4
Eukaryotic Microbial Structure and Function
CHAPTER OVERVIEW
This chapter focuses on eukaryotic cell structure and function. Although prokaryotic organisms are immensely
important in microbiology, eukaryotic microorganisms—such as fungi, algae, and protozoa—are also
prominent members of many ecosystems, and some have medical significance as etiological agents of disease
as well. The detailed discussion of eukaryotic microbial structure and function is followed by a comparison of
eukaryotes and prokaryotes. The chapter ends with specific overviews of protist and fungal cell structure and
function.
CHAPTER OBJECTIVES
After reading this chapter you should be able to:
•
•
•
•
•
•
•
•
•
•


identify major eukaryotic cell structures in a drawing or photomicrograph
discuss the various elements of the cytoskeleton (microfilaments, intermediate filaments, microtubules)
with regard to their structure and various functions within the cell
discuss the composition, structure, and function of each of the internal organelles, such as the
endoplasmic reticulum, Golgi apparatus, lysosomes, ribosomes, mitochondria, chloroplasts, nucleus, and
nucleolus
discuss the mechanism of endocytosis and the difference between phagocytosis and pinocytosis
compare mitosis and meiosis
compare and contrast prokaryotes and eukaryotes
discuss the types of locomotion, and specialized organelles of protists
discuss the various morphological characteristics of protists
discuss asexual and sexual reproduction of protists
discuss the various types of nuclei found in protists
discuss the morphological characteristics of fungi
explain the formation of both asexual and sexual spores for reproduction
CHAPTER OUTLINE
I.
Common Features of Eukaryotic Cells
A. Eukaryotic cells have membrane-delimited nuclei
B. In addition to the nucleus, eukaryotic cells have membrane-bound organelles that perform specific
functions within the cell; this allows simultaneous independent control of cellular processes
C. Eukaryotic cells also contain a large intracytoplasmic membrane complex, which provides a large
surface area allowing greater respiratory and photosynthetic activity; this complex of membranes
also serves as a transport system to move materials to different cell locations
II. Eukaryotic Cell Envelopes
A. Eukaryotic membranes are phospholipid bilayers with sphingolipids and sterols, but the lipids in the
outer layer have been shown to differ from those in the inner layer
B. Certain microdomains in the membranes differ in lipid and protein content to suit specific functions
C. The cell wall composition in eukaryotic microbes varies and can include the polymers cellulose,
glucan, or chitin, while others have a rigid silica shell
III. Cytoplasm of Eukaryotes
A. The cytoplasmic matrix provides the complex structured environment required for many cellular
activities
B. The cytoskeleton is a vast network of interconnected filaments and tubules important for motion and
act as a scaffold for maintaining cell organization
35
C.
Microfilaments (4 to 7 nm) composed of actin may be scattered throughout the matrix or organized
into networks and parallel arrays; they play a major role in cell motion and changes in cell shape
D. Microtubules are hollow cylinders (25 nm) composed of tubulin that help maintain cell shape, are
involved (with microfilaments) in cellular movement, participate in intracellular transport of
substances, and participate in organelle movements; they also form the mitotic spindle during cell
division and are present in cilia and flagella
E. Intermediate filaments (8 to 10 nm), along with microfilaments and microtubules, are major
components of the cytoskeleton, and are particularly prominent in nuclear lamina
IV. Organelles of the Secretory and Endocytic Pathways
A. Endoplasmic reticulum
1. The endoplasmic reticulum (ER) is a complex interconnected array of internal membranous
tubes and sacs that may have ribosomes attached (rough endoplasmic reticulum; RER) or may
be devoid of ribosomes (smooth endoplasmic reticulum; SER)
2. The ER has many important functions:
a. It transports proteins, lipids, and other materials within the cell
b. ER-associated enzymes and ribosomes synthesize lipids and many proteins
c. It is a major site of membrane synthesis
B. The Golgi apparatus
1. The Golgi apparatus is a set of membranous sacs (cisternae) that is involved in the
modification, packaging, and secretion of materials; the cisternae exist in stacks called
dictyosomes
