Actin

Question 1

What are Actin Filaments essential for?

Answer 1

Cell Movement
-required for crawling along surfaces
-muscle contractions
required fro phagocytosis
required for cell divison

Question 2

Interactions with actin-binding proteins allows actin filaments too

Answer 2

adopt a variety of different shapes and helps carry out different functions

Question 3

what is the structure of an actin filament

Answer 3

-thins and flexible protein threads with identical globular actin molecules
-have polarity ( + and - ends)

Question 4

Actin Monomers

Answer 4

A single polypeptide with an N and C terminus and ATP bound
-monomer contains and ATPase enzyme that binds ATP and hydrolyzes is
-> ATP hydrolysis makes a conformational change allowing for growth at the positive end

Question 5

Actin Filaments dynamic instability

Answer 5

Actin filaments grow by added actin monomers to the positive end
-grows by actin monomers having ATP bound to them
When the Actin monomers reaches the filament ATP hydrolyzes to ADP
***which reduced the strength of actin-binding monomers and decreases the stability of actin filaments

Question 6

Treadmilling

Answer 6

Occurs with Actin Filaments
-occurs when ATP-actin adds to the + end of an Actin filament att he same rate that ADP-actin is lost from the minus end.

Occurs at an equal rate and the filament remains the same length

Question 7

Actin Related Proteins

Answer 7

Control the Behavior of Actin Filaments

Question 8

Cell Crawling is Dependant on

Answer 8

Cortical Actin
–Dynamic Instability and Tread-milling allow this action

Question 9

Process of Cell Crawling

Answer 9

1. Cell establishes polarity
2. The cell pushes out membrane protrusions at its “front” or leading edge
3. protrusions adhere to the surface the cell is crawling to
4. rest of the cell drags itself forward by traction

Question 10

Where is the actin Meshwork bound to on the Cortical Actin?

Answer 10

Integrins: A translocated proteins

-Actin meshwork is attached tto these integrins

Question 11

Myosin

Answer 11

Actin dependent motor protein

Question 12

Function of Myosin II

Answer 12

myosin pulls on actin filaments, shortens sarcomeres for muscle contractions

Question 13

Process of muscle contractions

Answer 13

Bundles of myosin-II molecules form a thick filament and travel along a think actin filament.

-myosin move toward the + end which pulls the sarcomere together forming a contracting muscle