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

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)

Two Classifications* of Cells O Prokaryotic Cells O 1st form of life O Have NO nucleus – DNA is free (called the “nucleloid”) O ONLY form Unicellular organisms (one-celled) O Example: Bacteria (e. coli, staph, salmonella) O Eukaryotic Cells O Evolved from prokaryotes O Have a nucleus with bundled DNA O Can form unicellular or multi- cellular organisms. O 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.

Cell Organelles 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 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?

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? Plant Organelles

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)

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

Summary of the Cell

Assessment & Homework Go to Ms. Cedillo’s website (8 th 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