Growth Exam 4 Muscle Differentiation & The Contractile Proteins

Front 1

MUSCLE FIBERS (or Muscle Cells)
Other names for muscle cells.

Back 1

Myocytes OR Myotubes

Front 2

Largest muscle cell in body.

Back 2

Mature muscle cell (myofiber, myotube, fiber)

Front 3

Multinucleated

Back 3

Developed by fusion of individual uninucleate cells called myoblasts.

Front 4

Primary function of muscle fibers.

Back 4

Motion & Force generation.
- Keeps an animal upright by tendon and bone connections.

Front 5

HOW DO FIBERS ARISE?

Back 5

From the precursor cell - myoblast (a muscle cell).

Front 6

Myoblasts

Back 6

- Mononucleated & miotic(cell dividing)
- Undifferientiated b/c they cannot contract.

Front 7

Myoblast division & contraction.

Back 7

- Myoblasts must stop divison before concentration occurs.
- Once stopped they will never divide again.

Front 8

Formation of a tube structure.

Back 8

Myoblasts line up and fuse membranes.

Front 9

Myogenin

Back 9

- The trigger for fiber formation.
- The one protein in muscle that is required to make an animal survive & to make it able to contract.

Front 10

Distinguishing feature of a fiber.

Back 10

Production of contractile proteins.

Front 11

WHEN DO MUSCLE FIBERS APPEAR?

Back 11

- Embryogenesis (primary)
- Fetal Phase (secondary)
- No Fiber addition in the postnatal animal.

Front 12

Embryogenesis (primary)

Back 12

- First wave
- Occurs in somites
- Original muscle in animal heart is the back muscle.

Front 13

Fetal Phase (secondary)

Back 13

- Cells are long, multinucleated, & near the myoblast.
- Ocurring in fetus, organogenesis is complete at this time.

Front 14

Postnatal (hyperplasia)

Back 14

- Have total # of muscle cells at birth.
- Can get bigger or smaller but never gain # of cells.

Front 15

HOW ARE FIBERS ORGANIZED INTO A MUSCLE?

Back 15

- Connective tissue
- Endomysium
- Perimysium
- Epimysium

Front 16

Connective Tissue

Back 16

Surrounds individual muscle fibers, allowing for graded motion that is controlled.

Front 17

Muscle Fascicle

Back 17

Bundle of skeletal muscle fibers surrounded by connective tissue.

Front 18

Endomysium

Back 18

- Literally meaning with in the muscle.
- A layer of connective tissue that ensheaths a muscle fiber.

Front 19

Perimysium

Back 19

A sheath of connective tissue which groups individual muscle fibers into bundles.

Front 20

Epimysium

Back 20

Layer of connective tissue that ensheaths the entire muscle.

Front 21

WHY ARE MUSCLES STRIATED?

Back 21

Alignment of banding within a muscle fiber.The arrangement of thick & thin filaments.

Front 22

Sarcomere

Back 22

The portion of a myofibril b/w one Z disc and the next Z disc.

Front 23

Fiber

Back 23

Cell

Front 24

Fibryl

Back 24

Cable

Front 25

How do muscles grow?

Back 25

In length and diameter by adding sarcomeres.

Front 26

Z line

Back 26

The middle of each I band.

Front 27

Myofibrils contain 2 kinds of myofilaments.

Back 27

1) Thick Filaments
2) Thin Filaments

Front 28

WHAT ARE THE COMPONENTS OF THE THICK FILAMENT?

Back 28

Proteins that do enymatic work.

Front 29

Myosin

Back 29

- #1 protein of thick filament
- Found in huge abundance.

Front 30

Myosin heads

Back 30

- Projection from myosin molecule.
- Has 2 binding sites: one for actin and the other for ATP.

Front 31

Binding site for ATP.

Back 31

Is an enzyme (ATPase) that uses ATP to accomplish motion.

Front 32

Myosin tail

Back 32

For structural purposes.

Front 33

Pair of proteins in the thick filament.

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1) C-Protein
2) Titin

Front 34

Titin

Back 34

- Largest known protein
- important in the contraction of striated muscle tissues.

Front 35

Myosin Proteins

Back 35

- Light chains
- Actin binding site
- ATPase activity

Front 36

Light Chains

Back 36

- Small polypeptide subunit of a protein complex.
- Structural support

Front 37

The neck domain.

Back 37

Can serve as a binding site for myosin light chains.

Front 38

Actin binding site.

Back 38

Where it can physically associate with proteins of thin filaments.

Front 39

Thick Filament Proteins.

Back 39

- C-Protein
- Titin

Front 40

C-Protein

Back 40

Acts as rubberband that holds everything together.

Front 41

Titin

Back 41

- Considered giant proteins
- Has springlike actions.
- Maintains orginal state.

Front 42

WHAT ARE THE COMPONENTS OF A THIN FILAMENT?

Back 42

- Actin vs. Sk-actin
- Polymer (G vs. F)

Front 43

Actin

Back 43

- Found in every cell of body
- Involved in making limbs.

Hint 43

Major component in thin filaments.

Front 44

Polymer G-actin (What does it form?)

Back 44

Form chains of F-actin

Hint 44

Each actin molecule is a globular protein.

