Atoms, Molecules, and Life Chapter 2 Atoms, Molecules, and Life

2.4 Why Is Carbon So Important To Life? Carbon can combine with other atoms in many ways to form a huge number of different molecules. This is possible because carbon has _______________ in its outermost shell, leaving room for four more electrons from other atoms. Therefore, carbon can form many bonds with other atoms.

2.4 Why Is Carbon So Important To Life? The great variety of substances found in nature is therefore constructed from a limited pool of atoms. Organic molecules have a ____________ and some __________________. Much of the diversity of organic molecules is due to the presence of functional groups.

2.4 Why Is Carbon So Important To Life?

2.4 Why Is Carbon So Important To Life? PLAY Animation—Functional Groups

2.5 How Are Biological Molecules Joined Together Or Broken Apart? Dehydration synthesis The construction of large molecules yields ___________. Small molecules are joined together to form large molecules. During the joining of small molecules, water is released. This water-releasing reaction is called ____________________.

2.5 How Are Biological Molecules Joined Together Or Broken Apart? Dehydration synthesis dehydration synthesis + O HO O H HO OH HO OH O H H (a) Dehydration synthesis Fig. 2-12a

2.5 How Are Biological Molecules Joined Together Or Broken Apart? Hydrolysis reactions During the breakdown of large molecules, __________________ bonds are broken, separating the subunits

2.5 How Are Biological Molecules Joined Together Or Broken Apart? Hydrolysis hydrolysis + O HO OH HO O H HO OH O H H (b) ___________________________________ Fig. 2-12b

2.5 How Are Biological Molecules Joined Together Or Broken Apart? PLAY Animation—Dehydration Synthesis and Hydrolysis

2.6 What Are Carbohydrates? Carbohydrates are molecules composed of_________,___________, and ___________ in the ratio of 1:2:1. They can be small single sugar molecules or long chains of single sugar molecules strung together.

2.6 What Are Carbohydrates? A simple sugar CH2OH H O H H H O H H H H 6 5 4 3 2 1 H C C C C C C H HO OH H OH O O O H O O H H H H H OH (a) Glucose, linear form (b) Glucose, ring form Fig. 2-13

2.6 What Are Carbohydrates? ___________________ : a carbohydrate consisting of one sugar molecule Disaccharide: _________ sugars linked together Polysaccharide: three or more sugars linked together

2.6 What Are Carbohydrates? Simple sugars, such as glucose, provide important _________ sources for organisms. Sucrose, such as table sugar, is a disaccharide containing one __________ molecule attached to a ___________ molecule.

2.6 What Are Carbohydrates? Manufacture of a disaccharide glucose fructose sucrose CH2OH CH2OH O HOCH2 O O HOCH2 O H H H H H H H H + dehydration synthesis OH H H HO OH H O H HO HO O H HO CH2OH HO CH2OH H OH OH H H OH OH H O H H Fig. 2-14

2.6 What Are Carbohydrates? PLAY Animation—Carbohydrates

2.6 What Are Carbohydrates? Some complex sugars, such as _____________, provide support for cells or even the entire bodies of organisms. Complex sugars are made by the dehydration synthesis of simple sugars. Cellulose is the most _________________ on Earth because it provides support for plants in fields and forests. Cellulose is made of long chains of ____________ subunits.

2.6 What Are Carbohydrates? Cellulose structure wood is mostly cellulose plant cell with cell wall close-up of cell wall Hydrogen bonds cross-linking cellulose molecules CH2OH H OH CH2OH H OH O O H H H H H O OH H H O OH H O OH H H O OH H H O H H H H individual cellulose molecules bundle of cellulose molecules cellulose fiber O O H OH CH2OH H OH CH2OH Fig. 2-15

2.6 What Are Carbohydrates? PLAY Animation—Carbohydrate Functions PLAY Animation—Structure Determines Function

Molecular characteristics of lipids 2.7 What Are Lipids? Molecular characteristics of lipids Lipids are molecules with long regions composed almost entirely of ___________ and __________________. The ______________ regions of carbon and hydrogen bonds make lipids hydrophobic and insoluble in water.

