Chapter 2. The Chemistry of Life

Transcription

1 Chapter 2 The Chemistry of Life

2 Introduction Cells, tissues and organs composed of chemicals Chemical reactions important for function Chemistry is the study of elements, compounds, chemical reactions, molecular structure 2

3 Atomic Structure Atoms smallest particles of elements maintain all characteristics of element nucleus contains protons and neutrons electrons orbit nucleus in shells 3

4 Elements, Isotopes, Compounds Element - atoms contain same numbers of protons and electrons Compound - contains two or more elements Isotope - number of neutrons varies Periodic Table of the Elements arranges elements by increasing atomic number 4

5 Bonds and Energy Ionic - one atom gains and one atom loses electrons Covalent - atoms share electrons Hydrogen - weak bonds, hold water molecules together Bonds are energy containing 5

6 Common Substances in Living Systems Water - most abundant substance in cells universal solvent transport absorbs and reduces heat protects 6

7 Carbon Dioxide Waste product of cellular respiration Used in photosynthesis to produce usable energy sources Must be removed quickly from cells Carbon in molecules comes from carbon dioxide gas 7

8 Amonia (NH 3 ) By-product of amino acid breakdown amino acids are building blocks of proteins amino acids contain nitrogen Converted to urea in the liver 8

9 Mineral Salts Composed of small ions Calcium - muscle contraction and strong bones Phosphate - ATP synthesis Sodium, potassium and chloride are necessary for muscle contraction and nervous transmission 9

10 Carbohydrates 1:2:1 ratio of carbon, hydrogen and oxygen Five- and six-carbon simple sugars are smallest five-carbon: deoxyribose and ribose six-carbon: glucose and fructose Functions - energy storage and cell structure 10

11 Lipids Insoluble in water 95% of fats in body are triacylglycerols Saturated fat - fatty acids have single convalent bonds Unsaturated fat - fatty acids have one or more double convalent bonds Functions - energy, insulation and protection 11

12 Proteins Contain carbon, oxygen, hydrogen, nitrogen and sulfur Amino acids are building blocks of protein Protein type is based on structure Functions - energy and structure Enzymes - protein catalysts for chemical reactions 12

13 Nucleic Acids Deoxyribonucleic acid - genetic material of the cell Ribonucleic acid - protein synthesis 13

14 Nucleic Acids Nucleic acids are made up of chains of nucleotides nucleotide - nitrogen base, sugar and phosphate group nitrogen bases - purines (two) and pyrimidines (three) 14

15 Adenosine Triphosphate (ATP) Fuel for cell function and maintenance Molecule consists of sugar, adenine, and three phosphates energy is stored in the second and third phosphates Breakdown of glucose provides energy to make ATP 15

16 Movement of Materials Into and Out of Cells

17 Diffusion Movement of molecules from area of high concentration to low concentration Brownian movement - random collision of diffusing molecules Accelerated by increased temperature O 2 -CO 2 exchange is an example of diffusion 17

18 Osmosis Movement of water through semipermeable membrane from high water concentration to low water concentration Isotonic solution - salt concentration is the same outside the cell as inside Hypotonic solution - salt concentration inside cell is higher than outside cell Hypertonic solution -salt concentration higher outside the cell than inside 18

19 Osmosis 19

20 ph Acids - ph values below 7 Bases - ph values above 7 Buffers - help maintain ph levels 20

21 ph 21