Front 45

F-actin

Back 45

Gives rise to microfilaments of the cytoskeleton

Hint 45

(What is the appearance and what does it give rise to?)

Front 46

THIN FILAMENT PROTEINS

Back 46

- Troponin
- Tropomyosin
- Nebulin

Hint 46

(What are the proteins?)
Hint: T, T, N

Front 47

Troponin

Back 47

- Core of thin filament.
- Attached to the protein tropomyosin.

Front 48

Tropomyosin

Back 48

- Actin-binding protein that regulates actin mechanics.

Hint 48

Associates with actin, like troponin, in muscle fibers and regulates muscle contraction by regulating the binding of myosin.

Front 49

Nebulin

Back 49

- Actin binding protein
- Localized to the I-band of the Sarcomeres.
- Regulates thin filament length during sarcomere assembly.
- Allows Sarcomere to relax.

Hint 49

-(What kind of binding protein?)
-(Where is Nebulin localized?)
-(Inelastic or Elastic?)
-(What does it regulate?)
-(What does Nebulin allow the Sarcomere to do?)

Front 50

WHAT IS A Z-DISK?

Back 50

- The ends
- Holds thin filaments in place.
- Allows you to push off & bring together the filament ends.

Hint 50

-(What does the Z-disk do within the sarcomere?)
-(What does the Z-disk allow?)

Front 51

Desmin (primary component of Z-disk)

Back 51

- Found near the Z-line in sarcomeres.
- Type III intermediate filament
- Anchors thin filaments, allowing for proper funtioning sarcomere.

Hint 51

-(Where is it found?)
-(What type of filament?)
-(What does Desmin do for the sarcomere?)

Front 52

A-actinin (primary component of Z-disk)

Back 52

- Microfilament protein.
- Attaches actin filaments to the Z-line.

Front 53

Filamin

Back 53

- Cables that wrap around to help glue together.
- crosslinks actin filaments into orthogonal networks.
- Participates in the anchoring of membrane proteins for the actin cytoskeleton.

Hint 53

(Actin-binding Protein)

Front 54

Synemin

Back 54

- Cables that wrap around to help glue together.
- Acts as a mechanical linker in transmitting force laterally throughout the tissue.

Hint 54

(Intermediate filament)

Front 55

ADDITIONAL STRUCTURAL PROTEINS.

Back 55

- Dystrophin
- Utrophin
- Sarcoglycans

Hint 55

(3 additional proteins)
Desmosomes

Front 56

What protein is missing or defective in Duchennes MD?

Back 56

- Dystrophin is missing or defective in Duchennes MD

- Dystrophin deficiency is one of the root causes of muscular dystrophy.

Hint 56

A Desmosome protein.

Front 57

What protein is absent in Beckers MD?

Back 57

Utrophin

Hint 57

A Desmosome protein.

Front 58

What is defective/absent in LimbMuscleGirdle MD.

Back 58

Sarcoglycans

Hint 58

A Desmosome protein

Front 59

Summary of additional structural protein functions.

Back 59

- Collection of proteins that link the plasma membrane of the muscle cell with the sarcomere.

- The Desmosome proteins allow for the entire muscle cell to recognize constriction/relaxation

Hint 59

- (What do these proteins link together?)
- (What do these collection of proteins allow?)

Front 60

HOW ARE THE CONTRACTILE PROTEINS ASSEMBLED?

Back 60

- Myofibrillogenesis
- N-RAP
- Actin & Z-band
- Myosin?

Hint 60

Possibly 5 things.

Front 61

Myofibrillogenesis

Back 61

- Process of making interior cables.
- Includes adding actin & z disks at the ENDS.

Hint 61

- (What does it make?)
- (What does this process add to the ENDS?)

Front 62

N-RAP

Back 62

Nebulin-related anchoring protein.

Hint 62

(What does the acronym stand for?)

Front 63

Myosin?

Back 63

- Not usually considered to be a 1st part of the process b/c myosin is not held in part by Z disk.

Hint 63

(Why is it not usually considered to be a 1st part of the process?)

Front 64

What are multi-protein complexes composed of 3 different filament systems?

Back 64

Sarcomere

Front 65

Myosin is found in huge abundance and is the #1 protein in what filament?

Back 65

Thick Filament

Front 66

What filament is assembled by actin monomers bound to nebulin, which also involves tropomyosin.

Back 66

Thin Filament

Front 67

Nebulin and titin give what to the sarcomere.

Back 67

Structure and stability.

Front 68

What are the borders called that separate and link sarcomeres within a muscle?

Back 68

Z-lines or Z disks

Front 69

State the name of the junction at which mutually adhering glycoprotein filaments from 2 adjacent cells intermingle across the space b/w the cells.

Back 69

Desmosome

Hint 69

(Collection of proteins)
- Dystrophin
- Utrophin
- Sarcoglycans

Front 70

Name the large protein that interacts with another protein, actin, to generate force.

Back 70

Myosin

Hint 70

1) Referred to as contractile proteins.
2) Component of thick filament.

Front 71

What is found in every cell of the body and involved in making limbs?

Back 71

Actin

Hint 71

Referred to as contractile proteins.