Chapter 2: Chemistry What does chemistry have to do with biology? BIO 105 Vocabulary 1. Matter anything that takes up space and has mass Atoms are the smallest units of matter that can participate in chemical reactions 2. Mass measure of how much matter is contained within an object 3. Atom smallest unit of matter that cannot be broken down by ordinary chemical means 1
Elements Definition an element is a pure form of matter that contains a single type of atom Of all of the elements listed on the periodic table, only 20 or so are represented in the human body. 2
Atomic # Atomic mass Element symbol The Periodic Table Practice Practice Element # protons # neutrons # electrons C H O P Mg K Element # protons # neutrons # electrons C 6 6 6 H 1 0 1 O 8 8 8 P 15 16 15 Mg 12 12 12 K 19 20 19 3
Isotopes & Radioisotopes Although all the atoms of a particular element contain the same number of protons, they do not necessarily all have the same number of neutrons. Atoms that have the same number of protons but differ in # of neutrons are called isotopes. i.e. C 12, C 13, C 14 Radioisotopes are unstable, radiation-emitting isotopes. Uses of Radiation Uses of radiation 4
Chemical bonds When atoms from two or more different elements are combined to form a new chemical substance, a compound is formed. The atoms that make up these compounds are held together by chemical bonds. Covalent bonding Covalent bonds form when two or more atoms share electrons in their outer orbitals. The number of bonds an atom can form depends on how many empty spots exist in the outer shell. Each pair of electrons is shared equally between the carbon and individual hydrogen atoms. 5
A molecule is a chemical structure held together by covalent bonds. It may be composed of atoms of one or more elements. Ionic bonding Ionic bonding results from the mutual attraction of oppositely charged ions. Ion = charged atom 6
Hydrogen bonding Hydrogen bonding is the result of polar covalent bonds. Atoms may have a slight negative or positive charge depending on electron distribution. Polar molecules Water as a solvent Water is considered the best polar solvent, due to its ability to form hydrogen bonds with other molecules. 7
Solvent Transport medium Properties of water High heat capacity High heat of vaporization Lubricant Dehydration Synthesis When dehydration reactions occur, a larger product is formed. In the process, one molecule of H 2 O is produced. Dehydration Synthesis example 8
Hydrolysis Reactions These types of reactions occur when we are breaking down a large molecule into smaller pieces. Acids, bases, and salts When an acid is added to water, it dissociates into H + and one or more ions. The concentration of hydrogen ions is increased. H 2 CO 3 H + + HCO 3 - Acids, bases, and salts cont. Bases, on the other hand, remove H + from solution and are therefore proton acceptors. HCl + NaOH H + + Cl - + Na + + OH - NaCl + H 2 O Bases decrease the amount of free H + present in an aqueous solution. 9
ph scale The ph scale is a measure of the concentration of free H + in a solution in moles/l. ph is the negative logarithm of the H + concentration in a solution ph = - log 10 [H + ] ph A solution with a H + concentration of 1 x 10-4 has a ph of. Is this classified as an acid or a base? **A change of one whole number on the ph scale represents a tenfold change in the H + concentration.** 10
a. ph = 9 b. ph = 7 c. ph = 3 d. ph = 1 Which solution has the highest concentration of free H +? A solution with a ph of 6: a. is an acid b. is a base c. has 10 times more H + ions than a solution with a ph of 5 d. both a and c above Buffers A buffering system is composed of a mixture of two compounds * One substance can yield free H + when [H + ] drops * One substance binds with free H + when [H + ] increases What are the four classifications of macromolecules? Bicarbonate/carbonic acid buffering system CO 2 + H 2 O H 2 CO 3 H + + HCO3-11
Biomolecules Biomolecules are made up of repeating subunits called monomers. When these monomers are attached together in a chain they are referred to as polymers. Carbohydrates Monosaccharides Composed of three types of atoms: Ratio between the atom types: Monomer = monosaccharides (simple sugars) have from 3-9 carbons within their structure 12
Disaccharides Disaccharides are formed by the covalent linkage of two monosaccharides. Common disaccharides Polysaccharides Maltose = Sucrose = Lactose = 13
Functions of carbohydrates 1. Energy storage 2. Energy production Lipids Biological molecules that are insoluble in water (hydrophobic) but soluble in organic solvents Simplest type of lipid is called a fatty acid. 3. Cell recognition Saturated vs. unsaturated fats 14
1. Triglycerides Lipid subclasses 2. Phospholipids 3. Steroids Triglycerides 15
Triglycerides Long-term energy storage Phospholipids Stored in the cells of adipose (fat) tissue Protection Insulation Steroids 16
Proteins Proteins are made up of monomers called amino acids. 17
Peptide bond formation Protein formation Sickle Cell Anemia 18
1. Structural 2. Hormones 3. Contraction 4. Transport 5. Immune 6. Enzymes Protein functions 19
Nucleic acids Sugars that make up nucleotides Nucleic acids are made of monomers called nucleotides. 20
Nitrogenous bases Deoxyribonucleic acid (DNA) Cytosine (C) Thymine (T) Uracil (U) double-stranded molecule sugar = deoxyribose nucleotides = A,T,C,G specific base pairing A & T G & C Adenine (A) Guanine (G) RNA Structure Differs from DNA single stranded uracil replaces thymine Types of RNA within the cell, each with a specific function messenger (m)rna ribosomal (r)rna transfer (t)rna 21
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