Cellular Structure and Function Chapter 7 Cellular Structure and Function

CELLS!

Chapter 7.1 Cell Discovery and Theory Robert Hooke observes the structures of cork (oak bark) and calls the units cells.

History of Cell Theory What did Anton Van Leeuwenhoek see through his microscope? He was surprised to find what looked like tiny animals. He named these animals “animalcules”.

How do you develop a theory?

Cell Theory All living organisms are composed of one or more cells. Cells are the basic unit of structure and organization of all living organisms. Cells arise only from previously existing cells, with cells passing copies of their genetic material on to their daughter cells.

Microscopes Review Figure 7.1 on page 182-183, Microscopes in Focus Why were there long periods between significant discoveries about cells? How Big? http://www.cellsalive.com/howbig.htm

Types of Microscopes Compound Light Microscopes Electron Microscopes Transmission Electron Microscope Scanning Electron Microscope Scanning Tunneling Electron Microscope Based on the names of these microscopes, how do you think each type magnifies objects?

Compound Light Microscope Uses series of glass lenses and visible light to produce a magnified image Specimens must be thin Specimens can be alive or dead Maximum magnification is 1000x

Compound Light Microscope

Calculating Total Magnification Compound light microscopes use a series of lenses to magnify; each lens magnifies the image For example, if eyepiece lens magnifies at 10x and the objective lens magnifies at 10x, the total magnification is 100x (10 X 10) What would the total magnification be if the eyepiece magnified at 10x and the objective lens magnified at 4x? Answer = 40 x = 10 X 4

Helpful Hints: Diaphragm Usage Course Adjustor v. Fine Adjustor Location and purpose Movement of stage Lowest power to highest power! DON’T USE COURSE ADJUSTOR IN HIGH POWER!

Compound Light Microscope Microscope Part Function Ocular (eyepiece) Nosepiece High Power Objective Lens Low Power Objective Lens Stage and Stage Clips Diaphragm Fine Adjustment Course Adjustment Base/Arm

Compound Light Microscope Microscope Part Function Ocular (eyepiece) Used for viewing object; hold lens with 10x magnification Nosepiece Holds objective lens High Power Objective Lens Lenses with magnification of 10x, 40x, 100x, or more Low Power Objective Lens Lens with magnification of 4x Stage and Stage Clips Hold microscope slide in place Diaphragm Controls the light entering the field of view Fine Adjustment Brings object into sharp focus Course Adjustment Brings object into focus Base/Arm Support for the microscope

Electron Microscopes – Uses beams of electrons to magnify images Transmission Electron Microscope (TEM) Scanning Electron Microscope (SEM) Scanning Tunneling Electron Microscope (STM) Aim a beam of electrons at a thin slice of cells Electrons are passed through a specimen to a screen Thick parts of the specimen absorb more electrons than thin parts forming a black-and-white shaded image of specimen Can magnify up to 500,000x Specimen must be dead, sliced thin, and stained Directs electrons over the surface of the specimen produces a three dimensional image Specimen must be nonliving Brings a charged tip of a probe extremely close to the specimen so that the electrons “tunnel” through the small gap between Creates a three-dimensional image Can use live specimens

Transmission Electron Microscope (TEM) Scanning Electron Microscope (SEM) Scanning Tunneling Electron Microscope (STM)

Transmission Electron Microscope Bacteriophages (viruses that infect bacteria)

Scanning Electron Microscope

Human atrial (heart) muscle

Scanning Electron Microscopy Stainless Steel Screen

Scanning Electron Miscroscopy Table Salt

Scanning Electron Miscroscopy Insect on the leg of a daddy long-leg spider

Scanning Electron Miscroscopy Eye of an Ant

Scanning Electron Miscroscopy Spider

Scanning Tunneling Microscope STM of DNA molecule

Quiz Tomorrow History of Cell Theory Cell Theory Types of Microscopes Hooke and Van Leeuwenhoek Cell Theory Types of Microscopes Electron Microscopes Compound Light Microscopes Parts Functions Calculating total magnification (NOT Basic Cell Types)

