Teaching plan of Cell Biology
Chapter 8
Cytoskeleton System
Biology Department of Xinjiang Medical University
Teaching plan of Cell Biology
Lesson plans
roll number：_______8________
Course Title
Teacher
Medical Cell
Biology
Major
Xiamixinuer.Yilike Plan hours
clinic
4 hours
Class
Professional level undergraduate
course
Professional
Title
Biology Professor
The time of
writing
Name of the
Lecture
Chapter 8: The Cytoskeleton
Using time
Teaching
Purposes
and
Requiremen
t
Teaching Purposes: To learn the structure, chemical composition, assembly
and functions of microtubules, microfilaments and intermediate filaments.
Teaching Requirements:
1. Mastering: concepts of the cytoskeleton; structure, chemical composition,
and assembly of microtubules and microfilaments.
2. Comprehending: functions of microtubules and microfilaments.
3. Understanding: functions of the cytoskeleton; types and functions of
Important Important points ： Concepts of the cytoskeleton; structure, chemical
and Difficult composition, and assembly of microtubules and microfilaments.
points
Difficult points: movement of flagella and cilia.
Update
teaching
content
Teaching
methods
and
organization
al
Teaching
tools
Textbook
and
reference
books
collective
preparation
of
Opinion of
the
department
Add animation to demonstrate the movement of flagella and cilia.new cases
increased.
Teaching methods ： Multimedia lectures given . Heuristic teaching methods
will be used.
organizational arrangements ：Microtubules 2 hours,Microfilaments and IF
will be teach 2 hours.
multiedia will be used.
text book ：Cell Biology , China Medical University（6th edition）
Reference ：1.Essential Cell Biology.Bruce Albert’s；2.Cell and Molecular
Biology，Gerald Karp；3. Molecular Biology Disc；4. Lysosomes in biology
and pathology J. T. Dingle5.The cytoskeleton: an introductory survey/
Q28/C74,M. Schliwa;6.Essentials of cell biology/2d ed. Q28/C71=2,Dyson,
Mainly Teach the concepts of the cytoskeleton; structure, chemical
composition, and assembly of microtubules and microfilaments.
Agreed to carry out prepared the lessons plan. Give attention to use appopirate
signature of the dean：
teaching methods .
Biology Department of Xinjiang Medical University
Teaching plan of Cell Biology
Test for Endomembrane System (Print the page let students do it before the class
in 10-15min)
Name
RolL No
Marks ______
1. Endomembrane System: The structural and functional relationship organelles
including endoplasmic reticulum,
,
, endosomes and secretory
vesicles.
cells.
2. Membrane-bound structures (organelles) are found in all
3. RER has ribosomes on the
side of continuous, flattened sacs(cisternae);
4.SER is an interconnecting network of
membrane elements.
are heterogeneous mixtures of similar-sized vesicles, formed from
5.
membranes of the ER and Golgi complex.
6.Proteins synthesized on ribosomes of RER include:
.
and
,
7.SRP has three main active sites: One that recognizes and binds to
;
One that interacts with the
to block further translation; One that binds to
the
.
8.Signal hypothesis: explain the process how the free ribosome
become
.
(1)Once the ER signal sequence emerges from the ribosome, it is bound by a
(SRP) and causes a pause in translation.
(2)The SRP delivers the ribosome/nascent polypeptide complex to the
in the ER membrane.
(3) Transfer of the ribosome/nascent polypeptide to the
(protein
translocator) leads to opening of this translocation channel and insertion of the signal
sequence and adjacent segment of the growing polypeptide into the central pore.
(4)Both the SRP and SRP receptor, once
from the translocon and then
are ready to initiate the insertion of another polypeptide chain.
(5)
start again.
(6)As the polypeptide chain elongates, it passes through the translocon channel into
the ER lumen, where the signal sequence is cleaved by
and is
rapidly degraded.