2. The Golgi apparatus is present in many eukaryotic cells, but many fungi and ciliated protozoa
lack it
C. Lysosomes are membrane-bound vesicles that contain hydrolase enzymes needed for intracellular
digestion of all types of macromolecules
D. Secretory pathway
1. Proteins destined for the cell membrane, lysosomes, or secretion are transported in vesicles
that bud off the ER and join the cis face of the Golgi apparatus; the proteins are modified and
transported in vesicles that bud off of the trans face of the Golgi apparatus
2. Transport vesicles move the material to the cell membrane or lysosome; secretory vesicles
hold their contents until signaled to release them through fusion with the plasma membrane
3. Proteasomes are a nonlysosomal protein degradation system found in eukaryotic cells that
degrades proteins marked with ubiquitin
E. Endocytic pathway
1. Endocytosis is the process in which the cell takes up solutes or particles by enclosing them in
vesicles (endosomes) pinched off from the plasma membrane
a. Phagocytosis—endocytosis of large particles by engulfing them into a phagocytic
vacuole (phagosome)
b. Pinocytosis—endocytosis of small amounts of liquid with its solute molecules; there are
three types of pinocytosis: fluid-phase endocytosis; receptor-mediated endocytosis using
clathrin-coated pits and vesicles; and a type of endocytosis that forms special vesicles
(caveolae), whose contents are not degraded
2. Most endosomes fuse with early lysosomes (newly formed lysosomes) to form late lysosomes;
late lysosomes are important to cell functioning
a. Some function as food vacuoles, digesting and releasing nutrients into the cytoplasm
b. Some function to destroy invading bacteria
c. Autophagosomes fuse lysosomes to selectively digest portions of the cell’s own
cytoplasm as part of the normal turnover of cellular components (macrophagy)
3. Undigested materials accumulate in lysosomes called residual bodies
V. Organelles Involved in Genetic Control of the Cell
A. Nucleus
1. Nuclei are membrane-bound structures that house most of the genetic material of the cell
2. Nuclear structure
36
a.
Chromatin is the dense fibrous material seen within the nucleoplasm of the nucleus; the
nucleoplasm is the DNA-containing part of the nucleus; when the cell is dividing,
chromatin condenses into visible chromosomes
b. The nucleus is bounded by the nuclear envelope, a double-membrane structure (two lipid
bilayers), which is penetrated by nuclear pores; the nuclear pores allow materials to be
transported into or out of the nucleus
c. The nucleolus is a very noticeable structure within the nucleus; it is involved in the
synthesis of rRNA and the production of ribosomes
B. Eukaryotic ribosomes
1. Eukaryotic ribosomes are 80S, with 60S and 40S subunits
2. Eukaryotic ribosomes are responsible for synthesis of cellular proteins; they can either be
attached to the ER or are free in the cytoplasm
a. ER-associated ribosomes synthesize integral membrane proteins or proteins that are
secreted out of the cell
b. Free ribosomes synthesize nonsecretory, nonmembrane proteins
VI. Organelles Involved in Energy Conservation
A. The endosymbiotic hypothesis holds that the three energy-conserving organelles are thought to be
derived from bacterial cells engulfed by host cells early in evolutionary history
B. Mitochondria
1. Mitochondria are the site of the energy-conserving tricarboxylic acid cycle and the generation
of ATP by electron transport and oxidative phosphorylation
2. Mitochondria have an outer membrane and an inner membrane enclosing a fluid matrix
a. The inner and outer membranes have different lipids and enzymes
b. The enzymes of the tricarboxylic acid cycle and the -oxidation pathway for fatty acid
degradation are located within the matrix
c. Electron transport and oxidative phosphorylation occur only in the inner mitochondrial
membrane
3. Mitochondria use their own DNA and their own ribosomes to synthesize some of their
proteins; mitochondrial DNA and mitochondrial ribosomes are similar to bacterial DNA and
ribosomes in terms of size and structure; mitochondria reproduce by binary fission
C. Hydrogenosomes are small organelles in some anaerobic protists that conserve energy by
fermentation and generate hydrogen; composed of a double membrane they share some features
with mitochondria
D. Chloroplasts
1. Chloroplasts are the site of photosynthesis in protists and higher plants
2. Chloroplasts are surrounded by two membranes; the inner membrane encloses a fluid matrix
called the stroma; within the stroma is a system of flattened membrane sacs called thylakoids
