Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

MCAT > 1A: Structure & function of proteins and their constituent amino acids > Flashcards

1A: Structure & function of proteins and their constituent amino acids Flashcards

1
Q

Amino Acids

A

Contain a carboxylic group, alpha carbon, alpha amino group and alpha hydrogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Absolute Configuration at the α position (Optical Activity)

A

D (+) = clockwise rotation of polarized light

L (-) = counterclockwise rotation of polarized light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Naturally occurring amino acids

A

L-Amino Acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Absolute Configuration at the α position (Stereochemistry)

A

R (right) vs S (left)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Amino Acids as Dipolar Ions

A

Low pH = cationic
High pH = anionic
Isoelectric Point = Neutral Zwitterion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Acidic Amino Acids [2] (-)

A 
Aspartic Acid (Aspartate)
Glutamic Acid (Glutamate)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Basic Amino Acids [3] (+)

A

Arginine
Lysine
Histidine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Hydrophobic/Lipophilic Amino Acids [8]

A 
Alanine (A)
Valine (V)
Leucine (L)
Isoleucine (I)
Proline (P)
Methionine (M)
Phenylalanine (F)
Tryptophan (W)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Hydrophilic/Lipophobic Amino Acids [12]

A 
Glycine (G)
Serine (S)
Threonine (T)
Arginine (R)
Asparagine (N)
Aspartate (D)
Glutamate (E)
Glutamine (Q)
Cysteine (C)
Lysine (K)
Histidine (H)
Tyrosine (Y)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Sulfur Linkage Reaction

A

Cysteine-SH + HS-Cysteine -> Cystine-S-S-Cystine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Importance of cystine

A

Important for tertiary structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How are peptide bonds formed?

A

The carboxyl group of one amino acid reacts with the amino group of a second amino acid; releases water a product

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How are peptide bonds broken?

A

A water molecule is introduced into the peptide bond releasing a free amino acid from the peptide chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Primary Structure of Proteins

A

Linear sequence of amino acids, linked by peptide bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Secondary Structures of Proteins

A

Consists of alpha helices and beta sheets; linked by hydrogen bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Tertiary Structure of Proteins

A

Chains of peptides folded onto themselves, linked by disulfide bonds, ionic interactions, van der waals, hydrogen bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Importance of Proline

A

Introduces kinks that cause turns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Importance of Cysteine/Cystine

A

Forms disulfide bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Hydrophobic Bonding

A

Occurs within the core of proteins between the non-polar/hydrophobic R-groups creating stability (hydrophobic collapse)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Quaternary Structure of Proteins

A

3D structure with multiple subunits of proteins interacting; linked by non-covalent interactions between subunits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Conformational Stability

A

The dG difference between the native state (folded) and unfolded state of a protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Denaturation

A

Occurs due to temperature, chemicals, enzymes and pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How does temperature denature?

A

It disrupts all bonding expect peptide bonds; this increases hydrophobic interactions since active globular proteins will fold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How do chemicals denature?

