Study Guide
Chapter 6
A Tour of the Cell
Key Concepts
6.1 To study cells, biologists use microscopes and the tool of biochemistry.
6.2 Eukaryotic cells have internal membranes that compartmentalize their functions.
6.3 The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by
the ribosomes.
6.4 The endomembrane system regulates protein traffic and performs metabolic functions
in the cell.
6.5 Mitochondria and chloroplasts change energy from one form to another.
6.6 The cytoskeleton is a network of fibers that organizes structures and activities in the
cell.
Questions
Interactive Question 6.1
a) Define cytology: the study of cell structure
b) What do cell biologists use a TEM to study? the internal ultrastructure of cells
c) What does an SEM show best? the three-dimensional surface topography of a
specimen
d) What advantages does light microscopy have over TEM and SEM? Light
microscopy enables study of living cells and may introduce fewer artifacts than to
TEM and SEM
Interactive Question 6.2
a) If a eukaryotic cell has a diameter that is 10 times that of a bacterial cell,
proportionally how much more surface area would the eukaryotic cell have? 102,
or 100 times the surface area
b) Proportionally how much ore volume would it have? 103, or 1000 times the
volume
Interactive Question 6.3
How does the nucleus control protein synthesis in the cytoplasm?
The genetic instructions for specific proteins are transcribed from DNA into messenger
RNA (mRNA), which then passes into the cytoplasm to complex with ribosomes where it
is translated into the primary structure of proteins.
Interactive Question 6.4
Name the components of the endomembrane system shown in this diagram and review
the functions of each of these membranes.
a) Smooth ER: synthesize lipids; detoxifies drugs, alcohol; stores calcium ions
b) Nuclear Envelope: Double membrane encloses the nucleus with pores
c) Rough ER: attached ribosomes where proteins are produced
d)
e)
f)
g)
Transport Vesicles: carries products to various parts of the wall
Golgi Apparatus: Processes products from the ER
Plasma Membrane
Lysosomes: Digests molecules with hydrolytic enzymes
Interactive Question 6.5
Sketch a mitochondrion and a chloroplast and label their membranes and compartments.
Mitochondria:
Chloroplast:
Interactive Question 6.6
Why are peroxisomes not considered part of the endomembrane system?
They do not bud from the endomembrane system. They grow by incorporating proteins
and lipids from the cytosol. They increase in number by dividing.
Interactive Question 6.7
Fill in the following table to organize what you have learned about the components of the
cytoskeleton. You may wish to refer to the textbook for additional details.
Cytoskeleton
Microtubules
Structure and Monomers
a. Hollow tube, formed
from columns of tubulin
dimers.
Microfilaments
(actin filaments)
c. Two twisted chains of
actin molecules.
Intermediate filaments
e. Supercoiled fibrous
proteins of keratin family
Functions
b. Cell shape and support
tracks fro moving
organelles, chromosome
movement, beating cilia and
flagella. (25 nm diameter)
d. Muscle contraction,
maintain (tension bearing)
and change cell shape,
pseudopod movement,
beating of cilia and flagella.
(7 nm diameter)
f. Reinforce cell shape,
anchors the nucleus. (8-12
nm diameter)
Interactive Question 6.8
Sketch two adjacent plant cells, and show the location of the primary and secondary cell
walls and the middle lamella.
Interactive Question 6.9
Return to your sketch of plant cells in Interactive Question 6.8 and draw in a
plasmodesma.
Structure Your Knowledge
1. The table below lists the general functions performed by an animal cell. List the
cellular structures associated with each of these functions.
