Chapter 5

Question 1

just four main classes:

Answer 1

carbohydrates, lipids, proteins, and nucleic
acids. On the molecular scale, members of three of these classes—carbohydrates,
proteins, and nucleic acids—are huge and are therefore called macromolecules.

Question 2

what do large bio mols show? like water

Answer 2

Like water and simple organic molecules, large biological molecules
exhibit unique emergent properties arising from the orderly arrangement of their
atoms.

Question 3

what is a polymer

Answer 3

. A polymer 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 car

Question 4

.what forms a polymer and what do these molecules have

Answer 4

The repeating units that serve as the building blocks of a polymer are
smaller molecules called monomers (from the Greek monos,
single). In addition to forming polymers, some monomers
have functions of their own

Question 5

enzymes?

Answer 5

enzymes,

specialized macromolecules that speed up chemical reactions

Question 6

what is dehydration synthesis

Answer 6

a dehydration reaction, a reaction in which two molecules are covalently bonded to each other with the loss of a
water molecule

Question 7

what is a n ex of hydrolysis that occurs within out own bodies

Answer 7

An example of
hydrolysis within our bodies is the process of digestion. The
bulk of the organic material in our food is in the form of polymers that are much too large to enter our cells. Within the
digestive tract, various enzymes attack the polymers, speeding
up hydrolysis. Released monomers are then absorbed into the
bloodstream for distribution to all body cells. Those cells can
then use dehydration reactions to assemble the monomers
into new, different polymers that can perform specific functions required by the cell. (Dehydration reactions and hydrolysis can also be involved in the formation and breakdown of
molecules that are not polymers, such as some lipids.)

Question 8

. Building
a huge variety of polymers from such a limited number of
monomers is analogous to constructing hundreds of thousands of words from only 26 letters of the alphabet. what is the key?

Answer 8

The key
is arrangement—the particular linear sequence that the units
follow

Question 9

what are carbs? what are the simplest carbs? what are more complex carbs built from? wat are disacchs and what are they made of? what are carbohydrate macromolecules calle and composed of?

Answer 9

Carbohydrates include sugars and polymers of sugars. The
simplest carbohydrates are the monosaccharides, or simple
sugars; these are the monomers from which more complex
carbohydrates are built. Disaccharides are double sugars, consisting of two monosaccharides joined by a covalent bond.
Carbohydrate macromolecules are polymers called polysaccharides, composed of many sugar building blocks.

Question 10

. Not only are simple-sugar molecules a major fuel for cellular work, but ….

Answer 10

their carbon skeletons
also serve as raw material for the synthesis of other types of
small organic molecules, such as amino acids and fatty acids

Question 11

Sugar molecules that are not immediately used in these ways are generally incorporated as

Answer 11

monomers into disaccharides or

polysaccharides, discussed next.

Question 12

wat is the most prevalent disacch? what is a disach? what kind of bond is between the monomers?

Answer 12

sucrose is the most prevaletnddisachh
A disaccharide consists of two monosaccharides joined
by a glycosidic linkage, a covalent bond formed between
two monosaccharides by a dehydration reaction (glyco refers to
carbohydrate

Question 13

describe how maltose bonds? what would happen if the monomores were joined differently?

Answer 13

The bonding of two glucose
units forms maltose. The 1–4
glycosidic linkage joins the
number 1 carbon of one
glucose to the number 4
carbon of the second glucose.
Joining the glucose monomers
in a different way would result in a different disaccharide.

Question 14

amylopectin

Answer 14

Amylopectin, a more complex
starch, is a branched polymer with 1–6 linkages at the branch
points

Question 15

The simplest form of

starch, amylose, is unbranched/branched

Answer 15

unbranched

Question 16

Hydrolysis of glycogen in these cells
releases glucose when
why does glycogens branching fit its fxn

Answer 16

the demand for sugar increases. (The
extensively branched structure of glycogen fits its function:
More free ends are available for hydrolysis.)

Question 17

r. In humans, for

example, glycogen stores are depleted in about a day unless

Answer 17

they are replenished by eating. This is an issue of concern in lowcarbohydrate diets, which can result in weakness and fatigue.

Question 18

how much cellulose is made per year? how abundant of a organic compound is it

Answer 18

Globally, plants produce almost 1014 kg
(100 billion tons) of cellulose per year; it is the most abundant
organic compound on Earth.

Question 19

is celulose brnched?

Answer 19

no

Question 20

e primary structure of a protein is its sequence of

Answer 20

amino

acids

Question 21

However, the
precise primary structure of a protein is determined not by the
random linking of amino acids, but by

Answer 21

inherited genetic information.

Question 22

e primary structure in turn dictates secondary and tertiary

structure, due to

Answer 22

the chemical nature of the backbone and the side

chains (R groups) of the amino acids along the polypeptide.

Question 23

how do most porteins have their polypep chains arranged? what is a secondary structure? where does it come from? where does it NOT come from?

Answer 23

Most proteins have segments of their polypeptide chains repeatedly
coiled or folded in patterns that contribute to the protein’s overall
shape. ese coils and folds, collectively referred to as secondary
structure, are the result of hydrogen bonds between the repeating constituents of the polypeptide backbone (not the amino acid
side chains)

Question 24

how do hydrogen bonds work to stabilise a shape of a protein

Answer 24

. Individually, these hydrogen
bonds are weak, but because they are repeated many times over a
relatively long region of the polypeptide chain, they can support a
particular shape for that part of the protein.

