CHAPTER 7 CELL STRUCTURE & FUNCTION PGS. 168 - 199 CELL STRUCTURE & FUNCTION

ANTON VAN LEEUWNENHOEK One of the first person’s to use a microscope. Looked at pond water and saw small organisms.

ROBERT HOOKE Looked at plant tissues in 1665. He specifically looked at cork. Looked like tiny chambers he called “cells”

THE CELL THEORY 1. All living things are composed of cells. 2. Cells are the basic unit of structure & function in living things. 3. New cells are produced by existing cells.

Cells are the basic unit of life. Cells come in all different shapes & sizes. All living things are made up of cells!

Microscopy Today: Compound Light Microscope Biology, 9th ed,Sylvia Mader Chapter 04 Microscopy Today: Compound Light Microscope Cell Structure and Function Light passed through specimen Focused by glass lenses Image formed on human retina Max magnification about 1000X Resolves objects separated by 0.2 mm, 500X better than human eye

Compound Light Microscope Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 85 µ m amoeba, light micrograph eye ocular lens light rays objective lens specimen condenser lens light source a. Compound light microscope © Robert Brons/Biological Photo Service

Microscopy Today: Transmission Electron Microscope Biology, 9th ed,Sylvia Mader Chapter 04 Microscopy Today: Transmission Electron Microscope Cell Structure and Function Abbreviated T.E.M. Electrons passed through specimen Focused by magnetic lenses Image formed on fluorescent screen Similar to TV screen Image is then photographed Max magnification 1000,000sX Resolves objects separated by 0.00002 mm, 100,000X better than human eye

Transmission Electron Microscope Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 200 nm pseudopod segment, transmission electron micrograph electron source electron beam electromagnetic condenser lens specimen electromagnetic objective lens electromagnetic projector lens observation screen or photographic plate b. Transmission electron microscope © M. Schliwa/Visuals Unlimited

Microscopy Today: Scanning Electron Microscope Biology, 9th ed,Sylvia Mader Chapter 04 Microscopy Today: Scanning Electron Microscope Cell Structure and Function Abbreviated S.E.M. Specimen sprayed with thin coat of metal Electron beam scanned across surface of specimen Metal emits secondary electrons Emitted electrons focused by magnetic lenses Image formed on fluorescent screen Similar to TV screen Image is then photographed

Scanning Electron Microscope Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 500 µ m amoeba, scanning electron micrograph electron gun electron beam electromagnetic condenser lenses scanning coil final condenser electron lens detector secondary electrons TV specimen viewing screen c. Scanning electron microscope © Kessel/Shih/Peter Arnold, Inc.

Microscopy and Amoeba proteus Biology, 9th ed,Sylvia Mader Chapter 04 Microscopy and Amoeba proteus Cell Structure and Function Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 85 µ m 200 nm 500 µ m amoeba, light micrograph pseudopod segment, transmission electron micrograph amoeba, scanning electron micrograph electron source electron gun eye electron beam ocular lens electron beam light rays electromagnetic condenser lens electromagnetic condenserl enses specimen electromagnetic objective lens objective lens scanning coil specimen condenser lens final Condenser lens electromagnetic projector lens electron detector secondary electrons observation screen or photographic plate TV Viewing screen specimen light source a. Compound light microscope b. T ransmission electron microscope c. Scanning electron microscope a: © Robert Brons/Biological Photo Service; b: © M. Schliwa/Visuals Unlimited; c: © Kessel/Shih/Peter Arnold, Inc.

Cells are the basic unit of life. Cells come in all different shapes & sizes. All living things are made up of cells!

Structures common to most cells 1. cell membrane 2. DNA 3. cytoplasm

Biologist divide cells into one of two types: 1. PROKARYOTE: do not contain a membrane bound nucleus (all bacteria are prokaryotes) 2. EUKARYOTE: DO contain a membrane bound nucleus, and most have other specialized organelles.

Chapter 7, Section 2 The Plasma Membrane Main Idea: The plasma membrane helps to maintain a cell’s homeostasis. Essential Questions: How does a cell’s plasma membrane function? What are the roles of proteins, carbohydrates, and cholesterol in the plasma membrane?

Function of the Plasma Membrane Separates cells from the watery environment Maintain homeostasis – the process of maintaining balance in an organism’s internal evnrionment How does it do this? Selective permeability – a property of the plasma membrane that allows some substances to pass through while keeping others out.

Cell Boundries Cell membrane is selectively permeable & provides protection & support Small particles move more easily than large particles Neutral molecules more easily than charged ions Non polar more easily than polar Substances that move across the cell membrane can vary from cell to cell, or the same cell from moment to moment Major component of the cell membrane is a lipid bilayer Proteins & carbohydrates are also found in the cell membrane

Cell membrane

Cell Wall Found in plants, algae, fungi, and nearly all prokaryotes. MAIN FUNCTION: provide support & protection for the cell Animal cells DO NOT have cell walls!

Maintaining Homeostasis All cells must regulate what materials enter & leave; sometimes no energy is required to do this, other times energy is required Passive transport – no energy is required to move substances from an area of high concentration to an area of low concentration

Types of Passive Transport Diffusion – the movement of a solute from an area of high conc. To an area of low conc. Equilibrium is reached when an equal number of molecules move in both directions

Types of Passive Transport Osmosis – the diffusion of water across a membrane from a region of high water concentration to a region of low water concentration http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html

Types of Passive Transport Facilitated diffusion – process by which transport proteins carry certain molecules across a membrane from high concentration to low concentration

Types of Osmotic Solutions Isotonic solution – solution has the same solute concentration as that of the living cell, there is no net movement of H2O

Types of Osmotic Solutions Hypertonic solution– solution has a higher solute concentration than the inside of the cell; H2O moves out of the cell; animal cell will shrink (crenate); vacuole collapses in plant cells

Types of Osmotic Solutions Hypotonic solution – solution has a lower solute concentration than the inside of the cell; H2O moves into the cell; animal cell will burst (lyse); plant cell will not (why?)

Types of Osmotic Solutions http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter21/animation__hemolysis_and_crenation.html (animation of isotonic, hypertonic, hypotonic solutions)

Types of Osmotic Solutions

Active Transport Energy is required to move substances from an area of low concentration to an area of high concentration; allows cells to have internal environments that are different chemically from the external environment

Types of Active Transport Molecular transport - proteins in the cell membrane work as “pumps” to move substances against the concentration gradient

Types of Active Transport Endocytosis - process by which a cell takes material into the cell by infolding of the cell membrane Phagocytosis – large particles taken in Pinocytosis – H2O or small particles are taken in Exocytosis – process by which cell releases large amounts of material; vacuole membrane fuses with the cell membrane

Types of Active Transport http://bcs.whfreeman.com/thelifewire8e/content/cat_040/0504003.html