Proteins

Question 1

what does the term protein mean in Greek

Answer 1

first importance

Question 2

what do proteins provide us with

Answer 2

Hydrogen, Carbon, Nitrogen, and Sulfur. Nitrogen and Sulfur are not available in fats or carbs

Question 3

what are the most abundant macro molecules in the cell

Answer 3

proteins

Question 4

______ are biological catalysts, and most of them are proteins. Reactions that would take days or weeks or require extremely high temperatures without these are completed in an instant.

Answer 4

enzymes

Question 5

Defense proteins include ______ (also called _________)

Answer 5

antibodies

immunoglobulins

Question 6

antibodies are are specific protein molecules produced by specialized cells of the immune system in response to foreign ______

Answer 6

antigens

Question 7

foreign invaders include _____ and _____ that infect the body.

Answer 7

bacteria

viruses

Question 8

Each antibody has regions that precisely fit and bind to a single _____, helping to destroy it or remove it from the body.

Answer 8

antigen

Question 9

_________ carry materials from one place to another in the body.

Answer 9

transport proteins

Question 10

The protein ________ transports iron from the liver to the bone marrow, where it is used to synthesize the heme group for hemoglobin.

Answer 10

transferrin

Question 11

The proteins _____ and _______ are responsible for transport and storage of oxygen in higher organisms, respectively.

Answer 11

hemoglobin

myoglobin

Question 12

__________ control many aspects of cell function, including metabolism and reproduction.

Answer 12

Regulatory proteins

Question 13

For life to exist, ________, ________, and ________ must be carefully regulated.

Answer 13

body temp
pH of blood
blood glucose levels

Question 14

Many of the hormones that regulate body function, such as ____ and _____, are proteins.

Answer 14

insulin

glucagon

Question 15

__________ provide mechanical support to large animals and provide them with their outer coverings.

Answer 15

Structural proteins

Question 16

Our hair and fingernails are largely composed of the protein _____.

Answer 16

keratin

Question 17

__________ are necessary for all forms of movement.

Answer 17

Movement proteins

Question 18

Our muscles, including that most important muscle, the heart, contract and expand through the interaction of ___ and ____ proteins.

Answer 18

actin

myosin

Question 19

Sperm can swim because they have long ___ made up of ____.

Answer 19

flagella

proteins

Question 20

_______ serve as sources of amino acids for embryos or infants.

Answer 20

Nutrient proteins

Question 21

Egg ____ and ____ in milk are examples of nutrient storage proteins.

Answer 21

albumin

casein

Question 22

The proteins of the body are made up of some combination of twenty different subunits called _______

Answer 22

α-amino acids

Question 23

Nineteen of the twenty amino acids that are commonly isolated from proteins have this same general structure; they are _______ on the _____. The remaining amino acid, ______, is a secondary amine.

Answer 23

primary amines
α-carbon
proline

Question 24

Notice that the α-carbon in the general structure is attached to a _______ (a carboxyl group that has ______, −COO−) and a ________ (an amino group that has _______, −N+H3).

Answer 24

carboxylate group
lost a proton
protonated amino acid
gained a proton

Question 25

At _____, a condition required for life functions, you will not find amino acids in which the carboxylate group is _____(−COOH) and the amino group is ______(−NH2).

Answer 25

pH 7
protonated
unprotonated

Question 26

Any neutral molecule with equal numbers of positive and negative charges is called a ____

Answer 26

zwitterion

Question 27

Thus, amino acids in water exist as _____ called ______.

Answer 27

dipolar ions

zwitterions

Question 28

The α-carbon of each amino acid is also bonded to a ______ and a side chain, or ______

Answer 28

Hydrogen atom

R group

Question 29

In a protein, the R groups interact with one another through a variety of ___________

Answer 29

weak attractive forces

Question 30

The interactions in the R groups participate in ____ the protein chain into a precise _____ that determines its ______.

Answer 30

folding
3D shape
ultimate function

Question 31

The R group interactions also serve to maintain that 3D _____

Answer 31

conformation

Question 32

The d-l notation is very similar to that discussed for carbohydrates, but instead of the −OH group we use the ____ group to determine which is d- and which is L-

Answer 32

N+H3

Question 33

most oxidized part of protein

Answer 33

carboxyl group

Question 34

Almost all of the α-amino acids isolated from proteins in nature are members of the

Answer 34

L-Family

Question 35

The α-carbon is attached to four different groups in all amino acids except

Answer 35

glycine

Question 36

The α-carbon of most α-amino acids is therefore

Answer 36

chiral

Question 37

The α-carbon of most α-amino acids is therefore ____, allowing ______ forms, ______, to exist

Answer 37

chiral
mirror images
enantiomers

Question 38

Glycine has two _____ attached to the α-carbon and is the only amino acid commonly found in proteins that is _____.

