Equivalent to home and end keys and spell-check question
Home is function-left arrow, end is function-right arrow. The commands to move to the visible top or bottom are vo-home and vo-end, respectively; add shift to move to the top or bottom, regardless of visibility on screen. I usually use the latter, with the shift key.
Putting that together, you get a rather awkward keystroke: beginning is ctrl-option-function-shift-left arrow, and end is ctrl-option-function-shift-right arrow. Again, you can leave off shift, but that may not always do what you want. Remember, too, to interact with the item whose beginning or end you want to jump to, as these commands act on whichever object VoiceOver is interacting with at the moment.
If you want, you can assign these to commanders to make life easier. Personally, I use control with a two-finger flick down for end, and up for home, but you can use whatever you want to. The relevant commands should be in the "navigation" submenu of VoiceOver commands when you are assigning them.