which often form stacks known as grana
a. The formation of carbohydrates from carbon dioxide and water (dark reactions) occurs in
the stroma
b. The trapping of light energy to generate ATP, NADPH, and oxygen (light reaction)
occurs in the thylakoid membranes of the grana
VII. External Structures
A. Cilia and flagella are locomotor structures that differ in length and how they move the cell with cilia
like oars and flagella like undulating propellers
B. Cilia and flagella are structurally similar; both are membrane-bound cylinders composed of
microtubules, in a 9+2 arrangement, embedded in a matrix; basal bodies have a 9+0 microtubule
pattern
VIII. Comparison of Prokaryotic and Eukaryotic Cells
A. Eukaryotes have a membrane-delimited nucleus and many complex membrane-bound organelles,
each of which performs a separate function for the cell
B. Prokaryotes lack a membrane-delimited nucleus and internal membrane-bound organelles; they do
not perform endocytosis
37
C.
Despite the significant differences between prokaryotes and eukaryotes, they have remarkable
biochemical similarities: the same basic chemical composition, the same genetic code, and some of
the same basic metabolic processes
IX. Overview of Protist Structure and Function
A. Protist morphology
1. Complex single-celled eukaryotes with specialized organelles
2. Protists have a cell membrane called a plasmalemma; some protists have a gelatinous layer of
cytoplasm, the ectoderm, just inside the plasmalemma and a fluid region of cytoplasm, the
endoplasm, toward the center of the cell; the pellicle includes the plasmalemma and structures
immediately inside it
3. Specialized organelles include contractile vacuoles (osmoregulation), phagocytic vacuoles
(food digestion in holozoic and parasitic species), cytosome (cell mouth), cytoproct (excretory
channel), pyrenoids (starch storage in chloroplasts)
4. Aerobic chemoorganotrophic species have mitochondria while most anaerobic protists lack
mitochondria, cytochromes, and the TCA cycle
5. Many protists have flagella or cilia with basal body-like kinetosomes, not only for movement
but also for making waves to aid feeding and respiration
B. Encystment and excystment
1. Many protists can de-differentiate (become simpler) into cysts, a dormant form with a cell wall
and little metabolic activity; encystation protects the organism from adverse environments, can
be reproductive, and can be used for transfer to new hosts
2. Excystment (escape from cysts) is usually triggered by a change to favorable conditions
C. Reproduction
1. Most protists reproduce asexually by binary fission or budding; some filamentous forms
fragment
2. Most protists can reproduce sexually by producing haploid gametes called gamonts and
gamete fusion called syngamy with two morphologically similar gametes (isogamy) or
different gametes (anisogamy); nuclear material may be exchanged between individuals
(conjugation) or between genetically distinct nuclei in a single individual (autogamy)
3. There is considerable diversity in nuclear structure
a. Vesicular nucleus—most common, spherical 1 to 10 µm with distinct nucleolus and
uncondensed chromosomes
b. Ovular nucleus—larger bodies (10 to 100 µm) with many peripheral nucleoli
c. Chromosomal nucleus—single nucleolus associated with one chromosome; chromosomes
remain condensed during interphase
d. Ciliophora have two nuclei, a large macronucleus with distinct nucleoli and condensed
chromatin, and a diploid micronucleus with dispersed chromatin and no nucleoli
X. Overview of Fungal Structure and Function
A. Fungal structure
1. Thallus—body or vegetative structure of a fungus; fungal cell walls are usually composed of
chitin, a nitrogen-containing polysaccharide consisting of N-acetyl glucosamine residues
2. Yeast—unicellular fungus with single nucleus; reproduces asexually by budding or sexually by
spore formation; daughter cells may separate after budding or may aggregate to form colonies
3. Mold—a fungus with long, branched, threadlike filaments
a. Hyphae—the filaments of a mold; may be coenocytic (no cross walls within the hyphae)
or septate (having cross walls)
b. Mycelia—bundles or tangled masses of hyphae
B. Fungal reproductive cells and structures
1. Asexual reproduction—occurs by several mechanisms
a. Transverse fission
b. Budding of somatic vegetative cells
c. Spore production
1) Hyphal fragmentation—resulting cells behave as arthrospores or chlamydospores (if
enveloped in thick cell wall before separation)
38
2)
2.
