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MCAT Biology (Mine) > Chapter 3 part 1 > Flashcards

Chapter 3 part 1 Flashcards

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1
Q

What are the characteristics of an amino acid structure?

A

Has an amino group at the first end, an alpha carbon, an R group, & an alpha carboxyl group

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2
Q

All 20 aa share the same ________________ backbone

A

Nitrogen-carbon-carbon backbone

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3
Q

What are the two types of covalent bonds between amino acids in proteins?

A
  1. Peptide bonds
  2. Disulfide bonds
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4
Q

Peptide bonds

A

Links amino acids together into polypeptides chains

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5
Q

Disulfide bridges

A

Bridges between cysteine R groups

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6
Q

Polypeptides are formed by linking amino acids together in __________ bonds

A

Peptide

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7
Q

A peptide bond is formed between the ___________ group of one amino acid & the alpha-amino group with the loss of ________

A

Carboxyl group, water

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8
Q

In a polypeptide chain the ___________ pattern from the amino acid is known as the backbone of the polypeptide

A

N-C-C-N-C-C (A single amino acid is known as a reisdue)

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9
Q

The ________________ is the 1st end made during polypeptide synthesis& the carboxyl terminus last

A

Amino acid terminus

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10
Q

The ________________ residues is always written first

A

Amino terminal

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11
Q

Proteolysis (Proteolytic cleavage)

A

Hydrolysis of a protein by another protein

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12
Q

Proteolytic enzyme (Protease)

A

Hydrolysis of a protein by another protein

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13
Q

____________ can form disulfide bonds (sulfur-sulfur bonds) with each other

A

Cysteines

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14
Q

When cysteine becomes disulfide-bonded to one another its called ___________ instead of cysteine

A

Cystine

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15
Q

Proteins fold into a unique 3D structure so that it can _____________ properly

A

function

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16
Q

Denatured proteins

A

Improperly folded that are non-functional

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17
Q

Denaturation

A

Refers to the disruption of a protein’s shape without breaking peptide bonds

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18
Q

Proteins are denatured by what conditions?

A
  1. Urea- which disrupts hydrogen bonding interactions
  2. Extreme pH
  3. Extreme temperature
  4. Changing salt concentration (tonicity)
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19
Q

Primary (1) structure

A

Linear sequence of amino acid residues( & peptide bonds determines its structure)

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20
Q

Secondary (2) structure

A

Contains hydrogen bonds between backbone groups

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21
Q

Secondary structure is the initial folding of a polypeptide chain into shapes stabilized by ____________ bonds between backbone NH & CO groups

A

Hydrogen bonds

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22
Q

Secondary structure contains what 2 types of motifs?

A
  1. Alpha helix
  2. Beta pleated sheets
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23
Q

Parallel beta pleated sheets

A

Have adjacent polypeptides strands running in the same direction

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24
Q

Anti-Parallel beta-pleated sheets

A

Polypeptides strands running in opposite directions

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25
Q

If a single polypeptide folds once & forms a beta-pleated sheet with itself it would be _________________

A

Antiparallel

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26
Q

Tertiary (3) structures are stabilized by _________________ interactions

A

hydrophobic/hydrophilic

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27
Q

Secondary structures such as ___________ fold into 3 structures driven by the interation of the R groups with eaxh toeher & water

A

Alpha helices

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28
Q

In forming the 3 structures the hydrophobic R groups fold into the interior of the protein & the hydrophilic R groups tend to be exposed to water or the surface of the protein and this process is known as what?

A

Hydrophobic effect

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29
Q

Quaternary (4) structure involves the interactions between polypeptide _________

A

Subunits

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30
Q

A subunits is what?

A

Is a single polypeptide chain that is part of a large complex containing many subunits (a multisubunit complex)

31
Q

What forces stabilize the 4 & 3 structures?

A

Non-covalent, interactions, van der waals forces, hydrogen bonds, disulfide bonds & electrostatic interaction stabilize 4 & 3 structures

32
Q

__________ bonds_ aren’t involved in 4 structures (ex. The difference between 4 disulfide & 3 disulfides bonds is that 4 disulfides are bonds that form between chains that aren’t linked by peptide bonds & 3 disulfides are bonds that form between residues in the same polypeptide

A

Peptide bonds

33
Q

Carbohydrates can be broken down to CO2 in a process called _________ which is also the burning or combustion

A

Oxidation

34
Q

Monosaccharides (simple sugars)

A

Is a single carbohydrate molecule (have the general formula CnH2nOn)

35
Q

What are some examples of monosaccharides?

A

Fructose, Glucose, & Ribose

36
Q

Two monosaccharides bonded together form a _______________, a few form an oligosaccharide & many form a polysaccharide

A

Disaccharide

37
Q

Glycosidic linkage

A

The bond between two sugars molecules

38
Q

What are lipids physiological roles?

