Cell Theory Plant And Animal Cells Transport History

Cell Theory Plant And Animal Cells Transport

History of the Cell Theory • 1500 s-Eyeglass makers-several lenses magnifies objects • Anton van Leeuwenhoek: First to describe cells. “Animalcules” (bacteria) • Robert Hooke: Studied cork (dead cells of oak tree); monastery; cells born. • Robert Brown (1833): Dark structure near the center of the cell (nucleus) • Matthias Schleiden(1838): Plants made of cells • Theodore Schwann (1839): Animals are made of cells. • Rudolf Virchow (1855): Cells come from pre-existing cells

Hooke

Cell Theory • All organisms are composed of one or more cells. • Basic unit of organization of organisms. • All cells come from pre-existing cells.

Modern Cell Theory The cell contains hereditary information which is passed on from cell to cell during cell division. All cells are basically the same in chemical composition and metabolic activities.

Cell Size • 5 to 50 micrometers in diameter – Smallest Mycoplasma bacteria (0. 2 micrometers across) – Giant amoebas Chaos chaos (1000 micrometers/1 mm) in diameter; unaided eye

Cell membrane/plasma membrane • Thin flexible barrier • Many cells in direct contact with fluid portion of blood called plamsa.

Nucleus (plural: nuclei) Large membrane enclosed structure that contains genetic material in the form of DNA and controls cell’s activities.

Prokaryotic vs. Eukaryotic PROKARYOTES PRO- “Before” EUKARYOTES EU- “True” • Generally smaller and simpler (exceptions) • Do not separate genetic material in a nucleus. • All characteristics of life. • Single Cells • Lack organelles • Ex. bacteria • • • Larger, more complex Dozens of structures Internal membranes Highly specialized Genetic material in nucleus • Single celled, multicellular • Ex. Plants, animals, fungi

Eukaryotic and Prokaryotic Cells Organelles: Membrane bound structures.

Microscopes-use lenses to magify the image of an object by focusing light or electrons

Compound Light Microscope: Uses two or more lenses that lets light throught to magnify objects. Used to examine living cells, small organisms and preserved cells. See cells and structures as small as 1 millionth of a meter Magnification: Up to 1500 x

Compound Microscope • Objective lens-just above specimen-enlarges image • Ocular lens-eyepiece-further magnifies image • Most living things nearly transparent : : use dyes. – Toluidine blue-cell boundaries and nuclei – Fluorescent-give off light of a particular color when viewed under specific wavelengths of light. • Fluorescence microscopy-identify locations of molecules and watch movement.

Electron Microscope: beam of electrons that are focused by a magnetic field Magnify object up to 500, 000 x Produce realistic, 3 -D pictures.

Electron Microscopes • Transmission and scanning • Explore cell structures and large protein molecules. • Electrons pass through thin samples-cells and tissues must be cut ultrathin. • Electrons scatter: : uses a vacuum • Chemically preserved samples • Nonliving cells and tissues only

Scanning Tunneling Microscope: Probe is brought near specimen. Electrons flow between the tip of the probe and atoms on the specimen’s surface. As probe follows surface contours, 3 -D image is created on a computer. Magnification: hundred million times

Transmission Electron Microscope: Aims a beam of electrons through a specimen. Denser objects allow fewer electrons to pass through. Magnification: hundreds of thousands of times

Cell structures and functions

Cell Boundaries Cell Membrane Cell Wall (PLANTS ONLY)

Plasma/Cell Membrane • Structure: A lipid bilayer with protein molecules and carbohydrate chains embedded throughout the bilayer • Function: A selectively permeable membrane which controls what enters and leaves the cell.

FLUID MOSAIC 1. Flexible 2. Phospholipids move like water molecules in a current of a lake

Selective Permeability: Process by which the plasma membrane of a cell allows some molecules into the cell while keeping others out.

Phospholipids: Lipids with a phosphate group attached to them.

