Clearing pixel from texture changes the asset as well?

My code creates a sprite texture from a asset. It then clears the bottom pixel of that sprite. That works fine, but what I don't get is that the actual itself that I created the sprite from also has a cleared pixel, and until I reset Unity it stays that way. So why/how is that happening? here's a screen shot Unity to show you what I mean.

And here's the code I'm using that does that.

 backSprite = Resources.Load(assetName, typeof(Sprite)) as Sprite;
         
         //Create a new gameobject
         obj = new GameObject("RedSquare");
         
         //Attach a SpriteRenender to the newly created gameobject
         SpriteRenderer rend = obj.AddComponent(typeof(SpriteRenderer)) as SpriteRenderer;
         
         //obj.transform.position = new Vector2 (0, 0);
         
         //Assign the sprite to the SpriteRenender
         rend.sprite = backSprite;
         
         increment = 0;
         speed = 4;
         
         startPoint = transform.position;
         endPoint = transform.position;
         
         myTexture = backSprite.texture;
 
         MyPixel = myTexture.GetPixel(0,0);
 
         myTexture.SetPixel (0, 0, Color.clear);
 
         myTexture.Apply ();