(7)The peptide chain continues to elongate as the
3’ end.
is translated toward the
(8)Once translation is complete, the
is released, the remainder of the
protein is drawn into the ER lumen, the translocon closes, and the protein assumes its
native folded conformation.
8. N-linked: linked to the amide nitrogen of
Biology Department of Xinjiang Medical University
(ER).
Teaching plan of Cell Biology
O-linked: linked to the hydroxyl group
or threonine (in Golgi)
proteins do not leave ER.
9. Quality control: ensuring that
10. Functions of the SER: (1)Synthesis of
in endocrine cells.
(2)Detoxification of organic compounds in liver cells. (3)Release of glucose 6phosphate in liver cells. (4)Sequestration of
.
(CGN),
11. The structure of Golgi complex: Cis face and trans face;
cisterna(cis, medial, trans),
(TGN).
12. The Functions of Golgi complex: (1)Glycosylation. (2)
.
(3)Cell secretion (4)Biogenesis of
13. Proteins are imported into organelles by three mechanisms:
(1)
: Transport through nuclear pores (2)
transport: ER, Mit, Chl, Per (3)
transport: ER-Golgi-PM-Lys,
Endosome
14.
15.
the ER.
-coated vesicles move materials from the ER to the Golgi.
-coated vesicles transporting Escaped ER resident Proteins Back to
16. Soluble ER protein bear Retrieving signal—
mammal.
(Lys-Asp-Glu-Leu)in
17.
-coated vesicle: Transporting Cargo from the TGN to
endosomes, Lysosomes, and also move materials from the
to
cytoplasmic compartments along the endocytic pathway.
18. Two pathway for cell’s secretion:
secretory pathway.
secretory pathway and
19. Targeting of soluble lysosomal enzymes to endosomes and lysosomes by
tag
20. The mannose 6-phosphate pathway, the major route for targeting lysosomal
:
enzymes to
(1)Precursors of lysosomal enzymes migrate from the rER to the
mannose residues are
.
(2)In the
, the phosphorylated enzymes bind to
direct the enzymes into vesicles coated with the clathrin.
where
, which
(3)The clathrin lattice surrounding these vesicles is rapidly depolymerized to its
subunits, and the uncoated transport vesicles fuse with late
.
(4) Within this low-pH compartment, the phosphorylated enzymes dissociate from the
M6P receptors and then are
.
(5)The receptors
back to the Golgi.
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Teaching plan of Cell Biology
(6) The enzymes are incorporated into a different transport vesicle that buds from the
late endosome and soon fuses with a
.
Teaching Purposes: To learn the structure, chemical composition, assembly and
functions of microtubules, microfilaments and intermediate filaments.
Teaching Requirements:
1. Mastering: concepts of the cytoskeleton; structure, chemical composition, and
assembly of microtubules and microfilaments.
2. Comprehending: functions of microtubules and microfilaments.
3. Understanding: functions of the cytoskeleton; types and functions of intermediate
filaments.
Teaching Outline:
A．Introduction
B．Structure, chemical composition and functions of MT
C．Structure, chemical composition and functions of MF
D．Structure, chemical composition IF
attention： master point※※※；comprehending point※※；understand※
Textbook
<Cell Biology> Abridgen by department of Cell Biology China Medical
University,sixth edition,2000.
Reference
(1) Arberts, B. et al. Molecular Biology of the Cell, Garland Publishing, Inc.
2002, 2004, 2008.
(2) Arberts, B. et al. Essential Cell Biology, An Introduction to the Molecular
Biology of the cell, Garland Publishing, Inc. 1997, 2004.
(3) Karp, G. Cell and Molecular Biology--Concepts and Experiments, John &
Whley Sons, Inc. 2002, 2005, 2007.
(4) Lodish H. et al. Molecular Cell Biology, W.H.Freeman, Inc. 1999, 2007.
Biology Department of Xinjiang Medical University
Teaching plan of Cell Biology
(5) Becker W.M. The World of the Cell, The Benjamin/Cummings Publishing
Company. 2000 .
