How hard is it for a CS undergrad to switch to computational biology? I have no biology background (I studied in India where nobody can study biology and computer science together). How can I pursue computational biology in grad school?

Get into a good university where u have both ... You must be signed in to read this answer.Connected to GoogleConnected to FacebookBy continuing you indicate that you have read and agree to the .  Loading account...Complete Your ProfileFull NameChecking...EmailChecking...PasswordChecking...By creating an account you indicate that you have read and agree to the .

First of all, I would like to clarify one thing that It is POSSIBLE to study Biology and Computer Science TOGETHER at BITS Pilani, INDIA. Coming to your question, http://www.nature.com/nbt/journal/v31/n11/full/nbt.2740.html I personally think (and the above link also says alike “Knowledge of biology is vital in the interpretation of computational results.”) that at least basic biology is necessary to start with computational biology, if not in-depth study. Though there are some sub-topics like  https://en.wikipedia.org/wiki/Biomedical_text_mining ( you can check http://www.sciencedirect.com/science/article/pii/S0167779906002423 and further references), Gene function prediction (http://www.ncbi.nlm.nih.gov/pubmed/14534170), and others along the same lines which basically requires knowledge of Machine Learning (text mining, data mining), others like https://en.wikipedia.org/wiki/Protein%E2%80%93protein_interaction prediction, https://en.wikipedia.org/wiki/Computational_genomics requires much more knowledge of biology. Yes, there is a requirement of Statistics, Algorithms, etc. which you study in Computer Science in Computational Biology, and if you show some projects which uses these in the field of Biology, I am sure you pass the basic eligibility criteria, for example http://qb3.berkeley.edu/ccb/research-education/phd-in-computational-biology/. So, what you need to do is projects related to Biological Data, may be this will get you doing a PhD in Computational Biology.