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Biochemistry I > Chapter 6 > Flashcards

Chapter 6 Flashcards

1
Q

Negative allosteric effector

A

2,3-BPG
H+
CO2

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2
Q

Positive allosteric effector

A

O2

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3
Q

Lower Kd

A

Higher affinity

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4
Q

Thick filaments

A

(myosin)
Bind ATP
Connected to Z disks via titin protein
Composed of myosin filaments

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5
Q

Thin filaments

A 
(Actin)
Bind calcium
Composed of actin monomers
Contain tropomyosin 
Composed of troponin complex
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6
Q

TnC

A

Binds to Ca 2+ and controls muscle contraction

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7
Q

TnI

A

Inhibits myosin binding to actin

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8
Q

TnT

A

Binds to tropomyosin

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9
Q

Ca2+ initially binds to

A

Troponin

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10
Q

Calciums role in muscle contraction

A

Ca2+ binds to troponin which induces a conformational chance on the actin filaments that exposes myosin binding sites on actin sub units

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11
Q

muscle contraction shortens the distance between:

A

Z-disk proteins

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12
Q

Z-disks contain the following proteins:

A

Vimentin
α-actinin
Desmin

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13
Q

Ѳ =

A

[PL] / [PL] + [P]

OR

Occupied binding sites / total binding sites

OR

[L] / Kd + [L]

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14
Q

Kd =

A

[P] [L] / [PL]

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15
Q

To find Kd by looking at a graph

A

Find fractional saturation 0.5 on Y-axis and locate Kd on X-axis

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16
Q

Oxygen Binding Curves for Myoglobin

and Hemoglobin

A

Myoglobin = Hyperbolic

Hemoglobin= Sigmoidal

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17
Q

Ligand binding is a ______ process

involving ______ interactions

A

reversible

noncovalent

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18
Q

P 50 =

A

Kd

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19
Q

______ is more effective at transporting Oxygen than ______

A

Hemoglobin

Myoglobin

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20
Q

As pH incresaes

A

Affinity for binding oxygen increase

Explains why pH is higher in lungs where O2 must bind

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21
Q

Equation for dissolving of CO2

A

CO2 + H2O HCO3- + H+

With help of enzyme carbonic anhydrase

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22
Q

As [CO2] increases

A

[H+] also increases, and affininty for binding O2 goes down

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23
Q

in tissue —–> pH is ________ because of ________

—–> ________

A

Low in blood
Accumulation of CO2
O2 is released by hemoglobin

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24
Q

In lungs ——> pH is ______ because _______ is being _____ ——> ___________

A

Higher
CO2, Exhaled
O2 is bound to HG

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25
Q

2,3-BPG

A

Traps HG is the T state

Aids in the binding of HG

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26
Q

2,3-BPG bindig to HG

A

2,3-BPG has a -5 charge which binds tot he +8 charger in the central canal

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27
Q

In lungs 2,3-BPG is

A

mostly unbound

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28
Q

In tissue 2,3-BPG is mostly

A

Bound, stabilizing T- state

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29
Q

BPG also plays an important role in adaptation to:

A

higher altitudes

30
Q

When O2 binds central canal ________ and ________ is released

A

Narrows

2,3-BPG

31
Q

[O2] is much ______ at high altitudes.

Therefore ________ is produced in larger amounts

A

lower

2,3-BPG

32
Q

The O2 binding curve at high altitudes:

A

85% sat in lungs
45% sat in tissues

40% release of O2

33
Q

The O2 binding curve at high altitudes if 2,3-BPG was not produced:

A

90% sat in lungs
57% sat in tissues

33% release of O2

34
Q

Arterial bood flow

A

Lungs to tissue

35
Q

Venous blood flow

A

Tissue to lungs

36
Q

Anemia is due to a mutation in

A

α or β hemoglobin

subunits

37
Q

Anemia is characterized by

A

Reduced oxygen transport efficiency from the

lungs to the tissue caused by altered hemoglobin function or reduced number of red blood cells

38
Q

SIckle cell disease

A

Beta subunit mutation in Hemoglobin S

39
Q

Sickle cell genotype

A

Glu6 (A3) —> Val6

40
Q

Sickle cell phenotype

A

Globin protein aggregation

41
Q

In sickle-cell hemoglobin Glu6 in the β chain is

mutated to Val, thereby creating:

A

a hydrophobic patch on the surface of the molecule

42
Q

Effect of sickle-shaped cells

A

clog small blood vessels,
causing pain and life threatening
crises.

43
Q

This patch happens to ______ a hydrophobic
pocket in the _________ of another
hemoglobin molecule.

A

fit and bind

deoxygenated form

44
Q

When hemoglobin in the blood capillaries delivers its

oxygen:

A

the hydrophobic interactions can occur and
the highly concentrated hemoglobin in the cells
polymerizes into fibers

45
Q

Together, actin and myosin make up more

than ____ of the protein mass of muscle.

46
Q

muscle fibers

A

large single multinucleated cell

composed of many myofibrils

47
Q

Muscle fiber AKA

48
Q

Myofibril

A

Composed of actin myosin

Contains many sarcomeres

49
Q

Bundle of muscle fibers

50
Q

During muscle contraction The length of ________ decreases. The length of _________ remain
constant

A

sacromere

thick and thin filaments

51
Q

Model by which muscle contraction occurs

A

Sliding Filament Model

sliding of the thick and thin filaments past each other
so that the Z disks in neighboring I bands approach each other

52
Q

Myosin length

A

1600 angstroms

53
Q

Actin and tropomyosin bind with

54
Q

Tropomyosin

A

A second thin filament protein

Tightly associated with actin

55
Q

G actin

A

Globular

Monomeric sub units that make up f actin

56
Q

F actin

A

The thin filament actin

Filamentous

assemblage of G-actin monomers

57
Q

Each _________ can bind a

single myosin head.

58
Q

The _________ regulates muscle contraction by controlling the access of ________ to their binding sites on actin.

A

tropomyosin-troponin complex

the myosin heads

59
Q

Titin protein functions as ______, which connects ______ filaments to _______

A

a spring

myosin

Zdisk proteins

60
Q

Tropomodulin

A

an actin filament capping protein

61
Q

ELC and RLC

A

Essential light chains

Regulatory light chain

62
Q

____ and _____ required for muscle contraction

63
Q

I band contains

A

thin filaments

70 angstrom diameter

64
Q

A band contains

A

thick filaments

150 angstrom diameter

65
Q

Myosin is made up of ________

A

6 polypeptide chains

2 heavy and 4 light chains

66
Q

______ is converted to ______

A

Chemical energy

Motion

67
Q

e- density in A band vs I band

A

A - Higher

I - Lower

68
Q

e- density in H zone vs M disk

A

M disk - higher

H zone- lower

69
Q

two areas that compact during contraction

A

H zone

I band

70
Q

When Ѳ is 0.5

71
Q

Troponin complex consists of:

72
Q

Longest known protein in nature

Biochemistry I (13 decks)

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