Chapter 5: The Structure and Function of Large Molecules

Question 1

Four Main Classes of Macromolecules

Answer 1

carbohydrates, lipids, proteins, and nucleic acids

Question 2

Polymer

Answer 2

is a long molecule consisting of many similar or identical building blocks linked by covalent bonds, much as a train consists of a chain of cars

Question 3

Monomers

Answer 3

the repeating units that serve as the building blocks of a polymer

Question 4

Enzymes

Answer 4

specialized macromolecules that speed up chemical reactions

Question 5

Chemical Reactions

Answer 5

the chemical mechanisms by which cells make and break down polymers

Question 6

Dehydration Reaction

Answer 6

reaction in which two molecules are covalently bonded to each other with the loss a water molecule (one monomer provides hydroxyl group –OH and another provides a —-H)

Question 7

Hydrolysis

Answer 7

bond between monomer is broken by the addition of a water molecule with a hydrogen from water attaching to one monomer and the hydroxyl group attaching to the other

Question 8

Monosaccharides

Answer 8

generally have molecular formulas that are some multiple of the unit CH2O (i.e. Glucose C6H12O6)

Question 9

Trademarks of a Sugar

Answer 9

the molecule has a carbonyl group and multiple hydroxyl groups; aldose = Carbonyl group at end of carbon skeleton; ketose = carbonyl group within skeleton; size of carbon skeleton (3, 5, and 6)

Question 10

Function of Monosaccharides/Simple Sugars

Answer 10

major nutrients for cells (through cellular respiration cells extracts energy); their carbon skeletons serve as raw material for the synthesis of other types of small organic molecules (i.e. amino acids and fatty acids)

Question 11

Disaccharide

Answer 11

consists of two monosaccharides by glycosidic linkage (must be broken down into monosaccharides to be used for energy by organisms)

Question 12

Glycosidic Linkage

Answer 12

covalent bond formed between two monosaccharides by a dehydration reaction

Question 13

Linear and Ring Forms of Glucose

Answer 13

chemical equilibrium (condition in the course of reversible chemical reaction in which no net change in reactants/products) between the linear and ring structures greatly favors the formation of rings

Question 14

Polysaccharides

Answer 14

macromolecules, polymers with a few hundred to few thousand monosaccharides joined by glycosidic linkages (serve as storage, hydrolyzed as needed to provide sugar for cells)

Question 15

Polysaccharides: Structure and Function

Answer 15

architecture and function of a polysaccharide are determined by its sugar monomers and by the positions of its glycosidic linkages

Question 16

Starch (Storage Polysaccharides)

Answer 16

a polymer of glucose monomer (unbranched amylose with 1-4 linkage and more complex branched amylopectin with 1-6 linkage form helix), as granules within cellular structures known as plastids includes chloroplasts (stored energy that releases by hydrolysis)

Question 17

Glycogen (Storage Polysaccharides)

Answer 17

a polymer of glucose that is like amylopectin but more extensively branched/helix = more free ends for hydrolysis (stored energy in liver & muscle cells–hydrolysis of glycogen in cells release sugar when demand rises/deplete fast)

Question 18

Cellulose (Structural Polysaccharides)

Answer 18

Major component of the tough walls that enclose plant cells (never branched; hydroxyl groups on its glucose monomers are free to hydrogen-bon with hydroxyls of cellulose molecules lying parallel to it due to every beta glucose ring (upside down)) enzymes can digest starch by hydrolyzing its alpha linkages but can’t hydrolyze beta linkages)

Question 19

Chitin (Structural Polysaccharides)

Answer 19

the carbohydrate used by arthropods to build the exoskeleton (similar to cellulose with beta linkages with a nitrogen-containing attachment)

Question 20

Lipids

Answer 20

any of a group of large biological molecules (doesn’t include true polymers) that mix poorly, if at all, with water. Although they may have some polar bonds associated with oxygen, they consist mostly of hydrocarbon regions

Question 21

Fat (Lipid)

