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

Chapter 3 part 1 Flashcards

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
If a single polypeptide folds once & forms a beta-pleated sheet with itself it would be _________________
Antiparallel
26
Tertiary (3) structures are stabilized by _________________ interactions
hydrophobic/hydrophilic
27
Secondary structures such as ___________ fold into 3 structures driven by the interation of the R groups with eaxh toeher & water
Alpha helices
28
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?
Hydrophobic effect
29
Quaternary (4) structure involves the interactions between polypeptide _________
Subunits
30
A subunits is what?
Is a single polypeptide chain that is part of a large complex containing many subunits (a multisubunit complex)
31
What forces stabilize the 4 & 3 structures?
Non-covalent, interactions, van der waals forces, hydrogen bonds, disulfide bonds & electrostatic interaction stabilize 4 & 3 structures
32
__________ 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
Peptide bonds
33
Carbohydrates can be broken down to CO2 in a process called _________ which is also the burning or combustion
Oxidation
34
Monosaccharides (simple sugars)
Is a single carbohydrate molecule (have the general formula CnH2nOn)
35
What are some examples of monosaccharides?
Fructose, Glucose, & Ribose
36
Two monosaccharides bonded together form a _______________, a few form an oligosaccharide & many form a polysaccharide
Disaccharide
37
Glycosidic linkage
The bond between two sugars molecules
38
What are lipids physiological roles?
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
The main characteristic of the lipid is its _________________
hydrophobicity
40
A hydrophobic molecule is also a _____________ molecule
lipophilic
41
Hydrophilic molecule is ____________
Lipophobic (lipid-rearing)
42
Fatty Acids contain _____________ at its end & are usually 14 to 18 carbons long
carboxylic acids
43
Only ________ numbered fatty acids are made in human cells
Even
44
Saturated fatty acids
A fatty acid with no double bond
45
Unsaturated fatty acids
Contain one or more double bonds & are usually cis (or Z)
46
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
Hydrophobic
47
The storage form of a fatty acid is _______ which is triacylglycerol or triglyceride
Fat
48
The triglyceride is composed of ____ fatty acids esterified to a glycerol molecule & glycerol is a 3-carbon triol with the formula HOCH2-CHOH-CH2OH
3
49
Lipases
Are enzymes that hydrolyzed fats
50
Triacylglycerols
Are stored in fat cells as an energy source
51
Fats are more efficient energy storage molecules than carbohydrates for what two reasons?
1. Packing 2. Energy content
52
Packing
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
Energy content
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
Phospholipids form what when interacting with water?
Lipid Bilayer
55
Double bonds in phospholipids fatty acids tend to ______ membrane fluidity
Increase
56
_______________ prevents the membrane from solidifying by disrupting the orderly packing of the hydrophobic lipid tails
Unsaturation
57
Decreasing the length of fatty acids tails also increases _____________
Fluidity
58
At low temperatures cholesterol ___________ fluidity in the same way as kinks in fatty acid tails, therefore its known as membrane antifreeze
Increase
59
At high temp, cholesterol keeps fluidity at an _____________
Optimum level
60
What are the structural determinants of membrane fluidity?
1. Degree of saturation 2. Tail length 3. Amount of cholesterol
61
A terpene has a general formula ____________, they come from an isoprene units
(C5H8)n
62
Steroids are similar to________
Fats
63
All steroids have the basic ______________
tetracyclic ring system (based on the structure of cholesterol)
64
Cholesterol is a ____________
Steroid (ex. testosterone & estradiol)
65
Phosphate is also known as _______________
orthophosphate
66
Two orthophosphates bound together via an anhydride linkage form ___________
Pyrophosphate where the P-O-P bond in Pyrophosphate is an example of a high energy phophosphate bond
67
What are the 3 reasons that phosphate anhydride bonds store so much energy?
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
Two monosaccharides joined with a ____________ linkage form a disaccharide
Glycosidic linkage (common disaccharides are maltose, sucrose, & lactose)
69
Glycogen (animals) & starch (plants) are ________ units for glucose & can be broken down for energy
Storage (cellulose is a glucose polymer but its beta linkage prevents digestion)
70
Lipids are found in triglycerides, ________________, cholesterol, and steroids, and terpenes
Phospholipids
71
Triglycerides and phospholipids are linear while cholesterol and steroid have _______ structure
Ring
72
Lipids are _________
Hydrophobic
73
Triglycerides are used for _________ storage, phospholipids form ________ & cholesterol is the precursor to the steroid hormones
Energy, membranes
74
The building blocks of nucleic acids (DNA & RNA) are ____________ which are comprised of pentose sugar, a purine or pyrimidine base & 2-3 phosphate units
nucleotides

MCAT Biology (Mine) (5 decks)

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