Brainscape's Knowledge GenomeTM

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


See full index

MGD > Amino Acids/Enzymes/Proteins etc > Flashcards

Amino Acids/Enzymes/Proteins etc Flashcards

1
Q

What is the R group of glycine?

A

H

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

How can amino acids be classified?

A

Charge, polarity, aromatic/aliphatic, acid/base properties

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

What are aliphatic amino acids?

A

Amino acids with carbon chains as their side chains

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

Aromatic?

A

Has a ring- often benzene

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

Which amino acid shows no stereoisomerism? Why?

A

Glycine, it’s R group is only a H

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

In aqueous solution, what tends to happen to non-polar AA’s?

A

The hydrophobic effect- the side chains cluster together in the interior of a protein

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

Why are cysteine residues so important?

A

Their side chains have sulphydryl groups and so can form disulphide bonds

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

What is KA?

A

Acid dissociation constant

=[H+][A-]/[HA]

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

Larger the KA….

A

The stronger the acid

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

What is the general rule regarding pK/pH values and whether it will be protonated or not?

A

pH will be protonated

pH>pK–> will be deprotonated

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

If the pH is lower than the pK value, will the amino acid be protonated or not?

A

Protonated

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

What are characteristics of a peptide bond?

A

In trans form, planar, has partial double bond characteristics TF cannot rotate, uncharged yet polar

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

Why are peptide bonds always in trans form?

A

Due to steric interference

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

Define isoelectric point

A

pH at which there is no overall net charge on the protein

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

If pH is lower than the pI, will the protein be protonated or not?

A

Protonated

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

If pH is higher than pI, will the protein be protonated or not?

A

Deprotonated

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

Give a rough pI range for an acidic protein

A

pI

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

Give a rough range of pI for a basic protein

A

High pH

pH>7

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

Give characteristics of an alpha helix

A

Right handed
3.6 AA per turn
R groups of AA play no role in making the helix(lie outside of helix)
0.54nm pitch
Stabilised by H bonds between aside H and carbonyl O

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

Which amino acids are helix breakers? Why?

A

Proline and Glycine

Proline S R group is so large and isn’t geometrically compatible with the α helix and forms a kink

21
Q

Give some characteristics of B sheet

A

Can be parallel OR anti-parallel OR mixed
Has multiple inter strand H bonds
Presence of H bonds stabilises structure

22
Q

In anti-parallel B sheet, which direction(s) do the strands run in?

A

One runs N terminus –> C terminus and the other goes C–>T

23
Q

How do detergents denature proteins?

A

Interfere with hydrophobic interactions

24
Q

What are amyloid fibres?

A

Misfolded, insoluble form of a protein

25
Q

At physiological pH, what form are amino acids in?

A

Zwitterion form- carboxyl is dissociated (COO-) amino is protonated (NH3+)

26
Q

Define Vmax

A

Maximal velocity- maximal obtainable rate when all active sites are saturated with substrate

27
Q

What are the units for Vmax?

A

Mol/min

28
Q

Define Km and what is it?

A

Michaels Constant- substrate concentration at half the maximal velocity. It is a measure of affinity.

29
Q

What affinity would an enzyme with a low Km have?

A

High affinity

30
Q

What affinity would an enzyme with high km have?

A

Low affinity

31
Q

How can you overcome the effects of a competitive inhibitor?

A

Increase the amount of substrate

32
Q

How would/not Vmax and Km change with the addition of a competitive INHIBITOR?

A

Vmax unaffected. Km would be affected (increased) as it would decrease the amount of available active sites Therefore require a higher [substrate] to reach Km TF Km increases

33
Q

How would/not Vmax and Km be affected with the addition of a non-competitive INHIBITOR?

A

Vmax would be affected (decreases) because binding of non-competitive inhibitor alters structure of active site and so reduces no. of free/usable active sites. TF there are less available to saturate.
Km unaffected

34
Q

With Vmax/Km graphs? What are the Y and X axes?

A

(Y to the sky)

Y axis= Reaction velocity. X axis= [substrate]

35
Q

What is Michaelis Constant?

A

Km- substrate conc at half maximal velocity ([s] when half active sites are occupied)

36
Q

What is reaction velocity?

A

Speed in a certain direction

37
Q

In general terms, what effect will a non-competitive inhibitor or activator have on Vmax and Km?

A

Affects Vmax, doesn’t affect Km

38
Q

In general terms, what effect will a competitive inhibitor or activator have on Vmax and Km?

A

Affect Km, won’t affect Vmax

39
Q

Why will the addition of a competitive INHIBITOR increase Km?

A

Because to overcome the effect of the inhibitor you add a lot of substrate in, TF [s] increases ^

40
Q

What is the Michaelis Menten equation?

A

Vo= Vmax X [s] / Km + [s]

41
Q

What is the purpose/function of a Lineweaver Burk plot?

A

Allows for easy estimation of Km and Vmax

42
Q

What are the Y and X axes in Lineweaver Burk Plots?

A 
Y= 1/V
X= 1/[s]
43
Q

REMEMBER!! Regarding Lineweaver Burk plots…

A

The axes are 1 over eg 1/V. TF if Km^, the line will become steeper.

44
Q

In Lineweaver Burk plots, what is the Y intercept?

A

1/Vmax

45
Q

In Lineweaver Burk plots, what is the X intercept?

A

-1/Km

46
Q

List three ways enzymes may be regulated

A

Allosteric regulation (inhibition/activation)
Covalent modification
Proteolytic activation

47
Q

Difference between alpha helix and double helix?

A

Alpha helix is tertiary protein structure, double helix is two strands of DNA wound together

48
Q

How does a drop in pH denature a protein?

A

Rise in H+ ions causes change in ionisation of side chains of AA’s in protein, can affect H & ionic bond formation, causing structural change to protein.

MGD (9 decks)

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