Answer 21

large molecules assembled from smaller molecules (glycerol and fatty acids) by dehydration reactions

Question 22

Glycerol

Answer 22

an alcohol that each of it’s 3 carbon bears a hydroxyl group

Question 23

Fatty Acid

Answer 23

long carbon skeleton (16-18 carbon atoms); carboxyl group at one end = acid; rest consist of hydrocarbon chain = nonpolar C–H bonds makes fats hydrophobic

Question 24

Ester Linkage

Answer 24

linkage that joins 3 fatty acids to glycerol by a dehydration reaction between hydroxyl group and carboxyl group

Question 25

Triacylglycerol (Triglyceride)

Answer 25

consists of 3 fatty acids linked to one glycerol molecule

Question 26

Saturated Fatty Acid

Answer 26

no double bonds between carbon atoms composing a chain, as many hydrogen atoms as possible are bonded to the carbon skeleton; solid at room temperature = lack of double bonds allows flexibility for fat molecules to pack together tightly; most animal fats

Question 27

Unsaturated Fatty Acid

Answer 27

has one or more double bonds, with one fewer hydrogen atom on each double-bonded carbon (cis double bond creates a kink in hydrocarbon chain); liquid at room temperature ; kinks in cis double bonds prevent the molecules from packing together closely enough to solidify at room temperature

Question 28

Trans Fatty Acid

Answer 28

an unsaturated fat, formed artificially during hydrogenation of oils, containing one or more trans double bonds

Question 29

Fats Function

Answer 29

energy storage; a gram of fat stores twice a much energy as a gram of a polysaccharide

Question 30

Adipose Cells

Answer 30

stores long-term food reserves for human/mammals; cushions some vital organs; layer of fat under skin insulates body

Question 31

Phospholipids (Lipid)

Answer 31

major constituents of cell membranes; like fat molecule but has only two fatty acids (one with a cis double bond) attached to glycerol; 3rd hydroxyl group joins to phosphate group with negative charge; typically an additional polar molecule (i.e. Choline) is also linked to the phosphate group allowing formation of a variety of phospholipids that differ from each other; head is hydrophilic and tail is hydrophobic

Question 32

Phospholipids in Water

Answer 32

phospholipids self-assemble into a double-layer sheet called a “bilayer” that shields their hydrophobic fatty acid tails from water

Question 33

Cell Membrane

Answer 33

hydrophilic heads are on the outside of the bilayer in contact with aqueous solutions inside and outside cell; hydrophobic tails point toward the interior of the bilayer, away from water; forms a boundary between the cell and its external environment; establishes separate compartments within eukaryotic cells; existence of cells depends on the properties of phospholipids

Question 34

Steroids (Lipids)

Answer 34

characterized by a carbon skeleton consisting of four fused rings; different steroids are distinguished by the particular chemical groups attached to this ensemble of rings

Question 35

Cholesterol (Steroid)

Answer 35

crucial molecule in animals = common component of animal cell membranes, molecule from which other steroids (i.e. vertebrate sex hormones) are synthesized

Question 36

Catalyst

Answer 36

Chemical agents that selectively speed up chemical reactions without being consumed in the reaction

Question 37

Peptide Bond

Answer 37

when two amino acids are positioned so that the carboxyl group of one is adjacent to amino group joined through dehydration

Question 38

Polypeptide

Answer 38

polymer of amino acids

Question 39

Protein

Answer 39

one or more polypeptides, each folded and coiled into a specific three-dimensional structure (all proteins constructed same set of 20 amino acids) = backbone of protein is everything except side chains (amino end & carboxyl end)

Question 40

Amino Acid

Answer 40

alpha carbon (4 different partners): a amino group, a carboxyl group, a hydrogen atom, and side chains/R group (protein monomer)

Question 41

Protein Functions

Answer 41

enzymatic, defensive, storage of amino acids, transport, hormonal, receptor and motor

Question 42

Primary Structure

Answer 42

linking of amino acids by inherited genetic information (not random); dictates structure of secondary & tertiary due to the chemical nature of the backbone and the side chains of the amino acids

