Append where clause in to SQL statement without IF..ELSE ?

Hi,

I have SQL Statement like this.

CREATE PROCEDURE [dbo].[GetRecords] @option AS BIT = NULL
AS
BEGIN
	IF @option = '1'
	BEGIN
		SELECT *
		FROM testTable
		WHERE column1 IS NOT NULL AND Column2 IS NOT NULL AND Column3 IS NOT NULL
	END
	ELSE
	BEGIN
		SELECT *
		FROM testTable
		WHERE column1 IS NOT NULL
	END
END

Please help me to write in to single statement with out IF... ELSE

Thank you.