Chapter 8 (Part 1): Mitosis Cell Division: Asexual Reproduction 8.1 – 8.2; Pgs Objective: I can describe the difference between how prokaryotic cells and eukaryotic cells divide. I can also describe different DNA: chromatin vs. chromosome.

Why do Cells Divide? (Mainly for) Reproduction (property of …): spread DNA (genes) to continue species But other specific reasons for different organisms Multicellular Organisms Replace cells that have died (heal wounds/injuries) To help organism grow (another prop. of life) Unicellular Organisms Reproduction (how else have more?)

Prokaryotes vs. Eukaryotes No Nucleus Simple cell cycle DNA in a loop: 1 single circular chromosome Division is called: Binary Fission Has Nucleus Complex Cell Cycle DNA in chromatin and/or chromosomeS Division is called: Mitosis + (Cytokinesis)

Binary Fission Mitosis

Mitosis: Overview Mitosis is made up of 4 phases Prophase = prepare Metaphase = middle Anaphase = split Telophase = wrap-up Eukaryotic Cell Cycle: Overview Interphase: growing stage (between cell division) G1 = Cell Grows (G = grow) S = DNA replicates (S = synthesize new DNA) G2 = Prepares for division (replicate organelles) Cytokinesis: cell splits (cytoplasm divides) = division of nucleus (karyokinesis)

Types of Reproduction DNA must be copied to have full set for each cell = replication (NOT reproduction) One cell forms two daughter cells For both binary fission and mitosis, daughter cells are genetically identical…so what type of reproduxn? Binary Fission and Mitosis = asexual reproduction Meiosis = cell division to prepare for sexual reproduction

Intro to DNA Details Type of nucleic acid (macromolecule) In the shape of a double helix (from a distance…) Sequence of nucleotides (nitrogenous base: ACTG) determines traits (hidden in code) ACTG = complementary base pairs (helps replicate) When DNA replicates, 50% old, 50% new (more later…) Sections of DNA = genes (hold specific info) Single DNA molecule can hold 140 million nucleotides (5 centimeters in a straight line) Nucleus is about 1 micrometer (10,000x smaller)

Packaging DNA Chromatin = DNA wrapped up with proteins Chromosome = chromatin further condensed and wound into a structure Looks like a rod or an “X” (butterfly) 1 chromosome made of 1 DNA molecule

Chromosome Coiling DNA wraps around proteins called histones Group of 8 histones w/ DNA = nucleosome Nucleosomes coil up into a solenoid This is what chromatin is made out of

Chromosome Coiling cont’d Solenoid can loop around scaffold protein Forms width of chromosome

Chromatin vs. Chromosome You know the difference, but why does cell change DNA: chromatin  chromosome? Hint: Happens for mitosis Chromosomes easier to move and divide evenly so both cells have same DNA

Chromosome Parts Chromatid = “Half chrmsme.” Has full amount of DNA Sister chromatids identical 2 sister chromatids = doubled chromosome  Preparing for mitosis Centromere = center Connects sis. chromatids “Marker” to count chromosomes Telomere = edges (factor in aging)