3.
Sporangiospores are produced in sporangium (sac) at the end of an aerial hypha
(sporangiophore)
3) Conidiospores are unenclosed spores produced at the tip or on the sides of an aerial
hypha
4) Blastospores are produced from a vegetative mother cell by budding
Sexual reproduction
a. Involves the union of compatible nuclei
b. Some fungi are self-fertilizing, producing male and female gametes on the same
mycelium (homothallic), while others require outcrossing between different but sexually
compatible mycelial mating types (heterothallic)
c. Zygote formation proceeds by one of several mechanisms
1) Fusion of gametes
2) Fusion of gamete-producing bodies (gametangia)
3) Fusion of hyphae
4) Sometimes there is immediate fusion of nuclei and cytoplasm; however, more
common is a delayed fusion of nuclei, resulting in the formation of a cell with two
haploid nuclei (dikaryotic stage)
d. Zygotes can develop into spores (zygospores, ascospores, or basidiospores)
Both sexual and asexual spores are used for identification purposes and aid fungal
dissemination
TERMS AND DEFINITIONS
Place the letter of each term in the space next to the definition or description that best matches it.
____ 1.
____ 2.
____ 3.
____ 4.
____
____
____
____
____
5.
6.
7.
8.
9.
____ 10.
____ 11.
____ 12.
____ 13.
____ 14.
____ 15.
____ 16.
____ 17.
____ 18.
____ 19.
Intracellular structures that perform specific functions
Minute protein fibers (4 to 7 nm diameter), either scattered within the cytoplasmic matrix or
organized into networks and parallel arrays, that may play a role in cell movement
Hollow cylinders (25 nm diameter) that help maintain cell shape and that participate in cell
movement
Protein fibers (8 to 10 nm diameter) that help maintain cell shape and that participate in cell
movement
Combination of microtubules and filaments that support cell shape and movement
Arrangement of microtubules along the length of flagella and cilia
Endoplasmic reticulum to which are attached many ribosomes
Endoplasmic reticulum that is mostly devoid of attached ribosomes
The general process of importing solutes or particles by enclosing them in vesicles pinched off from
the plasma membrane
The specific process of importing large particles by enclosing them in vesicles pinched off from the
plasma membrane
The specific process of importing solutes but not large particles by enclosing them in vesicles
pinched off from the plasma membrane
Spherical complexes of proteins that are observed on the inner membrane of mitochondria and are
responsible for the synthesis of ATP during cellular respiration
Organelles of algae and higher plants that often possess pigments and are the sites of synthesis and
storage of food reserves
A region of the pellicle of ciliates where phagocytic vacuoles empty their contents after food
digestion has taken place
Infoldings of the mitochondrial inner membrane
A dense region found in the chloroplast that is composed of protein surrounded by polysaccharides
Vesicles formed by endocytosis
An articulated, proteinaceous structure inside the plasma membrane that is rigid but somewhat
flexible
A protein that functions in the movement of cilia and eukaryotic flagella
39
____ 20.
____ 21.
____ 22.
____ 23.
____ 24.
____ 25.
____ 26.
____ 27.
____ 28.
____ 29.
____ 30.
____ 31.
____ 32.
____ 33.
____ 34.
____ 35.
____ 36.
____ 37.
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
l.
