LIFE 120 wk 2
LIFE 120 wk 2 Life 120
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This 7 page Class Notes was uploaded by Skylar Hoscheit on Wednesday September 14, 2016. The Class Notes belongs to Life 120 at University of Nebraska Lincoln taught by Dr. Peter Angeletti in Fall 2016. Since its upload, it has received 9 views. For similar materials see Fundamentals of Biology I in fundamental biology at University of Nebraska Lincoln.
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Date Created: 09/14/16
08/29 Aside from water, living organisms consist mostly of carbon- based compounds, organic compounds. Carbon is unparalleled in its ability to form large, complex, and diverse molecules Carbon is the most versatile atom on Earth. produce a vast array of chemical structures - diverse molecules. Isomers are molecules that have the same molecular formula and molecular weight, but a different arrangement of atoms! The seven functional groups that are most important in the chemistry of life: o Hydroxyl group o Carbonyl group o Carboxyl group o Amino group o Sulfhydryl group o Phosphate group o Methyl group Carbon covalent bonds can connect with many different chemical groups. The valences of carbon and its most frequent partners are the “building code” that governs the architecture of living molecules. The properties of an organic molecule also depend on the chemical groups. Critically important molecules of all living things fall into four main classes o Carbohydrates o Lipids (NOT macromolecules, associate by hydrophobic interactions) o Proteins o Nucleic acids Carbohydrates, Proteins, and Nucleic acids can form huge molecules called macromolecules. Diversity of Polymers: Each cell has thousands of different macromolecules; Macromolecules vary among cells, within a species, between species Critically important molecules of all living things fall into four main classes o Carbohydrates o Lipids o Proteins o Nucleic acids Carbohydrates o Contain carbon, hydrogen and oxygen in the proportion CH 2. Monosaccharides o The simplest carbohydrates are monosaccharides, or simple sugars, such as Glucose (C H6O12 6 Disaccharides Polysaccharides o Carbohydrate macromolecules o Polymers of many sugar building blocks Carbohydrates serve as fuel and building material. o Cells store and release energy using a variety of carbohydrates, both simple and complex. o Carbohydrates are used to build the molecules needed for cell structure and function. Monosaccharides are the simplest form of sugar Monosaccharides serve as a major fuel for cells and as raw material for building molecules Monosaccharides are classified by the number of carbons in the carbon skeleton and the placement of the carbonyl group (C=O) Polysaccharides, the polymers of sugars, have storage and structural roles. The structure and function of a polysaccharide are determined by its sugar monomers and the positions of glycosidic linkages. Polysaccharides: Starch, Glycogen, Cellulose, and Chitin Critically important molecules of all living things fall into four main classes o Carbohydrates o Lipids o Proteins o Nucleic acids Lipids large molecules; do not form true polymers Lipids are a diverse group of hydrophobic molecules Hydrophobic o The unifying feature of lipids is having little or no affinity for water (not soluble in water) o Lipids are hydrophobic because they consist mostly of hydrocarbons, which form nonpolar covalent bonds Two FAs + phosphate group attached to glycerol Phosphate & glycerol group (hydrophilic head) Fatty acid tails (hydrophobic) Kink is cis double bond (hydrogen atoms on the same side of the double bond) 08/31 Critically important molecules of all living things fall into four main classes o Carbohydrates (starch, glycogen, cellulose, chitin) o Lipids (fats, phospholipids, steroids) o Proteins o Nucleic acids Nearly every dynamic function of a living being depends on proteins. Proteins account for more than 50% of the dry mass of most cells Proteins are structurally and functionally complex: a diversity of structures, resulting in a wide range of functions Proteins perform a vast array of functions within living organisms. A protein is a biologically functional molecule that consists of one or more polypeptides. o Polypeptides are unbranched polymers built from the same set of 20 amino acids. Amino acids are organic molecules with carboxyl and amino groups. Polypeptides