Topic 2

Question 1

Water is the biological medium here on Earth, and is the most abundant substance in living systems, making up ____ of the weight of most organisms.

Answer 1

70% or more

Question 2

What are the four emergent properties of water?

Answer 2

1. Cohesion and Adhesion of Water Molecules
2. Moderation of Temperature by Water
3. Evaporative Cooling of Water
4. Water as the Solvent of Life

Question 3

Water molecules stay close to each other as a result of ___ and these bonds that hold the water together, is a phenomenon called ____.

Answer 3

hydrogen bonding; cohesion

Question 4

Cohesion contributes to the _____ in plants.

Answer 4

transport of water and dissolved nutrients against gravity

Question 5

Combined with cohesion is adhesion
which is the ____.

Answer 5

clinging of one substance to another

Question 6

This ____ helps counter the downward pull of gravity.

Answer 6

adhesion of water to cell walls by hydrogen bonds

Question 7

Water moderates air temperature by _____.

Answer 7

absorbing heat from air that is warmer and releasing the stored heat to air that is cooler

Question 8

It relates to which ___ in order to break hydrogen bonds; by the same token, heat is released when ___.

Answer 8

heat must be absorbed; hydrogen bonds are formed

Question 9

As a liquid evaporates, the surface of the liquid that remains behind cools down. This
evaporative cooling occurs because ____.

Answer 9

the “hottest” molecules, those with the greatest kinetic energy, are the most likely to leave as a gas

Question 10

It is a sphere of water molecules around each dissolved ion.

Answer 10

hydration shell

Question 11

4 Biomolecules

Answer 11

1. Nucleic Acids
2. Proteins
3. Lipids
4. Carbohydrates

Question 12

The monomers of nucleic acids are ___.

Answer 12

nucleotides

Question 13

A nucleotide is composed of three parts: (3)

Answer 13

1. a nitrogenous base,
2. a five-carbon sugar
3. one or more phosphate groups.

Question 14

The portion of the nucleotide without any phosphate groups is called a ___.

Answer 14

nucleoside

Question 15

There are two families of nitrogenous bases:

Answer 15

1. Pyrimidine - 6 membered ring (cytosine, thymine, uracil)
2. Purine -6 membered ring fused to a 5 membered ring (adenine, guanine)

Question 16

The complementary base pairing states that ____, while ____.

Answer 16

adenine always pairs with thymine in DNA or uracil in RNA; guanine always pairs with cytosine

Question 17

In terms of sugar, in DNA, it is called ____and RNA has the sugar, ____.

Answer 17

deoxyribose; ribose

Question 18

The two sugar phosphate backbones run in arrangement called “______”.

Answer 18

antiparallel

Question 19

Monomers of proteins.

Answer 19

Amino acids

Question 20

Many proteins are roughly spherical (____), while others are shaped like long fibers (____).

Answer 20

globular proteins
fibrous proteins

Question 21

Folding of proteins are done by ____ and when proteins are transferred from an aqueous environment to a non-polar solvent, it unravels and loses its native shape by a process called ____.

Answer 21

chaperonins; denaturation

Question 22

It is a linked series of amino acids with a unique sequence. It is determined not by the random linking of amino acids, but by
inherited genetic information.

Answer 22

primary structure of proteins

Question 23

This is collectively referred to as coils and folds, which are the result of hydrogen bonds between the repeating constituents of the polypeptide backbone.

Answer 23

secondary structure of proteins

Question 24

It is a delicate coil held together by hydrogen bonding between every fourth amino acid.

Answer 24

a-helix

Question 25

Two or more strands of the polyopeptide chain lying side by side (called b strands) are connected by hydrogen bonds between parts of the two parallel polypeptide backbones.

Answer 25

b pleated sheet

Question 26

It is the overall shape of a polypeptide resulting from interactions between the side chains (R groups) of the various amino acids.

Answer 26

tertiary structure of proteins

Question 27

caused by the exclusion of nonpolar substances by the water molecules.

Answer 27

hydrophobic interaction

Question 28

___ are between polar side chains and ____ are between positively and negatively charged side chains.

Answer 28

hydrogen bonds; ionic bonds

Question 29

These further reinforce the shape of a protein. They are formed when two cysteine monomers which have sulfhydryl groups (-SH) on their side chains are brought closer together by the folding of protein.

Answer 29

disulfide bridges

Question 30

It is the overall protein structure that results from the aggregation of these polypeptide subunits, the a and b subunits.

