Chapter 6: A Tour of the Cell
1. State the principles of cell theory. Why are cells considered the fundamental (smallest) units of
life?
All organisms are made of one or more cells. The cell is the smallest unit of life. All cells come from pre-
existing cells. All cells contain DNA and are surrounded by a membrane. Cells are the fundamental unit
of life because they are the smallest structures that can perform all life functions.
2. What are microscopes and what is their function?
Microscopes are tools used to see cells and tiny structures that cannot be seen with the naked eye.
3. Define magnification, resolution, and contrast.
Magnification – how much bigger the image is compared to real size.
Resolution – ability to see two close objects as separate.
Contrast – difference in brightness that makes structures visible.
4. What are the two types of microscopes and how do they differ?
Light microscope (LM) – uses light, lower resolution.
Electron microscope (EM) – uses electrons, much higher resolution.
SEM – shows surface (3D image).
TEM – shows internal structures.
5. What is cell fractionation? How does it help scientists study cells?
A technique that separates cell parts using centrifugation. It helps scientists study specific organelles and
their functions.
6. What features do all cells share?
Plasma membrane, Cytosol, DNA (chromosomes), and Ribosomes.
7. What are the major differences between prokaryotic and eukaryotic cells?
Prokaryotic: No nucleus, DNA in nucleoid, no membrane-bound organelles, and is smaller
Eukaryotic: Has nucleus, has membrane-bound organelles, and is larger
8. The plasma membrane is a?
Selectively permeable barrier
9. Why is the surface area-to-volume ratio important for cells?
As cells get bigger, volume increases faster than surface area. Cells must stay small so materials can move
in and out efficiently.
10. Who has bigger cells: a baby pig or an elephant?
Same size cells. An elephant has more cells, not bigger ones.
11. Label each example below with the cellular component whose function most closely matches:
a. The mayor’s office = Nucleus
b. Industrial zone and oil refinery = Smooth ER
c. UPS/FedEx = Vesicles
d. Wates management = Lysosome
e. Delivery trucks = Transport Vesicles
f. Water tower = Central Vacuole
g. Power plant = Mitochondria
h. Hazardous waste plant = Peroxisome
i. Highways and roads = Cytoskeleton
, 12. What is in the nucleus of a cell?
DNA organized into chromosomes.
13. Describe the purpose and function of nuclear pores and nuclear lamina proteins.
Nuclear pores regulate what enters and leaves nucleus. Nuclear lamina proteins maintain nucleus shape.
14. Where are ribosomal RNAs synthesized?
In the nucleolus.
15. What is the function of a ribosome and where are they found in the cell?
Makes proteins. Found free in cytosol or bound to rough ER.
16. List the components of the endomembrane system.
Nuclear envelope, ER, Golgi apparatus, Lysosomes, Vacuoles, Plasma membrane, and Vesicles
17. How does the rough ER differ from the smooth ER in both structure and function?
Rough ER: Has ribosomes and Makes proteins
Smooth ER: No ribosomes, makes lipids, Detoxifies, and Stores calcium
18. Describe the function of the Golgi apparatus.
Modifies, sorts, and packages proteins and lipids.
19. What are lysosomes, and what role do they play in cellular digestion?
Contain digestive enzymes. Break down food, waste, and old organelles.
20. Compare the types of vacuoles and their functions in different types of cells.
Food vacuole – digestion
Contractile vacuole – pumps water out
Central vacuole (plants) – stores water & maintains pressure
21. Explain the endosymbiont theory. What evidence supports this theory?
Mitochondria and chloroplasts were once free-living bacteria engulfed by early cells.
Evidence: Double membranes, Own DNA, Own ribosomes, and Divide independently
22. Compare the structures and functions of mitochondria and chloroplasts.
Mitochondria – cellular respiration → makes ATP
Chloroplasts – photosynthesis → makes glucose
23. In which kind of cells (plant, animal) do we find mitochondria? In which cells do we find
chloroplasts?
Mitochondria – plant & animal cells
Chloroplasts – plant cells only
24. Peroxisomes perform Oxidative reactions and produce hydrogen peroxide.
25. What is the overall function of the cytoskeleton?
Maintains shape, organizes cells, moves organelles.
26. List the three cytoskeleton structures in order from largest to smallest.
Microtubules → Intermediate filaments → Microfilaments
27. What are microtubules composed of? What are microfilaments composed of?
Microtubules = tubulin
Microfilaments = actin
28. List examples of microtubules and describe their function.
Cilia, Flagella, Centrioles, and Spindle fibers (cell division)
29. What protein is commonly associated with microfilaments as a helper protein?
Myosin
1. State the principles of cell theory. Why are cells considered the fundamental (smallest) units of
life?