m.
n.
o.
p.
q.
r.
s.
t.
u.
v.
w.
x.
y.
z.
aa.
bb.
cc.
dd.
ee.
ff.
The dormant form of a protozoan
Semisolid or gelatinous cytoplasm just beneath the plasma membrane
Fluid cytoplasm in the interior of protozoa
The single site of phagocytosis in some ciliated protozoans
Formation of the cyst stage from the vegetative stage
Formation of the vegetative stage from the cyst stage
Nuclear mitotic division followed by division of the cytoplasm
The process whereby there is an exchange of gametes between paired protozoans of complementary
mating types
The vegetative structure of a fungus
The cross walls observed in some fungal hyphae
Filaments that are uninterrupted by cross walls
Filaments with cross walls
Asexual spores produced within a sac
Asexual spores produced without a sac
Asexual spores produced by budding from a vegetative cell
Cells that behave like spores, are produced by fragmentation of hyphae, but are not surrounded by a
thick wall
Cells that behave like spores, are produced by fragmentation of hyphae, and are surrounded by a
thick wall
Gamete-producing bodies that can fuse to form a zygote during sexual reproduction of some fungi
arthroconidia (arthrospores)
axoneme
binary fission
blastospores
chlamydospores
coenocytic hyphae
conidiospores
conjugation
cristae
cyst
cytoproct
cytoskeleton
cytostome
dynein
ectoplasm
encystation
endocytosis
endoplasm
endosomes
excystation
F1 particles
gametangia
intermediate filaments
microfilaments
microtubules
organelles
pellicle
phagocytosis
pinocytosis
plastids
pyrenoids
rough endoplasmic reticulum
40
gg.
hh.
ii.
jj.
kk.
septa
septate hyphae
smooth endoplasmic reticulum
sporangiospores
thallus
IDENTIFICATION OF EUKARYOTIC STRUCTURES
Label the appropriate structures indicated on the accompanying figure using the following terms. In the space
beside each term provide a brief description of its structure and/or function.
1.
Chromatin:
2.
Golgi apparatus:
3.
Lysosome:
4.
Mitochondrion:
5.
Nucleolus:
6.
Nucleus:
7.
Plasma membrane:
8.
Ribosomes:
9.
RER:
10. SER:
41
COMPARISON OF PROKARYOTIC AND EUKARYOTIC CELLS
Complete the following table by providing a brief description of the properties/structures listed for both
prokaryotes and eukaryotes.
Property/Structure
Prokaryote
Organization of Genetic Material
1. Membrane-bound nucleus
2. Chromosome structure
3. Number of chromosomes
4. Nucleolus
5. Plasmids
Organelles
6. Mitochondria
7. Chloroplasts
8. Plasma membrane
9. Flagella
10. Cilia
11. Endoplasmic reticulum
12. Golgi apparatus
13. Lysosomes
14. Ribosomes
Functions
15. Photosynthesis
16. Differentiation
42
Eukaryote
MATCHING
Match the following structures with the appropriate functions. Answers may be used once, more than once, or
not at all.
