- Biology 1-H Study Guide Chapter 4 Section 4.1 Water: one of the most important substances on earth. It has very unique properties which make it essential for life on this planet. · 3 phases – solid, liquid and gas · density is interesting: is ice denser than water? How do you know? Why it that? Ice is denser than water. The bonds which hold the molecules together expand as they freeze. You can tell because ice floats when placed in water. Polarity of water: polarity is the uneven distribution of charge within the water molecule. Difference in charges act as magnets attracting other water molecules. Opposites attract hold water together and other polar molecules to water. Mixtures: 2 or more elements mixed, but not chemically combined. · Can be mixed in any amounts b/c not chemically combined – ratios do not matter · Polarity of molecules greatly aid in this. · Examples: salt and pepper; sugar and salt 2 kinds of mixtures · solutions: a mixture in which one substance dissolves in another · solute: substance being dissolved · solvent: substance which does the dissolving Water is the greatest solvent – due to its polarity and its ability to dissolve so many substances. Examples: sugar water, salt water Substances that are bound chemically together break apart upon entering a solution HCl ----------> H+ + Cl- +/- show the charges when the molecule is separated. Opposite charges attract which causes them to come together in the first place. H+ is a proton – a particle within the nucleus of an atom · Very strong, attacks other molecules · When an atom releases a proton H+ as HCl does = ACID Bases: release OH- particles into solution similar to how acids release H+ ions NaOH ------------------> Na+ + OH- When acids and bases are added together they neutralize each other – when they are added in equal quantities. Why? H+ + OH- -------------------------> H2O Acids and Bases are measured on pH scale · Determines relative concentration of H+ and OH- · 0-14 scale with 7 being neutral · acids lower than 7 · bases higher than 7 Suspensions · A solution has a substance breaking into individual molecules once in the solution. · Conversely, when a substance does not break into individual parts it can break into small pieces which stay within the water molecules = suspensions · Example – blood both a solution and a suspension · Made mostly of water · Solution: plenty of dissolved elements · Suspensions: clotting agents which do not dissolve in the blood but use it only as a medium by which to travel. Section 4.2 Earth’s crust contains 90 naturally occurring elements (of the 112 that have been discovered) o Only 11 of these are common in living things o And 20 more are only found in trace amounts o 96.3 % of the human body is made of C, H, O and N C, H, O and N, in varying amounts make up all living things · Organic compounds – contain carbon · Inorganic compounds – do not contain carbon Inorganic compounds: · H20 and CO2 are both inorganic and make up a large percentage of the human body · Bodies also contain calcium phosphate which makes up bone and many salts found in cells and in blood. Organic Compounds: o Carbon is a unique element because it can form strong and stable covalent bonds Covalent bond: sharing electrons with another atom o Has the ability to share up to 4 electrons – make 4 bonds – with other atoms. Can form bonds with almost any other element . o Carbon can also easily form bonds with other carbon atoms to form chains of unlimited number – seen in lipids o Carbon chains can also be bent and bonded into rings - seen with sugars o Remember all of these properties of carbon once we start talking about the types of macromolecules. Polymerization: creating large molecules from smaller subunits. o Small subunits are called monomers – and they get put together to form polymers. o Can you think of any polymers – either organic or inorganic? o Macromolecules – carbohydrate, proteins, lipids and nucleic acids are all polymers put together from monomers. o Think of the alphabet – only 26 letters that can be put together in millions of ways to form all different kinds of words – just changing one letter can change the entire word and the meaning. Section 4.3 Carbohydrates o Sugars and starches o Ratio of 2 hydrogen molecules for each oxygen molecule o Polymer made of monomers called monosaccharides o Many monosaccharides: glucose, fructose, galactose o All have the chemical formula C6H12O6 o Carbohydrates are important because they store energy to be used by living things Where is the energy stored? In chemical bonds o Breaking the chemical bonds will release the energy to be used. Making complex carbohydrates: di- and polysaccharides Putting many monosaccharides together with a reaction known as dehydration synthesis: Loss of a water molecule due to the joining of two monosaccharides Polysaccharides: · Made form many monosaccharides linked in a long chain · Used to store excess energy from sugars · Starch and glycogen are used in humans to store energy · Cellulose is very similar to starch, but used to store energy in plants – humans and many other animals cannot digest cellulose – why we cannot eat grass. In order to get energy – we need to break the bonds of polysaccharides to release the stored energy Hydrolysis reaction: opposite of dehydration synthesis – add water to the bonds to get the monosaccharides back out. Lipids · Waxy or oily compounds · Used to store energy, make membranes and as chemical messengers · Made of the combination of a fatty acid and glycerol · What is the chemical reaction used to put the fatty acid and the glycerol together? Dehydration synthesis Saturated and unsaturated lipids Saturated: each carbon is bonded to another carbon with a single bond, yielding the maximum amount of hydrogen atoms. Unsaturated: carbon atoms are attached with a double bond, thus lessening the amount of hydrogen atoms When lipids are broken down, they contain more energy per gram of fat than carbohydrates do. Sterols and Phospholipids: Sterols: common one – cholesterol, builds cell walls and function in carrying messages. Phospholipids: made from glycerol, 2 fatty acids and a phosphate group. Contains parts which like water and parts which hate water. Used to make a double cell membrane – we will learn more when we study cells. Proteins · Organic compounds which contain nitrogen in addition to hydrogen, oxygen and carbon. · Polymers of amino acids o Have an amino group -NH3 o Have a carboxyl group -COOH o Have an R group – what makes each amino acid different · Amino acids are linked together to form polypeptide chains o Linked with peptide bonds – dehydration synthesis Nucleic Acids · Organic compounds containing carbon, hydrogen, oxygen, nitrogen, and phosphorus · Polymer of nucleotides – made of three parts · 5 – carbon sugar · phosphate group · nitrogenous base · Two basic types of nucleic acids · RNA – ribonucleic acid · DNA – deoxyribonucleic acid