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My MCAT Cards: Biochemistry > Ch 3: Carbon and the Molecular Diversity of Life (copied from Campbell Biology) > Flashcards

Ch 3: Carbon and the Molecular Diversity of Life (copied from Campbell Biology) Flashcards

1
Q

Single sugar molecules are called __________.
These molecules generally have molecular formulas that are some multiple of the unit ___.

A

monosaccharides

CH2O

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2
Q

In the structure of glucose, we can see the trademarks of a sugar: the molecule has a ________ group, and multiple hydroxyl (-OH) groups.

A

carbonyl

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3
Q

A carbonyl group is called a ______ if the carbonyl group is within a carbon skeleton, and an ________ if the carbonyl group is at the end of a carbon skeleton.

A

ketone

aldehyde

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4
Q

The carbon skeleton of a monosaccharide ranges from _ to _ carbons long.

A

3 to 7

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5
Q

In aqueous solutions, glucose and other 5- and 6- carbon sugars form _____, which is the most ______ form of these under physiological conditions.

A

rings

stable

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6
Q

The valences of carbon and its most frequent partners (_______, ______, and ________) are the building code for the architecture of living molecules.

A

hydrogen, oxygen, and nitrogen

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7
Q

Valence, the number of covalent bonds an atom can form, is generally equal to the # of electrons needed to complete the valence shell. What are the valences of these major elements of organic molecules?

hydrogen?

carbon?

nitrogen?

oxygen?

A

1

4

3

2

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8
Q

What are isomers?

A

compounds with the same molecular formula, but different structures, and therefore, properties

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9
Q

What are cis-trans isomers?

A

isomers which differ in their arrangement about a double bond

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10
Q

Enantiomers are mirror images of one another. They differ in their spatial arrangement around an ________ carbon. They are designated by L- and D- meaning “levo” or “dextro”. In Latin, levo means left, and dextro means right.

A

asymmetric

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11
Q

Which drug has two isomers that can be interconverted within the body and caused many birth defects 50 years ago?

A

thalidomide

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12
Q

The FDA has approved thalidomide for treatment of what condition?

A

multiple myeloma

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13
Q

What other factors besides arrangement of the carbon skeleton are important for determining molecular function?

A

functional groups

(e.g. estradiol vs testosterone; the only difference is testosterone has an extra methyl group, and a carbonyl group in place of a hydroxyl group)

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14
Q

Peptide bonds are formed by _________ reactions, which link the carboxyl group of one amino acid to the amino group of the next.

A

dehydration

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15
Q

Why is the term polypeptide not synonymous with the term ‘protein’?

A

Even for a protein consisting of a single polypeptide, the relationship is somewhat analogous to that between a long strand of yarn and a sweater of particular size and shape that can be knitted from the yarn. A functional protein is not just a polypeptide chain, but one or more polypeptides precisely twisted, folded, and coiled into a molecule of unique shape, which can be shown in several different types of models. And it is the amino acid sequence of each polypeptide that determines what three-dimensional structure the protein will have under normal cellular conditions.

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16
Q

If you had a polypeptide chain 127 amino acids long, how many possible configurations exist if left to chance?

A

20127

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17
Q

What protein accounts for 40% of the protein in the human body?

A

collagen

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18
Q

For instance, sickle-cell disease, an inherited blood disorder, is caused by the substitution of one amino acid (______) for the normal one (_______ ____) at the position of the sixth amino acid in the primary structure of hemoglobin, the protein that carries oxygen in red blood cells.

A

valine

glutamic acid

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19
Q

What method is most commonly used to determine the 3-D shape of a protein?

A

X-ray crystallography (depends on the diffraction of an X-ray beam by the atoms of a crystallized molecule)

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20
Q

What exactly are intrinsically disordered proteins?

A

Proteins which do not have specific 3-D shape until they interact with a target protein or other molecule. This indefinite structure gives them flexibility.

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21
Q

There are 9 amino acids with hydrophobic (nonpolar) side chains. Name them.

A

GAVLIMP-TP

glycine, alanine, valine,

leucine, isoleucine, methionine, phenylalanine, tryptophan, proline

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22
Q

What are nucleic acids?

A

Polymers made of monomers called nucleotides.

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23
Q

What is the name of the process during which a bond between two monomers is broken?

This process is the opposite of what reaction?

A

Hydrolysis is the opposite of a condensation reaction. During hydrolysis, a water molecule is used up in the breaking of a bond between two monomers. An H is added to one monomer, and an OH is added to the other.

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24
Q

Which chemical group is most likely to be responsible for an organic molecule behaving as a base?

a. hydroxyl
b. carbonyl
c. amino
d. phosphate

A

c. amino

(from Concept 2.5, p. 39: “A substance that reduces the hydrogen ion concentration of a solution is called a base. Some bases reduce the H+ concentration directly by accepting hydrogen ions. Ammonia (NH3) for instance, acts as a base when the unshared electron pair in nitrogen valence shell attracts a hydrogen ion from the solution, resulting in an ammonium ion (NH4+).