2.7 What Are Lipids? Lipid classification Group 1: Oils,__________, and waxes Group 2:_______________ Group 3: Steroids

Group 1: Oils, fats, and waxes 2.7 What Are Lipids? Group 1: Oils, fats, and waxes Contain only carbon, hydrogen, and oxygen Contain one or more fatty acid subunits—long chains of C and H with a ________________ (–COOH) They usually ____________ have a ring structure.

Group 1: Oils, fats, and waxes (continued) 2.7 What Are Lipids? Group 1: Oils, fats, and waxes (continued) Fats and oils form by dehydration synthesis from three fatty acid subunits and one molecule of __________________. etc. CH2 CH2 CH2 H O CH H C OH HO C CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH O H C OH + HO C CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 etc. O H C OH HO C CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 etc. H glycerol fatty acids Fig. 2-16

Group 1: Oils, fats, and waxes (continued) 2.7 What Are Lipids? Group 1: Oils, fats, and waxes (continued) Fats and oils formed by dehydration synthesis are called______________. Triglycerides are used for ___________________ energy storage in both plants and animals. etc. CH2 CH2 CH2 O H O CH + H H H C O C CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH O O + H H H C O C CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 etc. O O H C O C CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 etc. + H H H 3 water molecules triglyceride Fig. 2-16

2.7 What Are Lipids? PLAY Animation—Lipids

Group 1: Oils, fats, and waxes (continued) 2.7 What Are Lipids? Group 1: Oils, fats, and waxes (continued) Characteristics of fats Fats are ___________ at room temperature. Fats have all carbons joined by single covalent bonds. The remaining bond positions on the carbons are occupied by hydrogen atoms.

Group 1: Oils, fats, and waxes (continued) 2.7 What Are Lipids? Group 1: Oils, fats, and waxes (continued) Fatty acids of fats are said to be saturated and are straight molecules that can be stacked. (a) Beef fat (saturated) Fig. 2-18a

Group 1: Oils, fats, and waxes (continued) 2.7 What Are Lipids? Group 1: Oils, fats, and waxes (continued) Characteristics of oils Oils are ____________ at room temperature. Some of the carbons in fatty acids have double covalent bonds. There are fewer attached hydrogen atoms, and the fatty acid is said to be________________.

Group 1: Oils, fats, and waxes (continued) 2.7 What Are Lipids? Group 1: Oils, fats, and waxes (continued) Unsaturated fatty acids have bends and kinks in fatty acid chains and can’t be stacked. (b) Peanut oil (unsaturated) Fig. 2-18b

Group 1: Oils, fats, and waxes (continued) 2.7 What Are Lipids? Group 1: Oils, fats, and waxes (continued) Characteristics of waxes Waxes are _________ at room temperature. Waxes are highly________________. Waxes are not a food source. Waxes form _________________ over plant leaves and stems.

Group 1: Oils, fats, and waxes (continued) 2.7 What Are Lipids? Group 1: Oils, fats, and waxes (continued) Bees use waxes to store food and honey. Fig. 2-17b

2.7 What Are Lipids? PLAY Animation—Lipid Function

2.7 What Are Lipids? Group 2: Phospholipids Phospholipids have _____________ heads and _________________ tails. They are found in cell membranes in a double layer. They are like ____________ except one fatty acid is replaced by a phosphate group attached to glycerol.

Group 2: Phospholipids (continued) 2.7 What Are Lipids? Group 2: Phospholipids (continued) The _______________ end of the molecule is water soluble; the fatty acid end of the molecule is water insoluble. CH3 CH2 CH2 CH3 O– CH2 CH2 CH2 H3C - N+ - CH2 - CH2 - O - P - O - CH2 O CH2 CH2 CH CH3 O HC - O - C - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH O H2C - O - C - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH3 polar head glycerol fatty acid tails (hydrophilic) (hydrophobic) Fig. 2-19

2.7 What Are Lipids? Group 3: Steroids Steroids contain _____________ carbon rings fused together. Various functional groups protrude from the basic steroid “skeleton”. _________________________ is a steroid found in cell membranes.

