Muscle

Question 1

3 Main Molecular Motors in Euk Cells

Answer 1

Kinesin, dynein, and mysoin

Question 2

Why did muscle cells first evolve

Answer 2

To move things around inside single-celled organism

Question 3

How did muscle cells evolve

Answer 3

Evolved from molecule switches in which an enzyme or other activity is turned on/off by binding ATP or CTP and undergoing a conformational change

Question 4

Where did skeletal muscles first appear

Answer 4

Cnidaria

Question 5

Muscle fiber

Answer 5

Muscle cell

Question 6

Multinucleate

Answer 6

The bigger the cell, the more nuclei

Question 7

Myofibrils

Answer 7

Found in muscle fibers, full of actin and myosin filaments

Question 8

Why is skeletal muscle striated?

Answer 8

Myofibrils are precisely aligned

Question 9

Electrical nature of muscle

Answer 9

Skeletal muscle is excitable

Question 10

Myosin

Answer 10

Thick filament, contractile proteins that attach to and exert force on actin filaments

Question 11

Actin

Answer 11

Thin filaments

Question 12

Z-line

Answer 12

Structural protein that anchors actin

Question 13

Sarcomere

Answer 13

Functional unit of skeletal muscle, defined as part from 1 z-line to the next, lined up end to end from tendon to tendon

Question 14

Crossbridge Cycle

Answer 14

Cycle of binding, ratcheting, and unbinding of myosin head to actin filament

Question 15

Myosin and actin bond

Answer 15

chemical bond that can only be broken by energy, ATP

Question 16

ATP in Crossbridge Cycle

Answer 16

Breaks crossbridge and recocks myosin head

Question 17

Sarcoplasmic Reticulum (SR)

Answer 17

Ca++ reservoir

Question 18

Tropomyosin

Answer 18

Filament that runs along actin and has a troponin complex attached at regular intervals

Question 19

T-tubules

Answer 19

transverse tubules, tubes of excitable membrane that course into the fiber

Question 20

Is muscle myelinated

Answer 20

no

Question 21

Does skeletal muscle have t-tubules

Answer 21

yes

Question 22

Does smooth or skeletal muscle have longer actin

Answer 22

smooth

Question 23

How do skeletal muscle actins run

Answer 23

parallel to the length of the fiber

Question 24

T-tubule system

Answer 24

Used to get Ap signal simultaneously to all myofibrils for max power in skeletal muscles

Question 25

Smooth muscle

Answer 25

Has no striations and no sarcomeres, much thinner than skeletal and have a single nucleus

Question 26

Dense Bodies

Answer 26

Actin attach to these in smooth muscle instead of z-line in skeletal

Question 27

Is smooth muscle voluntary or involuntary

Answer 27

Involuntary, most is spontaneously active

Question 28

Does smooth muscle have troponin

Answer 28

no

Question 29

Which muscle is adapted for slow, sustained contraction using less energy

Answer 29

Smooth muscle, contracts 10x more slowly than skeletal