I have a mid-2009 Macbook Pro 17" 500GB, and I am trying to replace the HD with a larger 2TB HD. The main reason for doing so is so I will have more room for all my projects, and also so I will finally be able to upgrade to Yosemite. Right now my HD does not have enough room to upgrade. So, I bought a 2.5" 2TB HD, and I am having difficulties trying to make the new HD a startup disc, so I can boot from it. I have looked up how to "install a new HD on a Macbook Pro" on Youtube, but all those videos only show you how to physically install the hardware. I can't find any info on how to load the OS onto the new HD so I can boot from it after I install it internally. I've tried the TimeMachine way as well. All that did was put all my files on it, but I still can't boot from it. It just seems that this should be a very easy thing to do, but I can't seem to figure it out. What am I missing here? Anybody out there can help me? Please do! Thank you in advance!