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Transcript
Chapter 4 The Cell and Its Environment Standard 3: Students know and understand the characteristics and structure of living things, the processes of life, and how living things interact with each other and the environment. Introduction to the Cell Introduction and Evolution of the Cell (26:13) Vocabulary • • • • • • • • • • Active transport Osmosis Cell theory Passive transport Cell wall Phagocytosis Diffusion Pinocytosis Dynamic equilibrium Plasma membrane Endocytosis Exocytosis Facilitated diffusion Transport protein Fluid Mosaic model Vesicle Middle Lamella Selectively permeable membrane 4.1 Membrane Structure • Key Terms: – Cell Theory – Plasma Membrane – Selective Permeability – Lipid Bilayer – Membrane proteins – Fluid mosaic model E-Coli • Plasma Membrane animation Kingdoms • On Earth, there are five kingdoms that include specific organisms that fit into that kingdom based on similar characteristics. What are they? Kingdoms • On Earth, there are five kingdoms that include specific organisms that fit into that kingdom based on similar characteristics. They are: – Monera – Protista – Plantae – Fungi (There’s a fungus among us) – Animalia Life Inside A Cell Animal Cell (3:10) Plant Cell Cell Theory • What are the 3 components of the cell theory? Cell Theory • All organisms are composed of 1 or more cells or cell fragments. • The cell is the basic unit of structure and function in organisms. • All cells are produced from other cells. • So, what are cells exactly? It’s alive! Animal cell (Click on the picture) Scientists and Cell Theory • Who was the first scientist to see cells? • Who was the first scientist to declare that plants are made up of cells? • Who was the first scientist to declare that animals are made up of cells? Scientists Behind Cell Theory • Robert Hooke: 1665 – First discovery of cells • Matthias Schleiden: 1838 – Concluded all plants are made of cells and cells are the basis of a plant’s function • Theodor Schwann: 1839 – All animals are made of cells • Rudolf Virchow: 1858 – All cells come from other cells. Robert Hooke and friends Click on picture (3:32) Plasma Membrane • What are three properties of the plasma membrane? Properties of Plasma Membrane • All cells live in a fluid environment • Each cell is a separate unit of life that receives and releases substances from their environment through the plasma membrane. • Plasma membrane is the cell’s gatekeeper. Plasma Membrane (1:29) Selective Permeability • What is meant by selective permeability? • What kind of substances can easily pass in and out of a cell? Selective Permeability • The cell’s membrane selectively lets things in and out in order to maintain organization. • Substances that go in and out include: – Amino acids that make polypeptides. – Glucose molecules used in cellular respiration. – Oxygen in and Carbon Dioxide out. Substances go into and out of the cell membrane (1:01) Lipid Bilayer • Describe the lipid bilayer. – What is it made of? – What substances are most likely to pass through it? Lipid Bilayer • Two layers of phospholipids form the plasma membrane. • Each layer has a polar head and 2 nonpolar tails. • Which layer would be more “friendly” to water molecules? Phospholipids on the town Click on the picture (2:28) Diffusion vs. Osmosis • • • • What is diffusion? What is osmosis? How are they different? How are they similar? Diffusion vs. Osmosis Diffusion (:39) Random movement of particles is called diffusion. Particles go from a greater concentration to a lesser concentration to create a dynamic equilibrium. What is dynamic equilibrium? (6:07) Diffusion across a membrane (:53) Osmosis • Diffusion across a cell membrane is called osmosis. • For any cell to survive, it must be in osmotic balance with its environment. • Osmotic balance occurs when movement of water in and out of the cell is equal. Isotonic, Hypotonic, Hypertonic • Using the scenario where there is a red blood cell in the following solutions: • What is isotonic? – What happens to the cell? • What is hypotonic? – What happens to the cell? • What is hypertonic? – What happens to the cell? Facilitated Diffusion • What are two types of proteins that facilitate diffusion? • Which of these uses energy? • What kind of transport is that called? • Which of these does not use energy? • What kind of transport is that called? Facilitated Diffusion Channel Protein Passive Transport System Channel Protein Action Carrier Protein Active Transport System Carrier Protein Action Comparison of channel to carrier proteins Active Transport • It takes ENERGY for a cell to move substances from a region of lesser concentration to a region of greater concentration. • Through active transport, cells use transport proteins called pumps. Transport protein pump Plant Cells • How are plant cells different than animal cells? • How are plant cells similar to animal cells? • What is the carbohydrate in a plant cell that provides structure to a plant? Plants Have Cell Walls!!! • Unlike animal cells, plants have cell walls made of cellulose. • Cell walls are made up of dead cells that provide protection and support. • The middle lamella, made of pectin, is sandwiched between the two primary cell walls. Cell walls (1:53) • What is a second messenger? • It’s a molecule that is generated when a specific substance attaches to a receptor on a cell membrane ant that causes changes within the cell. • What is a receptor protein? • A protein that binds with a specific molecule, causing the cell in which the substance is found to respond. • What does a signal do? • It carries information between cells. • How does a cell recognize only the signals meant for it? • It has receptor proteins in the cytoplasm that have specific shapes that certain molecules fit in. • How might a cell membrane change in response to a signal? • Transport proteins may open or close. • How can a signal trigger a specific chemical reaction in a target cell? • By activating an enzyme in the cell membrane. • How are membrane proteins held in place in the cell membrane? • The amino acids have polar and nonpolar parts. • How do many animal cells avoid the swelling that osmosis can cause? • By pumping solutes out of the cytoplasm. • A cell that has a solute concentration of 1% is placed in a 5% solution, what will happen? • The water will move out of the cell to try and achieve equilibrium with the external environment. • A signaling cell produces a signal molecule that then binds to what? • A receptor protein.