Answer 30

quaternary structure of proteins

Question 31

how do proteins act as enzymes?

Answer 31

selectively accelerate chemical reactions, e.g. digestive enzymes on hydrolyzing bonds inn food molecules

Question 32

how do proteins act as storage of amino acids?

Answer 32

e.g. ovalbumin, the protein of the egg white serve as storage of amino acid for the developing embryo.

Question 33

how do proteins act as the coordinator of an organism’s activities?

Answer 33

e.g. insulin regulating blood sugar concentration

Question 34

how do proteins act as motor proteins?

Answer 34

for movement e.g. actin and myosin for the contraction of muscles

Question 35

proteins as protection against diseases

Answer 35

e.g. antibodies inactivating bacteria and viruses

Question 36

proteins as transporter of nutrients

Answer 36

e.g. hemoglobin transports oxygen

Question 37

as one function of proteins, to which do they respond?

Answer 37

chemical stimuli

Question 38

proteins as support

Answer 38

e.g. collagen and elastin providing a fibrous framework in connective tissues

Question 39

___ are the one class of biomolecules that does not include true polymers, and they are generally not big enough to be considered as macromolecules.

Answer 39

Lipids

Question 40

why are lipids grouped together?

Answer 40

they mix poorly with water

Question 41

3 types of lipids:

Answer 41

1. fats 2. phospholipids 3. steroids

Question 42

A fat is constructed from two kinds of smaller molecules:

Answer 42

glycerol and fatty acids

Question 43

___ is an alcohol; each of its three carbons bear a hydroxyl group.

Answer 43

glycerol

Question 44

A ___ has a long carbon skeleton, having a carbon at one end which is a part of the carboxyl group.

Answer 44

fatty acid

Question 45

Fatty acids are hydrophobic (away from water) due to the ____.

Answer 45

nonpolar C-H bonds

Question 46

In making a fat or triacylglycerol, ____ by an ester linkage, a bond between a hydroxyl group and carboxyl group.

Answer 46

three fatty acid molecules are each joined to glycerol

Question 47

The major function of fats is ____.

Answer 47

energy storage

Question 48

These are formed if there are no double bonds between carbon atoms composing a chain, then as many hydrogen atoms as possible are bonded to the carbon skeleton. They lack double bonds, and their flexibility allows the fat molecules to pack together tightly.

Answer 48

saturated FAs

Question 49

It has one or more double bonds , with one fewer hydrogen atom on each double-bonded carbon. Its double bonds are cis which has kinks to prevent the molecules from packing together closely enough to solidify at room temperature.

Answer 49

unsaturated FA

Question 50

they are essential on making up the cell membranes

Answer 50

phospholipids

Question 51

A phospholipid is similar to a fat molecule but has only ___ fatty acids attached to glycerol rather than three.

Answer 51

two

Question 52

The two ends of phospholipids show different behavior toward water. The hydrocarbon tails are ____ while its hydrophilic head has ___.

Answer 52

hydrophobic; an affinity for water

Question 53

When phospholipids are added to water, they self-assemble into double-layered structures called “___”, shielding their hydrophobic portions from water.

Answer 53

bilayers

Question 54

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

Answer 54

steroids

Question 55

____, a steroid, is a crucial molecule in animals since it is a component of animal cell membranes and is also the precursor from which other steroids are synthesized, such as the sex hormones.

Answer 55

cholesterol

Question 56

The simplest carbohydrates are the _____; these are the monomers from which more complex carbohydrates are constructed.

Answer 56

monosaccharides, or simple sugars

Question 57

____ are double sugars, consisting of two monosaccharides joined by a covalent bond.

Answer 57

disaccharides

Question 58

Carbohydrates also include macromolecules called ____, polymers composed of many sugar building blocks.

Answer 58

polysaccharides

Question 59

____, the most common monosaccharide, is of central importance in the chemistry of life.

Answer 59

glucose (C6H12O6)

Question 60

Monosaccharides are classified by the ____. (2)

Answer 60

1. location of the carbonyl group (C=O) 2. the size of the carbon skeleton.

Question 61

___ consist of two monosaccharides joined by a glycosidic linkage, a covalent bond formed by a dehydration reaction.

Answer 61

disaccharides

Question 62

___ are macromolecules, polymers with a few thousand monosaccharides joined by linkages.

Answer 62

polysaccharides