Answer 38

hydrogen atoms

not chiral

Question 39

Because all amino acids have a carboxyl group and an amino group, all differences between amino acids depend upon their

Answer 39

side chain R groups

Question 40

The side chains of some amino acids are _____. They prefer contact with one another over contact with water and are said to be ______ amino acids.

Answer 40

nonpolar

hydrophobic

Question 41

where are hydrophobic amino acids found

Answer 41

in the interior of proteins, where they can associate with one another and remain isolated from water

Question 42

list the 9 hydrophobic amino acids

Answer 42

“Grandma Always Visits London In May For Winston’s Party”

alanine, valine, leucine, isoleucine, proline, glycine, methionine, phenylalanine, and tryptophan.

Question 43

The ____ of proline is unique; it is actually bonded to the α-amino group, forming a ______.

Answer 43

R group

secondary amine

Question 44

The hydrophobic interaction between nonpolar R groups is one of the forces that helps maintain the

Answer 44

proper three-dimensional shape of a protein.

Question 45

The side chains of the remaining amino acids are polar. Because they are attracted to

Answer 45

polar water molecules

Question 46

The side chains of the remaining amino acids are polar. Because they are attracted to polar water molecules, they are said to be

Answer 46

hydrophilic amino acids

Question 47

The hydrophilic side chains are often found

Answer 47

on the surfaces of proteins

Question 48

The polar amino acids can be subdivided into three classes

Answer 48

polar neutral amino acids
Negatively charged amino acids
Positively charged amino acids

Question 49

_____ is another weak interaction that helps maintain the proper 3D structure of a protein

Answer 49

Hydrogen bonding

Question 50

the positively and negatively charged amino acids within a protein interact with one another to form ________ that also help to keep the protein chain folded in a precise way

Answer 50

ionic bridges

Question 51

have R groups that have a high affinity for water but are not ionic at pH 7

Answer 51

Polar, neutral amino acids

Question 52

examples of Polar, neutral amino acids

Answer 52

“Santa’s Team Crafts all grinches together”

serine, threonine, tyrosine, cysteine, asparagine, and glutamine

Question 53

most of the amino acids that are polar neutral associate with one another by _____. but cysteine molecules form _______ with one another

Answer 53

hydrogen bonding

disulfide bonds

Question 54

have ionized carboxyl groups in their side chains. At pH 7, these amino acids have a net charge of −1.

Answer 54

negatively charged amino acids

Question 55

examples of negatively charged amino acids

Answer 55

Aspartate and glutamate

Question 56

why are Aspartate and glutamate acidic amino acids

Answer 56

because ionization of the carboxylic acid releases a proton.

Question 57

examples of positively charged amino acids

Answer 57

Lets argue here

lysine, arginine, and histidine

Question 58

Positively charged amino acids._____ , lysine, arginine, and histidine have a net ___ charge because their side chains contain _______.

Answer 58

pH 7
positive
positive groups

Question 59

positively charged amino acids are basic. why?

Answer 59

because the side chain reacts with water, picking up a proton and releasing a hydroxide anion.

Question 60

Proteins are linear polymers of

Answer 60

L-α-amino acids

Question 61

which groups are linked together in a protein

Answer 61

the carboxyl group of one amino acid is linked to the amino group of another amino acid.

Question 62

the peptide bond is technically a ____ bond

Answer 62

amide

Question 63

the peptide bond in a protein is formed between what

Answer 63

the −COO− group of one amino acid and the α-N+H3 group of another amino acid.

Question 64

when glycine and alanine react what do they form

Answer 64

glycyl-alanine

Question 65

what reaction do glycine and alanine undergo to form glycyl-alanine

Answer 65

condensation (removal of a water molecule)

Question 66

The molecule formed by condensing two amino acids is called a

Answer 66

dipeptide

Question 67

the amino acid with a free α−N+H3 group is known as

Answer 67

the amino terminal, or simply the N-terminal amino acid residue or N-terminus

Question 68

the amino acid with a free −COO− group is known as

Answer 68

the carboxyl, or C-terminal amino acid residue or C-terminus.

Question 69

structures of proteins are conventionally written with their N-terminal amino acid on the ___

Answer 69

left

Question 70

The number of amino acids in small peptides is indicated by the prefixes di- (__units), tri- (___units), tetra- (__units), and so forth.

