I strongly disagree with your sentiments regarding animal experiments. Having done animal research for all four years of my undergraduate career, one thing that doesn't wait for you is the life of another. Gels can be run at any point in the day typically. When you have a month long animal experiment that requires bi-daily injections of drug candidates, you truly understand just how long animal work takes. Yes running gels can take you to midnight--while you wait on your computer on SDN as the machine does all the "gel running" for you.
Other animal examples:
Measuring changes in weight of the animal or thickness of joints on a daily basis for 40+ mice experiments: Easily over 10 hours a week
Harvesting ex vivo cells (e.g. neutrophils): Injection of stimulant = Wait 4 to 16 hours. Harvest cells and use before they undergo apoptosis: Easily surpasses 8 hours depending on the experiment
Harvesting biological samples (e.g. spleens, liver, serum) at the end of your experiment: Can be 4-5 hours of continuous work.
I don't think Holmwood was suggesting mice work requires less time than yeast or bacterial bench work. OP likely isn't going to be harvesting primary cells and then using them for experiments. OP isn't going to have an independent project, unless the PI really has that much faith in him/her. If OP is just maintaining or genotyping mice lines, then it would be less of a commitment. OP's mentor will split up the work amongst other undergrads as well. Perhaps what Holmwood was getting at is that blots are multi-day processes that make you come in at different times. Again, it depends on the nature of the work.
Point being, OP's mentor will allot an appropriate amount of work based on OP's schedule. OP won't responsibly accept a position that requires him/her to work during class hours, and hopefully, nor will he be asked to do so.
To OP, I would initially avoid animal model work. You are likely going to get marginal academic growth relative to other model organisms, simply because it takes too much time. I think your time would be better spent working in labs that use bacteria, yeast, flies, nematodes or even plants if your major is molecular biology related (biochem, cell bio, genetics, etc). If you are interested in physiology, I would look into cell culture work--cells harvested from their native environment and cultured on plastic. Animal work is for
in vivo verification of
in vitro work, having a more relevant model as far as biomedical applications are concerned, or if your hypothesis is not easily testable
in vitro.
Again, I wouldn't recommend animal work over other systems of study, though I am sure Joeshie can highlight aspects which may appeal to you OP.