Question 43

Secondary Structure

Answer 43

are the result of hydrogen bonds between the ionized (-) oxygen atoms of carboxyl group and ionized (+) hydrogen atoms attached to nitrogen

Question 44

Secondary Structure Helix

Answer 44

delicate coil held together by hydrogen bonding between every fourth amino acid

Question 45

Secondary Structure Pleated

Answer 45

polypeptide chain lying side by side connected by hydrogen bonds between parts of the two parallel segments of polypeptide backbone

Question 46

Tertiary Structure

Answer 46

overall shape of a polypeptide resulting from interactions between side chains of various amino acids

Question 47

Hydrophobic Interaction

Answer 47

amino acids with hydrophobic (nonpolar) side chains usually end up in clusters at end up in clusters at the core of the protein, out of contact with water = contributes to tertiary structure

Question 48

Disulfide Bridges

Answer 48

where two cysteine monomers, which have sulfhydryl groups (–SH) on their side chairs are brought close together by folding of protein

Question 49

Quaternary Structure

Answer 49

overall protein structure that results from the aggregation of polypeptide subunits

Question 50

Sickle Cell Disease

Answer 50

an example how a slight change (change amino acid glutamic acid for valine) in primary structure can affect a proteins shape and ability to function

Question 51

Denaturation

Answer 51

pH, salt concentration, temperature or other aspects of environment are altered, the weak chemical bonds and interaction within protein are destroyed (can sometimes be reversed)

Question 52

Gene

Answer 52

segment of amino acid sequence from polypeptide programmed with inheritance info to make particular protein

Question 53

Deoxyribonucleic Acid (DNA)

Answer 53

nucleic acid molecule, usually double stranded helix, each polynucleotide stand consists of nucleotide monomers (deoxyribose sugar, nitrogenous bases [A, C, G, T] and phosphate group –> capable of being replicated and determining the inherited structure of a cell’s proteins

Question 54

Ribonucleic Acid (RNA)

Answer 54

Polynucleotide made up of nucleotide monomers with a ribose sugar, nitrogenous bases [A, C, G, U] and phosphate group; usually single-stranded; functions in protein synthesis, in gene regulation, and as the genome of some viruses

Question 55

Gene Expression

Answer 55

a given gene along a DNA molecule directs synthesis of a type of RNA called messenger RNA (mRNA) — mRNA interacts with ribosome (cell’s protein-synthesizing machinery) to direct production of a polypeptide, which folds into all or part of a protein {linear order of nitrogenous bases in polynucleotides specifies amino acid sequence in proteins}

Question 56

Nucleotides

Answer 56

3 parts: a five carbon sugar (DNA = deoxyribose; RNA = ribose); a nitrogenous base; and 1 -3 phosphate groups

Question 57

Phosphodiester Linkage

Answer 57

phosphate group that links the sugars (at 5’ and 3’ carbons of sugar) of two nucleotides through dehydration reaction

Question 58

Nucleotide Polymer Structure

Answer 58

sugar phosphate backbone; nitrogenous bases attached along back bone; one end is phosphate group attached to 5’ carbon (sugar); other end is hydroxyl group on a 3’ carbon (sugar)

Question 59

Pyrimidine Bases

Answer 59

one six membered ring of carbon and nitrogen atoms; cytosine (C), thymine (T, in DNA), uracil (U, in RNA)

Question 60

Purine Bases

Answer 60

six membered ring fused with five membered ring; Adenine (A); Guanine (G)

Question 61

Structure of DNA

Answer 61

double helix; with sugar-phosphate backbones of the antiparallel (run in opposite directions) polynucleotide strands; hydrogen bonds between bases hold strands together; A & T only; G & C only

Question 62

Complementary of Double Helix

Answer 62

two strands of the double helix are complementary, each the predictable counterpart of the other; cell divides the copies are distributed to the daughter cells, making them genetically identical to the parent cell; structure of DNA accounts for its function whenever cell divides