Answer 70

two units
three units
four units

Question 71

Peptides are named as derivatives of the

Answer 71

C-terminal amino acid, which receives its entire name

Question 72

For all other amino acids, the ending -ine is changed to

Answer 72

-yl

Question 73

The dipeptide formed from alanine and glycine that has alanine as its _________ is named alanyl-glycine

Answer 73

N-terminal amino acid

Question 74

the backbone of a peptide contains the repeating sequence

Answer 74

N-C2-C1-N-C2-C1-N-C2-C1

Question 75

what do the three N, C2, and C1 represent

Answer 75

N=α-amino group
C2= awlays bonded to the hydrogen atom and the R group side chain
C1= carboxyl group

Question 76

Pauling discovered that peptide bonds are

Answer 76

both planar (flat) and rigid and that the N−C bonds are shorter than expected.

Question 77

Pauling concluded that the peptide bond has a partially

Answer 77

double bond character because it exhibits resonance.

Question 78

This means that there is free rotation around only

Answer 78

two of the three single bonds of the peptide backbone

Question 79

having free rotation around two of the three single bond of the peptide bonds limits what

Answer 79

the number of possible conformations for any peptide.

Question 80

A second feature of the rigid peptide bond is that the R groups on adjacent amino acids are on

Answer 80

opposite sides of the extended peptide chain

Question 81

The primary structure of a protein is the

Answer 81

amino acid sequence of the protein chain.

Question 82

what does the primary structure result from

Answer 82

the covalent bonding between the amino acid residues in the chain (peptide bonds).

Question 83

The primary structures of proteins are translations of information contained

Answer 83

genes

Question 84

Each protein has a different ______ with different _______ in different _________. This sequence of amino acid residues is dictated by the sequence of the ___.

Answer 84

primary structure
amino acid residues
places along the chain
gene

Question 85

Ultimately, it is the primary structure of a protein that will determine its

Answer 85

biologically active form

Question 86

The interactions among the R groups of the amino acids in the protein chain depend on

Answer 86

the location of those R groups along the chain.

Question 87

what do the interactions among the R groups of the amino acids govern

Answer 87

how the protein chain folds

Question 88

how the protein chain folds dictates what

Answer 88

its final three-dimensional structure and its biological function.

Question 89

Regions of the primary sequence of a protein, the chain of covalently linked amino acids, fold into regularly repeating structures that resemble designs in a tapestry. These repeating structures define the

Answer 89

secondary structure of a protein

Question 90

The secondary structure is the result of ____ bonding between _______ and __________ of the peptide bonds.

Answer 90

hydrogen
the amide hydrogens
carbonyl oxygens

Question 91

_______ are needed to maintain the secondary structure and thereby the overall structure of the protein.

Answer 91

many hydrogen bonds

Question 92

Some regions of a protein chain may have a random or non regular structure; however, the two most common types of secondary structure are the ____ and the ______ because they _________ in the backbone.

Answer 92

α-helix
β-pleated sheet
maximize hydrogen bonding

Question 93

The most common type of secondary structure is a coiled, helical conformation known as the

Answer 93

α-helix

Question 94

a feature of α-helix is that Every amide hydrogen and carbonyl oxygen associated with the peptide backbone is involved in a

Answer 94

hydrogen bond when the chain coils into an α-helix.

Question 95

what do the hydrogen bonds do to the α-helix (features of alpha helix)

Answer 95

lock it into place

Question 96

Every carbonyl oxygen is ________ to an amide hydrogen ____ amino acids away in the chain.
(features of alpha helix)

Answer 96

hydrogen bonded

four

Question 97

The hydrogen bonds of the α-helix are parallel to the

features of alpha helix

Answer 97

long axis of the helix

Question 98

The polypeptide chain in an α-helix is

features of alpha helix

Answer 98

right handed

Question 99

The repeat distance of the helix, or its pitch, is _____, and there are ________.
(features of alpha helix)

Answer 99

5. 4 angstroms (A)

3. 6 amino aicds/ turn of the helix

Question 100

are structural proteins arranged in fibers or sheets that have only one type of secondary structure.

Answer 100

fibrous proteins

Question 101

The ____ are fibrous proteins that form the covering (hair, wool, nails, hooves, and fur) of most land animals.

Answer 101

α-keratins

Question 102

Human hair provides a typical example of the structure of the

Answer 102

α-keratins

Question 103

The proteins of hair consist almost exclusively of

Answer 103

polypeptide chains coiled up into α-helices.

