AP Chapter 5

Chapter 5

The Structure and Function of Large Biological Molecules

Overview: The Molecules of Life

          All living things are made up of four classes of large biological molecules: ___________________



          Within cells, small organic molecules are joined together to form larger molecules

          _____________________________________________ are large molecules composed of thousands of covalently connected atoms

          Molecular structure and function are _________________________________

Concept 5.1: Macromolecules are polymers, built from monomers

          A _________________________________ is a long molecule consisting of many similar building blocks

          These small building-block molecules are called __________________________________

          Three of the four classes of life’s organic molecules are polymers:




The Synthesis and Breakdown of Polymers

          A ___________________________________________________ or more specifically a _________________________________________________ occurs when two monomers bond together through the loss of a water molecule

          Enzymes are macromolecules that _____________________________ the dehydration process

          Polymers are disassembled to monomers by ________________________________, a reaction that is essentially the reverse of the dehydration reaction

The Diversity of Polymers

          Each cell has thousands of different kinds of macromolecules

          Macromolecules vary among cells of an organism, vary more within a species, and vary even more between species

          An immense variety of polymers can be built from a small set of monomers

Concept 5.2: Carbohydrates serve as fuel and building material

          _______________________________ include sugars and the polymers of sugars

          The simplest carbohydrates are _______________________________________, or single sugars

          Carbohydrate macromolecules are ________________________________________, polymers composed of many sugar building blocks


          Monosaccharides have molecular formulas that are usually multiples of _________________

          Glucose (_________________________________) is the most common monosaccharide

          Monosaccharides are classified by



          Though often drawn as ______________________ skeletons, in aqueous solutions many sugars form ______________

          Monosaccharides serve as a ________________________________________ for cells and as __________________________________________ for building molecules

          A _________________________________ is formed when a dehydration reaction joins two monosaccharides

          This covalent bond is called a ______________________________________________________


          ____________________________________, the polymers of sugars, have storage and structural roles

          The structure and function of a polysaccharide are determined by its sugar monomers and the _____________________________ of glycosidic linkages

Storage Polysaccharides

          _________________________________, a  storage polysaccharide of plants, consists entirely of glucose monomers

          Plants store surplus starch as granules within _________________________________________


          ____________________________________ is a storage polysaccharide in animals

          Humans and other vertebrates store glycogen mainly in _________________________________


Structural Polysaccharides

          The polysaccharide _______________________________ is a major component of the tough wall of plant cells

          Like starch, cellulose is a polymer of glucose, but the ___________________________________ differ

          The difference is based on two ring forms for glucose: alpha (a) and beta (b)    

          Polymers with a glucose are______________________________

          Polymers with b glucose are ______________________________

          In straight structures, ___________________ on one strand can bond with _______________________ on other strands

          Parallel cellulose molecules held together this way are grouped into ____________________________, which form strong building materials for plants

          Enzymes that digest starch by hydrolyzing a linkages _________________ hydrolyze b linkages in cellulose

          Cellulose in human food passes through the digestive tract as ____________________________


          Some __________________________ use enzymes to digest cellulose

          Many herbivores, from cows to termites, have _____________________________ relationships with these microbes

          ______________________________, another structural polysaccharide, is found in the exoskeleton of _________________________________________

          Chitin also provides __________________________________________________ for the cell walls of many fungi

Concept 5.3: Lipids are a diverse group of hydrophobic molecules

          _________________________ are the one class of large biological molecules that ___________

_____________ form polymers

          The unifying feature of lipids is having little or no ______________________________________

          Lipids are ________________________________ because they consist mostly of hydrocarbons, which form ____________________________ covalent bonds

          The most biologically important lipids are __________________, phospholipids, and steroids


          Fats are constructed from two types of smaller molecules: ________________________ and ______________________________________

          Glycerol is a ______________________________ alcohol with a ____________________ group attached to each carbon

          A fatty acid consists of a _________________________ group attached to a long carbon skeleton

          Fats separate from water because water molecules form _________________________ with each other and exclude the fats

          In a fat, three fatty acids are joined to glycerol by an ester linkage, creating a ________________________________________, or triglyceride

          Fatty acids vary in _________________ (number of carbons) and in the number and locations of _________________ bonds

          _______________________________ fatty acids have the maximum number of hydrogen atoms possible and __________________ double bonds

          ______________________________ fatty acids have one or more __________________ bonds

          Fats made from saturated fatty acids are called saturated fats, and are ___________________ at room temperature

          Most ____________________ fats are saturated

          Fats made from unsaturated fatty acids are called unsaturated fats or _____________, and are ____________________ at room temperature

          _________________ fats and _____________________ fats are usually unsaturated

          A diet rich in saturated fats may contribute to ____________________________________ disease through _______________________ deposits

          __________________________________________ is the process of converting unsaturated fats to saturated fats by adding hydrogen

          Hydrogenating vegetable oils also creates unsaturated fats with trans double bonds

          These trans fats may contribute more than saturated fats to cardiovascular disease

          The major function of fats is ____________________________________________

          Humans and other mammals store their fat in _________________________________ cells

          Adipose tissue also ___________________________ vital organs and _____________________ the body


          In a ___________________________, two fatty acids and a phosphate group are attached to glycerol

          The two fatty acid tails are _____________________________, but the phosphate group and its attachments form a _____________________________________ head

          When phospholipids are added to water, they self-assemble into a _______________________, with the hydrophobic tails pointing toward the interior

          The structure of phospholipids results in a bilayer arrangement found in ___________________


          Phospholipids are the major component of all cell membranes


          ____________________________ are lipids characterized by a carbon skeleton consisting of four fused rings

          _____________________________, an important steroid, is a component in animal cell membranes

          Although cholesterol is essential in animals, high levels in the blood may contribute to cardiovascular disease

