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MCAT Practice Test 4 > Chem/Phys Section > Flashcards

Chem/Phys Section Flashcards

(114 cards)

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1
Q

How are amino acids connected to each other and formed into proteins?

A

The amino terminus of one amino acid attacks the carboxylic-terminal of another.
This is a nucleophilic attack.

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2
Q

What does the interaction of R groups contribute to in the formation of proteins?

A

Tertiary structure.
The connection of the amino acids contributes to primary structure.
H-bonding between carboxy and amino terminals account for secondary structure such as alpha helices and beta sheets

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3
Q

What amino acid is not optically active?

A

Glycine because it is the only amino acid without a chiral center

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4
Q

What is a free radical?

A

An unpaired valence electron.

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5
Q

Nitrile Group

A

(-CN)

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6
Q

How do we make an electrophile even more electrophilic?

A

Attach another electron withdrawing group in order to make part of the molecule even more electron deficient so it want the electrons even more.

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7
Q

Grignard Reagent

A

Grignard reagent is a stronger nucleophile than water. The product of a reaction with Grignard reagent would create new C-C bonds.

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8
Q

Ring Closure of a molecule

A

Count number of carbons in original molecule! Should match ring. Penultimate OH group acts as the nucleophile that attacks the carbonyl carbon. It is deprotonated and left with an extra pair of electrons.
Carbonyl oxygen turns into another OH group.
Carbonyl is turned into the anomeric carbon in the ring (carbon directly to the right of the O in ring)
Downright Up lefting
Those of Fischer diagram that are on the right point down in the ring and those of Fischer diagram that are on left point up in the ring.
If a D sugar then last group points up in the ring. If an L sugar then last group points down in the ring.

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9
Q

Pyranose

A

6 membered ring

5 carbons in ring and one Oxygen

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10
Q

Furanose

A

5 membered ring

4 carbons in ring and one Oxygen

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11
Q

Humans and animals mostly use what kind of sugars?

A

D sugars

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12
Q

What form of Amino acids is used by cells?

A

L amino acids. Some D amino acids found in cell walls of bacteria but not in bacterial proteins.

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13
Q

Alpha Anomer in Ring configurations

A

Alpha anomer points opposite direction of OH to left of O in ring. Alpha anomer is in the axial position.
Fishies are down in the sea

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14
Q

Beta anomer of ring

A

OH of anomeric carbon is in the equatorial position and points in same direction as the OH group to the left of the O in the ring
Birds are found in the air

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15
Q

Will the material with the lowest index of refraction enable light to travel fastest or slowest?

A

Lowest index of refraction allows light to travel the fastest

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16
Q

What is myopia and what lens corrects it?

A

Nearsightedness. Light focuses in front of the retina. Corrected using a concave lens. This lens moves the image back to the retina

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17
Q

What is Hyperopia and how is it treated?

A

Farsightedness. Object is focused behind the retina. It is treated with a convex (converging) lens

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18
Q

When is the image real for a converging (convex) lens?

A

Image is real if it placed outside the focal length. Any real image formed by a converging lens is inverted. The retina is small so for it to be possible for it to view an object that is larger than the retina, the formed image must be reduced.

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19
Q

What is etiology?

A

The cause or set of cause for a disease or condition

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20
Q

What is pathogenesis?

A

The manner of development of disease

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21
Q

What are anomers?

A

Anomers differ ONLY in the absolute configuration at their anomeric carbon.
Example is alpha-D-glucose and Beta-D-Glucose.

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22
Q

What are enantiomers?

A

Enantiomers are mirror images of each other and polarize light oppositely. Example is D-Glucose and L-Glucose

Have SAME physical properties with the exception of direction of polarization of light

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23
Q

What is a reducing sugar?

A

They are Monosaccharides with a hemiacetal because their open-chain form contains an aldehyde. If the structure lacks any hemiacetal functional groups then it is locked in its cyclic form and is not a reducing sugar.

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24
Q

What is a hemiacetal?