____ 1.
____ 2.
____ 3.
____ 4.
____ 5.
____ 6.
____ 7.
____ 8.
____ 9.
____ 10.
____ 11.
____ 12.
____ 13.
____ 14.
Major route by which proteins, lipids, and other
materials are transported through the cell
Involved in the modification, packaging, and secretion
of materials
Contain the enzymes needed to digest all types of
macromolecules
Structures responsible for the synthesis of proteins
Responsible for ATP synthesis by electron transport
and oxidative phosphorylation
Major site of cell membrane synthesis
Responsible for the synthesis of ATP and carbohydrate
using light as the energy source
Responsible for the production of ribosomes
Repository for the cell’s genetic information
A complex structure or set of structures lying
underneath the plasma membrane that gives some
eukaryotic cells their characteristic shape
A rigid structure outside the plasma membrane that
gives some cells their characteristic shape
Short fibers containing microtubules that are
responsible for locomotion for some eukaryotes
Long fibers containing microtubules that are
responsible for locomotion for some eukaryotes
A huge cylindrical complex of proteins that plays a
major role in the degradation and recycling of proteins,
as well as the production of peptides for antigen
presentation during immunological responses
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
l.
m.
cell wall
chloroplasts
cilia
endoplasmic reticulum
flagella
Golgi apparatus
lysosomes
mitochondria
nucleolus
nucleus
pellicle
proteasome
ribosomes
FILL IN THE BLANK
1.
2.
3.
4.
5.
6.
Organelles are located in an apparently featureless, homogeneous substance called the ____________
____________, which is also the location of many important biochemical processes.
The Golgi apparatus consists of ____________ in stacks, often called ____________, which can be
clustered in one region or scattered throughout the cell.
The
theory proposes that mitochondria, chloroplasts, and perhaps other organelles were once
free-living prokaryotes, which were engulfed by an ancestral phagocytic cell, survived within the host
cell, eventually lost their ability to live independently of the host, and became an organelle.
Newly formed lysosomes, or ____________ lysosomes, fuse with phagocytic vesicles to yield
____________ lysosomes; ____________ ____________ are lysosomes that have accumulated large
quantities of indigestible material.
Enzymes and electron carriers involved in electron transport and oxidative phosphorylation are located
only in the ____________ membrane of the mitochondrion, while the enzymes of the tricarboxylic acid
cycle are located in the ____________.
Photosynthetic reactions occur in separate compartments of the chloroplast. The formation of
carbohydrate from carbon dioxide and water (the dark reaction) takes place in the ____________ or fluid
matrix, while the trapping of light energy to form ATP, NADPH, and oxygen (the light reaction) takes
place in the ____________ of the chloroplast.
43
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
The nucleus is bounded by the
, which consists of an inner and outer
membrane. It is penetrated by many
, each of which is surrounded by a ring
of granular and fibrous material called the annulus.
Many protozoa and some algae have a structure consisting of a relatively rigid layer just beneath the
plasma membrane and including the plasma membrane. This structure is called the ____________, and
although it is not as rigid as a ___________ __________, it does provide a characteristic shape to a cell
that possesses it.
Cilia beats have two distinctive phases. In the ____________ stroke, the cilium moves like an oar to
propel the organism through the water. The cilium then bends along its length while it is pulled forward
during the ____________ stroke.
Material is transported from the ER to the ____________ face of the Golgi apparatus. It moves through
the Golgi apparatus by budding off the cisternal edges and moving to the next sac. After it has completed
its journey through the Golgi apparatus and has been appropriately modified, it is secreted from the
____________ face for transport to its final destination.
Several kinds of pinocytosis have been identified. In
, extracellular fluid is
taken in nonselectively. This may be a method for recycling the plasma membrane. A second type of
pinocytosis, called
, results in the formation of
This type of pinocytosis occurs at specialized regions of the membrane coated on the cytoplasmic side
with
. A third type of pinocytosis forms
(little caves), which may be involved in
signal transduction and active import of certain molecules (e.g., folic acid). Unlike other
, these vesicles do not fuse with
and their contents are not degraded.
Within the
of a chloroplast is a complex internal membrane system called
. In
some algae, several disk-like
are stacked on each other like coins to form
.