Question 104

A single α-helix is coiled in a bundle with two other helices to give a three-stranded superstructure called a

Answer 104

protofibril

Question 105

A single α-helix is coiled in a bundle with two other helices to give a three-stranded superstructure called a protofibril that is part of an array known as a

Answer 105

microfibril

Question 106

These structures, which resemble “molecular pigtails,” possess great ______, and they are virtually_________

Answer 106

mechanical strength

insoluble in water

Question 107

Structure of the α-keratins. These proteins are assemblies of triple-helical ____ that are assembled in an array known as a _____. These in turn are assembled into _____. Hair is a collection of _____and hair cells.

Answer 107

protofibril
microfibril
macrofibril
macrofibrils

Question 108

The major structural property of a coiled coil superstructure of α-helices is its

Answer 108

great mechanical strength

Question 109

The second common secondary structure in proteins resembles the pleated folds of drapery and is known as the

Answer 109

β-pleated sheet

Question 110

All of the carbonyl oxygens and amide hydrogens in a β-pleated sheet are involved in

Answer 110

hydrogen bonds

Question 111

the polypeptide chain in β-pleated sheet is nearly _______

Answer 111

completely extended

Question 112

The polypeptide chains in a β-pleated sheet can have

Answer 112

2 orientations

Question 113

If the N-termini are head to head, the structure is known as a

Answer 113

parallel β-pleated sheet

Question 114

And if the N-terminus of one chain is aligned with the C-terminus of a second chain (head to tail), the structure is known as an (β-pleated sheet)

Answer 114

antiparallel β-pleated sheet.

Question 115

The structure of silk fibroin is almost entirely

Answer 115

aantiparallel β-pleated sheet

Question 116

Some fibrous proteins are composed of β-pleated sheets. For example, the silk-worm produces _______, a protein whose structure is an ________

Answer 116

silk fibroin

antiparallel β-pleated sheet

Question 117

The polypeptide chains of a β-pleated sheet are almost completely _____, and silk does not _____

Answer 117

extended

stretch easily

Question 118

_____ accounts for nearly half of the amino acids of silk fibroin. ____ and ____ account for most of the others

Answer 118

glycine
alanine
serine

Question 119

The ____ groups of alanines and the _____groups of serines lie on ____ sides of the sheet.

Answer 119

methyl
hydroxymethyl
opposite

Question 120

Most fibrous proteins, such as silk, collagen, and the α-keratins, are almost

Answer 120

completely insoluble in water

Question 121

the majority of cellular proteins, however, are soluble in the

Answer 121

cell cytoplasm

Question 122

Soluble proteins are usually ________

Answer 122

globular proteins

Question 123

Globular proteins have three-dimensional structures called the _______ of the protein, which are distinct from their secondary structure.

Answer 123

tertiary structure

Question 124

Tertiary structure refers to the

Answer 124

3D shape of the entire peptide chain

Question 125

The regions of secondary structure, α-helix and β-pleated sheet, further ____ on themselves to achieve the _____

Answer 125

fold

tertiary structures

Question 126

We have seen that the forces that maintain the secondary structure of a protein are ______ between the _____ and the _____ of the peptide bond.

Answer 126

hydrogen bonds
amide hydrogen
carbonyl oxygen

Question 127

The globular tertiary structure forms spontaneously and is maintained as a result of

Answer 127

interactions among the side chains, the R groups, of the amino acids.

Question 128

name the molecular interactions that maintain the structure of globular tertiary proteins

Answer 128

van der Waals forces (London dispersion forces and dipole-dipole attractions)
Hydrogen bonds
Covalent bonds
Ionic bonds (salt bridges)

Question 129

van der Waals forces (London dispersion forces and dipole-dipole attractions) between the

Answer 129

hydrophobic R groups

Question 130

Hydrogen bonds between the

Answer 130

polar R groups

Question 131

Ionic bonds (salt bridges) between the

Answer 131

oppositely charged R groups

Question 132

Covalent bonds between the

Answer 132

thiol-containing amino acid residues. Two of the polar cysteines can be oxidized to a dimeric amino acid called cystine

Question 133

The disulfide bond of cystine can be a _____ between different proteins, or it can _____ within a protein together

Answer 133

cross-link

tie two segments

Question 134

it is the tertiary structure of the protein that defines its

Answer 134

biological function

Question 135

Most of the time, ____ side chains of amino acid residues are buried, closely packed, in the ____ of a globular protein, out of contact with ____

Answer 135

non polar
interior
water

Question 136

Polar and charged side chain amino acid residues lie on the _____ of globular proteins

Answer 136

surfaces

Question 137

Globular proteins are extremely

Answer 137

compact

Question 138

The tertiary structure can contain regions of ____ and regions of ________

Answer 138

α-helix

β-pleated sheet

Question 139

_____- regions of random coil connect regions of α-helix and β-pleated sheet.

Answer 139

Hinge

Question 140

Because of its ____ structure, ____ disrupts an _____. As a result, ____ is often found in these ____ regions.

