BCHM 1 contractile proteins

Question 1

What does actin make up other than in muscle?

Answer 1

• major component cytoskeleton

(microvilli, cell cortex, anherens belt, phagocytosis, contractile ring)

Question 2

ACtin filaments are assembled into what types of structures?

what assembles them?

Answer 2

1. Actin bundles and actin networks
2. accessory proteins

Question 3

Basics about actin bundles

vs

actin networks

Answer 3

bundles

• cross-linked into closely packed parallel arrays
  
  • usually same polarity is same so + end all on same side

networks

• loosely cross-linked in orthogonal arrays
  
  • form 3D meshwork with gel-like properties
  • can strech flex

Question 4

Actin-bundling proteins

Answer 4

Question 5

Closely spaced actin-bundling proteins

Answer 5

Question 6

What binds together close actin bundles

Answer 6

fimbrin

Question 7

Loosely bundled actin filaments

Answer 7

Question 8

Loose actin bundling protein that can make the space?

Answer 8

a-actinin

Question 9

actin filaments in networks (actin-bundling)

Answer 9

Question 10

Actin and the plasma membrane

Answer 10

• 3D networks abundant beneath the plasma membrane (determine shape, aid move, stabil, flex
• erythrocytes contain actin binding protein
  
  • spectrin
  • network forms a cortical cytoskel
  • spectrin actin network acts via ankyrin protein 4/1

Question 11

What do erythrocytes and actin interact via?

Answer 11

Spectrin

Question 12

Mutation in cortical cytoskeleton proteins in erythrocytes?

Answer 12

Hereditary spherocytosis

Question 13

Hereditary spherocytosis

Answer 13

Question 14

actin projections and plasma membrane

Answer 14

Question 15

Myosin is what?

Answer 15

SUPERFAMILY of motor proteins

• 20 diff types
• all move along actin filaments via ATP hydrolysis

Question 16

Myosin type in skeletal muscle

Answer 16

Myosin II

• bipolar filaments
• teals associate to form shaft of filament
• heads exposed at both ends
• head neck and tail

Question 17

Myosin head

Answer 17

Question 18

Myosin neck

Answer 18

Question 19

myosin tail

Answer 19

Question 20

What is the name for distance travelled and can it differ (myosin)

Answer 20

step size

more proteins at neck makes a longer neck which can travel further so have a larger step size

Question 21

Actin/myosin mechanism

Answer 21

Question 22

What causes a difference in velocity of actin myosin shortening?

Answer 22

Question 23

myosin moves to what end of actin?

Answer 23

most of myosin will move towards + end of actin

Question 24

Fill in the black bars

Answer 24

Question 25

Myosin contraction in smooth and non-muscle cells

Answer 25

Question 26

Non-muscle cell stable or non stable?

Answer 26

much less stable or organized than muscle fibers

Question 27

Cytokinesis

Answer 27

transient interaction actin/myosin f-actin with myosin II from contractile ring myosin movement shortens ring

Question 28

What myosin is used in vesicular transport?

Answer 28

Myosin V VI I

Question 29

Myosin V transport?

Answer 29

Question 30

Myosin 6/5

Answer 30

Question 31

Myosin I

Answer 31

Question 32

Cell migration

Answer 32

Positive end and a minus end. Growth happens at the + end and break down at the - end which can cause movent

Question 33

What causes Duchenne Muscular dystrophy?

Answer 33

Mutations within Dystrophin gene | (also causes becker muscular dystrophy)

Question 34

Mutation of dystrophin gene

Answer 34

Hundred of mutations * usually connects cytoskeleton to basal lamina * stabilizes membranes * Hundreds of mutations (mostly deletions) * half in frame and half out of frame

Question 35

In frame deletion vs out of frame deletion of dystrophin gene?

Answer 35

IN- Becker muscular dystrophy (milder) smaller protein with partial function OUT- Duchenne Muscular Dystrophy little to no expression of dystrophin

Question 36

What is dystrophins functino in cells? What happens without it?

Answer 36

helps relieve stress with transfer of energy or stress (multi directions) WIthout transfer of energy can cause burst of muscles and death of cells

Question 37

Symptoms of DMD

Answer 37

Progressive muscle wasting confined wheel chair 12 die of respiratory failure around 22