All organisms are made of one or more cells. The cell is the smallest unit of life. All cells come from pre-
existing cells. All cells contain DNA and are surrounded by a membrane. Cells are the fundamental unit
of life because they are the smallest structures that can perform all life functions.
2. What are microscopes and what is their function?
Microscopes are tools used to see cells and tiny structures that cannot be seen with the naked eye.
3. Define magnification, resolution, and contrast.
Magnification – how much bigger the image is compared to real size.
Resolution – ability to see two close objects as separate.
Contrast – difference in brightness that makes structures visible.
4. What are the two types of microscopes and how do they differ?
Light microscope (LM) – uses light, lower resolution.
Electron microscope (EM) – uses electrons, much higher resolution.
SEM – shows surface (3D image).
TEM – shows internal structures.
5. What is cell fractionation? How does it help scientists study cells?
A technique that separates cell parts using centrifugation. It helps scientists study specific organelles and
their functions.
6. What features do all cells share?
Plasma membrane, Cytosol, DNA (chromosomes), and Ribosomes.
7. What are the major differences between prokaryotic and eukaryotic cells?
Prokaryotic: No nucleus, DNA in nucleoid, no membrane-bound organelles, and is smaller
Eukaryotic: Has nucleus, has membrane-bound organelles, and is larger
8. The plasma membrane is a?
Selectively permeable barrier
9. Why is the surface area-to-volume ratio important for cells?
As cells get bigger, volume increases faster than surface area. Cells must stay small so materials can move
in and out efficiently.
10. Who has bigger cells: a baby pig or an elephant?
Same size cells. An elephant has more cells, not bigger ones.
11. Label each example below with the cellular component whose function most closely matches:
a. The mayor’s office = Nucleus
b. Industrial zone and oil refinery = Smooth ER
c. UPS/FedEx = Vesicles
d. Wates management = Lysosome
e. Delivery trucks = Transport Vesicles
f. Water tower = Central Vacuole
g. Power plant = Mitochondria
h. Hazardous waste plant = Peroxisome
i. Highways and roads = Cytoskeleton
, 12. What is in the nucleus of a cell?
DNA organized into chromosomes.
13. Describe the purpose and function of nuclear pores and nuclear lamina proteins.
Nuclear pores regulate what enters and leaves nucleus. Nuclear lamina proteins maintain nucleus shape.
14. Where are ribosomal RNAs synthesized?
In the nucleolus.
15. What is the function of a ribosome and where are they found in the cell?
Makes proteins. Found free in cytosol or bound to rough ER.
16. List the components of the endomembrane system.
Nuclear envelope, ER, Golgi apparatus, Lysosomes, Vacuoles, Plasma membrane, and Vesicles
17. How does the rough ER differ from the smooth ER in both structure and function?
Rough ER: Has ribosomes and Makes proteins
Smooth ER: No ribosomes, makes lipids, Detoxifies, and Stores calcium
18. Describe the function of the Golgi apparatus.
Modifies, sorts, and packages proteins and lipids.
19. What are lysosomes, and what role do they play in cellular digestion?
Contain digestive enzymes. Break down food, waste, and old organelles.
20. Compare the types of vacuoles and their functions in different types of cells.
Food vacuole – digestion
Contractile vacuole – pumps water out
Central vacuole (plants) – stores water & maintains pressure
21. Explain the endosymbiont theory. What evidence supports this theory?
Mitochondria and chloroplasts were once free-living bacteria engulfed by early cells.
Evidence: Double membranes, Own DNA, Own ribosomes, and Divide independently
22. Compare the structures and functions of mitochondria and chloroplasts.
Mitochondria – cellular respiration → makes ATP
Chloroplasts – photosynthesis → makes glucose
23. In which kind of cells (plant, animal) do we find mitochondria? In which cells do we find
chloroplasts?
Mitochondria – plant & animal cells
Chloroplasts – plant cells only
24. Peroxisomes perform Oxidative reactions and produce hydrogen peroxide.
25. What is the overall function of the cytoskeleton?
Maintains shape, organizes cells, moves organelles.
26. List the three cytoskeleton structures in order from largest to smallest.
Microtubules → Intermediate filaments → Microfilaments
27. What are microtubules composed of? What are microfilaments composed of?
Microtubules = tubulin
Microfilaments = actin
28. List examples of microtubules and describe their function.
Cilia, Flagella, Centrioles, and Spindle fibers (cell division)
29. What protein is commonly associated with microfilaments as a helper protein?
Myosin
