Download Chapter 4: A Tour of the Cell

Chapter 4: A Tour of the Cell
Name: ____________________________
1. How many cells are in your body?
Trillions of cells
2. How many red blood cells does your body produce every second?
2 million
3. Are the cells in a whale or a mouse bigger?
About the same size
4. We talked about scanning electron microscopes (SEM) in class briefly. Transmission
electron microscopes (TEM) are another type of very powerful microscopes. What are
they used for, and how many times is the TEM in the book magnified? (Figure 4.2)
60,000X
5. Did prokaryotic or eukaryotic cells appear on Earth first?
Prokaryotic cells
6. How does DNA control the cell (if it remains in the nucleus)?
Through the production of proteins based on the DNA code
7. Which organelles belong to the endomembrane system?
The endoplasmic reticulum (smooth and rough), the golgi apparatus, lysosomes, and
vacuoles
8. What chemical reaction takes place in the chloroplasts?
photosynthesis
9. What chemical reaction takes place in the mitochondria?
Mitochondria
10. What three types of fibers make up the cytoskeleton? Name the building blocks that
make up each type.
Microfilaments (actin)
Intermediate filaments (fibrous proteins)
Microtubules (tubulins)
11. What is the function of cilia and flagella?
Cell movement
12. What are cell junctions and plasmodesmata?
Cell junctions are structures which connect cells to one another. Plasmodesmata are
channels in the plant cell walls which allow materials to pass from the cytoplasm of
neighboring cells.
13. What is the extracellular matrix?
A sticky coat which holds cells together in tissues.
14. Sketch a phospholipid molecule. Label the phosphate head and lipid tails.
See figure 4.22a
15. Sketch figure 4.22 with labels.
16. What do we mean by the fluid mosaic model of the cell membrane?
“Fluid in the membrane’s molecular wanderings and mosaic in the diversity of proteins
that float like icebergs in the sea of phospholipids.”
17. Define the following:
a. selectively permeable
the membrane allows some substances to cross more easily than others and blocks the
passage of some substances altogether.
b. transport proteins
Specialized proteins which allow some substances to pass through the membrane which
cannot pass through the cell membrane.
c. active transport
A mode of transport which requires the cell to expend energy.
d. exocytosis
A vesicle containing the secretory contents of a cell fuses with the cell membrane and the
contents of the vesicle are spilled outside of the cell.
e. endocytosis
material is taken into the cell within vesicles that bud inward from the plasma membrane.
f. phagocytosis
A cell engulfs a particle and packages it within a food vacuole.
g. pinocytosis
the cell gulps droplets of fluid by forming tiny vesicles.