Biology
Unit 2 Notes:Cells & Organelles
(1) Cells• All living things must:
• Be made of at least one cell.
• Make new cells from pre-existing cells.
• Some living things are:• Made of just 1 single cell “Unicellular” or “Single Celled”
• Made of many specialized cells “Multicellular”
• Cells have to complete processes to keep us living and healthy using organelles.
• Organelles: Small structures found inside cells, each with a specialized structure and function.
MulticellularUnicellular
(2) Organelles to Know• Nucleus: Stores and protects genetic information.
• Ribosome: Connects amino acids to form proteins.
• Endoplasmic Reticulum: Folds proteins into correct structures and ships where needed.
• Golgi Body: Sorts, Packages and Ships cell molecules.
(“Organelles to Know” Continued)• Mitochondrion: Completes cellular respiration in all cells.
• Chloroplast: Completes photosynthesis in plant cells.
• Cell Membrane: Controls what enters and exits the cell.
• Cell Wall: Provides extra structure and support in plant cells.
(3) Why Organelles Inside Cells?• Organelles help cells complete a wide variety of functions.
• There are two types of cells:• Prokaryotic Cells = Cells without a nucleus, and few organelles.
• Eukaryotic Cells = Cells with a nucleus and many organelles.
• The Endosymbiotic Theory:• Provides an explanation for organelles inside cells.
(4) The Endosymbiotic Theory:• Organelles were once free-living single celled organisms.
• The smaller organisms could live inside larger ones.
• Smaller organisms became structures we now call “organelles”.
• Evidence for the Theory:• Organelles have a membrane just like the outside of cells.
• Mitochondria have their own genetic information.
• Mitochondria and Chloroplasts can reproduce and function without the cell.
• Organelles are similar in structure to bacteria.