Learn Before Lecture (LBL) 1 Worksheet:
Nucleus and Ribosomes (~20 min)
Type your answers in the boxes provided and save as a PDF. Upload your assignment as a PDF to your
EEE Dropbox before 9 am on Mon. Take the Lecture 4 online quiz (this material will be on the quiz!).
The nucleus is a membrane bound structure that contains the genetic library in all eukaryotic cells. Read pages
102-103, examine Figure 6.9 and answer the following questions.
1. What is chromatin?
2. What specific process takes place in the
nucleolus, a specialized region within the nucleus?
3. What structure allows proteins and other large
macromolecules to move into and out of the nucleus?
Ribosomes are the organelles involved in the synthesis of all proteins. Ribosomes are made of two subunits, one
large and one small (see fig. 6.10). These are found separately in the cytoplasm and they only combine when
mRNA binds to the small subunit. After mRNA binds, the large subunit binds and protein synthesis begins. Read
the short section on ribosomes, pg 102-103, to find out where ribosomes go to finish protein synthesis, and
answer the following questions.
4. Synthesis of all proteins begins first on free ribosomes
(True or False).
5. If synthesis of a protein is completed by a free ribosome,
where in the cell will the protein function?
6. If a protein is going to be secreted where will protein
synthesis be completed?
7. To understand how secreted proteins are synthesized look
carefully at Figure 17.22 in your text. In your own words, write
6 statements that describe each step shown in the process of
a ribosome that is making a secreted protein.
1.
2.
3.
4.
5.
6.