2.7 What Are Lipids? Group 3: Steroids _____________________ and estrogen are male and female reproductive hormones, respectively, and are steroids. OH CH3 CH3 HC CH3 CH2 HO CH2 (b) Estrogen CH2 HC CH3 OH CH3 CH3 CH3 CH3 HO O (a) Cholesterol (c) Testosterone Fig. 2-20

2.8 What Are Proteins? Functions of proteins Proteins act as _______________ to catalyze many biochemical reactions. They can act as energy______________. They are involved in ______________ around the body. They are involved in muscle______________.

2.8 What Are Proteins? Some proteins are ______________ and provide support in hair, horns, spider webs, etc. Fig. 2-21

Proteins are formed from chains of _________________. 2.8 What Are Proteins? Proteins are formed from chains of _________________. All amino acids have the same basic structure: A central _____________ An attached ________________ An attached carboxyl group An attached variable side group

2.8 What Are Proteins? Amino acid structure variable group R H O amino group carboxylic acid group N C C H O H H hydrogen Fig. 2-22

Amino acids join to form chains by dehydration synthesis. 2.8 What Are Proteins? Amino acids join to form chains by dehydration synthesis. Proteins are formed by ____________ reactions between individual amino acids. The –NH2 group of one amino acid is joined to the –COOH group of another, with the release of H2O and the formation of a new peptide (two or more amino acids).

2.8 What Are Proteins? More and more individual amino acids are added to the peptide until a ___________________ (protein) is formed. amino acid amino acid peptide water H R O H R O H R O H R O N C C + N C C N C C N C C + O H H O H H H O H H H H O H H H amino group carboxylic acid group amino group peptide bond Fig. 2-23

2.8 What Are Proteins? PLAY Animation—Proteins

Three-dimensional shapes give proteins their functions. 2.8 What Are Proteins? Three-dimensional shapes give proteins their functions. Long chains of amino acids fold into __________________ in cells, which allows the protein to perform its specific functions. When a protein is denatured, its shape has been disrupted and it may not be able to __________________ its function.

2.8 What Are Proteins? (a) Primary structure: The sequence of amino acids linked by peptide bonds (b) Secondary structure: Folding usually maintained by hydrogen bonds leu H R H N C C N val H C O H C H lys C N O N C O C lys H H C C N gly C N O C O H his C H C O C N N hydrogen bond O ala C H H C C lys N C N O C O (c) Tertiary structure: Folding results from bonds with surrounding water molecules and between amino acids val C H C O N O lys helix (d) Quaternary structure: Individual polypeptides are linked to one another pro Fig. 2-24

2.8 What Are Proteins? PLAY Animation—Protein Function

Structure of nucleic acids 2.9 What Are Nucleic Acids? Structure of nucleic acids Nucleic acids are long chains of similar, but__________________ , subunits called________________________.

Structure of nucleic acids (continued) 2.9 What Are Nucleic Acids? Structure of nucleic acids (continued) All nucleotides have three parts. A five-________ sugar (ribose or deoxyribose) A _____________ group A nitrogen-containing molecule called a base

Deoxyribose nucleotide 2.9 What Are Nucleic Acids? Deoxyribose nucleotide base NH2 phosphate C N C N OH HC O C CH N HO P O CH2 N O sugar H H H H OH H Fig. 2-25

2.9 What Are Nucleic Acids? Types of nucleotides Those that contain the sugar____________. Those that contain the sugar_____________. Nucleotides string together in long chains as nucleic acids with the phosphate group of one nucleotide bonded to the sugar group of another.

2.9 What Are Nucleic Acids? Nucleotide chain base sugar phosphate Fig. 2-26

DNA and RNA, the molecules of ____________, are nucleic acids. 2.9 What Are Nucleic Acids? DNA and RNA, the molecules of ____________, are nucleic acids. There are two types of nucleic acids. ______________________(DNA): contains the genetic code of cell Ribonucleic acid (RNA): is used in the synthesis of________________

2.9 What Are Nucleic Acids? Animation—Nucleic Acids PLAY Animation—Nucleic Acids PLAY Animation—Nucleic Acids

Other nucleotides perform other functions. 2.9 What Are Nucleic Acids? Other nucleotides perform other functions. Adenosine monophosphate: acts as a _____________ in the cell, carrying information to other molecules Adenosine triphosphate: carries ______________ from place to place in the cell