Yep, cellulose is a beta pleated sheet, unlike carbs/sugars, which are alpha helices. We're always ready to breakdown the alpha helices form of sugar, but due to the molecular structure of cellulose, we need help. This is were these enzymes come in from our microbiome. All this also ties into how in Western countries, most folks tend to be unable to breakdown cellulose due to the lack of the specific bacteria in our biome capable of producing this enzyme. However, in African and Asian countries, these bacteria are common place, so these cultures have been able to digest cellulose for ages!