Large Organic Compounds Containing

ANPS 019 09-07-11 DR. ELLEN BLACK

NUCLEIC ACIDS Large organic compounds containing: 1. Carbon 2. Oxygen 3. Hydrogen 4. Nitrogen 5. Phosphorous

Made of building blocks called nucleotides Store and process information at the molecular level -make up DNA and RNA “cell information system”

Each nucleotide contains: A sugar unit (ribose or deoxyribose

A phosphate group (PO4) A nitrogen containing bases 2 types: 1. Purines are double ringed molecules (adenine, guanine) MORE COMPLEX 2. Pyrimidines have a single ring (cytosine, thymine and uracil)

RNA AND DNA ARE BUILT BY FIRST LINKING NUCLEOTIDES TOGETHER INTO STRANDS RNA: ribonucleic acid RNA nucleotides contain: A ribose sugar A phosphate group and one of these base Adenine, Guanine, Cytosine and Uracil An RNA strand is formed by linking the sugar group of one nucleotide to the phosphate found of another nucleotide RNA has a single chain of nucleotides made with the bases AGCU

DNA: deoxyribonucleic acid Double stranded structure Each nucleotide contains a deoxyribose sugar, a phosphate group, and one of these bases: Adenine, Guanine, Cytosine, Thymine The DNA molecule is formed by linking one DNA strand with another by hydrogen bonds between complementary bases (A-T, C-G)

DNA has a pair of nucleotide chains The chains spiral around one another to for a DOUBLE HELIX, with bases of each chain facing each other Hydrogen bonds between complementary bases hold the chains together and stabilize Weak helix hydrogen bonds between complementary bases can be easily broken to separate the two DNA strands DNA is always being sipped and unzipped due to Hydrogen bonds Adenosine Triphosphate (ATP) is another important organic molecule Most important energy formed used by cells ATP is a high energy compounds which stores cellular energy in high energy bonds Made by adding a phosphate group to adenosine diphosphate (ADP) in a process referred to as phosphorylation Removal of terminal phosphate group converts ATP to ADP releasing energy ATP is the energy form driving most cellular activity

THE CELL IS THE SMALLEST LIVING UNIT Cell compnents are built with proteins, carbs, lipids and nucleic acids. Cells are the building blocks of all plants and animals Cells are produces by the division of preexisting cells --cannot create new ones, except during cell division Cells are the smallest units that perform all vital physiological functions 1. Obtain food 2. Grow 3. Reproduce 4. Respond to environment --environment cells are very complex

CELL BIOLOGY All cells have these parts in different quantities Cytology: the study of the structre and function of cells The human body contains 1. Somatic cells (body cells) 2. Sex cells (sperm or eggs)

HUMAN CELS ARE DIVERSE IN SHAPE AND FUNCTION Each specialize in different things

A TYPICAL CEL Is surrounded by extracellular fluid, which is the interstitial fluid of the tissue -extracelluar fluid = interstitial fluid --outside the cell Has an outer boundary called the cell membrane or plasma membrane Intracellular = fluid inside the cell

THE CELL MEMBRANE Bringing in nutrients, getting rid of waste The cell membrane is phospholipid bilayer with proteins, lipids and carbohydrates Membrane: 1. Physical isolation: separates cell from environment 2. Regulation of exchange with the environment, allow movement 3. Structural support of the cell 4. Also, sensitivity to the environment

PHOSPHOLIPID MOLECULES GIVE THE CELL MEMBRANE ITS STRUCTURE Structural lipid Bilayer: two sheets of phospholipid molecules arranged with fatty acid “tails” facing each other Phosphate containing head provides hydrophilic inner and outer membrane surface Hydrophobic interior of bilayer --nothing with a charge can pass thought hydrophobic Ions and water soluble compounds cannot enter cell: causing isolation

MEMBRANE PROTEINS FIVE THE CELL ITS UNIQUE FUNCTION Membrane proteins are classified as either 1. Integral proteins -embedded in membrane -cannot be removed or will ruint he cell structure 2. Peripheral Proteins (bound to inner and outer surfaces) -easily separated

MEMBRANE ENZYMES All cells have them in different amounts Some proteins act as enzymes They can be integral or peripheral: Catalyzes reaction inside of outside cell (depending on which direction the active site faces). For example, lactase protruding from epithelial cells lining your small intestine splits the disaccharide lactose in the milk you drink

RECEPTOR PROTEINS As binds, change how proteins act Integral: Recognizes specific ligand (which can be a small ion to a very complex hormone) and alters cell’s function in some way. For example, antidiuretic hormone binds to receptors in the kidneys and changes the water permeability of certain plasma membranes.

LINKER PROTEINS Structural integrity of tissues Integral and Peripheral: Anchors filaments inside and outside the plasma membrane, providing structural stability and shape for the cell. May also participate in movement of the cell of link two cells together.

RECOGNITION PROTEINS Cell identity marker (glycoprotein) Distinguishes your cells form anyone else’s (unless you are an identical twin) An important class of such markers are the major histocompatibility (MHC) proteins If found, they attack it!

TRANSPORT PROTEINS More material across the membrane Integral Transports specific substances across membrane by changing shape. For example, amino acids, needed to synthesize new proteins, enter body cells via transporters.

ION CHANNEL PROTEINS Highly specific Integral Allows specific ion to move through water filled pore. Most plasma membranes include specific channels for several common ions

MEMBRANE CARBOHYDRATES FORM THE GLYCOCALYX Extend away from cell surface 1. Lubricate and protect 2. Anchor cell 3. Bind extracellular compounds, function as receptors 4. Recognized by immune system cells in their search for foreign invaders Types of membrane carbohydrates 1. Proteoglycans: mostly sugar 2. Glycolipids: mostly lipid 3. Glycoproteins: mostly proteins

THE FLUID MOSAIC MEMBRANE MODEL The cell membrane is not a fixed entity Lipids move around with respect to their neighbors Proteins move aroundare added and removed as need to alter cell function

THE INTEROR OF THE CELL CONTAINS Fluid (cytosol) water fluid Organelles Nucleus

ORGANELLES 1. Nonmembranous organelles  Not enclose by a membrane  Include cytoskeleton, centrioles, ribosomes 2. Membranous organelles  Surrounded by phospholipid membranes  Include endoplasmic reticulum, golgi apparatus, lysosomes, mitochondria

CYTOSKELETON PROVIDES STRENGTH AND FLEXIBLITY Can also change shape Microfilaments Intermediate filaments Microtublues Thick filaments: unique to muscle cells

THE CYTOSKELETON Microfilaments: smallet, weblike arrangement inside plasma membrane (actin); help cell movemtn and support Intermediate filaments: strong, resis mechanical stress to cell, stabilize the position of organelles within cytoplasm Microtublues: largest, long and hollow, provide strength and ridigity to cell, anchored in centrosome, chromosome movement CENTRIOLES Organize the cytoskeleton Cytoplasm surrounding the centrioles is the centrosome Microtubule structure anchors with microtubules of cytoskeleton Direct the movement of chromoseomes during cell division