Brainscape's Knowledge GenomeTM

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


See full index

Biochemistry - Victor > Steele Proteins 2/3 > Flashcards

Steele Proteins 2/3 Flashcards

0
Q

Proteins are broken up into two class shapes: globular and structural (elongated, fibrous). Which class do enzymes fall under? Collagen?

A

enzymes are globular, collagen is structural.

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

Approximately how heavy is a 400 amino acid protein?

A

40,000 daltons (1 amino acid is approximately 100 daltons)

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

What kind of charge does phosphorylation add to a protein?

A

negative.

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

What is a zwitterion?

A

A molecule with two ionizable groups.

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

If both the carboxy and amine group are both protonated, is the amino acid more acidic or basic?

A

acidic.

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

What is pKa?

A

pKa is the pH of an aqueous solution of that amino acid at which the group is half protonated and half unprotonated (half acid, half base).

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

T or F. The higher the pKa, the more strongly the proton is held by the group that contains it.

A

True. (in general, if pH is more “acidic” than the pKa, then the aa is more in acid form. if the pH is more “basic” than the pKa, then the aa is more in basic form.)

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

What does buffering do?

A

Helps a molecule resist change in pH of a solution at 1 pH unit above and below the pKa.

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

What buffers blood?

A

carbonic acid and bicarbonate.

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

T or F. Proteins are good buffers.

A

False. Only histidine and alpha amino groups have pKas in range, but they are too sparse in serum.

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

T or F. Some membrane proteins have lipid anchors instead of embedding directly into the membrane.

A

True.

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

T or F. Glycosylation and disulfide bonds occur on the external domain.

A

True. Internal domain have reduced sulfhydrul groups, phosphorylation, and no complex carbs.

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

Where do the two major types of glycosylation occur? Hint, one involves asparagine, one involves serine/threonine.

A

Sugar is linked to side chain N of asparagine. Sugar is linked to OH of serine/threonine.

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

T or F. Some diseases result from proteins that are perfectly functional but improperly localized.

A

True.

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

What is NLS an example of?

A

Nuclear localization signal, example of targeting sequence. Importin protein recognizes NLS.

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

What are 4 methods of protein isolation?

A
  1. Ion exchange chromatography (based on charge)
  2. Gel filtration chromatography (based on size)
  3. Affinity chromatography (based on ligands/substrates/binding proteins/ab)
  4. absorption chromatography (based on hydrophobicity)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

T or F. Proteins of same function in difference species have related sequences.

A

True.

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

T or F. Tertiary structure may be more conserved than primary sequence.

A

True.

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

Bovine ribonuclease and human ribonuclease are examples of ______? (what word defines the relationship these two enzymes have)

A

Orthologs

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

Human ribonuclease and angiogenin are ________.

A

Paralogs. different functions.

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

What mutation causes sickle cell disease?

A

Glutamic acid at position 6 of Beta chain is changed to Valine. V is hydrophobic, Glu is charged).

21
Q

T or F. Electrophoresis can separate proteins based on size, charge or both.

A

True.

22
Q

What is an allozyme?

A

forms of a protein encoded by different alleles of a gene (eg maternal and paternal alleles). “Allo-Allele”

23
Q

What is an isozyme?

A

forms of a protein encoded by different genes but catalyzing the same reaction. “isolated genie”

24
Q

MB creatine kinase 2 (CK2) in the blood stream is a sign of ______. CK3 and no CK2 is a sign of ______.

A

Myocardial infarction. Skeletal muscle damage.

25
Q

Cardiac troponin is now used to detect MI. What makes it better than CK2?

A

Peak goes higher (more sensitive), stays up longer (persists for clinical discovery).

26
Q

What is exo N terminal proteolysis?

A

removal of n terminal amino acid (eg initiator methionine excision).

27
Q

What is endo N terminal proteolysis?

A

removal of peptide. (eg signal peptide removal).

28
Q

What does acetylation of the N terminus do?

A

Provides stability against degradation by random aminopeptidases. Protects amino terminus from non enzymatic glycation by reducing sugars. 80% of human cytosolic protein are acetylated.

29
Q

How is protein glycation a diabetes diagnostic?

A

Hb is not N acetylated, rendering it susceptible to N terminal glycation. Diabetics have lots of sugar in blood, higher levels of glycation.

30
Q

Which amino acids have an OH available for phosphorylation?

A

Serine, threonine, tyrosine

31
Q

What processes is protein phosphoryation involved in?

A 
1 signal transduction
2. cell cycle transduction
3. cytoskeletal rearrangements
4. molecular transport
5 transcription translation
6 many others.
32
Q

pSer:pThr:pTyr?

A

1800:200:1. Due to stability. Tyrosine often phosphorylated but its very transient.

33
Q

T or F. 2% of the human genome encodes protein kinases and phosphatases.

A

True.

34
Q

Describe the NFkB process of activation?

A

Inflammation leads to phosphorylate IkB-NFkB, leading to degradation of IkB, revealing the NLS on NFkB. NFkB translocates to nucleus, activates transx.

35
Q

Binding of 4 _____ molecules activates PKA by dissociating the holoenzyme (r2c2) into 2 regulatory subunits and 2 catalytic subunits.

A

cAMP

36
Q

Ubiquitin is a tag involved in ________.

A

Proteolytic destruction.

37
Q

T or F. Ubiquinated protein gets digested by proteosomes and release peptide fragments and releases ubiquitin.

A

True.

38
Q

How does velcade treat multiple myeloma (overproduction of plasma cells leading to elevated Igs)?

A

Velcade inhibits protease activity in proteasome, blocking degradation of proteins. Myeloma cells are more sensitive to the blockage, dies.

39
Q

Describe the structure of hemoglobin.

A

Heterotetramer, 2 alpha, 2 beta, (2 gamma in fetus). One heme per chain, (4 hemes per hemoglobin).

40
Q

What happens structurally when oxygen binds to the iron molecule in heme?

A

It pulls the histidine residue up, resulting in conformational change.

41
Q

The deoxy form of hemoglobin is also known as the ____ form. Oxy is the ____ form.

A 
deoxy= T (taut)
oxy= R (relaxed)
42
Q

Decrease in pH ______ affinity for oxygen in hemoglobin, facilitating its release.

A

lowers.

43
Q

How does 2,3 BPG affect hemoglobin?

A

Only binds hemoglobin in T form. binding stabilizes form, decreases affinity for oxygen. Hemoglobin can release more oxygen to tissues.

44
Q

T or F. Fetal hemoglobin has lower affinity for oxygen than adults.

A

Heavens no!

45
Q

T or F. Enzymes have a large effect on Keq of a reaction.

A

No, it does not affect Keq.

46
Q

A reaction can occur spontaneously if delta G is ______.

A

negative (exergonic).

47
Q

The initial reaction velocity can vary with varying substrate concentrations.

A

True.

48
Q

What is Km?

A

Kilometers.

Also, the concentration of substrate at which the rate of a reaction is half of the maximum possible rate.

49
Q

What is the michaelis menten equation?

A

Vo=Vmax [S]/([S] + Km). An enzyme with high Km achieves high catalysis only when the substrate concentration is high.

50
Q

What does the x intercept and y intercept of the lineweaver burk plot show?

A

x intercept: -1/Km

y intercept: 1/Vmax

Biochemistry - Victor (17 decks)

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