A
  • one OH group and one OR group attached to the same carbon.
  • in equilibrium with aldehyde/ketone
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25
What is an acetal (ketal)
- two OR groups attached to same carbon - not in equilibrium with aldehyde/ketone. - “locked”
26
How to find mass percent composition of an element in a product?
1. Figure out what the products are 2. Ignore starting number of moles 3. Look at molar masses of elements in the compound where your target element is 4. Divide mass of target element by total mass of product 5. Multiply by one hundred to get percent
27
What causes quaternary structure?
When multiple polypeptides interact to form a single protein with multiple subunits. Cysteines on different polypeptides can interact and form disulfide bridges which form cystines
28
Reducing agent
What is being oxidized. | Causes something else to be reduced.
29
What type of bonds are disulfide bonds?
They are covalent bonds.
30
What are the three basic amino acids?
Histidine, arginine, lysine
31
What is an Ester?
R-carbonyl-OR
32
What is an ether?
R-O-R No carbonyl
33
When an acyl halide reacts with a primary alcohol what forms?
An Ester | R-carbonyl-OR
34
Polysaccharides are held together by what?
Carbohydrate-to-carbohydrate glycosidic bonds hold the monosaccharides together within a polysaccharide. This means all polysaccharides have these bonds. Polysaccharides can contain branched chains but not all do.
35
What is a polypeptide?
A linear organic polymer consisting of a large number of amino acid residues bonded together in a chain, forming part of (or the whole of) a protein molecule. Amino acids are Linked by peptide bonds
36
What does the number stand for in an isotope?
Stands for the atomic mass of that isotope. For example C^12 versus C^14. Since the molecule is defined by the number of protons that means the protons stay the same and the thing that changed was the number of neutrons.
37
How many reactant molecules does second order kinetics involve?
Two reactant molecules
38
How many reactant molecules can a third order reaction involve?
3 reactant molecules
39
Reaction order 0 units for K and R
Units for K=M/s or M•s^-1 | Units for R are same as K
40
Units for K and R for a first order reaction
K=1/s or s^-1 | R=M/s or M•s^-1
41
Units for K and R for reaction order 2
K=1/M•s. Or M^-1•s^-1 | R=M/s. Or M•s^-1
42
What does it mean when Keq>1?
Reaction proceeds to the right. | Favors products
43
What does Keq=1 mean?
Same amount of reactants and products
44
What does Keq<1 mean?
Favors reactants
45
What is Keq?
[Products]^coefficients/[Reactants]^coefficients Only include gases and aqueous compounds
46
What does a positive delta G mean?
Not spontaneous reaction
47
What is the oxidation number of Oxygen?
-2
48
What is the oxidation number of Nitrogen?
-3
49
What is the trend for oxidation numbers on the periodic table?
Starts with hydrogen at +1, Be is +2, skip over d block elements, B is +3, carbon +4. Then goes negative, so N is -3, O is -2, and F is -1
50
What does increasing venous pressure do to the gut?
Increases hydrostatic pressure in the capillary best, leading to flow of fluid from the capillary into the gut section
51
Filtration occurs at which end of a capillary
The arterial end. Blood plasma containing nutrients moves out of the capillary.
52
Reabsorption occurs at which end of the capillary bed?
Venous end. Tissue fluid containing waste goes back into the capillary.
53
What is hydrostatic pressure?
The pressure of fluids in an enclosed space. Same as capillary blood pressure. Hydrostatic pressure is normally higher in blood then in tissues so fluids and blood solutes move out of the capillary and into the tissues.
54
What opposes hydrostatic force?
Osmotic (oncotic) pressures- Po Driven by protein (solute concentrations) in the blood and tissues. Normally blood has higher protein concentration due to albumin which drives water into the capillary.
55
Which end of the capillary has higher hydrostatic pressure?
The arterial end because it is closer to the heart. Osmotic pressure remains the same throughout the capillary. This causes net outward flow at the arterial end and net inward flow at the venous end.
56
What is the equation for pressure?
P=pgh P=pressure p(rho)=density of fluid g=gravity h=height
57
What does Work equal?
Work=force•distance
58
What does distance equal?
Distance=velocity•time
59
What does force equal?
Force=pressure•area
60
What does Bernoulli’s equation explain?
States that the sum of all forms of energy in a fluid flowing along an enclosed path is the same at any two points in that path.
61
The net torque determines the
Angular acceleration. | If the net torque is zero then the angular acceleration will also be zero and the level will not move.
62
Equation for torque
Torque=Frsinø F=Applied force r=distance to the center of spin from where the force is applied. Often called the lever arm Ø=angle between F and lever arm
63
What does it mean to be a triprotic acid?
Has three dissociable protons that undergo stepwise ionization. Means the acid will have 3 pKa values and 3 different acid states. Gives it ability to act as a buffer across 3 different pH ranges.
64
What kinds of side chains do leucine and phenylalanine have?
Both have hydrophobic side chains making them nonpolar.
65
When is a molecule more soluble in a organic solvents?
When it becomes deprotonated causing it to become neutral. Making a molecule neutral makes it more like an organic solvent that is neutral allowing it to dissolve. Like dissolves like. When the molecule is charged or deprotonated it is more likely to dissolve in water because it is more like water which is also polar.
66
What does racemization require?
Substitution at a chiral center
67
Is phenylalanine or is tyrosine more polar?
Tyrosine is more polar
68
Are silica plates polar or nonpolar?
