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Transcript
Notes: Chapter 7 Cell Structure & Function Section 7-1: Life is Cellular I. Discovery of the cell A. A. Early microscopes: In the 1600s scientists began using microscopes to observe living things 1. 1665 – Robert Hooke looked at cork, a plant material, and saw empty chambers which he called “cells” 2. 1674 – Anton van Leeuwenhoek observed pond water and saw many living cells 3. 1838 – Schleiden concluded that all plants are made of cells 4. 1839 – Schwann concluded that all animals are made of cells 5. 1855 – Virchow concluded that all cells come from other living cells B. B. The Cell Theory states: (from Schleiden, Schwann, & Virchow) 1. All cells are composed of living cells 2. Cells are the basic unit of structure & function 3. New cells are produced from existing cells II. Categories of Cells A. Prokaryotes – cells that don’t have a nucleus 1. Small in size 2. Contains genetic material, but not in a nucleus 3. Example: bacteria B. Eukaryotes – cells that have a nucleus 1. Larger & more complex than prokaryotes 2. Genetic material contained inside a nucleus 3. Example: plants, animals, fungi, & protists Section 7-2: Eukaryotic Cell Structure I. Eukaryotic cells contain organelles A. Organelles – tiny parts within a cell that have a specific function; “tiny organs” B. Organelles & their functions: 1. Cytoplasm – fluid portion outside of the nucleus 2. Nucleus – holds the genetic material 3. Chromosomes – genetic material; threadlike structures made of DNA 4. DNA – the instructions for making important proteins and other important molecules 5. Nuclear Envelope – surrounds the nucleus; contains tiny openings called nuclear pores 6. Ribosomes – make proteins 7. Endoplasmic Reticulum – transport system i. Rough ER – has ribosomes on its surface ii. Smooth ER – no ribosomes 8. Golgi Apparatus – modifies, sorts & packages molecules from the ER 9. Lysosomes – contains enzymes that break down unnecessary molecules within the cell; removes the “junk” 10. Vacuoles – storage area 11. Mitochondria – changes food molecules into energy 12.Cytoskeleton – helps the cell maintain its shape; also allows for transportation inside the cell 13. *Chloroplasts – changes energy from the sun into energy for use by the cell; Found only in plants, algae, and cyanobacteria 14.*Cell Wall – provides protection & support; Found only in plants, algae, fungi, & many prokaryotes Section 7-3: Cell Boundaries I. Cell Membrane A. Functions of the Cell Membrane: 1. Allows molecules into & out of the cell 2. Provides protection & support B. Structure of the Cell Membrane 1. Made of a lipid bilayer (2 layers of lipids) 2. Contains proteins in the lipid bilayer i. Channel proteins – allows molecules in & out of the cell ii. Marker proteins - “name tag” for a cell iii. Receptor proteins II. How Do Things Move Into & Out of the Cell? A. Passive Transport – no energy required 1. Diffusion – molecules move from an area of high concentration to an area of lower concentration 2. Osmosis – the diffusion of WATER from a lower solute concentration to a higher solute concentration across a SELECTIVELY PERMEABLE MEMBRANE i. Isotonic – solute concentration inside & outside a cell are equal, or in equilibrium ii. Hypertonic – solute concentration is higher outside the cell; cell shrinks iii. Hypotonic – solute concentrations is higher inside the cell; cell swells causing osmotic pressure against cell membrane or wall. If a cell does not have a cell wall, it may burst if the osmotic pressure is too high. 3. Facilitated Diffusion – large molecules such as glucose, move through protein channels B. Active Transport – energy (ATP) is required 1. “Pumps” – move certain molecules against a concentration gradient 2. Endocytosis – cell takes material into cell by folding in its membrane i. Phagocytosis – cell takes in material; eating ii. Pinocytosis – cell takes in liquid; drinking 3. Exocytosis – cell releases material from the vacuole to the outside of the cell Section 7-4: Diversity of Life I. Living organisms can be unicellular or multicellular A. Multicellular Organisms 1. Made of different types of cells 2. Cell Specialization – when cells develop into different types of cells that have different functions i. Example: muscle cells, blood cells, skin cells, bone cells, guard cells (in plants) B. Levels of Organization in a multicellular organism: 1. Cells 2. Tissues – a group of similar cells that have a specific function 3. Organs – groups of tissues working together 4. Organ Systems – groups of organs working together