Basic Cell Types What do all cells have in common? Plasma Membrane (barrier controls what moves in and out of cell) Genetic material

Basic Cell Types Prokaryotic Cells Eukaryotic Cells Smaller Larger Contain no organelles Contain membrane-bound organelles – specialized structures that carry out specific cell functions No nucleus Contain nucleus to hold genetic material Bacteria Protists, Fungi, Plants, and Animals

Prokaryotic Cells

Eukaryotic Cells

http://www.arsmachina.com/hooke.htm http://www.nndb.com/people/356/000087095/ http://www.kidsbiology.com/biology_basics/cells_tissues_organs/cell_history_discovery4.php http://nzforu.com/tag/a-transmission-electron-microscope-tem/

Chapter 7.2 http://www.youtube.com/watch?v=Qqsf_UJcfBc

Function of Plasma Membrane Thin, flexible boundary between the cell and its environment Maintains homeostasis by controlling what enters and exits the cell Allows nutrients to enter Allows waste and other products to leave

Selective Permeability The plasma membrane allows some substances to pass through while keeping others out Controls how, when, and how much of these substances enter and leave a cell

Structure of the Plasma Membrane Most molecules in the membrane are lipids Phospholipids containing Glycerol 2 fatty acids Phosphate group

Phospholipids

Structure of Plasma Membrane

Structure of the Membrane “Phospholipid bilayer” TWO layers of phospholipids Interior is hydrophobic (water fearing) Non-polar fatty acid tails Exterior is hydrophilic (water loving), polar Polar phosphate groups

Structure of the Plasma Membrane Phospholipids are arranged in a bilayer. hydrophilic (polar) heads are on the outside hydrophobic (nonpolar) tails are on the inside © Glencoe Biology 2007

Other Components of the Plasma Membrane Proteins are imbedded in the membrane. Transmit signals to the inside of the cell. Anchor the membrane to the internal support structure of the cell. Transport proteins act as tunnels for substances to enter and leave the cell. Cholesterol prevents fatty acid tails from sticking together. Carbohydrates attach to the proteins. Identify the cell Identify chemical signals in the cell’s environment.

The Fluid Mosaic Model “Fluid Mosaic Model” Phospholipids move sideways Other molecules float in the phospholipids like apples bobbing in a barrel of water © Glencoe Biology 2007

Cell Structures and Organelles Chapter 7.3 Cell Structures and Organelles

Cell Organelles Cell Part Function Cytoplasm Semfluid material that surrounds the organelles and provides a place for chemical reactions to take place. Cytoskeleton A network of long, thin protein fibers that form a framework and support system for the cell; anchors all the organelles Nucleus Control center of the cell; contains the cell’s DNA; surrounded by nuclear membrane (envelope) Ribosomes Produces proteins Nucleolus Produces ribosomes Endoplasmic reticulum Folded membrane system that is the site for protein and lipid production Smooth ER Area with no ribosomes attached; place where many carbohydrates and lipids are produced Rough ER Ribosomes are attached and produce proteins

Cell Organelles Cell Part Function Golgi Apparatus Flattened membranes that modified, sorts, and packages proteins Vacuoles Temporary storage for the cell; used to store food, enzymes, and other materials needed for the cell Lysosomes Structure containing enzymes used to digest waste Centrioles Used in cell reproduction Mitochondria Produce energy by breaking down sugars Chloroplasts Capture light energy and convert it to chemical energy (food); found in plant cells Cell wall Thick, rigid fibers that surround the plasma membrane and protects the cell Cilia and Flagella Used for cell movement in some eukaryotic cells

Chapter 7 Test History of Cell Theory Microscopes Hooke Leeuwenhoek Cell theory Microscopes Light microscopes Electron microscopes Prokaryotic & eukaryotic cells Plasma membrane Selective permeability Phospholipid bilayer Cell Organelles Function