Very polar, which makes the stationary phase polar. Molecules with an affinity for polar phases will have a low Rf value.
69
Metric prefixes base unit
Gram, meters or liters =10^0
70
Metric Unit prefixes pneumonic
Thank God Man Kind BASEically Dodged Comets Made of Microscopic Ninja Pilots Tetra, Giga, Mega, Kilo, Base Unit, Deci, Centi, Milli, Micro, Nano, Pico Exponents: 12,9,6,3,0,-1,-2,-3,-6,-9,-12
71
Enzymes only effect
The kinetics of a reaction NOT thermodynamics. So won’t effect deltaH
72
What is the equivalence point pH for a strong acid such as HCl with a strong base such as NaOH?
pH would be in between the other two pHs since it is at an equivalence point. Around 7
73
How do you find pH?
pH=-log[H3O+] for acids | Meaning a strong acid that starts out at a certain concentration will create the same concentration of H3O+
74
Molarity=
M=mol/L
75
pH of equivalence point for a strong base titrated with a weak acid
About 9
76
Ph of equivalence point of a weak base titrated with a strong acid
About 5
77
PH of equivalence point of a weak base being titrated by a weak acid
Around 7
78
What is a Purine?
Adenine and Guanine are the Purines. They are double ringed. Both RNA and DNA synthesis requires purines
79
How are vitamin deficiencies assessed?
By the levels in the blood, not the gut.
80
What is most likely being affected by the denaturation of a protein?
Denaturation of a protein means a loss of quarternary, tertiary, and secondary structure which is most likely do to the disruption of hydrogen bonds.
81
What is an ionic bond?
Complete transfer of valence electrons between atoms. Generates two oppositely charge ions. Between a metal and a non metal
82
What is a polar covalent bond?
Pair of electrons is unequally shared between two atoms. Creates partial charges on atoms. Example is water
83
Coordinate Covalent Bond
One atom donates a pair of electrons to create a bond. Example Lewis base and Lewis acid. Lewis base donates electron pair to Lewis acid to form a bond. Both electrons forming the bond must come from only one atom
84
What is Uracil?
A pyrimadine that replaces T in RNA.
85
Bacteria contain what kinds of amino acids?
Both D and L amino acids. Humans only use L amino acids.
86
Enzymes are stereospecific hence
D Amino acids cannot be substituted with L amino acids and vice versa
87
Are peptide bonds stable?
Peptide bonds are very stable under physiological conditions. Exhibit low reactivity. Peptide bonds are resonant. They have partial double bond character which restricts them to a planar molecular geometry
88
Serine and threonine are
Polar
89
Phenylalanine is
Aromatic nonpolar
90
Isoleucine is
Non polar
91
Histidine is
Basic
92
Bomb calorimetry
In a bomb calorimeter the energy is calculated at a constant volume. In a coffee cup calorimeter the energy is calculated at a constant pressure. Really bad for calculating enthalpy because doesn’t start at a standard state.
93
Enthalpy
Energy that is transferred only when measured at constant pressure.
94
Where do metalloids start on a periodic table?
Start at Boron go down diagonally stopping at Te. Includes Ge and Sb
95
Where are the alkali metals on a PT?
Everything down the column after H. group 1
96
Where are the alkaline earth metals on a PT?
Group 2. Be down
97
Where are the transition metals on a PT?
Start at Sc and end at Zn
98
Where are the noble gases on the PT?
Far right.
99
Where are the halogens?
Left of noble gases
100
What do plateaus in a titration curve mean?
Indicates regions where protons are being removed from functional groups. They occur at the pH equal to the pKa of the functional group.
101
Histidine has an
Amino acid ring structure with a pKa of around 6
102
Sanger method of DNA sequencing
Colored labeled ddNTs that terminate growing strands at random lengths with different colored labeled based on the nucleotide. If they are left out of the reaction mixture then all the strands will be copied as normal and a single dark band will show up on electrophoresis
103
Total pressure=
Atmospheric pressure + gauge pressure
104
Boyle’s Law
P1V1=P2V2 P1=first pressure P2=second pressure V1=first volume V2=second volume Describes how the pressure of gas tends to increase as the volume of the container decreases
105
For gravitational force to decrease what must decrease as well?
Mass must decrease as well. Fg =G [(m1•m2)/r^2] Fg is the force G is gravitational constant 6.7•10^-11 m1 and m2 are masses of the objects r is the distance between the objects
106
What does carbon dioxide do to the blood?
Decreases the pH of the blood. Leads to more carbonic acid in the bloodstream. Production of CO2 increases plasma bicarbonate levels to try to compensate
107
How do animals bodies react when they have a reduced metabolism and reduced access to oxygen?
Anaerobic metabolic mechanisms tend to dominate. This includes fermentation which produces lactic acid which is toxic. In order to compensate for lactic acid production there will be increases levels of lactate dehydrogenase.
108
Current in an axon will only flow when
There is a difference between the command potential and the measured membrane potential
109
Neurons and ions
The axon becomes more negative when positive ions leave the cell or when negative ions move into it.
110
Current equation
I=deltaV/R
111
Intramolecular bonding
Forces between two atoms in a molecule
112
Intermolecular forces
Forces between the molecules
113
Melting point, boiling point and water solubility did polar compounds are greatly effected by what?
The extent of their intermolecular hydrogen bonding since polar groups such as OH and NO2 like to bond with everyone whether they are in the same molecule or not
114
Transition elements tend to
Be an exception to the filling order of electrons

MCAT Practice Test 4 (2 decks)

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