Phospholipids • Glycerol backbone • Two fatty acid chains • Phospate group

Cholesterol • Stabilize phospholipids • Prevents fatty acid chains from phospholipids from sticking together

Transport Proteins • Allows substances and waste to move through the plasma membrane. • Examples: Protein Channels and Carrier Proteins

Proteins and Carbohydrates • Stick out of cells to help cells identify one another

Cell Wall • Structure: Fairly rigid structure located outside the plasma membrane. • Function: Shape, support and protection. • Found in plants cells, fungi, most bacteria, and some protists. • Cellulose.

Cilia And Flagella Cilia • Structure: Short, numerous, hairlike projections, that move in a wavelike motion. • Function: Aid in locomotion and feeding. Flagella • Structure: Long projections that move in a whip-like motion. • Function: Major means of cell locomotion— unicellular organisms.

Cellular Control Center Nucleus

Nucleus • Structure: Center of the Cell • Function : Control center of the cell; Contains the direction to make proteins and other important molecules (DNA). • Prokaryotes: DNA in cytoplasm • Plant and animal cells

Chromatin • Structure: Strands of genetic material, DNA; Forms Chromosomes • Function: Master set of directions for making proteins.

Nucleolus • Structure: Prominent structure in the nucleus. • Function: Make Ribosomes (RNA and Proteins)

Nuclear Envelope • Structure : Separates the nucleus from the cytoplasm; Double membrane made of two phospholipid bilayers contain pores for substances to pass through. • Function: Allow materials in and out of nucleus.

Cytoplasm • Structure: Clear, gelatinous fluid inside the cell. Area between cell membrane and nucleus. Dissolved in Cytosol are salts, minerals, and organic compounds. • Function: Contains various cell organelles.

• Organelles that Build Proteins Ribosomes Endoplasmic Reticulum Golgi Apparatus

Ribosomes • Structure: Most numerous in cell; no membrane; found free and attached; among smallest of organelles; Made up of RNA and Proteins • Function: Protein Assembly (DNA directions)

Endoplasmic Reticulum • Structure: Complex system of folded membranes suspended in the cytoplasm. • Function: – transportation system between the nucleus and the cytoplasm – Site of chemical reactions – Prepares proteins for export (r. ER) – synthesizes steroids – regulates calcium levels – breaks down toxic substances (s. ER) • Smooth (No Ribosomes); Rough (Ribosomes)

Golgi Apparatus/Body • Flattened system of tubular membranes. Flattened stack of pancakes. • Modifies, sorts, and packages proteins and lipids for storage and transport (Cell’s Post Office)

Organelles that Store, Clean-UP, and Support Vacuoles/Vesicles Lysosomes Cytoskeleton Centrioles

Vacuole Vacule in plants/Vesicle in animals • Structure: Sac surrounded by a membrane. • Function: Stores food, enzymes and other materials needed by the cell, and some vacuoles store waste products.

Plastids • Function: Stores starches and lipids; • Example chloroplast (one type) transfers energy from light to organic compounds.

In plants, plastids may differentiate into several forms, depending upon which function they need to play in the cell. Chloroplasts: for photosynthesis Chromoplasts: for pigment synthesis and storage Amyloplasts: for starch storage Statoliths: for detecting gravity Elaioplasts: for storing fat Proteinoplasts: for storing and modifying protein

Lysosomes • Structure: Small spherical organelles that enclose hydrolytic enzymes within a single membrane. • Function: Digest molecules, old organelles, and foreign substances (engulfs viruses or bacteria)

Cytoskeleton • Structure: Support structure made of tiny rods and filaments. • Function: Form a framework for the cell.

Microtubules and Microfilaments Assist in cell shape and assist organelles in moving from place to place within the cell. Microtubules: Thin hollow cylinders made of proteins. Microfilaments: Thin, solid protein fibers.

Centrioles • Pair of cylinder-shaped bodies found in the cells • Organize cell division • Animal Cells ONLY

Organelles that capture and release energy • Chloroplasts (PLANT ONLY) • Mitochondria

Chloroplast (PLANTS ONLY) • Structure: Disc shaped (ability to change shape and position in the cell as light intensity changes) Contains pigment in the inner series of thylakoid membranes. • Function: Convert solar energy to chemical energy stored in food.