Answer 140

cyclic
proline 
α-helix 
proline
hinge

Question 141

For many proteins, the functional form is not composed of a single peptide but is rather an aggregate of

Answer 141

smaller globular peptides

Question 142

For instance, the protein hemoglobin is composed of

Answer 142

four individual globular peptide subunits: two identical α-subunits and two identical β-subunits.

Question 143

Only when the four peptides are bound to one another is the protein molecule

Answer 143

functional

Question 144

The association of several polypeptides to produce a functional protein defines the ________ of a protein

Answer 144

quaternary structure

Question 145

The forces that hold the quaternary structure of a protein are the same as those that hold the

Answer 145

tertiary structure

Question 146

The forces that hold the quaternary structure of a protein are the same as those that hold the tertiary structure. These include _____ forces between hydrophobic R groups,_____ between polar R groups, ______ between oppositely charged R groups, and _______.

Answer 146

van der waals
hydrogen bonds
ionic bridges
disulfide bridges

Question 147

In some cases, quaternary structure of a functional protein involves binding to a

Answer 147

nonprotein group

Question 148

In some cases, quaternary structure of a functional protein involves binding to a nonprotein group. This additional group is called a

Answer 148

prosthetic group

Question 149

For example, many of the receptor proteins on cell surfaces are

Answer 149

glycoproteins

Question 150

For example, many of the receptor proteins on cell surfaces are glycoproteins. These are proteins with ___ groups ____ attached

Answer 150

sugar

covalently

Question 151

Each of the subunits of hemoglobin is bound to an

Answer 151

iron containing heme group

Question 152

The heme group is a_______________ with an ___ ion coordinated within it.

Answer 152

large unsaturated organic cyclic amine

iron

Question 153

As in the case of hemoglobin, the prosthetic group often determines the

Answer 153

function of a protein

Question 154

For instance, in hemoglobin it is the iron-containing heme groups that have the ability to

Answer 154

bind reversibly to oxygen

Question 155

what is the prosthetic group in hemoglobin

Answer 155

heme group

Question 156

The ____ structure of the protein is the amino acid sequence of the protein. The primary structure results from the formation of ______ between amino acids. Peptide bonds are ____ formed between the carboxylate group of one amino acid and the amino group of another.

Answer 156

primary
covalent peptide bonds
amide bonds

Question 157

As the protein chain grows, numerous opportunities for _____ interactions in the backbone of the polypeptide chain become available. These cause regions of the chain to fold and orient themselves in a variety of _______ arrangements. The secondary level of structure includes the ____ and the _____, which are the result of ______ between the amide hydrogens and carbonyl oxygens of the peptide bonds. Different regions of the chain may be involved in different types of secondary structure arrangements; some regions might be α-helix and others might be a β-pleated sheet.

Answer 157

non covalent
conformational 
α-helix
β-pleated sheet
hydrogen bonding

Question 158

When we discuss tertiary structure, we are interested in the overall ___ of the entire chain. In other words, we are concerned with the ____ of the secondary structure. Both _____ interactions between the R groups of the amino acids and _________ play a role in determining the tertiary structure. The noncovalent interactions include _____, ______, and ______

Answer 158

folding
further folding
noncovalent 
covalent disulfide bridges
Hydrogen bonding, ionic bonding, and van der waals forces (London dispersion forces and dipole-dipole attractions).

Question 159

It is the tertiary and quaternary structures of the protein that ultimately

Answer 159

define its function

Question 160

some of the tertiary and quaternary structures have _____ with great mechanical strength

Answer 160

fibrous structure

Question 161

fibrous structures make up what

Answer 161

the major structural components of the cell and the organism. Often they are also responsible for the movement of the organism.

Question 162

some of the tertiary and quaternary proteins fold into

Answer 162

globular shapes

Question 163

Most of the transport proteins, regulatory proteins, and enzymes are

Answer 163

globular proteins

Question 164

The very precise three-dimensional structure of each of these proteins allows each to carry out its

Answer 164

very specific function in the body

Question 165

the change of even a single amino acid in the primary structure of a protein can have far-reaching implications, including

Answer 165

loss of function that can be life threatening

Question 166

Our cells require a steady supply of oxygen, but oxygen is only slightly soluble in aqueous solutions. To overcome this solubility problem, we have an oxygen transport protein,

Answer 166

hemoglobin

Question 167

where is hemoglobin found

Answer 167

in RBCs

Question 168

what is hemoglobin

Answer 168

is the oxygen transport protein of higher animals.

