Chapter 2 “The Chemistry of Life” Coach Fults

Chemistry Why is studying chemistry important in Biology? All organism are chemical machines

Atoms What does all matter have in common? It is all made up of atoms Atoms- is the smallest unit of matter that cannot be broken down by chemical means Consist of protons, neutrons, and electrons

Atoms Protons and Neutrons make up the atom’s nucleus The electrons make up the electron cloud that orbit the nucleus Protons (+), Neutrons (no charge), and Electrons are (-) Usually the number of protons and electrons are equal, since they are equal the atom has no overall charge

Elements Element- pure substance made of only one kind of atom Elements differ in the number of protons they have Atoms of an element that have a different number of neutrons are called isotopes

Chemical Bonding Atoms can join with other atoms to form stable substances A force that joins the 2 is called chemical bonding Compound- is a substance made of joined atoms of 2 or more different elements EX: Na + Cl = NaCl “Table Salt”

Covalent Bonding Covalent bonding- when 2 or more atoms share electrons to form a molecule Molecule- is a group of atoms held together by covalent bonds Because the number of protons = the number of electrons the molecule has no net electrical charge EX: CO 2

Covalent Bonding The arrangement of their electrons determines how atoms bond together Electrons are grouped into levels; the levels close to the nucleus have less energy than those farther away Electron levels have limits on the number of electrons they can hold; some 2 some 8

Covalent Bonding An atom becomes stable when its outer level is full If the outer level isn’t full it will react with other atoms to fill its need Ex: water H 2 O hydrogen has 1 electron in its outer shell and oxygen has 6 = 8 2 hydrogen join 1 oxygen

Hydrogen Bonds Electrons in a water molecule are shared between hydrogen and oxygen, but the shared electrons are more attracted to oxygen nucleus than the hydrogen nucleus The water molecule therefore has partially positive and negative ends, or poles

Hydrogen Bonds The partially positive of one end of the water molecule is attracted to negative end of another water molecule This is what we call polar molecules These attraction between 2 water molecules is an example of a hydrogen bond- a weak chemical attraction between polar molecules

Ionic Bonds Sometimes atoms gain or lose electrons An atom or molecule has gained or lost one or more electrons are called Ions Ions have an electrical charge b/c they contain an unequal number of electrons and protons

Ionic Bonds An atom that has lost electrons are POSITIVELY CHARGED An atom that has gain electrons are NEGATIVELY CHARGED Ions of opposite charges can interact to form Ionic Bonds

Ionic Bonds Na is unstable because it has only 1 electron in its outer level, Na readily gives up this electron to become stable (Na + ); Cl has 6 electrons in its outer level Cl readily accepts an electron to become stable (Cl - ) Opposites attract to form Na + Cl -

Water and Solutions “Storage of Heat” Water heats more slowly and retains heat longer than many other substances Many organisms release heat through water evaporation (sweating); carries heat away from the body The ability to control an internal temp. despite of external temps. Water helps maintain Homeostasis

Water and Solutions “Cohesion and Adhesion” The hydrogen bonds between water molecules cause the cohesion of liquid water Cohesion- is an attraction between substances of the same kind B/c of cohesion water forms thin films and drops (surface tension) Surface tension prevents the surface of water from stretching or breaking

Water and Solutions “Cohesion and Adhesion” Water molecules are also attracted to many other similarly polar substances Adhesion- is an attraction between different substances B/c of adhesion some substances get wet Adhesion powers capillary action; like water moving up the stems of a plant

Water and Solutions “Cohesion and Adhesion” Water is sucked up b/c the force of gravity is less than the power of water clinging to the walls of the xylem Water moves upward from through the plant from roots to leaves b/c of capillary action, cohesion, and etc….

