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Question: What invention revolutionized the discovery of cells and these organelles? THE DISCOVERY OF CELLS The invention of the microscopes made it possible for scientists to view and study cells. Cells — basic units of all living organisms. The Cell Theory 1. All living things are made of one or more cells. 2. Cells are the basic units of structure and function in living things. 3. All cells come from other cells. Microscopes have helped scientists learn more about cells: Electron microscopes — allow objects to be magnified up to 500,000 x using beam of electrons instead of light Scanning electron microscope (SEM) — can help scientists see a cells three-dimensional shape Transmission electron microscope (TEM) — allows scientists to see structures inside a cell Scanning probe microscopes — produce images by tracing surfaces of cells or structures with a probe All cells contain small structures called organelles. Each organelle has a specific function in the cell. Two Major Classes of Cells: PROKARYOTIC CELL EUKARYOTIC CELL lacks a nucleus and most has nucleus surrounded by other organelles membrane and other membrane-bound organelles Ex. bacteria and archaea Ex. protists, fungi, plants and animals Question: Question: How Whatistwo a plasma organelles membrane do plant like cells a window have that screen? animal cells do not? EUKARYOTIC THE PLASMA CELL MEMBRANE STRUCTURE (aka protists, fungi, plant and animal cells) Plasma membraneOrganelle — flexible boundary of a cell that separates a cell from its Function Description surroundings. BOUNDARY Cell Wall rigid wall outside plasma membrane giving extra support – not found in animal cells The plasma membrane regulates what enters and leaves the cell and also provides protection and support. This is called selective permeability. Nucleus directs activity of cells organelles NUCLEUS Nuclear surrounds nucleus and has thousands of pores allowing AND Envelope material in and out ofto nucleus Selective permeability — some molecules are allowed pass through plasma membrane CELL at anytime - other molecules are only allowed at certain times or in limited amounts. CONTROL Chromatin strands of DNA located throughout the nucleus Some molecules are never allowed. Chromosomes condensed chromatin that contain genetic information Structure of Plasma Membrane passed on to offspring Nucleolus makes ribosomes inside nucleus Phospholipid bilayer — double-layered sheet that makes up nearly all plasma Ribosomes where proteins are assembled according to the DNA membranes. directions Phospholipid —Cytoplasm made up of glycerol, fatty acids, and a phosphate group thicktwo fluid outside nucleus throughout the cell Endoplasmic site where lipids for membrane are assembled along Carbohydrate chain Reticulum with proteins-two types: rough and smooth OUTSIDE CELL ASSEMBLY, Golgi sorts and packages proteins and materials into phosphate TRANSPORT apparatuscell structures called vesicles then “shipped” out fattyAND acid membrane STORAGE Vacuole saclike structure used for storage (water, food and chains enzymes) - large single one in plant cells INSIDE CELL Proteins Lysosomes remove wastes using digestive enzymes Protein Mitochondria transform chemical energy from food into useful energy for both channel Chloroplasts found in green plant cells and some protists capturing Plasma membranes contain protein are embedded in the phospholipid sun molecules energy andthat converting it to chemical energy bilayer. Carbohydrate molecules are attached to many of the proteins. The organization of all these structures is called the fluid mosaic model. Function SUPPORT AND LOCOMOTION Organelle Description Cytoskeleton network of protein filaments that help cell keep its shape and helps with movement of protein filaments called microtubules or microfilaments Centrioles made of microtubules and help with cell division Cilia short hair-like projections that wave to help move cell Flagella long whip-like projections that aid in movement – usually just one or two Question: What cell appeared earlier in history — eukaryotic or prokaryotic? PROKARYOTIC CELL STRUCTURE (aka Bacteria) Prokaryotes — bacteria that are unicellular organisms that do not have a nucleus or membrane—bound organelles Plasmid — genes separate from chromosome which can carry antibiotic-resistant genes. Capsule (slime layer) — sticky capsule around cell wall that enhances some bacteria to cause disease Chromosome — single DNA molecule not enclosed in nucleus; contains most of bacteria’s genes Flagellum — some bacteria have long whip-like projections that enable them to move (flagella-plural) Ribosomes — site of protein synthesis Food molecule Pilus — extensions of plasma membrane – helps bacteria stick to a surface and also acts as a bridge where two bacteria can exchange DNA (pili-plural) Plasma membrane — surrounds cell and regulates what enters and leaves cell Cell wall — surrounds the plasma membrane-gives cell its shape and prevents osmosis (water entering) from bursting cell Question: Does a cell use passive transport or active transplant to move molecules? CELLULAR TRANSPORT Every living cell exists in a liquid environment that it needs to survive. The plasma membrane is selectively permeable, meaning only certain molecules are allowed in and out of cells. Diffusion — particles tend to move from an area where they are more concentrated to an area less concentrated. — In cells substances can diffuse across membranes WITHOUT requiring use of energy — passive transport Osmosis — diffusion of water across a selectively permeable membrane — enables cell membrane to regulate cells internal environment — this is called homeostasis *Osmosis effects cells depending on the type of solution they are placed in: isotonic, hypertonic or hypotonic. Facilitated diffusion — molecules that cannot diffuse on their own, moves through protein channels in membrane Active transport — transport protein (carrier) protein requires ENERGY to help move particles across the membrane against a force (concentration gradient) Endocytosis large particles are engulfed, then enclosed by cell membrane — moves into cell vs Exocytosis large particles are released from cell by secreting them or expelling them out