Chlorophyll • Function: Traps light energy and gives leaves and stems their green color.

Mitochondria • Structure: Granular and rod shaped, with an inner membrane that forms long, narrow folds. • Function: Convert chemical energy in food to usable compounds (ATP).

Animal Cell

Diffusion—Movement of particles from an area of higher concentration to an area of lower concentration

Slide 59 Net Movement movement which changes concentration

Slide 60

Slide 61 Factors that affect diffusion l Particle size and shape l Temperature l Concentration gradient—Difference in concentration. l Cytoplasmic streaming—Continuous movement of materials in cytoplasm.

Slide 62 Diffuse in Membranes 1. Passive Transport Moving of materials across cell membrane without using cellular energy. • Diffusion (phospholipids) • Facilitated Diffusion (transport proteins) Uses Channel Proteins Active Transport Moving of materials across cell membrane using cellular energy Uses Carrier Proteins

Slide 63 Osmotic Pressure Force produced by the net movement of water out of or into a cell • Water moves from an area of HIGH water concentration (low solute) to an area of LOW water concentration (high solute) •

Slide 64 Aquaporins Water channel proteins

Slide 65 Osmosis

Slide 66 Osmotic Pressure Force produced by the net movement of water out of or into cell. Result: Turgid pressure-plants straight up Water purification (reverse osmosis) Desalinates Salt Water

Slide 67 Osmotic Condition—Cell concentrations versus environmental solution concentrations. Isotonic Hypertonic

Slide 68 Solution concentrations inside is the same as outside. No net movement of water. Animal cells: Normal Plant Cells: Flaccid Isotonic “Iso” means same

Slide 69 Solute concentrations outside is less than cell concentration. Animal Cell : Lysed Plant Cell: Turgid “Hypo” - under

Slide 70

Slide 71 Solute concentration outside is greater than cell concentration. Animal Cell: Shrink Plant Cell: Plasmolyzed “Hyper” - above

Slide 72 This is why it is dangerous to drink sea water - its a myth that drinking sea water will cause you to go insane, but people marooned at sea will speed up dehydration (and death) by drinking sea water. This is also why "salting fields" was a common tactic during war, it would kill the crops in the field, thus causing food shortages.

Slide 73

Slide 74 Hypertonic, Isotonic and Hypotonic

Slide 75

Slide 76

Slide 77 Active Trans. Port Using a protein molecule to move particles up the concentration gradient. Requires ATP (Adenosine Triphosphate)

Slide 78 Example of how the cell uses Active Transport Pump—Proteins that use active transport to move particles between the interior and exterior of the cell. e. g. Sodium/Potassium pump: Used to move sodium and potassium ions across nerve membranes.

Slide 79 Active Transport Versus Passive Transport

Slide 80 Large Molecules

Slide 81 Endocytosis: Cell membrane indents around molecule and forms a vesicle. l Pinocytosis—Uptaking fluid molecules l Phagocytosis—Uptaking solid molecules

Slide 82 Pinocytosis and Phagocytosis

Slide 83 Exocytosis Vesicles fuse with cell membrane to release materials.

Slide 84 Endocytosis and Exocytosis

Slide 85

Homeostasis maintain internal physical and chemical conditions

Unicellular organisms • • Grow Respond to environment Transform energy Reproduce

Multicellular organisms • Cells become specialized (move, react, produce substances) – particular tasks – communicate with one another

Levels of Organization • Cell-basic unit of life (muscle cell) • Tissue-Cells working together to perform particular function (smooth muscle tissue) • Organ-Group of tissues working together (heart, stomach) • Organ System-organs working together to perform specific function (stomach, pancreas, intestines form digestive system) • Organism-organisms working together; division of labor

Cellular Communication • Receptors-on or in cell, a specific protein to whose shape fits that of a specific molecular messenger (hormone)