Functions
Cell Division
Information storage and transferal
Energy conversions
Manufacture of membranes and products
Lipid synthesis, drug detoxification
Digestion, recycling
Conversion of H2O2 to water
Structural integrity
Movement
Exchange with environment
Cell to cell connections
Associated Organelles and Structures
a. nucleus, chromosomes, centrioles,
micro-tubules (spindle), microfilaments
(actin-myosin aggregates pinch apart cell)
b. nucleus, chromosome, DNA mRNA
ribosomesenzymes and other proteins
c. Mitochondria
d. Ribosomes, rough and smooth ER, Golgi
apparatus, vesicles
e. smooth ER (peroxisomes also detoxify
substances)
f. lysosomes, food vacuoles
g. peroxisomes
h. cytoskeleton: microtubules,
microfilaments, intermediate filaments;
extracellular matrix
i. cilia and flagella (microtubules),
microfilaments (actin) in muscles and
pseudopodia
j. plasma membrane, vesicles
k. desmosomes, tight and gap junctions
2. This table lists structures that are found in plant cells. Fill in the functions of these
structures.
Plant Cell Structures
Cell Wall
Central Vacuole
Chloroplast
Amyoplast
Plasmadesmata
Functions
a. structural support, middle lamella glues
cells together
b. storage, waste disposal, protection,
growth
c. photosynthesis, production of
carbohydrates
d. starch storage
e. cytoplasmic connections between cells
3. Label the indicated structures in this diagram of an animal cell.
a. rough endoplasmic reticulum
b. smooth endoplasmic reticulum
c. chromatin
d. nucleolus
e. nuclear envelope
f.
g.
h.
i.
j.
k.
l.
m.
n.
o.
p.
q.
r.
s.
nucleus
ribosomes
Golgi apparatus
plasma membrane
mitochondrion
lysosome
cytoskeleton
microtubules
intermediate filaments
microfilaments
microvilli
peroxisomes
centrosome (contains a pair of centrioles)
flagellum
4. Create a diagram or flow chart in the space below to trace the development of a
secretory product (such as a digestive enzyme) from the DNA code to its export
from the cell.
DNA  (transcription of gene) mRNA (moves into cytosol and complexes
with) RIBOSOME (becomes attached to) ROUGH ER (mRNA translated
into polypeptide; polypeptide moves into cisternal space; may be bonded to
carbohydrate to form glycoprotein) TRANSPORT VESICLES pinch off and join
cis face of GOLGI APPARATUS polypeptide may be modifiedTRANSPORT
VESICLES from trans face leave and fuse with  PLASMA MEMBRANE
Multiple Choice
1. c) mitochondria (page 98)
2. b) the sharpness or clarity of an image (page 95)
3. d) they are derived from the endoplasmic reticulum system (page 104)
4. e) all of the above (page 102)
5. a) transmission electron microscopy (page 96)
6. d) lysosome—food sac formed by phagocytosis (page 107)
7. a) protein (page 112)
8. c) taking up water into its central vacuole (page 108)
9. b) secondary cell wall (page 118)
10. d) actin filaments (page 116)
11. e) the pinching apart of the cytoplasm in animal cell division (page 114)
12. b) rough ERtransport vesiclesGolgivesiclesplasma membrane (page 104)
13. b) by free ribosomes (page 98)
14. c) gap junctions (page 120)
15. e) nuclei (page 97)
16. d) epithelial cell lining digestive tract (page 120)
17. c) macrophage (white blood cell) that engulfs bacteria (page 107)
18. e) ovarian cell that produces estrogen (a steroid hormone) (page 104)
19. b) pancreatic cell that manufactures digestive enzymes (page 102)
20. a) muscle cell in the thigh muscle of a long-distance runner (page 109)
Fill in the Blanks
1)
2)
3)
4)
transports membranes and products to various locations: transport vesicle
infoldings of the inner mitochondrial membrane with attached enzymes: cristae
consists of collagen, proteoglycans, and fibronectins: ECM
specialized metabolic compartments with enzymes that transfer hydrogen to
oxygen, producing H2O2: peroxisomes
5) stacks of flattened sacs inside chloroplasts: grana
6) anchoring structure for cilia and flagella: basal body
7) semifluid medium between nucleus and plasma membrane: cytosol
8) system of fibers that maintains cell shape, anchors organelles: cytoskeleton
9) connection between animal cells that creates impermeable layer: tight junction
10) membrane surrounding central vacuole of plant cells: tonoplast