Mary,, The annswer is the Dominant 13 (add 11 and 9. For example in the key of G:
GBD are the 1,3,5 of the chord if G is the root (I)
F is the flatted seventh that spells out the dominant seventh.
A is the ninth.
C is the eleventh (4 + (b)7th.
E is the thirteenth.
Hence, within that chord you have GBD (tonic)
NOw here's how it has to work. You have to be in the key of C. G is the dominant chord.
GBD is the V chord. FAC is the IV chord. DFA is the II (minor chord) CEG the I chord is the top part of the sequence (called a chord family). It's the 11th, 13th and the root of the chord found in the next octave.
It can be diagrammed like this.
1,3,5,(b)7,9,11,13 and the repeat of 1 in the next octave.
135 in the key of C if G is the root is the V chord. (GBD)
5,(b)7,9 is the II chord DFA
(b)7,9,11 is the IV chord (FAC)
11,13 and the 1 (root in the next octave) is the I chord (CEG)
The question is how are you going to apply this information?
Dick Grove's jazz arrangement classes use the method of chord families to derive triads (three-note chords) out of one big long chord such as G13 (add 11 and 9).
This is more information than you probably wanted to know but hope it helps.