In some species of protozoans, the cytoplasm immediately under the plasma membrane is gelatinous and
is termed ____________. The plasma membrane and structures immediately beneath it are referred to as
the ____________. The more fluid portion of the cytoplasm in the interior of the cell is referred to as the
____________.
One or more vacuoles are usually found in the cytoplasm of protozoans. Vacuoles that function as
osmoregulatory organelles are called ____________ vacuoles and are usually found in organisms that
live in a hypotonic environment, such as a freshwater lake. Holozoic and parasitic organisms have
____________ vacuoles, which serve as the site of food digestion. Vacuoles with enzymes that function
during the excystation process are referred to as ____________ vacuoles.
Members of the phylum Ciliophora have cilia and two types of nuclei. The
is associated
with trophic activities, and the
is diploid and involved in reproductive processes.
Ciliated protozoans reproduce sexually by a process called
. Two ciliates, called
,
fuse their pellicles at a contact point. Then the
in each is degraded and the
divide meiotically to produce haploid pronuclei. These are exchanged, fuse, undergo mitotic divisions,
and eventually develop into new nuclei.
Unicellular fungi that have a single nucleus and reproduce either asexually by budding and transverse
division or sexually by producing spores are called ____________, while ____________ consist of long,
threadlike filaments called ____________ that aggregate in bundles to form ____________. Some fungi
can alternate between the two forms and are said to be
.
Asexual spores that are produced in saclike structures known as ____________ are called
____________. Asexual spores that are not enclosed in a sac, but that are produced at the tips or sides of
hyphae are called ____________, while spores that are produced by budding from a vegetative cell are
called ____________.
The cell walls of most fungi contain
.
The body or vegetative structure of a fungus is called the
. Fungi may be grouped
into
(filamentous fungi) or
(unicellular fungi) based on the development
of this structure.
44
.
MULTIPLE CHOICE
For each of the questions below select the one best answer.
1.
2.
3.
4.
5.
What are the flattened sacs of the
endoplasmic reticulum called?
a. thylakoids
b. cristae
c. cisternae
d. vacuoles
Which of the following is one of the more
important functions of the Golgi apparatus?
a. synthesis of ribosomes
b. synthesis of lysosomes
c. synthesis of nucleosomes
d. synthesis of mesosomes
Which of the following do cells use to
selectively digest portions of their own
cytoplasm?
a. autophagic vacuole
b. turnover lysosome
c. suicide vacuole
d. recycling vacuole
6.
7.
8.
Which of the following is NOT a function of
the mitochondrion?
a. tricarboxylic acid cycle enzyme
reactions
b. electron transport
c. oxidative phosphorylation
d. All of the above are functions of the
mitochondrion.
9.
Which of the following directs the
construction of flagella and/or cilia?
a. axoneme
b. tubulin
c. centriole
d. basal body
Which term refers to stacks of cisternae
in the Golgi apparatus?
a. stigmata
b. golgisomes
c. dictyosomes
d. lamellosomes
Which of the following is NOT a major
function of cysts?
a. They have locomotory organelles for
movement through an aqueous
environment.
b. They protect against adverse changes in
the environment.
c. They play a role in reproduction.
d. They serve as a means of transfer from
one host to another in parasitic species.
In addition to the production of asexual
spores, fungi can reproduce asexually by
which of the following mechanisms?
a. transverse fission of a parental cell
b. fragmentation of hyphae whereby the
component cells behave as spores
c. budding of either somatic vegetative
cells or vegetative mother cells
d. All of the above are correct.
In most cases when sexual gametes of fungi
fuse, the cytoplasm fuses first, and the fusion
of the nuclei is delayed. This leads to a stage
in which there is one cell containing two
haploid nuclei. What is this stage called?
a. dikaryotic stage
b. dinucleated stage
c. monocytoplasmic stage
d. None of the above is correct.
