Chapter 16 Amino acids, proteins, Flashcards

1
Q

what is hemoglobin and myoglobin an example of?

A

proteins that transport oxygen in the blood

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2
Q

what is found in an amino acid?

A

central atom bonded to an ammonium group(NH3+) and a carboxylate group (COO-)

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3
Q

can amino acids be polar or non polar?

A

both

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4
Q

when is an amino acid nonpolar?

A

when the R group is H, alkyl, or aromatic (ex: attached to benzine ring or chain of carboxyl groups)

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5
Q

when is an amino acid polar?

A

when the R group is an alcohol, a thiol, or an amide (ex: anything with Oxygen or SH or O=C-NH2 at the end)

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6
Q

what is sickle-cell anemia caused by? What does it cause to happen?

A

an abnormality in one of the subunits (an amino acid) of the hemoglobin protein. This changes the shape of the blood cell to change form like a sickle shape, leaving it unable to adequately transport oxygen

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7
Q

what building blocks are proteins made of?

A

amino acids

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8
Q

are nonpolar amino acids water soluble? what’s the name for this?

A

no; hydrophobic

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9
Q

are polar amino acids water soluble? what’s the name for this?

A

yes; hydrophilic

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10
Q

what makes a polar amino acid neutral, acidic, or basic?

A

Neutral: contains neutrally charged ions in the R group of the amino acid
Acidic: contains negatively charged oxygen in the R group of the amino acid (a carboxylic acid)
Basic: contains positively charged Nitrogen in the R group of the amino acid (an amine)

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11
Q
A
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12
Q

are the alpha amino acids chiral or achiral?

A

all a-amino acids are chiral with exception for glycine

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13
Q

how do you tell if you are looking at the L or D enantiomer of a amino acid?

A

L: NH3+ appears on the left
D: NH3+ appears on the right

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14
Q
A
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15
Q

what are essential amino acids?

A

amino acids that cannot be produced in the body and need to come from our diet

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16
Q

what are examples of foods that contain complete proteins of all the essential amino acids?

A

meat, milk, eggs and fish

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17
Q

what are examples of foods that contain incomplete proteins of only some of the essential amino acids?

A

grains, beans, and nuts

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18
Q
A
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19
Q
A
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20
Q

amino acids can exist as positive ion or negative ion, how would you know which is it?

A

positive ion: if a solution is more acidic; lower pH than its pI
negative ion: if a solution is more basic; higher pH than its pI

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21
Q

what is the definition of pI?

A

Isoelectric point: when an amino acid with positive and negative charges is overall neutral in charge

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22
Q

would this have a pH higher or lower than 6?

A

lower than 6

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23
Q

what is another name for peptide bonds?

A

amide bonds

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24
Q

what is a peptide?

A

linking of two or more amino acids via peptide (amide) bonds

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25
Q

Where does a peptide (amide) bond form?

A

between one amino acid’s COO- group and another amino acid’s NH3+ group
gets ride of a water molecule (one oxygen from the COO- and two hydrogens from the NH3+)

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26
Q

what is the name of two/three/four amino acids bonded by peptide bonds?

A

dipeptides
tripeptides
tetrapeptides

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27
Q
A
28
Q

what is the name of the reaction that forms di/tri/tetrapeptides?

A

amidation reaction

29
Q

Since amino acids are the building blocks of proteins, how many amino acids does it take to form a functioning protein?

A

a protein is a polypeptide of 50 or more amino acids

30
Q

which protein was the first to have its primary structure determined?

A

insulin

31
Q

what does the primary structure of insulin contain?

A

two polypeptide chains linked by disulfide bonds

32
Q

how many amino acids are used to build proteins in the body and how many can be synthesized within it?

A

20
11
9 are essential amino acids that are obtained through diet

33
Q

what is the difference in appearance between primary and secondary structures of polypeptides?

A

primary: straight line
secondary: helix spiral or pleated sheet

34
Q

what are the differences of types of bonds found in primary vs secondary structures?

A

primary: only peptide bonds
secondary: peptide and hydrogen bonds

35
Q

where do hydrogen bonds form within the helix structure?

A

between the oxygen of C=O groups and the hydrogen of N-H groups of the amide bonds

36
Q

what holds the chains together within a triple helix? what important function does this have?

A

hydrogen bonds
added strength (as in with collagen and connective tissue)

37
Q

which amino acids will have salt bridges in tertiary structures?

A

only ones with positive NH3+ bonds

38
Q

what are examples of triple helixes in proteins? what type of structure are they?

A

collagen, connective tissue, skin, tendons, and cartilage
secondary struture

39
Q

what vitamin is important for the production of collagen?

A

vitamin C

40
Q

what are the five characteristics of tertiary proteins?

A

hydrophobic interactions
hydrophilic interactions
salt bridges
hydrogen bonds
disulfide bonds

41
Q

where do hydrophobic interaction occur within tertiary proteins? polar or nonpolar?

A

between two nonpolar amino acids at the center of the protein molecule

42
Q

where do hydrophilic interactions occur within tertiary proteins?

A

between the external aqueous environment and the R groups of the polar amino acids

43
Q

where do salt bridges occur within tertiary proteins?

A

between ionized R groups of basic and acidic amino acids (NH3+)

44
Q

where do hydrogen bonds occur within tertiary proteins?

A

between H of a polar R group and the O or N of another amino acid

45
Q

where do disulfide bonds occur between tertiary proteins?

A

between the SH groups of cysteine amino acids

46
Q

myoglobin is a ___________ structure protein

A

tertiary

47
Q

hemoglobin is a ____________ structure protein

A

quaternary

48
Q

what force is important in the primary structure of a protein?

A

peptide bond

49
Q

a-helix and b-sheet are in the ________ structure category of proteins?

A

secondary

50
Q

which amino acid forms disulfide bonds to stabilize the tertiary structure of a protein?

A

cysteine

51
Q

quaternary structure are made up of?

A

two or more protein subunits

52
Q

hemoglobin is made up of what?

A

two a-chains and two b-chains

53
Q

what kind of interactions are found in quaternary structures?

A

the same ones as with tertiary structures (hydrophilic/phobic, salt bridges, hydrogen bonds, and disulfide bonds

54
Q

when does denaturation occur within proteins?

A

when there is a change that disrupts the interactions that stabilize the secondary, tertiary, or quaternary structure

55
Q

Under what conditions can denaturation of proteins occur?

A

heat, organic compounds, acids and bases, heavy metals, and mechanical agitation (such as whipping a solution)

56
Q

the cooking of an egg is an example of ?

A

denaturation

57
Q

what are the bonds divided when heat is applied to proteins?

A

hydrogen bonds and hydrophobic interactions

58
Q

what are the bonds disrupted when acids or bases denature proteins?

A

hydrogen bonds between polar R groups (salt bridges are disrupted)

59
Q

what bonds are denatured when organic compounds are applied?

A

hydrogen bonds FORM and hydrophobic interactions are disrupted

60
Q

what bonds are disrupted when heavy metals denature proteins?

A

disulfide bonds (instead it forms ionic bonds)

61
Q

what bonds are disrupted when mechanical agitation denature proteins?

A

hydrogen bonds and hydrophobic interactions

62
Q
A
63
Q
A
64
Q
A
65
Q
A