range in length from a few to more than a thousand monomers Each polypeptide has a unique linear sequence of amino acids, from the amino end to the carboxyl end. The sequence of amino acids leads to a unique 3D structure. o The structure of a protein is described at 4 levels of complexity. Primary structure is the sequence of amino acids on the polypeptide chain A slight change in primary structure can affect a protein’s structure and ability to function Sickle-cell disease, an inherited blood disorder, results from a single amino acid substitution in the protein hemoglobin Critically important molecules of all living things fall into four main classes o Carbohydrates o Lipids o Proteins o Nucleic acids Nucleic acids store, transmit, and help express hereditary information There are two types of nucleic acids o Deoxyribonucleic acid (DNA) o Ribonucleic acid (RNA) Nucleic acids are polymers called polynucleotides Each polynucleotide is made of monomers called nucleotides Each nucleotide consists of a nitrogenous base, a pentose sugar, and one or more phosphate groups The portion of a nucleotide without the phosphate group is called a nucleoside Nucleic acids are polymers called polynucleotides Adjacent nucleotides are joined by covalent bonds that form between the hydroxyl (-OH) group on the 3 carbon of one nucleotide and the phosphate on the 5 carbon of the next These links create a backbone of sugar-phosphate units with nitrogenous bases as appendages Two polynucleotide chains spiraling around an axis - double helix Antiparallel – backbones in opposite 5 → 3 directions N bases pair by hydrogen bonds o (A) with (T) o (G) with (C) 09/02 All organisms are made of cells o Definition - cell is the simplest collection of matter that can live o Viruses are not cells Cell structure is correlated to cellular function o Structural order produces emergent properties o Structural variety is enormous o Basic continuity in cellular structure Microscopes o Most cells are between 1 and 100 m in diameter, too small to be seen by the unaided eye Cell Fractionation Microscopy o Light microscopy (LM), visible light; glass lens o Electron microscopy (EM), Electrons; magnetic lens o Image quality depends on Magnification LM – 1000x EM – 100,000 + Resolution LM – 200 nm EM - .002 nm Contrast Light Microscopy techniques to enhance contrast o Fluorescence – structures tagged with fluorescent dyes or antibodies o (artery cell) o Confocal – special aperture reduces stray light; focus in 3 dimensions o (nerve cells green; support cells red; yellow overlap) Electron Microscopy Techniques o Scanning electron microscopes (SEMs) Focus beam on specimen surface Images look 3-D o Transmission electron microscopes (TEMs) Focus beam through a specimen Examine internal structure Cell fractionation breaks up cells and separates the major organelles from one another Centrifuges fractionate cells into their component parts, and cell components separate based on their relative size. Basic features of all cells o Plasma membrane o Semifluid substance called cytosol o Chromosomes (carry genes) o Ribosomes (make proteins) Prokaryotic cell o No nucleus or organelles o Bacteria and Archaea Eukaryotic cell o Membrane-enclosed organelles o Well defined Nucleus o Plants, animals & fungi No nucleus - DNA called the nucleoid No membrane-bound organelles The plasma membrane is a selective barrier that allows sufficient passage of oxygen, nutrients, and waste to service the volume of every cell. The general structure of a biological membrane is a double layer of phospholipids. A eukaryotic cell has internal membranes that divide the cell into compartments—organelles The plasma membrane and organelle membranes participate directly in the cell’s metabolism DNA in nucleus – bounded by nuclear envelope Complex endomembrane system Plant and animal cells have most of the same organelles. The nucleus contains most of the DNA in a eukaryotic cell Nucleus is usually the most conspicuous organelle In the nucleus, DNA is organized into discrete units called chromosomes Each chromosome is one long DNA molecule associated with proteins o The DNA and proteins of chromosomes are together called chromatin o Chromatin condenses to form discrete chromosomes as a cell prepares to divide The nucleolus is located within the nucleus and is the site of ribosomal RNA synthesis Ribosomes are complexes of ribosomal RNA and protein