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Biochem > Unit 5 Test Two > Flashcards

Unit 5 Test Two Flashcards

1
Q

Functions of globular proteins

A

Storage of ions and molecules, transport of ions and molecules, defense against pathogens, muscle contraction, and biological catalysts

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2
Q

What is a ligand

A

Molecule that binds to protein

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3
Q

Ligands bind via what

A

Noncovalent forces such as hydrophobic, hydrogen bonds and van der waals

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4
Q

What is Kd

A

Dissociation rate, the concentration of ligand at which half of the available ligand binding sites are occupied

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5
Q

What is theta

A

Free ligand/ [free ligand] + Kd (fraction of bound sites)

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6
Q

Decrease Kd means what

A

Increase affinity value with molecule

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7
Q

Why do some ligands have units of pressure

A

When ligand is a gas, binding is expressed in terms of partial pressure

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8
Q

What is the problem with carrying oxygen and bound to just a protein lacking the heme

A

Protein side chains lack affinity for O2,must be a metal to bind to

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9
Q

Why are free metal ions in circulation or tissue have problems with carrying oxygen

A

Is now free radicals

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10
Q

What is the organic component of heme

A

Protoporphyrin 9

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11
Q

What is the inorganic component of heme

A

Iron

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12
Q

In a heme molecule, iron can potentially coordinate with how many atoms

A

6

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13
Q

What molecule binds at the 5th and 6th coordination sites if an iron atom

A

Distal is O2 and proximal is histidine

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14
Q

When O2 is not bound to the plane of porphyria what is the position

A

Iron is way from porphyrin ring (T state)

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15
Q

When O2 is bound to the plane of porphyrin is what position

A

In linear alignment (R state)

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16
Q

What is the role of the distal histidine

A

Help bind O2 to iron

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17
Q

What is the function of myoglobin

A

Transport O2 and CO2 in muscle as well as storage of O2

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18
Q

What are the types of amino acids inside myoglobin

A

Nonpolar except for two histidines

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19
Q

What are the types of amino acids found in the exterior of myoglobin

A

Polar amino acids

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20
Q

Where is myoglobin present

A

Found in cytosol with high respiration rate such as heart, muscle and liver

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21
Q

What are the factors which influence whether the ligand binds in myoglobin

A

Concentration of myoglobin and pO2

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22
Q

Myoglobin contains mostly what secondary structure

A

Alpha helices

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23
Q

How many heme groups in myoglobin

A

One

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24
Q

What is the oxidation state of metmyoglobin

A

Fe 3+, doesn’t bind to O2

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25
Q

Oxidation state of deoxyhemoglobin

A

Fe3+

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26
Q

Oxidation state of oxyhemoglobin

A

Fe2+

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27
Q

Is histidine needed when binding CO2

A

No

28
Q

What does O2 need for help with binding

A

Protein (histidine)

29
Q

What binds better O2 or CO2

A

CO2 especially with myoglobin

30
Q

Why is CO2 better at binding

A

No histidine needed, better plane for better binding

31
Q

Can myoglobin transport and release O2

A

Can bind but difficulty releasing O2

32
Q

For effective transport of O2 in myoglobin what needs to happen

A

Affinity must vary with pO2

33
Q

What is the shape of curve of hemoglobin graph

A

Sigmoidal

34
Q

Describe tense state of hemoglobin

A

More stable, lower affinity of O2, unload O2

35
Q

Describe relaxed state of hemoglobin

A

More flexible, high affinity of O2, binding of O2

36
Q

What is hemoglobin made up of

A

2 alpha and 2 beta which each group contains heme group

37
Q

Who has better affinity of O2 myoglobin or hemoglobin

A

Myoglobin

38
Q

How does hemoglobin bind to O2

A

Cooperatively

39
Q

Hgb binding to O2 depends on

A

Concentration of Hgb, pO2, pH, pCO2, and concentration of 2,3-BPG

40
Q

Does HbF bind O2 better than HbA

A

HbF

41
Q

Describe the role of factors influencing R form

A 
Increase pO2
Decrease pCO2
Decrease H+ concentration
Increase pH
Decrease 2,3-BPG
42
Q

Describe the role of factors in T form

A 
Decrease pO2
Increase pCO2
Increase H+ concentration
Decrease pH
Increase 2,3-BPG
43
Q

O2 binding causes what in T

A

Causes T to change to R

44
Q

What occurs when T state changes to R state

A

Breaking ion pairs

45
Q

What bonds occur between alpha beta dimer pairs in T state

A

Weak ionic and hydrogen bonds

46
Q

What interactions are between alpha and beta chains that form the stable alpha beta dimers in T state

A

Strong interactions such as hydrophobic

47
Q

In R state, what is the interactions between alpha and beta dimers that are broken

A

Ionic and hydrogen bonds

48
Q

What is the Bohr effect

A

O2 released from Hgb is caused by decrease in pH, increase H+, increase CO2. This helps stabilize the T form

49
Q

In what form most of CO2 transported from tissues to lungs

A

Bicarbonate

50
Q

What enzyme is used to create bicarbonate

A

Carbonic anhydrase

51
Q

What occurs to left shift of Hgb curve

A

Increase pH, decrease H+, decrease CO2, increase O2

52
Q

What occurs to right shift of Hgb curve

A

Decrease pH, increase H+, increase CO2, decrease O2

53
Q

What form does hemoglobin carry CO2?

A

Carbamate (carbaminohemoglobin)

54
Q

How does 2,3-BPG affect Hgb affinity for oxygen

A

Increase in 2,3 causes decrease in affinity of O2,

2,3 causes T form to stabilize

55
Q

What is the charge of 2,3 BPG

A

Negatively charge and binds to positive cavity of Hgb

56
Q

What is the molecular difference between the fetal and adult hemoglobin

A

Fetal contains gamma chain instead of beta chain causing a substitute serine for histidine causing removal of 2 positive charges of 2,3-BPG and reduces affinity of 2,3

57
Q

What causes sickle cell disease

A

Glutamate 6 switched with valine in beta chain

58
Q

What happens with sickle cell disease

A

Causes structural change of RBC and poor O2 binding

59
Q

What is alpha thalassemias

A

Synthesis of alpha chains decreases due to deletion mutation

60
Q

What is the outcome of alpha thalassemia

A

Bind O2 with high affinity but release is poor

61
Q

What causes Beta thalassemia

A

Beta globin chain decrease due to point mutations, excess alpha chain causing aggregation and unstable tetramers

62
Q

What is the symptom of beta thalassemia

A

Produces anemia

63
Q

Four steps of actomyosin cycle

A

ATP binds to myosin and myosin dissociates from ACtin, ATP is hydrolyzed causing conformational change of myosin, myosin reconnects to the actin filament at a different location and releases of Pi, release fo Pi causes power stroke where myosin initial state, shifting actin filament relative to the myosin tail and release of ADP

64
Q

How is muscle contraction regulated with what proteins

A

Troponin and tropomyosin

65
Q

What ion regulates muscle contraction

A

Ca2+

Biochem (7 decks)

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