Aqueous Solutions Many things dissolve in water; like when salt is added to water it is called a saltwater solution Solution- is a mixture in which 1 or more substances are evenly distributed in another substances Many important substances are dissolved in your blood

Aqueous Solutions B/c the substances can dissolve in water, they can easily move within and between your cells Sugar is dissolved in water, so that it can reach your cells to make energy

Aqueous Solutions “Polarity” The polarity of water allows many substances to be dissolved in it Ionic compounds and polar molecules dissolve best in water Polar water molecules attract to other positive and negative ends of other compounds which evenly distributes ions or molecules in the water

Aqueous Solutions “Polarity” Nonpolar molecules do not dissolve well in water Oil is nonpolar; water attracts to other polar molecules instead of the oil (don’t mix); the nonpolar molecules are shoved together The inability of nonpolar molecules to dissolve in polar molecules is very important to organisms

Aqueous Solutions “Polarity” It is important b/c, the shape and function of cell membranes depend on the interaction of polar water with nonpolar membrane molecules

Aqueous Solutions “Acids and Bases” While the bonds in a water molecule are strong, at any given time a tiny fraction of those bonds might break, forming a hydrogen ion H +, and a hydroxide ion, OH - H 2 O  H + + OH -

Aqueous Solutions “Acids and Bases” As a result, pure water always has a low concentration of hydrogen ions and hydroxide ions, which are present in equal numbers Acids- are compounds that form hydrogen ions when dissolved in water When an acid is added to water, the concentration of hydrogen in the solution is increased above that of pure water

Aqueous Solutions “Acids and Bases” Bases- are compounds that reduce the concentration of hydrogen ions when dissolved in water Many bases form hydroxide ions when dissolved in water Such bases lower the concentration of hydrogen ions b/c hydroxide ions react with hydrogen ions to form water molecules

Aqueous Solutions “Acids and Bases” pH scale measures the concentration of hydrogen ions in solutions All are between 0 – 14 Pure Water= 7 Acidic= less than 7 Basic= more than 7

pH Scale

Chemistry of Cells “ Carbon Compounds” Other than your water, your body is mostly made up of organic compounds Organic compounds contain carbon atoms that are covalently bonded to other elements- typically hydrogen and oxygen

Chemistry of Cells “ Carbon Compounds” 4 principal classes of organic compounds are found in living things: 1. Carbohydrates 2. Lipids (Fats) 3. Proteins 4. Nucleic Acids

Carbohydrates Carbohydrates- are organic compounds made of carbon, hydrogen, and oxygen atoms in the proportion of 1:2:1 Key source of energy; found in fruits, veggies, and grains The building blocks of carbs are called monosacchrides; Ex: Glucose C 6 H 12 O 6

Carbohydrates Monosaccharides are simple sugars Disaccharides are double sugars joined when 2 monosaccharides join together; Ex: Sucrose = glucose + fructose Polysaccharides= 3 or more monosaccharides join Ex: STARCH and CELLULOSE

Carbohydrates Polysaccharide is an example of a macromolecule, a large molecule made of many smaller molecules Polysaccharides can function as storehouses of energy

Carbohydrates Include sugars, starches, cellulose, and gums End in “OSE” Glucose Monosaccharides Pentose- 5 sided; deoxyribose,ribose, ribulose Hexose- 6 sided; glucose, galactose, fructose

Carbohydrates Disaccharides Maltose= glucose + glucose Sucrose= glucose + fructose Lactose= glucose + galactose

Carbohydrates Polysaccharides 1. Storage polysaccharides store energy a. starch in plants b. glycogen in animals 2. Structural polysaccharides- give support and protection a. cellulose in cell wall b. chitin in fungal cell wall and anthropod exoskeleton

Lipids Lipids- are nonpolar molecules that aren’t soluble in water; they include steroids, phospholipids, and waxes Very important in structure and function of cellular membranes Phospholipids make up the bilayer of the cell membrane

Phospholipid Bi-layer

Lipids Steroids include cholesterol, which is found in animal cell membranes Other lipids include pigments, such as chlorophyll Fats are lipids that store energy (2 times of carbohydrates) A typical fat includes 3 fatty acids bonded to a glycerol molecule backbone

A Fat

Lipids A fatty acid is a long chain of carbon atoms with hydrogen atoms bonded to them Saturated Fatty Acid- all carbon are bonded to 2 hydrogen atoms except for the end which has 3 hydrogen atoms; generally straight; solid at room temp.; butter, lard, grease, and animal fat

