Muscle

Question 1

What are the 3 types of muscle?

Answer 1

• Skeletal
• Smooth
• Cardiac

Question 2

Which muscle controls voluntary movement?

Answer 2

Skeletal

Question 3

Which muscle controls involuntary movement?

Answer 3

Smooth and cardiac

Question 4

Which muscle is striated?

Answer 4

Skeletal

Question 5

Which muscle is unstriated?

Answer 5

Smooth

Question 6

What are the two functional classes of muscles? Give examples of both

Answer 6

Slow - intestinal tract muscles

Fast - biceps

Question 7

What are the biochemical classes of muscles? What is the difference between both?

Answer 7

Red - lots of mitochondria

White - less glycolysis

Question 8

Which muscle is multinucleate (peripherally located)

Answer 8

Skeletal

Question 9

Which muscle has branched fibres?

Answer 9

Cardiac

Question 10

Which muscle has Purkinje fibres?

Answer 10

Cardiac

Question 11

Which muscle has unbranched fibres?

Answer 11

Skeletal and smooth

Question 12

Which muscle has transverse tubules?

Answer 12

Skeletal

Question 13

Which muscle has sarcoplasmic reticulum?

Answer 13

Skeletal

Question 14

Which muscle is semi-striated?

Answer 14

Cardiac

Question 15

Which muscle is myogenic?

Answer 15

Cardiac

Question 16

Which muscle has intercalated discs?

Answer 16

Cardiac

Question 17

Which muscles is uninucleate?

Answer 17

Smooth and cardiac

Question 18

Muscle zooming in

Answer 18

Fibre —> Fibrils —> Myofilaments

Question 19

What kind of cell can myogenesis occur from?

Answer 19

Satellite cells

Question 20

What do T-tubules in sarcolemma of skeletal muscles allow?

Answer 20

Co-ordinated contraction of muscle cells

Question 21

What does the sarcoplasmic reticulum store?

Answer 21

Calcium ions

Question 22

What does a myogenic muscle mean?

Answer 22

Cells initiate contraction without any external stimulation

Question 23

What molecule are Purkinje cells rich in?

Answer 23

Glycogen

Question 24

Sliding filament theory: what is the A-band?

Answer 24

The length of myosin

Question 25

Sliding filament theory: what is the I-band?

Answer 25

Length of actin that is not overlapped

Question 26

Sliding filament theory: what is the H-zone?

Answer 26

Actin-actin

Question 27

Sliding filament theory: what is the z-line?

Answer 27

The borders that separate and links the sarcomeres

Question 28

What is the name given to thin filaments in muscle fibres?

Answer 28

Actin

Question 29

What is the name given to thick filaments in muscle fibres?

Answer 29

Myosin

Question 30

How many actin molecules per filament?

Answer 30

380

Question 31

How many myosin molecules per filament?

Answer 31

300

Question 32

Structure of myosin

Answer 32

Coiled coil filaments with motor head domains on one end

Question 33

Structure of actin

Answer 33

G-actin molecules join to form thin filaments of F-actin

Question 34

What polypeptide wraps around actin?

Answer 34

Tropomyosin

Question 35

Which polypeptide do calcium ions bind to in the initiation of contraction?

Answer 35

Troponin

Question 36

What happens do the bands, zone and line during contraction?

Answer 36

During contraction, I bands and H zone shortens to bring the Z lines closer together, whilst A bands do not change their length

Question 37

What are the 3 biological activities that myosin performs?

Answer 37

- Spontaneously assembles into filaments - Enzyme ATPase - Binds polymerised actin

Question 38

What is myosin made up of?

Answer 38

Two major chains (200, 000 MW each) and four light chains (1 pair 16, 000 MW, 1 pair 20, 000 MW)

Question 39

What is actin made up of?

Answer 39

Individual globular proteins, G-actin which form filaments together, F-actin

Question 40

Which enzyme catalyses the polymerisation of G-actin to F-actin?

Answer 40

ATPase

Question 41

What structure does F-actin have?

Answer 41

Chain of two α-helices

Question 42

What is the structure of tropomyosin?

Answer 42

- Double α-helix | - About every 38.5 nm lies a troponin complex

Question 43

What are the three types of troponin? Give their functions

Answer 43

Tn I - inhibitory, binds actin Tn T - binds tropomyosin Tn C - binds calcium ions

Question 44

What occurs when calcium ions and Tn C are bound?

Answer 44

It unravels tropomyosin so that the myosin binding sites are revealed on the actin

Question 45

Why does myosin hydrolyse ATP?

Answer 45

To become reorientated an reenergised

Question 46

What does the binding of myosin heads to actin form?

Answer 46

Crossbridges

Question 47

What controls contraction?

Answer 47

Calcium ions and ATP

Question 48

How do calcium ions control contraction?

Answer 48

- Cytosolic calcium levels usually low - Few Tn C sites occupied by calcium ions and cross bridge formation is blocked my tropomyosin - Action potential releases calcium ions from the sarcoplasmic reticulum, which binds to Tn C, changes the conformation of tropomyosin revealing the myosin heads so cross bridges can form --> contraction