Question 169

myoglobin

Answer 169

is the oxygen storage protein of skeletal muscle.

Question 170

The ___ ion in the heme group is the binding site for ___ in both myoglobin and hemoglobin.

Answer 170

Fe2+

oxygen

Question 171

myoglobin has a _________for oxygen than does hemoglobin

Answer 171

greater attraction

Question 172

Hemoglobin (Hb) is a ____ composed of ____ polypeptide subunits: two α-subunits and two β-subunits

Answer 172

tetramer

four

Question 173

Because each subunit of hemoglobin contains a heme group, a hemoglobin molecule can bind

Answer 173

four molecules of oxygen

Question 174

Oxygen diffuses from the region of _________ to the region of ________

Answer 174

high pO2 in the lungs

low pO2 in the blood.

Question 175

Oxygen diffuses from the region of high pO2 in the lungs to the region of low pO2 in the blood. There it enters_____and binds to the _____ of the heme groups of ____, forming _____. This binding actually helps bring ____O2 into the blood.

Answer 175

RBCs
Fe2+ ions
deoxyhemoglobin
oxyhemoglobin
more

Question 176

he fetus, however, has a unique type of hemoglobin, called

Answer 176

fetal hemoglobin

Question 177

the fetal hemoglobin has _____ for oxygen ______

Answer 177

more affinity

than the mothers hemoglobin

Question 178

he biosynthesis of fetal hemoglobin stops _____ when the genes encoding fetal hemoglobin are switched ____ and the genes coding for adult hemoglobin are switched ____

Answer 178

shortly after birth
off
on

Question 179

is a human genetic disease that first appeared in tropical west and central Africa.

Answer 179

Sickle Cell Anemia

Question 180

sickle cell anemia individuals produce a ___

Answer 180

a mutant hemoglobin known as sickle cell hemoglobin (Hb S).

Question 181

Sickle cell anemia receives its name from the_____appearance of the _______ that form in this condition

Answer 181

sickled

red blood cells

Question 182

The sickled cells are unable to pass through the small capillaries of the circulatory system, and circulation is

Answer 182

hindered

Question 183

The sickled cells are unable to pass through the ______ of the circulatory system, and circulation is hindered. This results in damage to many organs, especially ___ and ____, and can lead to ____________

Answer 183

small capillaries
bone
kidney
death at an early age.

Question 184

Sickle cell hemoglobin differs from normal hemoglobin by a

Answer 184

single amino acid

Question 185

In the β-chain of sickle cell hemoglobin, what has replaced what

Answer 185

a valine (a hydrophobic amino acid) has replaced a glutamic acid (a negatively charged amino acid).

Question 186

the replacement of glutamic acid by valine provides a basis for the

Answer 186

binding of hemoglobin S molecules to one another

Question 187

When oxyhemoglobin S unloads its oxygen, individual deoxyhemoglobin S molecules ____________

Answer 187

bind to one another as long polymeric fibers

Question 188

When oxyhemoglobin S unloads its oxygen, individual deoxyhemoglobin S molecules bind to one another as long polymeric fibers. This occurs because

Answer 188

the valine fits into a hydrophobic pocket on the surface of a second deoxyhemoglobin S molecule.

Question 189

The fibers generated in this way radically alter the ___ of the red blood cell, resulting in the ____ effect.

Answer 189

shape

sickling

Question 190

Sickle cell anemia occurs in individuals who have

Answer 190

inherited the gene for sickle cell hemoglobin from both parents.

Question 191

Afflicted individuals with sickle cell anemia produce 90–100%

Answer 191

defective β-chains.

Question 192

Individuals who inherit one normal gene and one defective gene produce

Answer 192

both normal and altered β-chains.

Question 193

About 10% of African Americans carry a single copy of the defective gene, a condition known as

Answer 193

sickle cell trait

Question 194

people with sickle cell trait Although not severely affected, they have a

Answer 194

50% chance of passing the gene to each of their children.

Question 195

An interesting relationship exists between sickle cell trait and resistance to

Answer 195

malaria

Question 196

In some parts of Africa, up to 20% of the population has

Answer 196

sickle cell trait.

Question 197

The presence of sickle cell trait is linked to an

Answer 197

increased resistance to malaria because the malarial parasite cannot feed efficiently on sickled red blood cells.

Question 198

People who have sickle cell disease ______ those without sickle cell trait have a high probability of succumbing to _______.

Answer 198

die young

malaria

Question 199

people who have sickle cell trait do not suffer much from _______ and simultaneously resist ________

Answer 199

sickle cell anemia

deadly malaria

Question 200

Because those with sickle cell trait have a greater chance of ____ and _____, the sickle cell hemoglobin gene is ______ in the population.

