Ultrastructure

Question 1

what is the main type of muscle we care about

Answer 1

striated

Question 2

what does striated muscle connect

Answer 2

bones and/or tendons

Question 3

5 main subunits of muscle

Answer 3

muscle
muscle bundle
muscle fiber
myofibril
myofilament

Question 4

3 layers of connective tissue and what they surround

Answer 4

-epimysium(around muscle)
-perimysium(around muscle bundle)
-endomysium(around muscle fiber)

Question 5

what is the cell/basic unit of muscle

Answer 5

muscle fiber

Question 6

what is the specialized organelle of muscle

Answer 6

myofibril

Question 7

what are the muscle proteins

Answer 7

myofilament

Question 8

what surround muscle fiber, right below the endomysium

Answer 8

sarcolema

Question 9

what is the most abundant protein in the body

Answer 9

collagen

Question 10

what AA makes up 1/3 of collagen

Answer 10

glycine

Question 11

why is the AA makeup of collagen important

Answer 11

proline circles back to the amino group causing a kink in the chain, glycine has a small R group allowing more room. this causes a bend/helix which gives collagen its strength

Question 12

where are the nuclei located in muscle, why is muscle multinucleated

Answer 12

-located around the periphery of the cell
-multinucleated since muscle cells are so big

Question 13

5 regions of a sarcomere and what they are

Answer 13

H zone-end of thin filament to start of other thin filament
Z line-where actin is connected to
A band-width of thick filament
I band-end of one thick filament to the end of the other on an adjacent sarcomere
M line-middle of the sarcomere

Question 14

2 major filaments of muscle

Answer 14

actin(thin)
myosin(thick)

Question 15

what region of sarcomeres doesn’t change width during contraction

Answer 15

A band

Question 16

how many thin filaments surround 1 thick filament

Answer 16

6

Question 17

segments of thin filament and what they are

Answer 17

actin
troponin(surrounds actin)
tropomyosin(covers myosin binding site)

Question 18

2 types of actin

Answer 18

G actin(globular)
F actin(filament-G actin strung together)

Question 19

components of thick filament

Answer 19

heavy chain
hinge
2 heads

Question 20

how do the heads of thick filament help contraction of muscle

Answer 20

heads pull actin towards M line to pull them together

Question 21

What is titin? what does it do?

Answer 21

-its a large gap protein
-spans M line to Z disk to act as scaffolding for thick filament
-acts as spring to allow muscle to relax

Question 22

what is nebulin? what does it do?

Answer 22

gap filament that runs the length of the thin filament to regulate length

Question 23

what is tropomodulin

Answer 23

caps the end of thin filament to regulate length

Question 24

what is capZ

Answer 24

ties thin filament to Z disk

Question 25

what is the purpose of intermediate filaments

Answer 25

connect adjacent sarcomeres to each other

Question 26

what is the main intermediate filament? how does it impact tenderness?

Answer 26

Desmin degrades with age, which can increase tenderness

Question 27

what do costameric proteins do

Answer 27

connect myofibrils to the sarcolemma(cell membrane)

Question 28

what is the main costameric protein

Answer 28

costamere

Question 29

what surrounds the myofibril and stores calcium to initiate and maintain contraction

Answer 29

sarcoplasmic reticulum

Question 30

what is the purpose of T tubules

Answer 30

extend the cell membrane to the middle of the muscle fiber for communication

Question 31

what is innervation

Answer 31

the terminal nerve branches embedding themselves in the muscle cell membrane

Question 32

what is released from the nerve to signal the start of muscle contraction

Answer 32

acetyl choline

Question 33

what type of muscle cells contain high levels of mitochondria? why?

Answer 33

Type I/IIA -slow twitch/oxidative respiration -used for endurance exercises

Question 34

what type of muscle cells have low levels of mitochondria? why?

Answer 34

Type IIB -fast twitch/glycolytic respiration -used for sprints

Question 35

which muscle type is largest? why?

Answer 35

Type IIB. glycolytic respiration requires more space since it occurs in the sarcoplasm

Question 36

what caries oxygen to the mitochondria of muscle cells? how does this effect meat?

Answer 36

myoglobin Type I muscles are more red, Type IIB are white

Question 37

T/F glycolytic respiration can only be anaerobic

Answer 37

FALSE. it can be either

Question 38

products of glycolytic respiration? where do they go?

Answer 38

aerobic: 2 pyruvate, goes to mitochondria and enters TCA cycle anaerobic: 2 lactic acids, goes to liver, in converted back to glucose, reenters glycolytic respiration 4 ATP

Question 39

fuel for glycolysis

Answer 39

glucose

Question 40

fuel for oxidative phosphorylation(TCA cycle)

Answer 40

pyruvate protein fat

Question 41

by products of oxidative phosphorylation

Answer 41

CO2 and water