Adding commands from Update function to a UI button.

I have a jump command in my Update function that makes the player jump. Right now I’m making the player jump using the space key. But I want it to jump using a UI button. Please advice!
Here’s the code.
Thank You!

      private Rigidbody2D rb;
	public float power = 200f;
	public bool jump;


	void Start () {;

		rb = GetComponent<Rigidbody2D> ();	

		jump = true;
	}

	void Update () {

			if (jump) {
				if (Input.GetKeyDown (KeyCode.Space)) {
					
					rb.velocity = Vector2.zero;
					rb.AddForce (new Vector2 (0, power));
					

				}

			} 

	}
		

	void OnCollisionEnter2D(Collision2D col){
	
		if (col.gameObject.tag == "Ground") {
		
			jump = true;
		
		}
	}


	void OnCollisionExit2D(Collision2D col2){
		if (col2.gameObject.tag == "Ground") {
		
			jump = false;

		} 
}

}

Make your UI Button’s onClick function call this:

   void Jump(){
      if (jump){
        rb.velocity = Vector2.zero;
        rb.AddForce (new Vector2 (0, power));
      }
    }