Concept 4.1 Cells Provide Compartments for Biochemical Reactions
Cell size
Working in pairs, consider two cubes, one with a side that is 1 mm long
and the other with a side that is 6 mm long. For each cube calculate:
1. Surface area (= height × width × number of sides)
2. Volume (= height × width × length)
3. Surface area-to-volume ratio (= surface area:volume)
What pattern do you observe as the size of the cube increases?
What inferences can you make regarding cell size?
Take a few minutes to discuss, and then present your conclusions to
the class.
Concept 4.1 Cells Provide Compartments for Biochemical Reactions
The plasma membrane
a. acts as a selectively permeable barrier.
b. consists of a phospholipid bilayer and proteins.
c. functions in communication between cells.
d. contributes to cell shape.
e. All of the above
Concept 4.2 Prokaryotic Cells Do Not Have a Nucleus
Prokaryotic cells
Working individually, draw a prokaryotic cell and label the
following structures and components:
• Plasma membrane
• Nucleoid
• DNA
• Cytoplasm
• Ribosomes
• Cell wall
Then compare your drawing with that of a classmate.
Concept 4.2 Prokaryotic Cells Do Not Have a Nucleus
Prokaryotic cells can have all of the following except
a. flagella.
b. internal membranes.
c. a nucleus.
d. a cytoskeleton.
e. a cell wall.
Concept 4.3 Eukaryotic Cells Have a Nucleus and Other Membrane-Bound
Compartments
Comparing animal and plant cells
Working in pairs, compare and contrast animal and plant
cells.
First, draw a representative animal cell with the following
structures: nucleus, mitochondrion, rough endoplasmic
reticulum, smooth endoplasmic reticulum, Golgi
apparatus, and plasma membrane. As you draw each
structure, discuss its function.
Then draw a representative plant cell with these additional
structures: cell wall, vacuole, and chloroplast. Discuss
the functions of these structures.
Concept 4.3 Eukaryotic Cells Have a Nucleus and Other Membrane-Bound
Compartments
Cell structure reflects cell function. Using your knowledge
of the functions of particular organelles, select the
incorrect match of a type of cell and the organelle that
you might expect to be particularly abundant in that cell:
a. Pancreatic cell that secretes a digestive enzyme:
Rough endoplasmic reticulum
b. Mammalian skin cell: Central vacuole
c. Skeletal muscle cell: Mitochondria
d. Liver cell that modifies toxins: Smooth endoplasmic
reticulum
e. Leaf cell: Chloroplasts
Concept 4.4 The Cytoskeleton Provides Strength and Movement
The cytoskeleton
Working individually, characterize microfilaments,
intermediate filaments, and microtubules with respect to:
• Protein component(s)
• Major functions
• Presence of dynamic instability
Then discuss your characterizations with those of your
classmates.
Concept 4.4 The Cytoskeleton Provides Strength and Movement
Which of the following statements about cilia and flagella is
false?
a. Intermediate filaments form the interior skeleton for
cilia and flagella.
b. Cilia can either move a cell or move fluid over a
stationary cell.
c. Cilia typically outnumber flagella on a cell.
d. Motor proteins drive the motion of cilia and flagella.
e. Cilia and flagella have a 9 + 2 arrangement of
microtubules.
Concept 4.5 Extracellular Structures Allow Cells to Communicate with the External
Environment
Junctions between animal cells
Working in pairs, discuss tight junctions, desmosomes, and gap
junctions. Then determine which type of junction would most likely
be found in the following locations in the human body:
1. Epithelial lining of the urinary bladder (functions to prevent urine
from leaking out into the body)
2. Skin
3. Epithelial lining of the stomach (functions to prevent stomach
contents from leaking out into the body)
4. Cardiac muscle (the rapid spread of electric current mediated by
ions is critical for cardiac muscle cells to beat in unison)
Finally, which type of junction in animal cells is most similar to the
plasmodesmata of plant cells?
Present your answers to the class.
Concept 4.5 Extracellular Structures Allow Cells to Communicate with the External
Environment
The extracellular matrices of animal cells
a. contain the fibrous protein collagen.
b. contain the polysaccharide cellulose.
c. interact with cell membrane proteins to regulate cell
attachment.
d. contain proteoglycans in a gel-like matrix.
e. a, c, and d