Concept 5.4: Proteins have many structures, resulting in a wide range of functions

          Proteins account for more than ___________________ of the dry mass of most cells

          Protein functions include ________________________________________, ________________, _________________________, ____________________________________________________, ____________________________, and ______________________________________________

          _____________________________ are a type of protein that acts as a _____________________ to speed up chemical reactions

          Enzymes can perform their functions repeatedly, functioning as workhorses that carry out the processes of life


          _________________________________ are polymers built from the same set of 20 amino acids

          A ___________________ consists of one or more polypeptides

Amino Acid Monomers

          Amino acids are _________________________________________________________________


          Amino acids differ in their properties due to differing side chains, called ____________________

Amino Acid Polymers

          Amino acids are linked by _______________________________________

          A polypeptide is a polymer of amino acids

          Polypeptides range in _____________________ from a few to more than a thousand monomers

          Each polypeptide has a unique linear ________________________________ of amino acids

Protein Structure and Function

          A functional protein consists of one or more polypeptides __________________, ________________, and __________________ into a unique shape

          The ___________________________________ of amino acids determines a protein’s three-dimensional structure

          A protein’s _____________________________ determines its ___________________________

Four Levels of Protein Structure

          The ____________________ structure of a protein is its _________________ sequence of amino acids

          ____________________________________ structure, found in most proteins, consists of coils and folds in the polypeptide chain

          ____________________________________ structure is determined by interactions among various side chains (R groups)

          ____________________________________ results when a protein consists of multiple polypeptide chains

          Primary structure, the sequence of amino acids in a protein, is like the order of _____________ in a long word

          Primary structure is determined by ___________________________ genetic information

          The coils and folds of secondary structure result from __________________________________ between repeating constituents of the polypeptide backbone

          Typical secondary structures are a coil called an ______________________ and a folded structure called a _____________________________________

          Tertiary structure is determined by interactions between _______________________________, rather than interactions between backbone constituents

          These interactions between R groups include __________________________, _____________________________, ____________________________________________, and __________________________________________ interactions

          Strong covalent bonds called ___________________________________ may reinforce the protein’s structure

          Quaternary structure results when two or more polypeptide chains form one ______________________________________

          __________________________ is a fibrous protein consisting of three polypeptides coiled like a rope

          _______________________________ is a globular protein consisting of four polypeptides: two alpha and two beta chains

Sickle-Cell Disease: A Change in Primary Structure

          A slight ____________________ in primary structure can affect a protein’s structure and ability to function

          Sickle-cell disease, an inherited blood disorder, results from a single amino acid _____________________________ in the protein hemoglobin

What Determines Protein Structure?

          In addition to primary structure, _______________________ and _______________________ conditions can affect structure

          Alterations in pH, salt concentration, temperature, or other environmental factors can cause a protein to _________________________

          This loss of a protein’s native structure is called _______________________________________

          A denatured protein is biologically _____________________________

Protein Folding in the Cell

          It is hard to predict a protein’s structure from its primary structure

          Most proteins probably go through several states on their way to a ____________________ structure

          _______________________________________ are protein molecules that assist the proper folding of other proteins

          Scientists use _____________________________________________ to determine a protein’s structure

          Another method is __________________________________________________ (NMR) spectroscopy, which does not require protein crystallization

          Bioinformatics uses computer programs to ________________________ protein structure from amino acid sequences

Concept 5.5: Nucleic acids store and transmit hereditary information

          The amino acid sequence of a polypeptide is programmed by a unit of inheritance called a ______________________

          Genes are made of DNA, a ____________________________________

The Roles of Nucleic Acids

          There are two types of nucleic acids:



          DNA provides __________________________________ for its own replication

          DNA directs synthesis of ______________________________________ and, through mRNA, controls protein synthesis

          Protein synthesis occurs in _____________________________

The Structure of Nucleic Acids

          Nucleic acids are polymers called ___________________________________________

          Each polynucleotide is made of monomers called _________________________________

          Each nucleotide consists of a _________________________________, a ______________________________, and a ______________________________________

          The portion of a nucleotide without the phosphate group is called a nucleoside

Nucleotide Monomers

          Nucleoside = nitrogenous base + sugar

          There are two families of nitrogenous bases:

        _____________________________________(cytosine, thymine, and uracil) have a single six-membered ring

        _________________________________(adenine and guanine) have a six-membered ring fused to a five-membered ring

          In DNA, the sugar is _______________________________; in RNA, the sugar is ______________

          Nucleotide = nucleoside + phosphate group

Nucleotide Polymers

          Nucleotide polymers are linked together to build a polynucleotide

          Adjacent nucleotides are joined by covalent bonds that form between the ___________________________ on the 3¢ carbon of one nucleotide and the ___________________________on the 5¢ carbon on the next

          These links create a backbone of __________________________________________ units with _____________________________________________ as appendages

          The sequence of bases along a DNA or mRNA polymer is _____________________ for each gene

The DNA Double Helix

          A DNA molecule has two polynucleotides spiraling around an imaginary axis, forming a __________________________________________

          In the DNA double helix, the two backbones run in opposite _____________________________ directions from each other, an arrangement referred to as ______________________________

          One DNA molecule includes many genes

          The nitrogenous bases in DNA pair up and form hydrogen bonds: __________________________________________________________________________, and __________________________________________________________________________

DNA and Proteins as Tape Measures of Evolution

          The linear sequences of nucleotides in DNA molecules are passed from _________________ to ___________________________

          Two closely related species are more __________________________ in DNA than are more distantly related species

          Molecular biology can be used to assess ____________________________________ kinship

The Theme of Emergent Properties in the Chemistry of Life: A Review

          Higher levels of organization result in the emergence of new properties

          Organization is the key to the chemistry of life