A
  1. In adipose cells triglycerides (fats) store energy
  2. In cellular membranes phospholipids constitute a barrier between intracellular & extracellular environments
  3. Cholesterol is a special lipid that serves as the building block for the hydrophobic steroid hormones
39
Q

The main characteristic of the lipid is its _________________

A

hydrophobicity

40
Q

A hydrophobic molecule is also a _____________ molecule

A

lipophilic

41
Q

Hydrophilic molecule is ____________

A

Lipophobic (lipid-rearing)

42
Q

Fatty Acids contain _____________ at its end & are usually 14 to 18 carbons long

A

carboxylic acids

43
Q

Only ________ numbered fatty acids are made in human cells

A

Even

44
Q

Saturated fatty acids

A

A fatty acid with no double bond

45
Q

Unsaturated fatty acids

A

Contain one or more double bonds & are usually cis (or Z)

46
Q

When fatty acids interact with water (or an aqueous solution) they form a micelle where the long hydrophobic tails are in the center & the hydrophilic head is exposed & the _________________ interactions is the driving force for it

A

Hydrophobic

47
Q

The storage form of a fatty acid is _______ which is triacylglycerol or triglyceride

A

Fat

48
Q

The triglyceride is composed of ____ fatty acids esterified to a glycerol molecule & glycerol is a 3-carbon triol with the formula HOCH2-CHOH-CH2OH

A

3

49
Q

Lipases

A

Are enzymes that hydrolyzed fats

50
Q

Triacylglycerols

A

Are stored in fat cells as an energy source

51
Q

Fats are more efficient energy storage molecules than carbohydrates for what two reasons?

A
  1. Packing
  2. Energy content
52
Q

Packing

A

Their hydrophobicity allows fat to pack together much more closely than carbohydrates. Carbohydrates carry a great amount of water-of-solvation(water molecules hydrogen bonded to their hydroxyl groups)

53
Q

Energy content

A

All packing considerations asides, fat molecules store more energy than carbohydrates. In other words, regardless of what you dissolve it in, a fat has more energy carbon-for-carbin than a carbohydrate

54
Q

Phospholipids form what when interacting with water?

A

Lipid Bilayer

55
Q

Double bonds in phospholipids fatty acids tend to ______ membrane fluidity

A

Increase

56
Q

_______________ prevents the membrane from solidifying by disrupting the orderly packing of the hydrophobic lipid tails

A

Unsaturation

57
Q

Decreasing the length of fatty acids tails also increases _____________

A

Fluidity

58
Q

At low temperatures cholesterol ___________ fluidity in the same way as kinks in fatty acid tails, therefore its known as membrane antifreeze

A

Increase

59
Q

At high temp, cholesterol keeps fluidity at an _____________

A

Optimum level

60
Q

What are the structural determinants of membrane fluidity?

A
  1. Degree of saturation
  2. Tail length
  3. Amount of cholesterol
61
Q

A terpene has a general formula ____________, they come from an isoprene units

A

(C5H8)n

62
Q

Steroids are similar to________

A

Fats

63
Q

All steroids have the basic ______________

A

tetracyclic ring system (based on the structure of cholesterol)

64
Q

Cholesterol is a ____________

A

Steroid (ex. testosterone & estradiol)

65
Q

Phosphate is also known as _______________

A

orthophosphate

66
Q

Two orthophosphates bound together via an anhydride linkage form ___________

A

Pyrophosphate where the P-O-P bond in Pyrophosphate is an example of a high energy phophosphate bond

67
Q

What are the 3 reasons that phosphate anhydride bonds store so much energy?

A
  1. When phosphates are linked together, their negative charges repel each other strongly
  2. Orthophsophate has more resonance forms and thus a lower free energy than linked phosphates
  3. Ortohophoshates has a more favorable interaction with the biological solvent (water) than linked phosphates
68
Q

Two monosaccharides joined with a ____________ linkage form a disaccharide

A

Glycosidic linkage (common disaccharides are maltose, sucrose, & lactose)

69
Q

Glycogen (animals) & starch (plants) are ________ units for glucose & can be broken down for energy

A

Storage (cellulose is a glucose polymer but its beta linkage prevents digestion)

70
Q

Lipids are found in triglycerides, ________________, cholesterol, and steroids, and terpenes

A

Phospholipids

71
Q

Triglycerides and phospholipids are linear while cholesterol and steroid have _______ structure

A

Ring

72
Q

Lipids are _________

A

Hydrophobic

73
Q

Triglycerides are used for _________ storage, phospholipids form ________ & cholesterol is the precursor to the steroid hormones

A

Energy, membranes

74
Q

The building blocks of nucleic acids (DNA & RNA) are ____________ which are comprised of pentose sugar, a purine or pyrimidine base & 2-3 phosphate units

A

nucleotides

MCAT Biology (Mine) (5 decks)

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