Chapter 2- Proteins Part 1 Flashcards

1
Q

Proteins have many __________ roles

A

biological

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2
Q

What are proteins roles?

A

enzymes, structure, transport and binding

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3
Q

proteins are built from _____ amino acids which are the amino acids ____________.

A

the 20 common or standard, coded by genes into protein synthesis

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4
Q

Amino Acid structure is

A

Amine (NH3) + Carboxylic Acid (COO-) + H + R group

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5
Q

What type of isomer makes proteins and amino acids?

A

L isomer

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6
Q

What are the 4 classifications for the 20 standard amino acids?

A

non polar, polar, basic and acidic

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7
Q

Draw alanine.

A

CH3 sticking North, nonpolar, not strongly hydrophobic

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8
Q

Describe Glycine.

A

H sticking North, It is achiral, non polar, not strongly hydrophobic

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9
Q

Which amino acids are non polar?

A

Valine, Leucine, Isoleucine, Methionine (has a sulfur)

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10
Q

Which amino acid reacts with its backbone?

A

Proline (its backbone is a CH2 plus CH2 plus CH2 connected to the N+H2)

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11
Q

Which are the aromatic amino acid?

A

phenylalanine, tyrosine (non polar, has hydroxides) , tryptophan (biggest amino acid)

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12
Q

What are the 3 hydroxide amino acids?

A

Tyrosine, Serine, Threonine

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13
Q

Which amino acids are polar non ionizable Amino Acids?

A

Serine, Threonine, Asparagine, Glutamine

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13
Q

What is special about glutamine?

A

That it has a polar amide (a double bonded O to a C attached to a N) in the side chain

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14
Q

What is the most chemically reactive amino acid? And what does it look like?

A

Cysteine (amino acid structure plus CH2 attached to a S attached to a H)

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15
Q

Which amino acid has a 5 membered ring?

A

Hisitidine

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16
Q

Which are the acidic amino acids?

A

Aspartate and Glutamate

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17
Q

What is a characteristic of all acid base reactions?

A

Protonation

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18
Q

Low pH= net + or - charge?

A

+

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19
Q

High pH= net + or - charge?

A

-

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20
Q

Which pKa are approximately 3-4?

A
  1. terminal alpha carboxyl group
  2. aspartic acid
  3. glutamic acid
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21
Q

Which pKa are approximately 6-8?

A

Histidine (closer to biological pH which is 7.5)

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22
Q

Which pKa is approximately “fairly” high above 7?

A

terminal amino group

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23
Q

Which pKa is approximately “high” above 7?

A
  1. lysine
  2. arginine
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24
Q

What is the most reactive amino acid and why?

A

Cysteine because it can form a disulfide bonded cystine (two cysteines attach at the cystine). It has a thiol in its side chain

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25
Q

Amino acids can be held together by what?

A

amide bonds called peptide bonds

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26
Q

The peptide bond is most famous for…

A

breaking down pepsin (peptobismo, pepsi)

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27
Q

Biological polypeptides are divided into what?

A

peptides and proteins (depending on length)

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28
Q

Biological polypeptides are classified how?

A

Peptides (small, 30ish or smaller monomers long, short enough where it can’t have 3D structure)
Proteins (large, 30ish or longer monomers long, long enough to have 3D structure)

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29
Q

Protein structure is the basis of what?

A

protein function and its divided into levels because of its complexity.

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30
Q

Structure determines what?

A

function (just like a protein that bind to DNA can determine function because of its specificity)

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31
Q

A protein found in mammalian milk needs to have what in order to bind to what?

A

Needs to have high affinity and high specificity so that iron can bind

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32
Q

What are the levels of protein structure?

A

Primary structure
Secondary structure
Tertiary structure
Quaternary structure

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33
Q

What is proteins primary structure?

A

sequence of amino acids

34
Q

What is the longest, shortest and average amino acids?

A

longest 30,000 amino acids long
shortest 30 amino acids long
average 450 amino acids long

35
Q

What is protein secondary structure?

A

local or adjacent amino acids with a regular arrangement of the backbone

36
Q

What is a Ramachandran plot used for?

A

They show the constraints to the backbone and what it can rotate and what it cannot until it clashes.

37
Q

The two common types of protein secondary structure are what?

A

alpha helix and the beta sheet or beta strand

38
Q

What is a helix breaker?

A

Proline

39
Q

Alpha and beta secondary structure have what kind of bonds? Between where?

A

hydrogen bonds between backbone moieties.

40
Q

Which Amino Acid is a helix breaker?

A

Proline

41
Q

Do side chains matter when we talk about alpha secondary structure?

A

No they are not relevant. The bonds also are not relevant.

42
Q

Is a random coil a secondary structure?

A

No.

43
Q

Protein tertiary structure is the 3D what?

A

arrangement of the molecule in space

44
Q

What kind of beta sheets is a Fatty Acid binding protein?

