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CHAPTER 4
EUKARYOTIC CELL
STRUCTURE & FUNCTION
External Structures
Internal Structures
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Overview of Eukaryotic CellStructure
Eukaryote: Protozoa, Algae, Fungi larger than prokaryotic cell
more complex than prokaryotic cell
contains membrane-bound organellesthat perform specific functions
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Protozoa, Algae, Fungi
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Eukaryotic Cell Structure
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1. Cilia motility
5-20 m long
shorter and more numerous
than flagella
beat with two phases
2. Flagella
motility
100-200 m long
longer than cilia
eukaryotic flagellum moveslike a whip
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Structure of Flagella and Cilia membrane-bound cylinders ~2m in diameter
9 pairs of microtubule doublets circle around 2 central tubules
9 + 2 arrangement called axoneme
basal body
at base of flagellum or cilium directs synthesis of flagella and cilia
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3. Pellicle a thin layer supporting plasma membrane in various protozoa
not as strong or rigid as cell wall
provides characteristic shape to cell
Epidinium caudatum Pellicle of a mushroom
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4. Cell Wall
rigid covering outside plasma membrane
variable compositions in eukaryotes
Algae - ?
Diatoms - ? Fungi - ?
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Cellulose cell wall of algae Volvoxsp.
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Silica shell of diatoms
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Chitin & cellulose of fungi
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5. Plasma Membrane almost as similar as prokaryotes
Fluid-mosaic structure
greater variety oflipids, includephosphoglycerides, sphingolipids andcholesterol
contains sterols that adds rigidity toplasma membrane
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(1) is standard lipid bilayer(2) is a lipid raft.
Plasma Membrane
eucaryotic membranes contain
microdomains called lipid rafts
enriched for certain lipids and proteins
participate in a variety of cell processessuch as cell movement and transduction
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Eukaryotic Cell InternalStructures
Nucleus
EndoplasmicReticulum
Golgi Apparatus
Mitochondria
Chloroplast
Ribosome
Lysosome Peroxisome
Vacuoles
Cytoplasmicmatrix
Cytoskeleton
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Eukaryotic Cell Structure
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Nucleus
largest organelle ineucaryotic cell
contains geneticmaterial
enclosed by nuclear
envelope contains chromatin
and nucleolus
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Nucleus
Chromatin
dense fibrous materialwithin nucleus
contains genetic DNA
condenses to formchromosomes during cell
division mitosis/meiosis (refer
Prescotts Microbiology
pg. 92-94)
Nuclear envelope
double membrane (inner
& outer) structure that
surrounds nucleus
has nuclear pores
pores allow materials
to be transported intoor out of nucleus
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Nucleus
Nucleolus
1 nucleolus per nucleus
not membrane-enclosed
important in ribosome synthesis
directs synthesis and processing of rRNA directs assembly of rRNA and ribosomal
proteins to form ribosomes
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Endoplasmic Reticulum (ER)
consists of networkof membranous
tubules andflattened sacs calledcisternae
internalcompartment of ER= cisternal space
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Two types of ER:
rough ER
ribosomes attached, rough texture
smooth ER
lack of ribosomes, smooth texture
Endoplasmic Reticulum (ER)
Functions of ER: major site of cell membrane synthesis
transports proteins, lipids, and other materials to
Golgi apparatus
synthesis of lysosomes
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Golgi Apparatus
membranous organellemade of cisternae stacked
on each other dictyosomes
stacks of cisternae
involves in modification,packaging, and secretionof materials throughsecretory vesicles
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cis face (associated with ER)
trans face
cis face differs from trans face in thickness,enzyme content and vesicle formation
movement ofmaterial
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