// Private Methods

    private void OnClick()
    {
        if (cell == null)
        {
            switch (upgradeNumber)
            {
            case 1: upgradeHandler.InflammationUpgrade(); break;

            case 2: upgradeHandler.VaccineUpgrade(); break;

            case 3: upgradeHandler.AntibioticUpgrade(); break;
            }
            return;
        }
        BuyCell();
    }