Cellulose is made up of

Unbranched chain of glucose molecules linked by $\alpha ,1\to 4$glycosidic bond

Unbranched chain of glucose molecules linked by $\beta ,1\to 4$ glycosidic bond

Branched chain of glucose molecule linked by $\alpha ,1\to 6$ glycosidic bond in straight chain and $\beta ,1\to 4$ at the site of branching

Branched chains have both $\alpha -1$ bond and $\beta ,1-4$ glycosidic bonds