Saturated Fatty Acid

Lipids Unsaturated Fatty Acid- some carbon atoms are “double covalently bonded;” produces kinks in the chain Liquid at room temp. Olive oil and fish oil Some unsaturated can become saturated by adding hydrogens creating “Hydrogenated Vegetable Oils”

Unsaturated Fatty Acid

Lipids Steroids- are lipids that function as hormones Waxes- protection for plant/animal structures

Proteins Protein- large molecule formed by joining amino acids Amino acids- building blocks of proteins; 20 different amino acids found in proteins Proteins tend to fold depending on how the amino acids react with water and one another

Proteins Some proteins are enzymes which promote chemical reactions; some are for structure Antibodies are proteins that defend your body from infection Proteins in your muscles cause them to contract Hemoglobin in your blood is a protein that carries oxygen throughout your body, from your lungs to body tissues

Nucleic Acids All your cells contain nucleic acids Nucleic acid- is a long chain of smaller molecules called nucleotides Nucleotides- has 3 parts: a sugar, a base, and a phosphate group (which contains phosphorous and oxygen) There are 2 types of nucleic acids:1. DNA and 2. RNA; and each type contain 4 nucleotides

Nucleic Acids DNA- deoxyribonucleic acid, consists of 2 strands of nucleotides that spiral around each other Chromosomes contain long strands of DNA. Which stores hereditary information

DNA

Nucleic Acids RNA- ribonucleic acid; single strand of nucleotides Play many key roles in making proteins Can act as an enzyme, promoting the chemical reactions that link amino acids forming proteins

RNA

ATP “Adenosine Triphosphate” It is a single nucleotide with 2 extra energy-storing phosphate groups When food molecules are broken down inside cells, some of the energy in the molecules is stored temporarily in ATP Cells need steady supply of ATP to function

Energy and Chemical Reactions Energy- the ability to move or change matter We are surrounded by energy; electrical, kinetic, mechanical, thermal, and chemical One can be converted into the other Energy can be stored and released by chemical reactions

Chemical Reaction Chemical Reaction- is a process during which chemical bonds between atoms are broken and new ones are formed, producing 1 or more different substances Reactant- starting material Product- finishing material Chemical Reactions are written by chemical equations

Chemical Reaction A Chemical Reaction is written like this: Reactants  Products The arrow means “forms or changes”

Energy in Chemical Reactions Energy is absorbed or released when bonds are broken and formed Metabolism- all the chemical reactions that occur within an organism Your cells get most of the energy needed for metabolism from the food you eat; food is digested and chemical reactions convert the chemical energy in food to energy for cells

Activiation Energy Activiation Energy- energy needed to start a chemical reaction For a log to burn, ya gotta heat it up

Enzymes Most biochemical reactions- chemical reactions that occur in cells, need activation energy to begin The chemical reactions in cells occur quickly and at a relatively low temp. due to enzymes Enzyme- are substances that increase the speed of a chemical reaction ( by reducing the amount of activation energy)

Enzymes Enzymes help organisms maintain homeostasis W/out enzymes chemical reactions wouldn’t occur fast enough to sustain life p.40 gives an example

Enzyme Specificity Substrate- a substance on which an enzyme acts during a chemical reaction Enzymes act only on specific substrates An enzymes shape determines its activity An enzymes is typically a large protein with folds on its surface These folds form pockets called active sites

Enzyme Specificity Step 1- when an enzyme first attaches to a substrate during a chemical reaction, the enzyme shapes changes slightly so that substrate fit more tightly in the enzyme’s active site

Enzyme Specificity Step 2- at an active site, an enzyme and a substrate interact in a way that reduces the activation energy of a reaction, making the substrate more likely to react Step 3- the reaction is complete when products have formed. The enzyme is now free to catalyze further reactions

Factors in Enzyme Activity Any factor that can change the shape of the enzyme can change its effectiveness Usually have a temp range that they like, certain pH levels Those can change the bond which change its shape The enzymes that are active at any one time in a cell determine what happens in that cell