Muscles Flashcards

1
Q

Thick filament

A

Myosin

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2
Q

Thin filament

A

Actin

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3
Q

Largest protein known

A

Titin

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4
Q

Arrangements thick and thin filaments

A

Hexagonal arrangement: each thick filament has 6 thin filaments surrounding it. 6:3 ratio of thin : thick filaments

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5
Q

What links actin to Z-lines?

A

α-actin

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6
Q

What genes code for α-actin?

A

ACTN 1/2/3/4

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7
Q

What proteins aid in filament formation and muscle stability?

A

Actin capping proteins

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8
Q

Describe the structure of actin capping proteins?

A

Heterdimeric complex with α/β subunits

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9
Q

Genes that code for actin capping proteins

A

CAPZA 1/2/3

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10
Q

What is the main protein associated with the M line?

A

Myomesin

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11
Q

What genes express myomesin?

A

MYOM 1/2/3

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12
Q

Components of myosin

A

6 subunits, 2 heavy chains, 2 light chains

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13
Q

What digestion sites signify the point of hing in converting ATP hydrolysis into contraction/relaxation?

A

Trypsin and papain

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14
Q

What protein covers the myosin binding site on actin?

A

Tropomyosin

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15
Q

Which protein of troponin bind to Ca/regulates ca dependent muscle contraction?

A

TropC

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16
Q

What protein complex removes the “cover” from the myosin-binding sites of 7 G-actins?

A

Troponin

17
Q

What are the types of actin?

A

α, β, ɣ

18
Q

Which actin gene is primarily expressed in skeletal muscle?

A

ACTA 1

19
Q

Which actin gene is primarily expressed in smooth muscle?

A

ACTA 2

20
Q

Which actin gene is primarily expressed in cardiac muscle?

A

ACTC 1

21
Q

Mutations in which genes cause inherited cardiomyopathy?

A

Troponin I and T

22
Q

Dystrophin-glycoprotein complex

A

Multi-subunit complex that mediates interactions between cytoskeleton, membrane, and ECM.

23
Q

What gene codes for DGC?

A

DMD gene on Chromosome X

24
Q

Duchenne muscular dystrophy

A

X-linked recessive. Primarily expressed in males. S&s appear around 6months or at birth. Wheel chair dependance by 10-12 y/o/ Progressive muscle degeneration/weakness. Life expectancy 25y/o

25
Q

Signs of Duchenne MD

A

Sway back, child walking on toes, poor balance, thin/weak thighs, belly sticks out, knees may bend back to take weight, difficultly swallowing

26
Q

DMD Pathophysiology

A

DGC is ineffective. Have an abnormally influx of Ca that leads to cell necrosis

27
Q

Becker Muscular Dystrophy

A

Milder form of MD. Non-lethal disorder. Muscle weakness is very gradual. Caused by CTG trinucleotide repeat on chromosome 19.

28
Q

Signs of Becker MD

A

Sustained involuntary contractions, difficultly releasing grip when shaking hands, prominent forehead, narrow face, difficultly swallowing

29
Q

X-linked dilated cardiomyopathy

A

Cardiac muscle is unable to produce dystrophin due to mutation but skeletal muscle maintains DGC synthesis

30
Q

3 forms of energy metabolism in muscle

A

Creatine phosphate, glycolysis, oxidative phosphorylation