If you can take this class with a different professor, I would urge you to do so. While its definitely not the worse class I've ever taken, there is most certainly a lot of room for improvement.
Her lectures are often short, and she mainly reads off of the slides. The notes that she does jot down are typically illegible, so make sure you are listening closely to catch her saying what she is writing. You will want to write down pretty much any extra info she says. The weekly worksheets are sometimes helpful for preparing for her exams, however, the lecture slides and your notes are definitely what you want to be studying.
Her exams are hard. Start studying a week in advance so it does not snowball because there is so much content to know. The way she words the questions on her exams is often confusing, so read carefully and take advantage of her question asking time that she gives on exam day.
She also does not respond to emails, so if you need to ask a question about grades or content, go to office hours.

Class was ridiculously easy but I still feel like I didn't learn anything useful.

This class with Jarrett is terrible. Easy, but terrible. For starters, she is an awful lecturer. She goes through her lecture slides in an extremely robotic manner that has no rhyme or reason. She rarely explains things on her slides, it's kinda like she has a script she just goes through. One particular thing that drove me crazy was her use of the same 3 phrases about 40 times in a 50 minute lecture. It really just shows that she doesn't really know what she's doing when it comes to lecturing. Honestly, the only way I managed to get good grades on the exams was by attending the remote lecture, then rewatching the recorded lecture the same day and taking notes on what she says WORD FOR WORD. But if the exams weren't open note I wouldn't have done nearly so well. That being said, she does supply a lot of EC so you could get by with B's on all the exams and still get an A. It's an easy class, but it's frustrating. Maybe try another professor if you're an actual biochem major.

The material can be difficult to memorize since it is very dense. However, the professor really tries her best to explain everything in easier terms. I took the class online so I really benefited from the recorded lectures since I was able to re-watch them until I understood the topic throughly. The grading was based only on three exams. There were no homework assignments but there were supplemental exercises if you need to work through more problems for practice. She offers extra credit which helps take some of the weight off exams grades. The exams are not necessarily cumulative but sometimes topics overlap. She also gives you practice tests that are very similar to problems on the actual exam. We met 4 times a week, the first day we briefly discussed the topics that would be covered over the week and the last day we reviewed those topics and did practice problems together. Overall, she really does hope the best for her students and is very passionate about teaching. You will be very lucky if you have her for this course as the other professors (from what I've heard) are not as great.

Overall, Dr. Jarrett is very sweet and accommodating, but may not be the best lecturer. If you *need* to learn the material well for this class (i.e. if you're a Chem major or something of the sort that requires you to use this foundational knowledge), and don't want to rely on solely self-studying, I would say consider taking this class with another professor. On the other hand, if you're not super interested in Biochemistry and want a manageable workload/exams, take Jarrett!

Her exams are very content-based and taken primarily from her slides, so make sure to take notes on them.

I honestly really enjoyed this class. I feel like I learned biochem and content actually felt applicable. I took a few weeks of Chem 153A in Spring with Kat Ellis Guardiola but I had to drop because that class was so bad. In comparison, and overall, Jarrett's class is pretty clear and straightforward. She always started class on time, ended on time (or before the 50-min mark), uploaded recordings within 2 hours after finishing, posted class materials at the beginning of every week, returned quiz/exam scores within the week, etc. A complete 180 from her past quarters based on other reviews here. It made the class easy to navigate in the logistical sense.
First lecture of the week is always an introduction/overview of the content of the week; last lecture of the week consists of a quick 5-10 minute content review plus 5 or 6 practice problems. The lectures in between were an in-depth explanation of the content. Every lecture had a poll question at the end for participation grade (based on completion). Jarrett teaches reading off a script, but since the script makes sense I honestly can't complain.
For summer there were 5 weekly quizzes, 20 points each (4 questions over 30 minutes). The questions were easy though sometimes slightly specific.
Exams (midterm 100 points, 1.5 hrs; final 150 points,3 hrs) were kinda long but fair, though a couple of the questions on the final were, again, weirdly specific.
There was one activity worth 20 points. She gives you an extremely helpful guide on how to complete it though, so don't sweat it.
On top of the 400 points she also gave 10 extra credit points (first 5 were very easy to score; last 5 were from an extra credit question on quiz 5) that really help take the edge off of exams.
Overall I liked how cut and dry this class was. There was a lot -- a LOT -- of content but it's doable. I would recommend this class!