how to select and deselect all options in a select box

<select name="remaintextarea" id="studentremain" size="10">
    <option value="one">One</option>
    <option value="two">Two</option>
    <option value="three">Three</option>
</select>

<button type='button' id='selectall'>Select All</button>
<button type='button' id='deselectall'>De-Select All</button>

Got a select box above, select all and de-select all buttons above. My question is by using jquery, how can I get the button to select all the options and deselect all the options in the select box above when the relevant buttons are clicked on?

Below I just have the click handlers for both buttons:

$('#selectall').click(function() {

});   

$('#deselectall').click(function() {

});