(6) Kleinsmith L.J and Kish V.M. Principles of Cell and Molecular Biology,
Harper Collins College Publishers. 1995.
Cytoskeleton System
A. Introduction
ⅰConception of Cytoskeleton※※※: A complex network of interconnected
microfilaments, microtubules and intermediate filaments that extends throughout the
cytosol. Each type of cytoskeletal filament is constructed from smaller protein
subunits.
ⅱTypes※: Three types of cytoskeletal filaments are common to many eucaryotic
cells and are fundamental to the spatial organization of these cells.They are
Microtubule( MT), Microfilament( MF) and Intermediate filaments, (Ifs)
ⅲTechniques for studying the cytoskeleton
a.Fluorescent microscopy and Electron microscopy; b.Immunofluorescence:
fluorescently-labeled antibody;c.Fluorescence: microinject into living cells;d.Video
microscopy: in vitro motility assays ;e.Electron: Triton X-100, Metal replica’f.Drugs
and mutations (about functions),g.Biochemical analysis(in vitro)
ⅳThe function of the cytoskeleton※:The cytoskeleton is a dynamic structure with
many roles. The function of the cytoskeleton: (1) Structural support (2) Internal
framework maintaining position of the organelles (3) Machinery required for
movement of materials and organelles within cells (4) Force generating elements
responsible for movement of cells from one place to another.
B.Microtubule, MT
1.General conceptions:(1)Hollow (2)Tubular structures 25nm in
diameter (3)Assembled from protein tubulin (4)The tubulin
consists of alpha-beta tubulin heterodimers arranged in rows
(protofilaments) Tubulin heterodimers are the protein building
blocks of MTs (5)Form cytoskeleton, mitotic spindle, centrioles, core of
cilia and flagella. Arrangement of protofilaments in singlet, doublet, and triplet .MT
composes of singlet,doublet protofilaments exist in cilia and flagella and triplet
protofilaments exist in centrioles and basal bodies
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Teaching plan of Cell Biology
2. MTs assemble from microtubule-organizing centers (MTOCs).Microtubuleorganizing centers (MTOCs): is the region to assemble MT,Where includesγtubulin. MTOCs:include Centrosome, Mitotic spindle and Basalbody.
Centrosome is a microtubule
organizing center,
MTOCs.Centrosome containing a pair
centrioles( see picture left). Centrioles
are short cylinders with a 9 + 0 pattern
of microtubule triplets.
of
A pair of centrioles is surrounded by electron dense pericentriolar material.
Centrioles contain nine evenly spaced fibrils, each containing three microtubules, A,
B and C tubules. A tubule is connected to the center of the centriole by a radial spoke.
Centrioles are in pairs and at right angles to each other.Centrioles may be involved in
microtubule formation and disassembly during cell division and in the organization of
cilia and flagella. No centrioles in Plant and fungi .
MT is nucleated by a protein complex containingγ-tubulin Experiments supporting
that centrosome is the MTOC basal body structure.
Cilia and flagella:Cilia (small and
numerous) and flagella (large and single)
have a 9 + 2 pattern of microtubules and are
involved in cell movement. Cilia and
flagella move when the microtubule
doublets slide past one another.Each cilium
and flagellum has a basal body at its
base(see picture below).
3. Characteristics of MT assembly※※※:
Microtubules have a plus and minus ends. Typically
the minus is for anchoring and the plus is for
growing .Dynamic instability due to the structural
differences between a growing and a shrinking
microtubule end.The transition between MT growth
and MT shrinking is controlled in cells by special
proteins.GTP capped end growth rapidly, while loss of GTP caps shrinkage.