A

beta barrell

45
Q

What is a prosthetic? What is it made of? What is a good example of a prosthetic?

A

a tool that extends what a protein can do. It is not made of Amino Acids. A great example of this is the heme in an iron binding protein (like hemoglobin) so it can bind to O2.

46
Q

What type of interactions hold together tertiary structure?

A

Non-local interactions which are distant places in the chain.

47
Q

Name the types of non local interactions.

A
  1. Covalent
  2. ionic bond
  3. hydrogen bond
  4. hydrophobic interactions
48
Q

What is the strongest non local interaction?

A

covalent (but it is the least important and least abundant)

49
Q

Two covalent bonds create what?

A

a disulfide bridge

50
Q

Two ionic bonds create what?

A

a salt bridge between full charges

51
Q

Non-local interactions: most important to least important.

A
  1. hydrophobic interactions
  2. hydrogen bond
  3. ionic bond
  4. covalent bond
52
Q

Non-local interactions: most abundant to least abundant.

A
  1. hydrophobic interactions
  2. hydrogen bond
  3. ionic bond
  4. covalent bond
53
Q

Non-local interactions: strongest to weakest

A
  1. covalent bond
  2. ionic bond
  3. hydrogen bond
  4. hydrophobic interactions
54
Q

What is an example of a two covalent bond creating a disulfide bridge?

A

The two non local cysteines creating a cystine.

55
Q

What is an example of two ionic bonds creating a salt bridge between full charges?

A

An aspartate and a lysine coming together with the O (aspartate) and NH3+ (lysine). This interaction is not as strong in an aqueous solution.

56
Q

What is an example of two hydrogen bonds coming together between and donor and a acceptor?

A

A glutamine and a serine coming together with the O (glutamine, H donor) and the H (serine, H acceptor)

57
Q

What is an example of two hydrophobic interactions coming together?

A

It is between two non polar side chains. Like pheynlalanine (aromatic ring) and leucine (qt 2 ch3) it gives the most energy to the structure and it is not soluble in H2O

58
Q

Protein quaternary structure involves the association of what?

A

more than one tertiary structure into the functional protein

59
Q

What is a good example of quaternary structure?

A
  • Hemoglobin doesn’t function as a single chain but 4 chains put together.
  • Rhinovirus protein is very large it has 4 different chains with over 240 proteins and 240 quaternary structures together
60
Q

What creates fibrous proteins or structural proteins?

A

large quaternary structure complexes with is most abundant in humans.

61
Q

What is a good example of a large quaternary structure complex that creates fibrous proteins or structural proteins?

A

Collagen and keratin. The soluble protein and the comes together in quaternary structure

62
Q

What destroys protein function or its native structure?

A

Denaturation and aggregation

63
Q

What does protein denaturation do?

A

It unfolds the protein. And because of the unfolded structure it lacks 3D structure so it has no function.

64
Q

How do you denature a protein?

A

Temperature (ex. cooking a raw egg and the egg whites turn white)
Chemically (ex. Ceviche cooks in an acidic solution and denatures the proteins of the fish to be edible and cook)

65
Q

How does a protein unfold in chemical denaturation?

A

competes with non local bonds

66
Q

How do proteins fold? (think the example in class with the model)

A

process initiated by hydrophobic collapse

67
Q

How did us as humans almost understand and solve the protein folding issue?

A

Through AI they were able to predict a structure but not how it chemically comes together

68
Q

Can you have the same amino acid sequence and it be different structures?

A

Yes, this is why protein folding is so difficult.

69
Q

What does the term hydrophobic collapse entail?

A

parts of the protein runs away from water and then starts to fold into the protein

70
Q

What kind of environment is created inside a hydrophobic collapse?

A

A water poor environment

71
Q

What kind of process is protein folding?

A

cooperative kinetic process determined by primary structure

72
Q

What dictates the proteins fold?

A

The amino acid sequence which has the info to create the primary structure

73
Q

What do chaperons do for protein folding?

A

Keep proteins from misfolding not assist in folding

74
Q

The most favorable structure for a protein to fold to is….?

A

The native structure

75
Q

low energy in protein folding means…

A

more stability

76
Q

All proteins _____________ but some proteins are very _____________ __________________.

A

breathe
conformationally flexible

77
Q

What is confirmational change for a protein?

A

A protein changing shape due to outside factors. A protein in one environment can change into a different shape in another environment

78
Q

Why is post translational modification (PTM) important in the structure and function of mature proteins?

A

Because it is why

79
Q

What is most important for the structure and function of mature proteins?

A

Post-Translational modification or PTM

80
Q

Name an example of PTM.

A

disulfide bridges, green fluoroscent proteins found in jellyfish that PTM into a beta barrel

81
Q

What percentage of proteins are PTM?

A

60-80%

82
Q

What does PTM mean?

A

changes covalent structure of 3 or more AA

83
Q

What can extend what a protein can do chemically?

A

prosthetics and PTM