Question 25

a helix where is it found, def, how it is held tg

Answer 25

One such secondary structure is the α helix, a delicate coil held
together by hydrogen bonding between every fourth amino acid, as
shown above. Although each transthyretin polypeptide has only one
α helix region (see the Tertiary Structure section), other globular
proteins have multiple stretches of α helix separated by nonhelical
regions (see hemoglobin in the Quaternary Structure section). Some
fibrous proteins, such as α-keratin, the structural protein of hair,
have the α helix formation over most of their length.

Question 26

beta pleated sheet where is it found what does it do, how is it connected

Answer 26

e β pleated
sheet. As shown above, in this structure two or more segments
of the polypeptide chain lying side by side (called β strands) are
connected by hydrogen bonds between parts of the two parallel
segments of polypeptide backbone. β pleated sheets make up the
core of many globular proteins, as is the case for transthyretin (see
Tertiary Structure), and dominate some fibrous proteins, including
the silk protein of a spider’s web. e teamwork of so many hydrogen bonds makes each spider silk fiber stronger than a steel strand
of the same weight.

Question 27

tertirary structure n cc w secondary

Answer 27

While secondary structure involves interactions between
backbone constituents, tertiary structure is the overall shape of
a polypeptide resulting from interactions between the side chains
(R groups) of the various amino acids.

Question 28

hydrophobic interaction - when does it happen, and what is it caused by and def

Answer 28

One type of interaction that
contributes to tertiary structure is called—somewhat misleadingly—a
hydrophobic interaction. As a polypeptide folds into its functional
shape, amino acids with hydrophobic (nonpolar) side chains usually
end up in clusters at the core of the protein, out of contact with water.
Thus, a “hydrophobic interaction” is actually caused by the exclusion
of nonpolar substances by water molecule

Question 29

what holds amino acid side chains together. what role to h bonds play. how do these otherwise weak interactions help give a cumulative shape to the protein?

Answer 29

. Once nonpolar amino
acid side chains are close together, van der Waals interactions help
hold them together. Meanwhile, hydrogen bonds between polar side
chains and ionic bonds between positively and negatively charged side
chains also help stabilize tertiary structure. These are all weak interactions in the aqueous cellular environment, but their cumulative effect
helps give the protein a unique shape

Question 30

quat structure

Answer 30

Some proteins consist of two or more polypeptide chains aggregated
into one functional macromolecule. Quaternary structure is the
overall protein structure that results from the aggregation of these
polypeptide subunits. For example, shown above is the complete
globular transthyretin protein, made up of its four polypeptides.

Question 31

what is a polypeptide what level of structure

Answer 31

polypep is a tertiary stru cture

Question 32

what is denaturation and when does it occur and what happens to the protein

Answer 32

If the pH, salt concentration, temperature, or
other aspects of its environment are altered, the weak chemical bonds and interactions within a protein may be destroyed,
causing the protein to unravel and lose its native shape, a
change called denaturation (Figure 5.20). Because it is
misshapen, the denatured protein is biologically inactive.

Question 33

when do proteins become denatured (in what env) and why

Answer 33

Most proteins become denatured if they are transferred
from an aqueous environment to a nonpolar solvent, such
as ether or chloroform; the polypeptide chain refolds so that its hydrophobic regions face outward toward the solvent.

Question 34

why are they called nitrogenous bases in dna

Answer 34

. (They are called nitrogenous bases because the nitrogen atoms tend to take up H+
from solution, thus acting as
bases.) There are two families of nitrogenous bases: pyrimidines and purines

Question 35

pyrimidine

Answer 35

. A pyrimidine has one six-membered
ring of carbon and nitrogen atoms. The members of the
pyrimidine family are cytosine (C), thymine (T), and uracil (U).

Question 36

purine? and how do purines n pyrimidines differ

Answer 36

six-membered ring fused to a five-membered ring. The purines are adenine (A) and guanine (G). The specific pyrimidines and purines differ in the
chemical groups attached to the rings

Question 37

how to complete nucleotide consturctuion

Answer 37

. To
complete the construction of a nucleotide, we attach one
to three phosphate groups to the 5′ carbon of the sugar (the
carbon numbers in the sugar include ′, the prime symbol;
see Figure 5.23bWith one phosphate, this is a nucleoside
monophosphate, more often called a nucleotide.

Question 38

describe dnas backbone

Answer 38

The two sugar-phosphate backbones run in
opposite 5′ S 3′ directions from each other; this arrangement is referred to as antiparallel, somewhat like a divided
highway

Question 39

what has the genome sequencing advancements been?

Answer 39

The number of genomes that have
been fully sequenced has burgeoned, generating reams of
data and prompting development of bioinformatics, the
use of computer software and other computational tools that
can handle and analyze these large data se

Question 40

genomics

Answer 40

Biologists often look
at problems by analyzing large sets of genes or even comparing whole genomes of different species, an approach called
genomics

Question 41

proteomics

Answer 41

. A similar analysis of large sets of proteins, including their sequences, is called proteomics. (Protein sequences
can be determined either by using biochemical techniques or
by translating the DNA sequences that code for them.)

Question 42

describe the protein backbone

Answer 42

Within the backbone, the oxygen atoms have a partial
negative charge, and the hydrogen atoms attached to the nitrogens
have a partial positive charge (see Figure 2.14); therefore, hydrogen
bonds can form between these atoms