A

They break hydrogen bonds, disrupts all except peptide bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
How do enzymes denature?
They break down directly to peptide bonds
26
How does pH denature?
Ionic bonds are broken down so tertiary and quaternary structures are disrupted
27
How does a solvation layer affect stability?
It decreases the amount of ionic interactions between proteins
28
Isoelectric Point (Separation)
Proteins move until they reach the pH equal to their isoelectric point in electrophoresis
29
Electrophoresis (Separation)
Separates charged particles using an electric field
30
Agarose Gel Electrophoresis
Separates nucleic acids; their negatively charged structures move toward the cathode and help with identification of sizes of particles
31
SDS-PAGE
Separates proteins based on mass but not charge; SDS neutralizes charge; smaller particles move through the gel faster
32
Non-Enzymatic Protein Function
Binding of molecules Immune Function (Ab) Movement (Dynein & Kinesin) Transport (Hemoglobin)
33
Function of Enzymes in Biological Reactions
They act as catalysts, providing alternate pathways for reactions to occur; stabilize transition states
34
Types of Catalysis
Acid/Base Covalent Electrostatic
35
Acid/Base Catalysis
Acids donate protons, bases accept protons
36
Covalent Catalysis
Formation of covalent bonds in order to reduce energy for transition states; bonds are broken for the reuse of the enzyme
37
Electrostatic Catalysis
Formation of ionic bonds with intermediates in order to stabilize the transition states in chemical reactions
38
Types of Enzymes
1. Oxidoreductases 2. Transferases 3. Hydrolases 4. Isomerases 5. Lyases 6. Ligases (Synthetases)
39
Oxidoreductases
Transfers hydrogen and oxygen atoms or electrons from one substrate to another e.g. Dehydrogenase, Oxidase
40
Transferases
Transfer of a specific group from one substrate to another | e.g. Transaminase, Kinase
41
Hydrolases
Hydrolysis of a substrate | e.g. Esterases, Digestive Enzymes
42
Isomerases
Change of the molecular form of the substrate | e.g. Phosphoglucoisomerase, Hexoisomerase, Fumarase
43
Lyases
Nonhydrolytic removal of a group or addition of a group to a substrate e.g. Decarboxylase, Aldolase
44
Ligases (Synthetases)
Joining of 2 molecules by the formation of new bonds | e.g. Citric Acid Synthetase
45
Reduction of Activation Energy
Enzymes reduce the energy of activation by providing alternate pathways for reactions; which increases the rate of the reaction
46
Saturation Kinetics
The idea that as concentration of substrate increases, so does the rate of the reaction
47
What do enzymes NOT affect?
Keq, dG & Thermodynamics
48
What do enzymes affect?
Rate Constant, Kinetics, Forward & Reverse reaction (no change in equilibrium)
49
Substrate Specificity
Substrate binds at the enzymes active site; their structure is specific to fit into the enzymes active site
50
Active Site Model of Enzyme Specificity
The enzymes active site has a shape that accommodates the shape of the substrate
51
Induced-Fit Model of Enzyme Specificity
Enzymes and their substrates conform to each others' shape in order to bind together
52
Cofactors
Inorganic molecules or Metal ions that certain enzymes use to catalyze a reaction/process
53
Holoenzyme
Enzyme + cofactor
54
Apoenzyme
Enzyme - cofactor
55
Prosthetic Group
Tightly bound coenzyme
56
Cosubstrates
Loosely bound coenzyme
57
Coenzyme
Small, organic, non-protein molecules that carry chemical groups (electrons, atoms, functional groups) between enzymes; vitamin derivatives
58
Water-Soluble Vitamins
``` B Complex (B1, B2, B6, Folate, B12, Biotin, Pantothenate) C ```
59
Fat-Soluble Vitamins
Vitamin A, D, E, K
60
How do local conditions affect enzyme activity?
pH, salt, temperature etc, can all affect the structure of the enzymatic protein and thus affect the availability of the active site
61
Michaelis-Menten Kinetics Equation
E + S -> ES -> E + P
62
Michaelis-Menten Approximations
Rapid Equilibrium & Steady-State
63
Rapid Equilibrium Approximation
It states that E, S and the ES complex equilibrate rapidly so that the total enzyme concentration is equal to the concentration of free enzyme and the concentration of bound enzyme; Etotal = Efree + ES
64
Steady State Approximation
That the rate of formation of the ES complex is equal to the rate of breakdown of the ES complex
65
Km (Michaelis Constant)
Breakdown[ES]/Formation[ES]
66
Factors that affect Km
pH, temperature, ionic strength, nature of substrate
67
Reaction Order (Enzyme Kinetics)
Zero Order; Rate is independent of substration formation
68
Vmax/2 (1/2 Vmax)
Km
69
Units of V
Moles/Time
70
Units of Substrate
Molar
71
Low Km indicates:
Not much substrate required to reach half maximal velocity; high affinity for the particular substrate
72
High Km indicates:
A lot of substrate required to reach half maximal velocity; low affinity for the particular substrate
73
Cooperativity
When a substrate binds to one subunit, the other subunits are stimulated and become active. It can be positive or negative
74
Positive Cooperativity & it's Curve
One oxygen molecule binds to the ferrous iron of a heme molecule which allows the other subunits heme to bind more molecules; Sigmoidal Shape
75
Feedback Regulation
The product of a pathway inhibits or activates its pathway; it can be positive (activation) or negative (inhibition)
76
Competitive Inhibition
Inhibitor competes with its substrate for the active site; can be overcome by increasing the amount of substrate; the Vmax is unchanged by the inhibitor; apparent Km increases
77
Noncompetitive Inhibition
Inhibitor binds to the enzyme at an allosteric site which deactivates it; substrate still has access to the A/S but cannot catalyze the reaction as long as the inhibitor binds; Decreases Vmax; Unchanged Km
78
Mixed Inhibition
Inhibitor can bind to the allosteric site or the ES complex; | Decreases Vmax; Increases or Decreases Km
79
Uncompetitive Inhibition
Inhibitor binds only to substrate-enzyme complex; Decrease Vmax; Decreases Km
80
Allosteric Enzymes
Contain 2 binding sites, one for substrate & others for effectors (which change the conformation of the enzyme, noncovalently & reversibly)
81
Homotropic Allosteric Enzymes
Acts as both the substrate for the enzyme and the effector of the enzyme's activity
82
Heterotropic Allosteric Enzymes
Acts only as the effector that regulates the enzyme's activity; does not act as substrate
83
Covalently-Modified Enzymes
``` Covalent modification (phosphorylation) activates or inactivates the enzymes activity e.g. Glycogen phosphorylase-a vs b ```
84
Zymogen
Inactive enzyme precursor; upon hydrolysis or change of configuration of the active site

MCAT (31 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions