Carbon & Molecules of Life

Organic Compounds Hydrogen and other elements covalently bonded to carbon Carbohydrates Lipids Proteins Nucleic Acids

p.34a sodium (Na) chlorine (Cl) magnesium (Mg) iron (Fe) calcium (Ca) phosphorous (P) potassium (K) sulfur (S) carbon (C) oxygen (O) hydrogen (H) nitrogen (N) Organic Compounds

structural formula for methane ball-and-stick modelspace-filling model p.34b Organic Compounds

Carbon’s Bonding Behavior Outer shell of carbon has 4 electrons; can hold 8 Each carbon atom can form covalent bonds with up to four atoms

Bonding Arrangements Carbon atoms can form chains or rings Other atoms project from the carbon backbone

or p.34e Simplified structural formula for a six-carbon ring icon for a six-carbon ring Organic Compounds

Fig. 3-2, p.35 Organic Compounds

Isomers Structural isomers – differ in the arrangement of their atoms Geometric isomers – differ in the arrangement of atoms around a double bond Enantiomers – Chiral Molecules – ◦ Molecules are mirror images of each other ◦ Cells can tell the two apart ◦ Usually one is biologically active while the other is not

Polymers Large molecules made by linking many individual building blocks together in long chains The building block subunits are called monomers Subunits are linked by a reaction called dehydration synthesis Can be cleaved by a reaction called hydrolysis

Functional Groups Atoms or clusters of atoms that are covalently bonded to carbon backbone Give organic compounds their different properties

Examples of Functional Groups Hydroxyl group - OH Amino group- NH 3 + Carboxyl group- COOH Phosphate group- PO 3 - Sulfhydryl group- SH

Common Functional Groups in Biological Molecules Fig. 3-4, p.36

Functional Groups in Hormones Estrogen and testosterone are hormones responsible for observable differences in traits between male and female wood ducks Differences in position of functional groups attached to ring structure (pg 63) An EstrogenTestosterone

Fig. 3-5b, p.36

Dehydration Synthesis Reactions Form polymers from subunits Enzymes remove -OH from one molecule, H from another, form bond between two molecules Discarded atoms can join to form water Also called condensation reactions

Dehydration Synthesis Fig. 3-6a, p.38

Hydrolysis A type of cleavage reaction Breaks polymers into smaller units Enzymes split molecules into two or more parts An -OH group and an H atom derived from water are attached at exposed sites

Hydrolysis Fig. 3-6b, p.38

Carbohydrates Monosaccharides (simple sugars) Oligosaccharides (short-chain carbohydrates) Polysaccharides (complex carbohydrates)

Monosaccharides Simplest carbohydrates Most are sweet tasting, water soluble Most have 5- or 6-carbon backbone Glucose (6 C)Fructose (6 C) Ribose (5 C)Deoxyribose (5 C)

Two Monosaccharides glucosefructose Fig. 3-7, p.38

Disaccharides Type of oligosaccharide Two monosaccharides covalently bonded Formed by condensation reaction + H 2 O glucosefructose sucrose Fig. 3-7b, p.38

Polysaccharides Straight or branched chains of many sugar monomers Most common are composed entirely of glucose ◦ Cellulose ◦ Starch (such as amylose) ◦ Glycogen

Cellulose & Starch Differ in bonding patterns between monomers Cellulose - tough, indigestible, structural material in plants Starch - easily digested, storage form in plants

Cellulose and Starch Fig. 3-8, p.38

Glycogen Sugar storage form in animals Large stores in muscle and liver cells When blood sugar decreases, liver cells degrade glycogen, release glucose Fig. 3-9, p.38

Chitin Polysaccharide Nitrogen-containing groups attached to glucose monomers Structural material for hard parts of invertebrates, cell walls of many fungi

Chitin Chitin occurs in protective body coverings of many animals, including ticks Fig. 3-10a, p.39

Fig. 3-10b, p.39

Lipids Most include fatty acids ◦ Fats ◦ Phospholipids ◦ Waxes Sterols and their derivatives have no fatty acids Tend to be insoluble in water

Fats Fatty acid(s) attached to glycerol Triglycerides are most common Fig. 3-12, p.40

Fatty Acids Carboxyl group (-COOH) at one end Carbon backbone (up to 36 C atoms) ◦ Saturated - Single bonds between carbons ◦ Unsaturated - One or more double bonds

Three Fatty Acids Fig. 3-11, p.40

Phospholipids Main components of cell membranes

Waxes Long-chain fatty acids linked to long chain alcohols or carbon rings Firm consistency, repel water Important in water-proofing

Waxes Bees construct honeycombs from their own waxy secretions Fig. 3-14, p.41

Sterols and Derivatives No fatty acids Rigid backbone of four fused-together carbon rings Cholesterol - most common type in animals Fig. 3-14, p.41

Amino Acid Structure amino group carboxyl group R group

Properties of Amino Acids Determined by the “R group” Amino acids may be: ◦ Non-polar ◦ Uncharged, polar ◦ Positively charged, polar ◦ Negatively charged, polar

Protein Synthesis Protein is a chain of amino acids linked by peptide bonds Peptide bond ◦ Type of covalent bond ◦ Links amino group of one amino acid with carboxyl group of next ◦ Forms through condensation reaction

Fig. 3-15b, p.42

Fig. 3-15c, p.42

Fig. 3-15d, p.42

Fig. 3-15e, p.42

Primary Structure Sequence of amino acids Unique for each protein Two linked amino acids = dipeptide Three or more = polypeptide Backbone of polypeptide has N atoms: -N-C-C-N-C-C-N-C-C-N- one peptide group

Protein Shapes Fibrous proteins ◦ Polypeptide chains arranged as strands or sheets Globular proteins ◦ Polypeptide chains folded into compact, rounded shapes

Primary Structure & Protein Shape Primary structure influences shape in two main ways: ◦ Allows hydrogen bonds to form between different amino acids along length of chain ◦ Puts R groups in positions that allow them to interact

Secondary Structure Hydrogen bonds form between different parts of polypeptide chain These bonds give rise to coiled or extended pattern Helix or pleated sheet

Examples of Secondary Structure

Tertiary Structure Folding as a result of interactions between R groups heme group coiled and twisted polypeptide chain of one globin molecule

Quaternary Structure Some proteins are made up of more than one polypeptide chain Hemoglobin

heme alpha globin beta globin Fig. 3-17, p.44

Polypeptides with Attached Organic Compounds Lipoproteins ◦ Proteins combined with cholesterol, triglycerides, phospholipids Glycoproteins ◦ Proteins combined with oligosaccharides

Denaturation Disruption of three-dimensional shape Breakage of weak bonds Causes of denaturation: ◦ pH ◦ Temperature Destroying protein shape disrupts function

Nucleotide Structure Sugar ◦ Ribose or deoxyribose At least one phosphate group Base ◦ Nitrogen-containing ◦ Single or double ring structure

Nucleotide Functions Energy carriers Coenzymes Chemical messengers Building blocks for nucleic acids

ATP - A Nucleotide three phosphate groups sugar base

Nucleic Acids Composed of nucleotides Single- or double-stranded Sugar-phosphate backbone Adenine Cytosine

Bonding Between Bases in Nucleic Acids THYMINE (T) base with a single-ring structure CYTOSINE (C) base with a single-ring structure Fig. 3-20, p.46

DNA Double-stranded Consists of four types of nucleotides A bound to T C bound to G

RNA Usually single strands Four types of nucleotides Unlike DNA, contains the base uracil in place of thymine Three types are key players in protein synthesis