Cell Structure and Function

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1. Which of the following organelles is most important in providing energy to the cell?
(a) mitochondrion
(b) centrosome
(c) Nucleus
(d) Peroxisome

2. Name the membrane valves that open and close for potassium efflux and sodium influx.
(a)ion channels
(b)Vacuoles
(c)Capillaries

3. What technique can be used to measure cell activity like a change in membrane potential?
(a) ion channel
(b) Apoptosis
(c) patch clamp

4. When a sodium channel opens and sodium rushes into a myocyte (heart cell), the cell membrane becomes...
(a) Polarized
(b) Depolarized
(c) Paralyzed

5. What role(s) does the cytoskeleton play in a living cell? (Hint: CHECK ONLY ONE ANSWER)
(a) maintaining cell shape
(b) movement
(c) contraction
(d) all of these

6. Name the violent membrane blebbing exhibited by a cell undergoing apoptosis.
(a) Fission
(b) Zeiosis
(c) Necrosis
(d) apoptotic cells do not bleb

7. The animal cell centriole is a ring of how many groups of microtubules?
(a) 9
(b) 12
(c) 36

8. Which is SMALLEST of these four?
(a) bacterium
(b) red blood cell
(c) virus
(d) lymphocyte

9. In what stage of mitosis do all chromosomes align in one plane?
(a) anaphase
(b) telophase
(c) prophase
(d) metaphase

10. A cell in interphase is sometimes said to be resting. Why is this misleading?
(a) interphase cells are actively dividing
(b) interphase cells are synthesizing RNA and proteins, and growing in size

Answer Grid: 1.(a); 2.(a); 3.(c); 4.(a); 5. (d); 6. (b); 7.(a); 8.(c); 9. (d); 10.(b)

Tutorial for Quiz Questions:

Question 1: Ion Channels

When Ions Rush In

Heart cell rhythm depends on the opening and closing of a complex series of valves on the cell membrane, called ion channels. Some valves let certain ions like potassium (K+) flow out, others let different ions like sodium (Na+) flow in. There are also pumps that actively move ions one direction or another.

The number of K+ ions is greater inside a resting cell than outside. But the number of Na+ ions is greater outside. When a heart cell beats, sodium channels open allowing a rapid, transient in-rush of Na+ ions, then close within about two one-thousandth's (2/1000) of a second. This depolarizes the membrane with the positive ions moving in. Then there is a slower, but prolonged (1/2 second), release of potassium to the outside of the cell which repolarizes the cell membrane.

The beat is actually much more complex and involves other ions. But the end result of this depolarization-repolarization is that the contractile filaments in the cell engage, and the cell contracts.

Question 2: The Patch Clamp

Making Single Cell Pipets ...