Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biocheem > Lecture 11 > Flashcards

Lecture 11 Flashcards

1
Q

What are the Polar Amino Acids?

A
  • Serine
  • Threonine
  • Tyrosine
  • Cysteine
  • Asparagine
  • Glutamine
  • Histidine
  • glycine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What do all the Polar Amino acids have in common?

A

They have side chains that contain an electronegative atom

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

Why are Polar Amino Acids reactive?

A

Because of the presence of functional groups

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

What are the two subgroups of polar amino acids?

A
  • Those that don’t carry a formal charge at pH 7

* Those that carry amino a formal charge at pH 7

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

What is the side chain of Glycine?

A

Just a hydrogen atom

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

Why is Glycine achiral?

A

Because the alpha carbon contains two H’s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the Polarity of Glycine?

A

Even though it is classified as a polar amino acid it is only weakly polar

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

What is the R group of Serine?

A

A CH2 group bonded to an OH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How many H-bonds can the side chain of Serine form?

A

Three. Two as an acceptor and one as a donor with the alcohol group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the way Serine can be modified?

A

Through Phosphorylation

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

What is the polarity and charge of serine?

A

It is polar and uncharged

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

Can the OH in Serine be deprotonated?

A

No. It it is very difficult to deprotonate the OH in serine

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

Can serine participate in H bonding interactions?

A

Yes with the polar OH group

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

What is meant by Serine can be phosphorylated?

A

The alcohol on the side chain can be used to create a phosphoester structure

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

What is the Polarity and charge of Threonine?

A

Threonine is polar and uncharged

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

What functional group does the side chain of Threonine have?

A

-OH

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

Can Threonine form H-bonds?

A

Yes. Thronine can form H-bonds with the OH on is R group

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

How can Threonine be modified?

A

It can be phosphorylated

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

Which three amino acids can be phosphorylated?

A
  • Serine
  • Threonine
  • Tyrosine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How many chiral carbons does Threonine have?

A

It has two chiral carbons

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

What is a Chiral Carbon?

A

A carbon that contains four different groups (not just carbon atoms)

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

Which amino acids contain Hydroxyl groups?

A
  • Serine
  • Threonine
  • Tyrosine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How does Tyrosine differ from Serine and Threonine?

A

It is much larger due to its aromatic group

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

Which Polar uncharged amino acid has an aromatic side chain?