Answer 200

survival
reproduction
maintained

Question 201

The blood plasma of a healthy individual typically contains _______ of protein.

Answer 201

60-80 g/L

Question 202

This protein can be separated into

Answer 202

five classes designated α through γ

Question 203

the seperation of proteins is based on the

Answer 203

overall surface charge on each of the types of protein.

Question 204

The most abundant protein in the blood is ____, making up about ____ of the blood protein.

Answer 204

albumin

55%

Question 205

Albumin contributes to the ______ of the blood simply because it is a ___ molecule.

Answer 205

osmotic pressure

dissolved

Question 206

what does albumin also serve as

Answer 206

a nonspecific transport molecule for important metabolites that are otherwise poorly soluble in water.

Question 207

Among the molecules transported through the blood by albumin are

Answer 207

bilirubin, Ca2+ , and fatty acids (organic anions).

Question 208

bilirubin

Answer 208

a waste product of the breakdown of hemoglobin

Question 209

________ make up 13% of the plasma proteins.

Answer 209

The α-globulins (α1 and α2)

Question 210

The α-globulins include

Answer 210

glycoproteins (proteins with sugar groups attached), high-density lipoproteins, haptoglobin (a transport protein for free hemoglobin), ceruloplasmin (a copper transport protein), prothrombin (a protein involved in blood clotting), and very low density lipoproteins.

Question 211

The most abundant α1-globulin is

Answer 211

α1-antitrypsin

Question 212

what does α1-antitrypsin do

Answer 212

the inactivation of an enzyme that causes damage in the lungs

Question 213

what is another inhibitor found the bloodstream

Answer 213

α1-Antichymotrypsin

Question 214

α1-Antichymotrypsin along with ___ proteins is found in the _____________________

Answer 214

amyloid

amyloid plaques characteristic of Alzheimer’s disease (AD)

Question 215

In the blood, α1-antichymotrypsin is also found complexed to ________

Answer 215

prostate specific antigen (PSA)

Question 216

prostate specific antigen (PSA), the protein antigen that is measured as an indicator of

Answer 216

prostate cancer

Question 217

Elevated PSA levels are observed in those with the

Answer 217

disease of prostate cancer

Question 218

It is interesting to note that PSA is a

Answer 218

chymotrypsin-like proteolytic enzyme.

Question 219

The β-globulins represent 13% of the blood plasma proteins and include

Answer 219

transferrin (an iron transport protein) and low-density lipoprotein.

Question 220

a protein involved in coagulation of blood, comprises 7% of the plasma protein

Answer 220

Fibrinogen

Question 221

IgG, IgM, IgA, IgD, and IgE, make up the remaining 11% of the plasma proteins.

Answer 221

the γ-globulins (antibodies)

Question 222

The γ-globulins are synthesized by

Answer 222

B lymphocytes

Question 223

most of the remaining plasma proteins are synthesized in the

Answer 223

liver

Question 224

In fact, a frequent hallmark of liver disease is

Answer 224

reduced amounts of one or more of the plasma proteins

Question 225

occurs when the organized structures of a globular protein, the α-helix, the β-pleated sheet, and tertiary folds become completely disorganized.

Answer 225

Denaturation

Question 226

denaturation does not alter the

Answer 226

primary structure

Question 227

The protein molecules are denatured as they lose their characteristic ______ and become completely _____

Answer 227

3D conformation

disorganized

Question 228

occurs as the protein molecules then unfold and become entangled

Answer 228

coagulation

Question 229

as the protein molecules then unfold and become entangled. At this point, they are no longer in solution; they have aggregated to

Answer 229

become a solid and will precipitate out of the solution

Question 230

Many of the proteins of our cells—for instance, the enzymes—are in the same kind of viscous solution within the cytoplasm. To continue to function properly, they must remain in solution and maintain the correct

Answer 230

3D configuration

Question 231

If the body temperature becomes too high, or if local regions of the body are subjected to very high temperatures, as when you touch a hot cookie sheet, cellular proteins become ____. They lose their ___, and the cell or the organism _____.

Answer 231

denatured
function
dies

Question 232

The positively and negatively charged R groups on the surface of the molecule interact with ___ and ____ molecules, and these ____ keep the protein in ____ within the ____.

Answer 232

ions 
water 
interactions
solution
cytoplasm

Question 233

When the pH of the solution is changed dramatically, the ___or ____ will change the _____ of the protein, interfering with the _____ and ______ that stabilize the tertiary structure.

