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Year 1 Cell Biology > Muscle > Flashcards

Muscle Flashcards

1
Q

What are the components of thin filaments?

A
  1. F-actin2. Troponin3. Tropomyosin
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2
Q

Actin, troponin, and tropomyosin are components of what muscle filament?

A

Thin filament

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3
Q

What constitutes thick filaments?

A

Myosin II

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4
Q

What is F-actin made up of?

A

Two G-actin polymers twisted to form a double stranded helix

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5
Q

Two G-actin polymers twisted to form a double stranded helix forms ___________

A

F-actin

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6
Q

What are the components of troponin?

A
  1. TnT2. TnC3. TnI
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7
Q

What is the function of TnT?

A

Troponin subunit that binds to tropomyosin

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8
Q

What is the function of TnC?

A

Troponin subunit that binds calcium

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9
Q

What is the function of TnI?

A

Troponin subunit that binds troponin to actin molecule; inhibits actin-myosin interaction

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10
Q

Where does the Tn complex bind to tropomyosin?

A

Grooves of actin filaments

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11
Q

What constitutes a tropomyosin molecule?

A
  1. Two polypeptide chains in an a-helix2. Each a-helix rests on 7 G-actin molecules, covering active site3. Head to tail of tropomyosins form tropomyosin filaments
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12
Q

What does trypsin do to myosin molecules?

A

Breaks them into heavy meromyosin and light meromyosin

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13
Q

What is the molecular composition of myosin?

A

2 heavy chains and 4 light chains

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14
Q

What constitutes heavy meromyosin?

A
  1. 4 light chains2. 2 globular chains3. Short twisted tail (a-helix)
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15
Q

What constitutes light meromyosin?

A

The shafts of the heavy chains wrapped around each other

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16
Q

What makes up a sarcomere?

A

Overlapping thick and thin myofilaments

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17
Q

Overlapping thick and thin myofilaments make up a _______________

A

Sarcomere

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18
Q

A series of sarcomeres joined end-to-end makes up a _______________

A

Myofibril

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19
Q

What makes up a myofibril?

A

A series of sarcomeres joined end-to-end

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20
Q

What makes up a muscle fiber (muscle cell)?

A

Many parallel myofibrils

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21
Q

Many parallel myofibrils make up a ______________

A

Muscle fiber (muscle cell)

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22
Q

What are the characteristics of the A band?

A
  1. Dark band - thick and thin filaments2. Widest band
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23
Q

What are the characteristics of the H band?

A
  1. Thick filaments only2. Bisects the A band
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24
Q

What are the characteristics of the I band?

A
  1. Thin filaments only2. Light band3. Made up of portions of adjacent sarcomeres
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25
Q

What are the characteristics of the Z disc?

A
  1. Attachment for thin filaments2. Contains a-actinin3. Bisects I band
26
Q

What are the characteristics of the M line?

A
  1. Consists of protein structures lying between thick and thin filaments, holding them together2. Creatine kinase is major protein3. Bisects H band
27
Q

What is the role of a-actinin?

A

Anchors thin filaments to Z disc

28
Q

What anchors thick filaments to the Z disc?

29
Q

What is the role of titin?

A

Anchors thick filaments to Z disc

30
Q

What is the role of myomesin and C protein?

A

Secures thick filaments at M line

31
Q

What is the role of dystrophin?

A

Cytoplasmic protein that binds actin filaments to laminin

32
Q

What makes up the sarcolemma?

A

Cell membrane + external lamina + reticular lamina

33
Q

What is endomysium?

A

Surrounds muscle fiber, consists of delicate layer of reticular fibers

34
Q

What is a fascicle?

A

Many muscle fibers bundled together

35
Q

What connective tissue surrounds a fascicle?

A

Perimysium

36
Q

What is perimysium?

A

Collagenous connective tissue that surrounds a fascicle

37
Q

What is epimysium?

A

Deep fascia, surrounds many fascicles

38
Q

What is the term for deep fascia taht surrounds many fascicles?

39
Q

What are T tubules?

A

Invaginations of sarcolemma which are continuous with extracellular space

40
Q

What is the function of T tubules?

A

Carry nerve impulses deep into cell

41
Q

What is the terminal cisterna of the sarcoplasmic reticulum?

A

Stores calcium in its lumen

42
Q

What is the triad located at the A-I junction of the sarcomere?

A

1 T tubule + 2 terminal cisternae

43
Q

What are satellite cells?

A

Regenerative cells that lie between the skeletal muscle cell and its external lamina

44
Q

New myoblasts are derived from ___________

A

Satellite cells

45
Q

What components make up the innervation of skeletal muscle?

A
  1. Motor unit2. Motor end plate
46
Q

What constitutes the motor unit?

A

A lower motor neuron and all muscle fibers it innervates

47
Q

What constitutes the motor end plate?

A
  1. Axon terminal2. Synaptic cleft3. Muscle cell sarcolemma
48
Q

What is myesthenia gravis?

A

Autoimmune disease causing muscle weakness

49
Q

What is the cause of myesthenia gravis?

A

Antibodies attack Ach receptors on sarcolemma of skeletal muscle, forming Ab-receptor complexes

50
Q

What is muscular dystrophy?

A

Genetic, degenerative disease affecting striated muscles

51
Q

What is the protein affected in Duchenne’s muscular dystrophy?

A

Dystrophin

52
Q

Which muscle type contains a lot of glycogen?

A

Cardiac muscle

53
Q

What are some characteristics of cardiac muscle?

A
  1. Weakly striated2. Short and branched cells3. Cells contain glycogen, lipid droplets, and lipofuscin4. 1-2 nuclei5. Atrial granules6. Many mitochondria7. Intercalated discs
54
Q

What are atrial granules?

A

Membrane-bound granules: 1. Contain atrial natriuretic factor and brain natriuretic factor2. Most common in right atrium

55
Q

What are intercalated discs?

A

Specialized intercellular junctions

56
Q

Are T tubules of the cardiac (ventricular) muscle larger or smaller than in skeletal muscle?

57
Q

What are Purkinje fibers?

A

Specialized cardiac muscle cells in the endocardium that act as batteries which relay electrical impulses to cardiac muscle fibers

58
Q

What are some characteristics of smooth muscle?

A
  1. Forms sheets2. No striations3. Mononuclear - nucleus is in center4. Dense bodies - crossing of myofilament bundles5. No T tubules6. Poorly developed SR
59
Q

What are dense bodies?

A

Criss-crossing of myofilament bundles

60
Q

What is a common component of dense bodies?

A

a-actinin (similar to Z discs)

61
Q

What are caveolae?

A

Pinocytotic vesicles that form bubble like structures on inner surface of cell membrane and release calcium into cell for contraction

Year 1 Cell Biology (40 decks)

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