The Twelve Days of Middle School Science

1. The Twelve Days of Middle School Science Day 1: Cell Theory (& structure, organelles& functions, processes)

2. Cell Theory • 1. All organisms (living things) are made of one or more cells. (Unicellular or multicellular) • 2. The cell is the basic unit of all LIVING things. • Hierarchy of all matter: (?)Quarks & Leptons  Protons/ Neutrons/Electrons Atoms Elements Molecules Compounds Proteins, Sugars, Acids, Lipids, Minerals  Cells (LIFE) Tissues Organs Organ Systems Organisms  Populations  Communities  Ecosystems  Biome Biosphere  Earth  Solar System  Galaxy  Local Group  Galaxy Clusters  Universe  Multiverse? • 3. All cells come from existing cells. (Mitosis=production of body cells or Meiosis=production of sex cells)

3. Two Classifications* of Cells • Prokaryotic Cells • 1st form of life • Have NO nucleus – DNA is free (called the “nucleloid”) • ONLY form Unicellular organisms (one-celled) • Example: Bacteria (e. coli, staph, salmonella) • Eukaryotic Cells • Evolved from prokaryotes • Have a nucleus with bundled DNA • Can form unicellular or multi-cellular organisms. • Example: Amoebas, plants animals, fungi, protists *Note: There many TYPES of cells (skin, muscle, hair, sex, etc.,); these are the two categories that ALL cells fall under! It is the DNA within cells that controls what type of cell they will be.

5. Organelle & Function *Cell Membrane: Outer cell lining for protection *Cytoplasm: Jelly-like liquid that organelles float in *Nucleus: “Control center” that contains organism’s DNA Nuclear Membrane: encloses and protects nucleus; DNA can travel through to get to the ER Nucleolus: Produces ribosomes *DNA: The hereditary material of organisms Chromosome: Thread-like structure of DNA that holds genes *Vacuoles: Store nutrients and waste *Mitochondria: Jelly-bean shaped producers of energy (ATP) for cell *Ribosomes: Where proteins are made *Endoplasmic Reticulum: Cell transportation system (rough=has ribosomes on top, smooth=no ribosomes) *Golgi Apparatus/Body/Complex: “Packaging center” which stores, modifies and secretes proteins and lipids Microtubules: protein filaments involved in cell movement, shape, and cell division (mitosis/meiosis). Centrioles: contain microtubules and involved in cell division (animals only) Lysosomes: responsible for intracellular digestion, “kamikazes” * = KNOW THESE Cell Organelles • EVALUATE: • What shape are the mitochondria? • How is the cell similar to a body system? • Is the animal cell an open or closed system? Why?

6. Plant Organelles PLANT-SPECIFIC organelles: *Cell Wall: Gives plant cells shape and structure (rigidity), made of cellulose *Chloroplast: Site where photosynthesis in plant cells occurs EVALUATE: • What are some similarities between plant and animal cells? • What do you notice about the vacuole of the plant cell? • Why do you think plants evolved to have cell walls and animals did not?

7. Cellular Processes • Respiration – the release of energy from sugar. Can be aerobic (with oxygen) or anaerobic (w/o oxygen—this is called fermentation) • **Photosynthesis**- process by which plants change light energy (sunlight) into chemical energy (sugar) • Mitosis – when cells split to create new body cells • Meiosis – when cells split to reproduce sex cells (ex: egg & sperm)

8. Cellular Processes, Cont. • Diffusion - Movement of molecules from an area of great concentration to an area of lesser concentration. • Osmosis– diffusion of water through cells

9. Summary of the Cell

10. Assessment & Homework • Go to Ms. Cedillo’s website (8th Grade Science The Twelve Days of Middle School Science) • Look under Day 1 for these notes and other resources • HOMEWORK: • STUDY cell structure & organelle functions – we will have an assessment over this tomorrow