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Cell division – process by which cells produce new cells 3 Types of Cell Division: Prokaryotes (Bacteria) Eukaryotes (Animals, Plants, Fungi, Protists) Binary Fission Mitosis Meiosis What you’ll learn about in this unit: Why and how cells divide The three types of cell division: Binary Fission, Mitosis and Meiosis What regulates or controls when cells start and stop dividing. How cells specialize during their life Mistakes that occur during division that can lead to cancer and genetic disorders Unit 5 Cell Division Key Concept: All cells come from preexisting cells – Cell Theory Cell division – process by which cells produce new cells Each new cells receive a copy of the genetic material (DNA) stored in chromosomes of the parent cell Chromosome Structure 2 Types of Molecules joined together 1. DNA (nucleic acid) 1 in each chromosome 2. Histones (protein) 1000’s in each chromosome Chromosomes are made of DNA coiled around protein molecules Chromosome Location in Cells Eukaryotic cells – Nucleus Prokaryotic cells– Cytoplasm (Nucleoid Region) Chromosome Shape Eukaryotic cells - Rod , Linear Prokaryotic cells – Circular Two Types of Chromosomes Autosomes – carry genes not related to sex Sex chromosomes – carry genes for sex traits XX – Female XY - Male Homologous Chromosomes Homologous Chromosome Pair hair color eye color skin color One autosome from each parent Same size and shape Similar but not identical genes Sex chromosomes are NOT homologous because they carry different genes Body Cells and Sex Cells have different numbers of chromosomes Somatic / Body Cells Have 2 copies of each chromosome 1 from each parent – Diploid 2n Members of a species have the same chromosome number in body cells Ex. Humans 46 Dogs 78 Fruit Flies 4 Made through Mitosis Body Cells and Sex Cells have different numbers of chromsomes Gametes / Sex Cells Have only 1 copy of each chromosome Haploid 1n Made through Meiosis Haploid 1n Diploid 2n 3 Major Types of Cell Division Binary Fission * Used by Prokaryotes and some unicellular Protists * Makes two genetically identical daughter cells (clones) Form of asexual reproduction Mitosis Used by eukaryotic organisms Process of making somatic/ body cells Ex Skin , nerve, muscle Used for growth, to repair damage or replace worn out cells 2 Daughter cells are created from the division on one parent cell Daughter cells are genetically identical to the parent cell –they “inherit” an exact copy of the same chromosomes Mitotic Cell Division X= Number of chromosomes Parent Cell X X X Daughter Cells Meiosis Used by sexually reproducing eukaryotics. Process of making gametes/ sex cells. 4 new cells are made from one parent cell. New cells are NOT genetically identical to the parent cell. Daughter cells have only half the number of chromosomes as the parent cell. Also known as Reduction Division Meiotic Cell Division X= Number of chromosomes Parent Cell ½X ½X ½X ½X X Daughter Cells Gametes are made in Meiosis Chromosome number is different in sex cells and body cells • Haploid (n) cells have only 1 copy of each type of chromosome • - Sex cells are haploid • Diploid (2n) cells have 2 copies of each type of chromosome. – Body cells are diploid. DNA in threadlike form – Chromatin DNA in coiled /condensed form - Chromosome The zygote (fertilized egg) doubles its chromosomes and divides millions of times resulting in growth. Each new cell receives a complete set of all the chromosomes 6.1 Chromosomes and Meiosis Meiosis occurs in the testicles and ovaries. – Produces sex cells: egg and sperm. – Sex cells are what transport/carry the parents DNA to their kids body cells sex cells (sperm) sex cells (egg) 6.1 Chromosomes and Meiosis • Haploid (n) cells have one copy of every chromosome. – Gametes are haploid. – Gametes have 22 autosomes and 1 sex chromosome. 6.1 Chromosomes and Meiosis • Chromosome number must be maintained in animals. • Many plants have more than two copies of each chromosome. • Mitosis and meiosis are types of nuclear division that make different types of cells. • Mitosis makes more diploid cells. 6.1 Chromosomes and Meiosis • Meiosis makes haploid cells from diploid cells. – Meiosis occurs in sex cells. – Meiosis produces gametes. Cell Division Vocabulary diploid (2N) – a cell with 2 chromosome sets in each of its cells; all body (somatic) cells haploid (N) – a cell with 1 chromosome set in each of its cells; all gametes (sperm, eggs)