Download Ch 7.3 review Short Answer

Ch 7.3 review
Short Answer
Limit your answers to no more than 150 words. Answers must be typed and written in complete sentences with
correct spelling and grammar. Include a word count with your answer.
Complete questions 7-12.
For many years, scientists thought of the nucleus as "a bag of chromatin floating in a sea of cytoplasm." Using
electron microscopes, scientists saw that the nucleus was much more complex. The nuclear envelope was two
layered and covered with pores.
Scientists began further research. Scientist S punched small holes in the nuclear envelope, allowing the
contents to pour out. He observed that the nucleus retained its spherical shape. From this, scientist S
hypothesized that the nucleus had some other structural framework, beyond the membrane itself. The next
experiment performed by scientist S revealed that the nucleus indeed had a fibrous protein framework, now
called the nuclear matrix.
Three other scientists repeated this experiment, but each changed one part of it. Scientist X used
detergents and salt to remove the nuclear contents. Scientist Y used chemicals, and scientist Z used enzymes.
All three observed that a nuclear matrix remained.
Further electron microscopy revealed that the chromatin strands were anchored to a fibrous layer that lines the
inner layer of the nuclear envelope.
1. Describe a procedure to determine whether the attachment of the chromatin to the nuclear envelope is
necessary for the chromatin to become chromosomes.
2. Why did scientists X, Y, and Z use different substances to remove the nuclear contents?
3. What was the variable in the experiments by scientists X, Y, and Z?
4. Why did scientists X, Y, and Z carry out their experiments?
5. What observation from scientist S's second experiment supported the original hypothesis?
6. What was the hypothesis of scientist S in his first experiment?
7. What structures are contained in eukaryotic cells that are not present in prokaryotic cells? What is the function
for each of these structures?
8. How do organelles in eukaryotic cells affect the cell’s processes and what does this suggest about processes in
prokaryotic cells?
9. Endoplasmic reticulum can be smooth or rough. What are the differences between the two types of ER?
10. Plant cells have cell walls. Animal cells do not have this structure. Create a hypothesis that might explain
these differences between plant and animal cells.
11. Describe how organelles move within the eukaryotic cell.
12. Folded membranes have important uses in the cell. Describe at least four of these uses.