TRUE/FALSE
____ 1.
____ 2.
____ 3.
____ 4.
____ 5.
____ 6.
In cells that produce large quantities of lipid, the endoplasmic reticulum is mostly devoid of
ribosomes and is referred to as smooth endoplasmic reticulum.
The Golgi apparatus is the major site of cell membrane synthesis.
Both eukaryotes and prokaryotes have ribosomes, but the eukaryotic ribosome is generally larger
and more complex than the prokaryotic ribosome.
The majority of mitochondrial proteins are manufactured under the direction of mitochondrial DNA
by mitochondrial ribosomes.
The cell walls of eukaryotic cells are constructed of polysaccharides (e.g., cellulose) that are simpler
than the peptidoglycan found in bacterial cell walls.
Unlike prokaryotes, many eukaryotes lack an external cell wall.
45
____ 7.
Proteins to be secreted out of the cell are synthesized by free ribosomes (those that are not attached
to the ER).
____ 8. Lysosomes join with phagosomes for defensive purposes as well as for acquisition of nutrients.
____ 9. Although different structurally, prokaryotes and eukaryotes are metabolically quite similar.
____ 10. In all fungi that have been observed to have a sexual reproduction cycle, male and female gametes
are produced on separate mycelia and must then find each other for fertilization to occur.
CRITICAL THINKING
1.
Describe how the “division of labor” associated with internal, membrane-delimited organelles enables
eukaryotic cells to be more efficient and thereby allows them to grow much larger than prokaryotes grow.
2.
Both prokaryotes and eukaryotes are capable of using large particles as nutrient sources. Eukaryotes bring
them into the cell by endocytosis. Prokaryotes cannot do this; they export digestive enzymes to digest the
particles externally and then transport the resulting small nutrient molecules into the cell. Why is the
prokaryotic process much less efficient? Use diagrams to support your answer.
3.
Many protozoans use contractile vacuoles as osmoregulatory organelles. How do these organelles
function to maintain osmotic balance? Why are they found in freshwater protozoans but not in marine
protozoans?
46
ANSWER KEY
Terms and Definitions
1. z, 2. y, 3. x, 4. w, 5. l, 6. b, 7. ff, 8. ii, 9. q, 10. bb, 11. cc, 12. u, 13. dd, 14. k, 15. i, 16. ee, 17. s, 18. aa,
19. n, 20. j, 21. o, 22. m, 23. m, 24. p. 25. t, 26. c, 27. h, 28. kk, 29. gg, 30. f, 31. hh, 32. jj, 33. g, 34. d, 35. a,
36. e, 37. v
Matching
1. d, 2. f, 3. g, 4. m, 5. h, 6. d, 7. b, 8. i, 9. j, 10. k 11. a 12. c 13. e, 14. l
Fill in the Blank
1. cytoplasmic matrix 2. cisternae; dictyosomes 3. endosymbiotic 4. early; late; residual bodies
5. inner; matrix 6. stroma; thylakoids 7. nuclear envelope; nuclear pores 8. pellicle; cell wall
9. effective; recovery 10. cis (forming); trans (maturing) 11. fluid-phase endocytosis; receptor-mediated
endocytosis; coated vesicles; clathrin; caveolae; endosomes; lysosomes 12. stroma; thylakoids, thylakoids;
grana 13. ectoplasm; pellicle; endoplasm 14. contractile; phagocytic; secretory 15. macronucleus;
micronucleus 16. conjugation; conjugants; macronucleus; micronuclei 17. yeasts; molds; hyphae; mycelia;
dimorphic 18. sporangia; sporangiospores; conidiospores; blastospores 19. chitin 20. thallus; molds; yeasts
Multiple Choice
1. c, 2. b, 3. a, 4. d, 5. d, 6. c, 7. a, 8. d, 9. a
True/False
1. T, 2. F, 3. T, 4. F, 5. T, 6. T, 7. F, 8. T, 9. T, 10. F
47