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Teaching plan of Cell Biology
4. Drugs affect the assembly of MTs :( 1) Colchicine Binding to tubulin dimers,
prevent MTs polymerization. (2) Taxol Binding to MTs, stabilizes MTs and called
antimitotic drugs, and has application in medical practice as anticancer drugs
5. Microtuble-associated proteins (MAPs): The set of accessory proteins is essential
for the controlled assembly of the cytoskeletal filaments (includes the motor proteins:
myosins, dynein and kinesin).Tau:In axon, cause MTs to form tight bundles; MAP2:
In dendrites, cause MTs to form looser bundles;
MAP1B: In both axons and dendrites to form
cross bridge between microtubules.
Functions of MTs※※ A. Maintenance of cell
shape(constitute the centriols and cilia or
flagella).B. Cell motility (see in cilia or flagella).C. Chromosome movements in cell
division D. Organelle movement (MT associated motor proteins: kinesins: towards +
end (anterograde transport) Golgi to ER or PM traffic;dyneins: towards - end
(retrograde transport) ER to
Golgi traffic.)
C.Microfilament, MF: 1. MFs
are made of actin(protein
subunit) ,two entertwined strands of actin ,7 nm in diameter and involved in cell
motility.
2.MF assembly and disassembly※※※: (a) Within a MF, all the actin monomers are
oriented in the same direction, so MF has a polarity; (b) In vitro, (Polymerization)
both ends of the MF grow, but the plus end faster than the minus. Because actin
monomers tend to add to a filament’s plus end and leave from its minus end---“Tread-milling” (c) Dynamic equilibrium between the G-actin and polymeric forms,
which is regulated by ATP hydrolysis and G-actin concentration.
(d) Dynamic equilibrium is required for the cell functions. Some MFs are temporary
and others permanent.
3. Specific drugs affect polymer dynamics: Cytochalasins: prevent the addition of
new monomers to existing MFs, which eventually depolymerize; Phalloidin:A cyclic
peptide from the death cap fungus, blocks the depolymerization of MF Those drugs
disrupt the monomer-polymer equilibrium, so are poisonous to cells
4. Actin-binding proteins: The structures and functions of cytoskeleton are mainly
controlled by its binding proteins. Proteins play important roles in muscle contraction:
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Teaching plan of Cell Biology
Myosin: The actin motor protein ,thymosin and (profilin) promoting the assembly of
MF.
D.Functions of MFs※※
(1) Maintenance of cell shape and enforce PM to change cell
shape i.e.Microvillus: Support the projecting membrane of
intestinal epithelial cells
(2) Cell migration or motility (as in pseudopodia)
(3) To form contractile ring in cell division: At cytokinesis
(4) Muscle contraction：Sarcomere is the unit of
the muscle cells.
(5)Cytoplasm streaming
Intermediate filaments, Ifs：IFs are the most abundant and stable
components of the cytoskeleton ，fibrous proteins super coiled into
thicker cables,8-12nm, composed of one of several
keratin family ,depending on cell type
Function※: 1.Maintenance of cell
shape,2.Anchore of nucleus and certain other
organelles,3.Formation of nuclear lamina
The comparison among three types of the cytoskeleton
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Teaching plan of Cell Biology
Summary of cytoskeleton system
Conceptionn types and the functions of the cytoskeleton
Structures of MT
building blocks of MTs and MFs
Arrangement of protofilaments
MTOC and its elements
Specific drugs stabilize MTs or MF
Functions of MTs and MFs
Cytoskeletal systems are dynamic and adaptable. Nucleation is rate-limiting step in
the formation of a cytoskeletal polymer.Regulation of the dynamic behavior and
assembly of the cytoskeletal filaments allows eucaryotic cells to build an enormous
range of structures from the three basic filaments systems.
Reference of Major Journals
Cell
Nature
Science
EMBO
Annual Review of Cell Biology
Trends in Cell Biology
Cell Research
Biology Website
http://www.ebiotrade.com/
http://www.bioon.com/
http://www.bbioo.com/
http://bbs.bioon.com/bbs/index.php
http://www.dxy.cn/
http://bbs.biooo.com/
NCBI-American http://www.ncbi.nlm.nih.gov
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