Sarcomere

Question 1

Skeletal muscles form from the

Answer 1

fusion of myoblasts to form myotubes which differentiate into multinucleated muscle cells (myofibers)

Question 2

Where does the formation of skeletal muscle cells occur?

Answer 2

In the fetus and juvenile

Question 3

Endomysium

Answer 3

around each muscle cell

Question 4

Perimysium

Answer 4

around a group of muscle cells which is a fascicle

Question 5

Epimysium

Answer 5

around the whole muscle which is tendon to bone

Question 6

What two cells participate in myogensis?

Answer 6

Stem cells and satellite cells

Question 7

Some satellite cells persist in skeletal muscles as

Answer 7

small, multipotent cells with little cytoplasm and are embedded in the endomysium

Question 8

Satellite cells can add

Answer 8

nuclei to adjacent muscle cells or in times of exercise, injury, or disease active and re-enter the myogenesis mode creating myoblasts, myotubes and more muscle fibers

Question 9

The sarcomere is the

Answer 9

functional (practical, useful) unit of a skeletal muscle

Question 10

Sarcomeres are highly stereotyped and are

Answer 10

repeated throughout muscle cells, and the proteins within them can change in length, which causes the overall length of a muscle to change

Question 11

Myofibers are multinucleate long,

Answer 11

cylindrical cells and may be several cm long and arranged in parallel

Question 12

Each skeletal muscle cell has myofibrils which are

Answer 12

rod-like structures, composed of an orderly (repeating) arrangement of myofilaments (actin and myosin) in units called sarcomeres

Question 13

A sarcomere is a functional unit of skeletal muscle bound at each end by a

Answer 13

Z-line (Z-disk)

Question 14

In a sarcomere, thin myofilaments extend from the Z-line (Actin) interdigitate with

Answer 14

thick myofilaments (Myosin)

Question 15

Characteristics of the A Band (Anisotropic band)

Answer 15

• has both actin and myosin that overlap
• densest
• polarizes visible light to dark

Question 16

H zone characteristics

Answer 16

is the center of the A band
lighter
only thick myofilaments (myosin)

Question 17

M line

Answer 17

in center of H zone

Question 18

I band characteristics

Answer 18

between two A bands
light color
Isotropic (doesn’t polarize visible light)

Question 19

Z line

Answer 19

common to two adjacent sarcomeres

Question 20

Cardiac muscle cells contain

Answer 20

muscle fibers which are myofibers

Question 21

Myofibers have

Answer 21

actin and myosin and in sarcomeres they are Z-line to Z-line

Question 22

Cardiac muscle cells are not as long as

Answer 22

skeletal muscle cells

Question 23

Cardiac muscle cells are often ________ cells and may be _________ or ________ and the nuclei are located ______ in the cell

Answer 23

Often branched cells
May be mononucleated or binucleated
And the nuclei are located centrally in the cell

Question 24

Cardiac muscle is also _______ and contains __________ ______

Answer 24

striated
intercalated discs

Question 25

Actin is a

Answer 25

complex of proteins

Question 26

Actin are twin intertwined

Answer 26

globular proteins

Question 27

Tropomyosin covers

Answer 27

active (myosin binding) sites on actin

Question 28

Troponin is affinity for

Answer 28

calcium

Question 29

Troponin attaches to the

Answer 29

Z line

Question 30

Myosin is shaped like a

Answer 30

golf club with pair of heads, necks, and tails

Question 31

Myosin has actin ____ ______ and _____ activity which means ______________

Answer 31

Myosin has actin-binding sites and has ATPase activity which means it breaks down ATPs which results in energy

Question 32

Light meromyosin

Answer 32

long parallel proteins (tails)

Question 33

Heavy meromyosin

Answer 33

extend out like an arm
S2- helix protein (arm)
S1- head with ATPase activity

Question 34

Heavy meromyosin S1 “walks”…

Answer 34

filament over the Actin

Question 35

M line is where the

Answer 35

myosin attach and are parallel to each other (tail to tail)

Question 36

Myosin is what type of protein? and what does it do when it is shortened?

Answer 36

Helical protein
Shortens when heated (cooking)

Question 37

During the myosin mechanism, the rapid hydrolysis of ATP to ADP + Pi triggers a

Answer 37

conformational change that rotates the myosin lever and increases the affinity of myosin for actin

Question 38

Z line (Z disk) German terminology

Answer 38

zwischen which means between

Question 39

M line german terminology

Answer 39

mittle (middle)

Question 40

Titin is a

Answer 40

large elastic molecule and largest known protein and has greater than 25,000 AA from Z-line to M-line

Question 41

If titin is an 8 ft ship rope then actin would be an

Answer 41

eyelash

Question 42

Titin stablizes __________ and returns muscle to ______ ________

Answer 42

myofilaments
resting length

Question 43

Nebulin are

Answer 43

inelastic large protein that attaches to Z-line lies alongside actin

Question 44

In the sliding filament theory of skeletal and cardiac muscle contraction, myofilaments (actin & myosin) do not

Answer 44

contract or shortern

Question 45

In the sliding filament theory of skeletal & cardiac muscle contraction, myofilaments (actin and myosin) do

Answer 45

slide over one another
decrease in width of the H band
decrease in the width of the I band (amount of overlap increases)