7 Cell Specialization Different body cells perform different functions Examples: skin, nerve, red blood cells, liver cells, platelets
8 Cell SpecializationDifferent cells live for different amounts of time
9 Cellular Reproduction New cells are made from copies of old cellsThis process began occurring before you were born and will continue until after you die
10 Types of Cellular Reproduction MITOSIS – results in two identical cells; used for the majority of cells in the bodyMEIOSIS – results in four cells that are different from the “parents”; used for sex cells only
11 Mitosis Results in body growth or body repair Two new cells are called “daughter cells”
12 A Review of Cell Features Cell MembraneCytoplasmNucleusNuclear MembraneChromosomes – strands that carry a cell’s DNACentrioles – strong, barrell-shaped organelle
13 MitosisGoals – duplicate chromosomes and move them to two new daughter cells
14 Before Mitosis Begins (interphase) Chromosomes are duplicated within the cells (exact copies)Held together at centerTwo strands are called “sister chromatids”
15 Mitosis Step 1: PROPHASE Sister chromatids thicken Nuclear membrane breaks downTwo centrioles move apartFibers (strands of protein) form between centrioles
26 How to remember order of phases? In Patiki, Men Are Tough. Stages of mitosis/meiosis including interphase as a phase! Interphase, Prophase, Metaphase, Anaphase, Telophase.
27 Importance of Chromosomes All chromosomes come in pairsHumans have 23 pairs, so a normal cell has 46 chromosomesAll cells need a full set to function properly (except sex cells)
28 Chromosome NumberBefore mitosis begins, cells have two of each chromosome (2N)After chromosomes duplicate, cells have four of each chromosome (4N)After mitosis, cells have two of each chromosome (2N)
40 THE MOST IMPORTANT DIFFERENCE In the first cell division, CHROMOSOME PAIRS are pulled apart.In the second cell division, SISTER CHROMATIDS are pulled apart.
41 MeiosisMeiosis: the division of a diploid nucleus to form four haploid genetically different daughter nuclei.Role of Meiosis• Increases genetic variation in the population – role in evolution• Makes sexual reproduction possible• Gamete formation in animals, fungi, protoctista e.g. ManSite of MeiosisAnimals• testis - forming sperm, the haploid male gametes;• ovary - forming egg cells, the haploid female gametes.Flowering plants:• anther of the stamen - forming the haploid male spores (microspores),• ovule of ovary - forming the haploid female spores (megaspores).