Answer 233

acid 
base
charge 
salt bridges
hydrogen bonds

Question 234

Polar organic solvents, such as ____________, denature proteins by disrupting __________ within the protein, in addition to forming hydrogen bonds __________

Answer 234

rubbing alcohol (2-propanol),
hydrogen bonds
with the solvent, water.

Question 235

the _____ regions of these solvents interfere with _____________ in the interior of the protein molecule, thereby disrupting the conformation.

Answer 235

nonpolar

hydrophobic interactions

Question 236

Traditionally, a 70% solution of rubbing alcohol was often used as a _________ or _________. However, recent evidence suggests that it is not an effective agent in this capacity.

Answer 236

disinfectant or antiseptic

Question 237

Detergents have both a _________ and a ________

Answer 237

hydrophobic region (the fatty acid tail)
a polar or hydrophilic region

Question 238

When detergents interact with ____, they disrupt _____________, causing the protein chain to ____.

Answer 238

proteins
hydrophobic interactions
unfold

Question 239

Heavy metals such as _______ may form bonds with ____________. This interferes with the _______ formed between amino acid R groups of the protein chain, resulting in loss of _______-.

Answer 239

mercury or lead
negatively charged side chain groups
salt bridges
conformation

Question 240

Heavy metals may also bind to ______ of a protein.

Answer 240

sulfhydryl groups

Question 241

Heavy metals may also bind to sulfhydryl groups of a protein. This may cause a profound change in the _____________ of the protein, accompanied by ________

Answer 241

3D structure

loss of function

Question 242

Stirring, whipping, or shaking can disrupt the

Answer 242

weak interactions that maintain protein conformation.

Question 243

Amino acids are also used in the biosynthesis of a large number of important molecules called the

Answer 243

nitrogen compounds

Question 244

the nitrogen compounds includes

Answer 244

some hormones, the heme groups of hemoglobin and myoglobin, and the nitrogen-containing bases found in DNA and RNA.

Question 245

Digestion of dietary protein begins in the

Answer 245

stomach

Question 246

The stomach enzyme ____ begins the digestion by _____ some of the ______ of the protein. This breaks the protein down into __________

Answer 246

pepsin
hydrolyzing
peptide bonds
smaller peptides

Question 247

Production of pepsin and other proteolytic digestive enzymes must be _________ because the active enzymes would ____ and ___ the _______

Answer 247

carefully controlled
digest
destroy
cell that produces them.

Question 248

pepsin is actually synthesized and secreted in an inactive form called

Answer 248

pepsinogen

Question 249

Pepsinogen has an additional __________ in its primary structure. These are removed in the stomach to produce ___________.

Answer 249

forty-two amino acids

active pepsin

Question 250

Protein digestion continues in the _____ where the enzymes ____,______,_______, and others catalyze the hydrolysis of _________ at different sites in the protein.

Answer 250

small intestine
trypsin, chymotrypsin, elastase
peptide bonds

Question 251

_______ cleaves peptide bonds on the carbonyl side of aromatic amino acids and _____ cleaves peptide bonds on the carbonyl side of basic amino acids. Together these __________ degrade large dietary proteins into amino acids that can be absorbed by cells of the ________.

Answer 251

chymotrypsin
trypsin
proteolytic enzymes
small intestine

Question 252

Amino acids can be divided into two major nutritional classes. ________ are those that cannot be synthesized by the body and are required in the diet. __________ are those amino acids that can be synthesized by the body and need not be included in the diet

Answer 252

Essential amino acids

Nonessential amino acids

Question 253

Proteins are also classified as

Answer 253

complete or incomplete

Question 254

Protein derived from animal sources is generally

Answer 254

complete protein

Question 255

complete protein provides all of the __________ in approximately the correct amounts for biosynthesis.

Answer 255

essential and nonessential amino acids

Question 256

In contrast, protein derived from vegetable sources is generally _________ because it lacks a sufficient amount of _________

Answer 256

incomplete protein

one or more essential amino acids

Question 257

Only a few _____ sources provide complete protein; among these are soy, quinoa, and buckwheat.

Answer 257

vegetable

Question 258

People who want to maintain a strictly vegan diet or for whom animal protein is often not available have the problem that most high-protein vegetables do not have all of the

Answer 258

essential amino acids needed to ensure a sufficient daily intake.

Question 259

Histidine and arginine are essential amino acids for _____ but not for ________

Answer 259

infants

healthy adults

Question 260

Cysteine and tyrosine are considered to be ____________amino acids. They are required by ________________.

Answer 260

semiessential

premature infants and adults who are ill

Question 261

list the essential amino acids

Answer 261

Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine