Some advice

In my opinion, truly understanding the material in chapter 7 is critical for making sense of the rest of the course.

(It's not a coincidence that we spent two lectures covering chapter 7)

I strongly recommend reading the chapter very thoroughly, and taking extensive notes as you read. I assure you that it is worth your time, even if it takes 12 hours.

Important note on reading the textbook:

I remember a time, long ago, when I used to be excited about textbook chapters that had a lot of pictures, diagrams, figures, and such. It seemed like fewer pages of reading, because I figured I only really needed to pay attention to the actual text part of textbooks. Many of my classmates and I had a sort of selective blindness toward diagrams, pictures, tables, and everything set apart in its own little box. (I'm sure many of you are free of this affliction.)

Eventually I discovered that I had it completely backwards. Understanding the figures is the key to understanding the material. Especially in genetics. The main text in the textbook is also very important because it gives the context and information you need in order to interpret and understand the figures (...the text also holds any important details that they couldn't fit inside the figures or that they couldn't work out how to illustrate).

If you can't explain each figure in your own words, then you aren't done reading yet.

In three words:

Understand the figures!