A

Tyrosine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Why is the side chain in Tyrosine considered Amphipathic?
Because the aromatic ring is non-polar but the alcohol group is polar
26
What kind of interactions can Tyrosine participate in?
Hydrophobic interactions
27
What is the difference in the hydroxyl group in Tyrosine when compared to Serine or Threonine?
The hydroxyl group is weakly acidic
28
What is the pKa of the Hydroxyl group in Tyrosin?
10.5 pKa
29
What is the overall charge of Tyrosine at pH 7?
It is neutral
30
What is the charge of the Tyrosine R group at high pH's?
It will have a negative charge because the OH group can be deprotonated
31
What charge will the amino acid Tyrosine have at pH 14?
Because the amine group will be deprotonated and the hydroxyl group will also be deprotonated it will carry a -2 charge because the O- and the COO-
32
What would be the charge on Tyrosine at pH 1?
It will have a +1 charge because the amine group will be NH3+ and the carboxyl group will be COOH (neutral) and the OH will also be neutral
33
What is the pKa of carboxyl groups?
2.0
34
What is the pKa of an amino group?
9.5 - 11
35
Which amino acids have an ionizable R group?
* Tyrosine * Histidine * Cysteine
36
What is the formal charge of Tyrosine, Histidine and Cysteine at pH 7?
They carry no formal charge
37
What are the Polar charged amino acids?
* Aspartate * Glutamate * Arginine * Glycine
38
What is the polarity and charge of Cysteine at pH 7?
Cysteine is Polar and uncharged
39
what is the difference between the side chain of Cysteine and the side chain of Serine?
Cysteines side chain has a thiol group Serines side chain has a hydroxyl group
40
Is Cysteine capable of forming H-bonds?
Cysteine can form H-bonds with the thiol group
41
How happens to the side chain of Cysteine at high pH's?
The Thiol group can be deprotonated
42
What is the pKa for the Thiol group of Cysteine?
pka is 8.5
43
What is the charge of Cysteine at pH 14?
-2 because the amine group is deprotonated to become neutral, the COO- group remains negative and the thiol group (SH) becomes deprotonated to become S-
44
What is unique about Cysteine?
It can form covalent bonds with other Cysteine residues through disulphide bonds
45
What are Disulphide bonds?
Sulphur Sulfur bonds that connect two Cysteine side chains together
46
What is Cystine?
The dimer of two Cysteine residues after they have been joined by disulphide bonds
47
What kind of environment is the cytosol within cells?
It is a reducing environment
48
Where does Cystine formation occur?
Not in the cytosol because it requires a reducing environment. It occurs in extracellular proteins
49
What is the polarity of cysteine disulfides and what is their acidity?
They are non-polar and they do not have a pKa so they are no acidic
50
What aspect does Asparagine have in its side chain?
It has an amide aspect (NH2 group)
51
What is the Polarity and charge of Asparagine?
It is polar and uncharged
52
What is the functional group in the Asparagine side chain?
Carboxamide functional group
53
Can Asparagine form H-bonds?
Yes with the carbonyl and NH2 group
54
What can be H-bonds acceptors and H-bond donors in Asparagine side chain?
The NH2 can donate two H bonds and the carbonyl can accept two H bonds
55
What functional group does Glutamine contain?
It contain a carboxamide functional group with one NH2 and one carbonyl the same as Asparagine
56
What is the Polarity and charge of Glutamine?
It is polar uncharged
57
What H bonds can the Glutamine side chain form?
It can be an H bond donor at NH2 and an H bond acceptor at the carbonyl
58
What is the three letter code for Asparagine and Glutamine?
* Asn | * Gln
59
Describe the side chain of Histidine?
Heterocyclic and Aromatic
60
What happens to the Histidine functional group at low and high pH values?
It's positively charged at low pH's by gaining a proton (acting as a base) and uncharged a high pH's by losing the proton it gained
61
What is the ring of Histidine known as?
Imidazole
62
What is the charge of the side chain of Histidine at pH 7?
It is mostly neutral but some of the side chain is protonated because the pKa is 6
63
What is the pKa of the histidine side chain and what does this mean?
6. At <6 pH the side chain will begin to accept H+
64
Why is histidine very frequently involved in enzymatic reactions?
Because it can act as either an acid or base
65
What does the ionization state of Histidine depend on?
It chemical environment
66
When can Histidine exclusively act as an H-bond donor?
When it is protonates
67
When can histidine act as donor and acceptor?
When it is in the base form
68
What are the charged amino acids?
* Aspartate * Glutamate * Lysine * Arginine
69
What is the rule surround pH and pKa?
If the pH is lower than the pKa the side chain will get protonated
70
What functional group does Aspartate have in its side chain?
It has a carboxyl group
71
What is the charge of aspartate at pH 7?
It is negatively charged due to the COO- in the side chain
72
What is the pKa of the side chain of the carboxyl group in Aspartate?
4.0
73
What kind of H bonds can Aspartate form?
It can be an H bond acceptor with its carbonyl groups
74
Why are Aspartate and Glutamate described as neutral amino acids?
Because their root NEUTRAL structure can be deprotonated but their structure in a solution of pH 7 only has COO- groups which are bases
75
Why is Aspartic Acid known as Aspartic acid at pH 1?
Because the carboxylate will gain H+ and become an acid
76
What is the charge of Glutamate at pH 7?
It is negatively charged because of the COO- in the side chain
77
What is the polarity of Glutamate?
It is very polar
78
What kind of H bond interactions can Glutamate form?
They can be H bond acceptors
79
What is Glutamate called at pH 1 and why?
It is called Glutamic acid because it has H's on its carboxyl groups that can act as acids
80
What is the pKa for the Glutamate and aspartate side chain?
Around 4

Biocheem (38 decks)

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