Some cells stop dividing and stay in interphase, temporarily or permanentlyII. Interphasea. 3 partsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.i. G11. Primary growth phase, cells do their normal functions (including protein production) ii. S (synthesis)1. Synthesis of DNA for next cell division (DNA replication)iii. G21. Final growth phase before cell division, more normal activates, duplication of organellesIII. Mitotic Phasea. Mitosisi. Nuclear division1. Duplicated DNA is distributed between two daughter nuclei b. Cytokinesisi. Division of cytoplasmii. Two new daughter cells are formediii. Occurs near end of mitosis IV. Replicationa. Duplication of all DNA in the celli. DNA strands uncoil and 'unzip'ii. Each single strand serves as a template for the creation of a new complementary strandiii. DNA nucleotides are positioned and linked by DNAA polymeraseiv. Precise base pairing (A-T, C-G) assures that an exact copy is made v. Each duplicated DNA molecule consists of one 'new' strand and one 'old' strandof DNA, called semi-conservative b. Mutationsi. Alterations of mistakes in the DNA codeii. Occur most frequently during DNA replication iii. Causes1. Chemical and physical forces (UV light, X-rays)iv. Some mutations are repaired by repair enzymesv. Effects of mutations1. Silent mutations have no effect2. Many mutations are harmful, may result in cell death or cancer3. Some mutations are beneficial or neutral V. Sister Chromatidsa. Chromosomes before replication consist of one DNA moleculeb. Chromosomes after replication consist of two duplicated DNA moleculesi. The duplicate daughter chromosomes are called sister chromatidsii. Sister chromatids are held together by VI. Homologous Chromosomesa. Homologs are pairs of chromosomes that are the same size and shape (usually) and contain the same genesb. One of each pair is inherited from your mother, the other from dadc. Humans have 23 pairs (or 46 total) chromosomes VII. Cell reproductiona. Two types of cell reproduction processesi. Mitosis1. Makes 2 new, genetically identical body cells2. For growth and development, and repair of lost, dead, or damaged cells 3. Generates new diploid cells (cells with 2 copies of each chromosome)ii. Meiosis1. Makes 4 genetically different sex cells (gametes- eggs or sperm)2. For reproduction3. Generates haploid gametes (cells with 1 copy of each chromosome) VIII. Mitosisa. Nuclear division (mitosis) followed by cytoplasmic division (cytokinesis)b. Sequence of phasesi. Prophaseii. Metaphaseiii. Anaphaseiv.Telophase