Topic 6- Contraction of muscles

Question 1

What model is used to explain muscle contraction?

Answer 1

Sliding fillament model

Question 2

The thick filaments within a myofibril are made up of myosin molecules: What type of protein are they and what kind of head do they have?

Answer 2

-Fibarous proteins
-Globular head

Question 3

What is the function of the fibarous part of the mysoin molecule?

Answer 3

• anchors the molecule into the thick filament

Question 4

In the thick filament, many myosin molecules lie next to each other with their globular heads all pointing 1.____ from the 2.___line

Answer 4

1. away
   2.M

Question 5

What type of proteins are Actin?

Answer 5

Globular

Question 6

How is one thin filament formed?

Answer 6

-Many actin molecules link together to form a chain
-Two actin chains twist together

Question 7

What type of protein is Tropomyosin?

Answer 7

Fibourous

Question 8

What is tropomyosin?

Answer 8

protein that is twisted around the two actin chains

Question 9

What protein is attached to the actin chains at regular intervals?

Answer 9

Troponin

Question 10

Explain what happens during muscle contration (according to SFT) using sacromeres and Z lines?

Answer 10

sarcomeres within myofibrils shorten as the Z discs are pulled closer together

Question 11

What is the 1st step in muscle contraction?

Answer 11

An action potential arrives at the neuromuscular junction

Question 12

What is a neuromuscular junction?

Answer 12

Interspace between effector and motor neurons

Question 13

What is the 2nd step in muscle contraction?

Answer 13

Calcium ions are released from the sarcoplasmic reticulum (SR)

Question 14

What is the 3rd step in muscle contraction?

Answer 14

This causes troponin and tropomyosin proteins to change position on the actin (thin) filaments

Question 15

What is the 4th step in muscle contraction?

Answer 15

Myosin binding sites are exposed on the actin molecules

Question 16

What is the 5th step in muscle contraction?

Answer 16

The globular heads of the myosin molecules bind with these sites, forming cross-bridges between the two types of filament

Question 17

What is the 6the step in muscle contraction?

Answer 17

The formation of the cross-bridges causes the myosin heads to spontaneously bend (releasing ADP and inorganic phosphate),
-pulling the actin filaments towards the centre of the sarcomere and causing the muscle to contract a very small distance