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25
Q

Which of the following terms is a category which includes all others on the list?

a. disaccharide
b. starch
c. carbohydrate
d. polysaccharide

A

c. carbohydrate

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26
Q

Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNA molecules treated with these enzymes?

a. The two strands of the double helix would separate.
b. The phosphodiester linkages of the polynucleotide backbone would be broken.
c. The pyrimidines would be separated from the deoxyribose sugars.
d. All bases would be separated from the deoxyribose sugars.

A

b. the phosphodiester linkages of the polynucleotide backbone would be broken

27
Q

In a polynucleotide, adjacent nucleotides are joined by a phosphodiester linkage. In this linkage, what type of bond exists between the phosphate group and the sugars of two nucleotides?

A

a covalent bond

p. 67

28
Q

alpha-helices and beta-strands or pleated sheets are formed by ________ ______.

A

hydrogen bonds

29
Q

Starch (including amylose & amylopectin), glycogen, and cellulose, are all polysaccharides composed entirely of _______ monomers.

Glycogen is extensively branched, but _______ is unbranched; ________ (also unbranched) forms very straight chains held close together like strands by hydrogen bonds.

Amylopectin is somewhat branched.

A

glucose

amylose

cellulose

30
Q

Why are lipids not true polymers?

A

They are not made up of chains of monomers in the same way that proteins and carbohydrates are. They vary more in form. They also do not covalently link like other polymers.

They are generally not big enough to be considered macromolecules.

31
Q

Not all proteins have ____________ structure.

A

quaternary

32
Q

Tertiary structure is formed by R-group interactions, including ________ bonds, ionic bonds, and hydrophobic interactions. Strong ________ bonds called disulfide bridges may reinforce the protein’s structure.

A

hydrogen

covalent

33
Q

Temperature, __, salts present, can alter the shape and function of proteins.

A

pH

34
Q

A given ____ along a DNA molecule can direct synthesis of a type of RNA called messenger RNA (mRNA). The mRNA molecule interacts with the cell’s protein-synthesizing machinery to direct production of a __________, which folds into all or part of a protein.

A

gene

polypeptide

35
Q

Which nitrogenous bases are considered pyrimidines?

A

cytosine, thymine (found in DNA), uracil (found in RNA)

36
Q

Which nitrogenous bases are called the purines?

A

adenine and guanine

37
Q

Name the components of a nucleotide?

Which part(s) are considered the ‘nucleoside’?

A

phosphate group + pentose sugar + nitrogenous base

A nucleoside is a nitrogenous base linked to a pentose sugar molecule. (Essentially, it’s the nucleotide minus the phosphate group.)

38
Q

Identify this amino acid.

A

glycine (Gly or G)

39
Q

Name this amino acid.

A

alanine

(Ala or A)

40
Q

Name this amino acid.

A

valine

(Val or V)

41
Q

Name this amino acid.

A

Leucine

(Leu or L)

42
Q

Name this amino acid.

A

Isoleucine

(Ile or I)

43
Q

Name this amino acid.

A

methionine (Met or M)

44
Q

Name this amino acid.

A

phenylalanine (Phe or F)

45
Q

Name this amino acid.

A

Tryptophan (Trp or W)

46
Q

Name this amino acid.

A

Proline (Pro or P)

47
Q

Name this amino acid.

A

Serine (Ser or S)

48
Q

Name this amino acid.

A

Threonine (Thr or T)

49
Q

Name this amino acid.

A

Cysteine (Cys or C)

50
Q

Name this amino acid.

A

Tyrosine (Tyr or Y)

51
Q

Name this amino acid.

A

Asparagine (Asn or N)

You can remember asparagine is N bc asparagus is Nasty.

52
Q

Name this amino acid.

A

Glutamine (Gln or Q)

Think Q-tamine.

53
Q

Name this amino acid.

A

Aspartic acid (Asp or D)

(a.k.a. aspartate - refers to the anionic or deprotonated form)

54
Q

Name this amino acid.

A

Glutamic acid (Glu or E)

(a.k.a. glutamate - refers to the anionic or deprotonated form)

55
Q

Name this amino acid.

A

Lysine (Lys or K)

56
Q

Name this amino acid.

A

Arginine (Arg or R)

57
Q

Name this amino acid.

A

Histidine (His or H)

58
Q

Name this amino acid:

A

Alanine (Ala or A)

59
Q

Which amino acid is abbreviated A?

A

alanine

60
Q

Which amino acid is abbreviated R?

A

arginine

61
Q

Which amino acid is abbreviated N?

A

asparagine

62
Q

Which amino acid is abbreviated D?

A

aspartic acid (aspartate)

63
Q

Which amino acid is abbreviated C?

A

cysteine

My MCAT Cards: Biochemistry (9 decks)

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