Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biochemistry > Amino Acid - Structure And Function > Flashcards

Amino Acid - Structure And Function Flashcards

1
Q

Amino acid with non-polar side chains

A

No acid/base chemistry (R-group does not bind or give protons )
Do not form hydrogen bonds
Have hydrophobic interactions

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

When does Cys and Tyr donate protons

A

When at alkaline pH

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

Can Ser,Thr,Tyr form hydrogen bonds and how ?

A

Yes they can ,they contains OH or SH

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

What do you need to form a disulfide bridge or a cystine dimer

A

2-SH groups

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

What can we consider about -CONH2 of Asn

A

May serve as the sight of attachment of oligosaccharide chains in glycoproteins (N-link gylcosyation )

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

True or false , Asp and Glu are proton acceptors

A

False , they are proton donors .

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

What is the state of Asp and Glu at a neutral PH

A

The side chains are almost fully ionized or dissociated (COO-) and carry a negative charge

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

Finish the statement : Lys and Arg are (a)_______ ionized and carry a (b)_________ charge

(a) fully | partially
(b) positive/ negative

A

Fully

Positive

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

Why is a histidine a good buffer ?

A

Histidine is weakly basic and partially positively charged at a physiological pH .In proteins histidine can be positive or uncharged .

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

3 letter abbreviation for Asparagine

A

Asn

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

What is Gln and how is different to Glu

A

Glutamine , it’s different to glutamate because it’s the major carrier of NH3

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

Difference between phenylalanine and Tyrosine in terms of structure

A

Tyrosine : has an OH

Phenylalanine: has no OH

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

Why do we say the alpha c is a choice, or optically active

A

It has four different groups attached (except Gly)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q 
Which of the following acids will have the highest pKa?
A.Nitric acid
B.Sulfuric acid
C.Hydrocholoric acid
D.Pyruvic acid
A

Pyruvic acid is the only acid on this list which is not strong.
•The higher the pKa the weaker the acid
•The lower the Ka, the weaker the acid: because  pKa = -log(Ka)

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

What is the Kw(ion-product ) of water (the value)

A

10^14

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

The water dissociation equation

A

pH =[H+][OH-]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q 
Which of the following amino acids will be most close to its zwitterionic form at neutral pH?
A.Alanine
B.Glutamate
C.Aspartate
D.Lysine
E.Argnine
A

Answer is alanine
•The charges available to alanine come from its amino functional group, and its carboxylic acid functional group. Its zwitterionic form occurs when both of these functional groups are charged, resulting in a net zero charge on the entire molecule (+1 – 1 = 0)
•The other amino acids listed have additional ionizable functional groups on the R-group, so the pH where they are zwitterions will be either higher or lower than for alanine.
•Identify other amino acids that also form there zwitter ion at near neutral pH

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

Explain the difference between D and L isomers (amino acids )

A

L amino acids are those with the alpha amino group on the left and the D amino acids have alpha amino group on the right

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

What is the location of non polar amino acids in soluble proteins

A

Interior of proteins (shielded from environment )

20
Q

What is the location of non polar amino acids in membranes or other hydrophobic environments

A

Found on Protein surfaces

21
Q

What is the Henderson -Hasselbach equation

A

PH= pKa +log [[A-]/[HA]]

22
Q

When titrating alanine what are the 3 forms in solution
Alanine in acid sol .
Alanine in neutral sol .
Alanine in basic sol.

A

Acid - +H3N and COOH
Neutral - +H3N and COO-
Base - 2HN and COO-

23
Q

What is the isoelectric point

A

It is the pH at which net charge is zero

24
Q

How do I calculate the pI

A

PI is pk1 + pk2 divided by 2

25
Q

What are the 3 ionizable groups on histidine

A

COOH ,NH+ , NH3+

26
Q

How do I calculate the pI of histidine

A

Pk2 + pk3 / 2

27
Q

What are the corresponding pHs of the 3 pks of histidine
pk1= COOH
Pk2 = R group
Pk3 = NH3

A

1-1.8
2-6
3-9.3

28
Q

Name 3 blood buffers

A 
Bicarbonate 
Phosphate 
Proteins 
Hemoglobin
NH3 /NH4+
29
Q

Name two strong acids that dissociate completely

A

Sulfuric acid and hydrochloric acid

30
Q

Name 4 weak acids

A

Carbonic acid ,lactic acid , pyruvic acid

Citric acid

31
Q

True or false : uncharged drugs don’t cross the intestinal lumen compared to charged drugs

A

False , they cross much more readily

32
Q

What happens when water self dissociates

A

Hydrogen bonds occur between the hydrogen of one atom and the oxygen of another . Forming hydroium ion (H30+ ) hydroxide (OH -)

33
Q

Increasing acidity means more ______ and less _______

[H+] or [OH-]

A

1.[H+] and 2.[OH-]

34
Q

Does sulfuric acid completely dissociate in water

A

Sulfuric acid is a weak acid and doesn’t dissociate completely in water (only the first dissociation is considered strong )

35
Q

Name some strong acids

A

HCl ,HBr ,HNO3 ,perchloric acid

36
Q

Name some strong bases

A

LiOH , NaOH , potassium hydroxide ,Ba(OH) 2 , Mg(OH )2

37
Q

How can Mg(OH)2 be ingested if it’s a strong base

A

It is a laxative , it has very low solubility in water.

38
Q

Describe the titration curve of a strong acid by a strong base

A

It has a sharp change where the equivalence point is the 1/2 of the region

39
Q

The higher the ka the ________ the acid

A

Stronger

40
Q

The lower the pKa the ____________ the acid

A

The stronger acid

41
Q

What is the difference between the strength of an acid and concentration of the acid

A

Strength - the extent of the proton dissociation

Concentration of the acid is the amount of dissolved substance

42
Q

What does it mean when the pH is equal to the pKa

A

There is equal amounts of the weak acid and it’s conjugate base (50% dissociated )

43
Q

The buffering region

A

This is the region on the curve which is demonstrated when the pH changes slowly

44
Q

Acetic acid has a pKa of 4.75.

a 0.1 M acetic acid solution from pH 4.75 and slowly add strong acid (HCl) , what predominates

A

The conjugate form
Protonated form
Neutral form

45
Q

Acetic acid has a pKa of 4.75.

a 0.1 M acetic acid solution from pH 4.75 and slowly add strong base (NaOH) , what predominates

A

Conjugate base form
Deprotonated form
Ionized form

46
Q

When is. Buffer formed

A

When a weak acid and a similar amount of its conjugate base are mixed

Biochemistry (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions