Lecture 12-Cell and Tissue form Flashcards
Tissues and Organs
What are tissues?
when it comes to shape cells,tissues and organs have?
– Tissue - a collection of cells that work together to
perform a specific function
Cells, tissues and organs have distinct shapes (form fits
function!)
Precap MOTOR PROTEINS
what are the motor proteins for the microtubules?
what are the motor proteins for the microfilaments
microtubules motor proteins are kinesin and dynein
microfilaments motor protein is myosin (actins motor proteins is myosin)
Two or more tissues combined and functioning together
organ
Cells, tissues and organs have distinct shapes (form fits
function!)
Cytoskeleton (in animals)
cell shape
Extracellular matrix (ECM) and cellular junctions
In plants why is ECM important?
what is adherence?
structural integrity of tissues or organs (adherence)
In plants –> ECM important in cellular shape and
adherence
Cytoskeleton
The protein fibers of cytoskeleton provide what?
internal support for cells
All eukaryotic cells have:
(micro,micro)
Animals cells have what?
Microfilaments and Microtubules
* Animal cells also have intermediate filaments
Cytoskeleton: Microtubules
what are microtubules?
what is each dimer composed of?
Microtubules are
polymers of protein
dimers.
* Each dimer is made of
two tubulin proteins:
* α tubulin
* β tubulin
Microtubule Examples
In animal cells:
what is centrosome
what does centrosome help maintain? and withstand?
– centrosome (microtubule
organizing center) this helps maintain a cell’s shape and allows it to withstand compression
MIcrotubules also provide? found in_________ appartus? and make up?
Examples:
Microtubules also provide tracks for the transport of
material
* Found in the spindle apparatus (cell division)
* They also make up cilia and flagella:
* Examples:Chlamydomonas the green alga Chlamydomonas moves by the motion of two long cilia:
* the protists paramecium is covered with short cilia that beat in a coordinated fashion, allowing the organism to move through its environment:
* sperm cells swim by movement of one long cilium which is sometime called flagellum. airway epithelial cells,
* epithelial cells lining the upper respiratory tract have cilia that sweep fluid with debris and pathogens out of the airway
Cytoskeleton: Microfilaments
Are polymers of?
monomers of?
double helix of?
length?
where?
reinforcement of?
organize?____ membrane
Polymers of actin
monomers; helix
*Thinnest
*Relatively short and
extensively branched
just beneath the plasma
membrane of a cell.
* Reinforcement of the
plasma membrane
* Organize membrane
proteins
*microfilament is a double helix of actin monomers
Microfilament Example:
Epithelial Cells of Small Intestine
where are these microfilament found?
What do these microfilaments also take part in?
found in microvilli (intestinal cells)
* Longer bundles form band
around circumference of
epithelial cells
Also take part in
* Transport of materials inside
cells
* Shortening of muscle cells–>
contraction
* Separation of the daughter
cells–>animal cell division
Microtubules and Microfilaments Are Dynamic
subunits added and lost from ends
faster growing end?
slower growing end?
and in animal cells the minus end is at? and plus end projects?
Usually, these polymers grow
faster at one end than the other
* Faster-growing end = plus end
* Slower-growing end = minus end
In animal cells:
* minus ends - at organizing center of centrosome
* plus ends - project outward toward
the plasma membrane
Dynamic Instability in Microtubules
Depolymerization?
and Polymerization?
Microtubule plus end undergoes?
- Microtubule plus ends also undergo random cycles of rapid
shrinkage (depolymerization) followed by slower growth
(polymerization) = dynamic instability
What does dynamic instability in Microtubules allow? (Spindle microtubules)
allows spindle microtubules to _____ find and attach to chromosomes during _____ _________
\
Allows spindle microtubules to quickly find and attach to
chromosomes during
cell division
Motor Proteins, Microtubules,
Microfilaments and Movement
Movement of microfilaments and microtubules is on their ___? by _____ and _______
when joined with motor proteins what happens?
What can both microfilaments and microtubules act as?
And move what in the cell?
Movement of microfilaments and microtubules on
their own, by polymerization and depolymerization,
is limited.
* When joined with motor proteins, they are able to
cause large movements.
* Both microtubules and microfilaments can act as
tracks
* Move substances in the cell
Motor Proteins
where does Kinesin and dynein move the cargo?
*kinesin carries cargo such as vesicles toward the plus end of microtubules
And what does motor protein undergo?
- Kinesin moves the cargo
towards plus end - Dynein moves it toward the
minus end
Motor proteins undergo
conformational changes
* Powered by ATP
Example of Kinesin and Dynein at Work:
Example?
how does it occur? (melanophores) with the help of?
Movement of pigment:
kinesin? (dispersal night)
dynein?(aggregrate day)
in the light melanin granules are aggregated inward by dynein causing
in the dark, melanin granules are dispersed outward by kinesin, causing?
If embryo remains dark after daybreak, would
you attribute it to a defect in dynein or kinesin?
Colour changes in fish and amphibian embryos
* E.g. Zebrafish embryos
Occurs via specialized skin cells,
melanophores - move pigment
granules in response to hormones or neuronal signals
* Movement of pigment along
microtubules with help of motor
proteins kinesin and dynein
* Kinesin –> moves granules to plus end of microtubule–> dispersal (night)
* Dynein–> moves granules to minus end–> aggregation (day)
*in the dark, melanin granules are dispersed outward by kinesin, causing the embryo to be darkly colored
*in the light melanin granules are aggregated inward by dynein, causing the embryo to be lightly colored
If embryo remains dark after daybreak, would
you attribute it to a defect in dynein or kinesin? dynein
What can microfilament act as? move? muscle contraction also uses?
Motor protein= myosin which moves towards what end of microfilaments?
- Microfilaments can also act as tracks
- move cellular cargo, such as transport vesicles
- Muscle contraction also uses microfilaments and myosin
Motor protein = myosin (moves towards the plus
end of microfilaments)
* ATP needed to drive this
Microtubules in Cilia and Flagellae
how are the microtubules in cilia and flagella arranged?how many pairs along periphery? and how many along center
cross-linking proteins connect? and dynein connects?
Microtubules in cilia and flagella
arranged in “9+2” arrangement
* Nine pairs of microtubules along
periphery and two microtubules at the center
Cross-linking
proteins connect
outer doublets to
centre pair
* Dynein (motor protein)
molecules
connect doublets
to each other
ATP powers the motion of cilia and flagella.
Actin and Tubulin are Evolutionarily
Conserved
what types of cells are actin and tubulin found in?
amino acid sequences of yeast tubulin and human tubulin are _____ identical?
amino acid sequences of amoeba acitin and human actin are ____ identical
Actin and tubulin are found in all eukaryotic cells
– Amino acid sequences of yeast tubulin and human
tubulin are 75% identical
– Similarly, amino acid sequences of amoeba actin and
human actin are 80% identical
- Prokaryotes also have system of proteins similar in
structure and function to cytoskeleton of eukaryotic
cells
– Also, at least one of these cytoskeleton-like proteins is
expressed in chloroplasts and mitochondria of some
eukaryotic cells
– Supports endosymbiotic theory
Cytoskeleton: Intermediate Filaments
Intermediate diameters are polymers of? they combine to form?
*provide mechanical strength
The proteins making up intermediate filaments diff from?
Many different kinds (hundreds)
Intermediate diameter
* Are polymers of intermediate
filament proteins that
combine to form strong,
cable-like structures
* Provide mechanical strength
* The proteins making up
intermediate filaments differ from
one cell type to the other.
* Many different kinds (hundreds)
Intermediate Filament Examples:
Intermediate filaments composed of keratins in the? are stained?
Intermediate filaments composed of lamins in the? are stained?
Associations of Desmosomes provides?
intermediate filaments linked to cell junction in keratinocytes provides?
Keratins and Lamins–> intermediate filaments composed of keratin in the cytoplasm are stained red
intermediate filaments composed of Lamins in the nucleus are stained blue
Associations with Desmosomes–>
* Provides strong support for the
cells, intermediate filaments linked to cell junctions in keratinocytes provides structural support to the skin
Intermediate Filament Defects:
Epidermolysis Bullosa
individuals with this defect have?
And as a result the intermediate filament?
weakening?
*the skin is fragile and easily blisters in individuals with mutations in the intermediate filaments
Individuals with this
condition have defective
keratin genes.
As a result, intermediate
filaments do not
polymerize properly,
weakening the
connections between
the layers of cells that
make up the epidermis.
*the skin is fragile and easily blisters in individuals with mutations in intermediate filaments
Microfilaments
Cytoskeletal Element
Subunits?
Major Functions?
cell ____ and support, ____ movement (by crawling), ____ division(cytokinesis), vesicle transport, muscle ___________.
Cytoskeletal Element: Microfilaments
Subunits: Actin Monomers
Major Functions: Cell shape and support, cell movement (by crawling), cell division (cytokinesis), vesicle transport, muscle contraction
Intermediate filaments
Cytoskeletal Element
Subunits
Major Functions
Intermediate Filaments
Subunits: proteinsubunits
Major Functions: Cell shape and support
Microtubules
Cytoskeletal element
Subunits
Major Functions
Cell ____ and support, cell ____ (by cilia, flagella), cell division (chromosome segregation), vesicle ____, ______ arrangement
Cytoskeletal Element: Microtubules
Subunits: dimers (each dimer is composed of two tubulin proteins (alpha tubuin and beta tubulin))
Major Functions: Cell shape and support, cell movement (by cilia, flagella), cell division (chromosome segregation), vesicle transport, organelle arrangement
Extracellular Matrix (ECM)
Provides what?
What is ECM?Insoluble ______ made up of ____ and _______ secreted/modified by many different types of ______
Different types of ECM
what does ECM contribute to?
(cytoskeleton=cellshape/structure)(cell juction=allows cell to stick/tissues).
*cytoskeleton –> cell shape/structure
*cell junctions–> allows cells to stick;tissue
Extracellular matrix (ECM) provides molecular framework for structure
What is ECM?
– insoluble meshwork made up of proteins and
polysaccharides
– secreted/modified by many
Different types of cells
Many different types of ECM
– Differ in amount, type and organization of proteins and
polysaccharides that make them up
– Contributes to structural support
Extracellular Matrix in Plants
What is the ECM in plants? it provides support by forming?
Composition of ECM in plants?
In plants, ECM is the cell wall (cellulose)
* Provides support by forming interconnected
network between cells
* Composition:
1. Middle lamella
2. Primary cell wall
3. Secondary cell wall
Where is cellulose part of ECM assembled (plant cells)
how are glucose monomers and enzymes for assembly transported
Cellulose part of ECM assembled outside of plasma membrane
– Glucose monomers and enzymes for assembly are transported outside from inside the cell via microtubules
Extracellular Matrix in Plants
1. Middle lamella (outermost)
2. Primary cell wall
-mainly cellulose + other molecules including pectin
3. Secondary cell wall
-many cellulose+lignin
- Middle lamella (outermost):
- Glue-like complex carbohydrate
- Allows cells to stick - Primary cell wall
– Thin, flexible
– Mainly cellulose + other molecules including pectin - Secondary cell wall((found in many but not all plant cells)
Mainly cellulose and lignin
– Lignin – hardens cell wall; also waterproofing
– Allows some plants (trees) to grow very large
Extracellular Matrix in Animals
Mixture of?
composition?
ECM of animal cells (like plants) is a
mixture of proteins and
polysaccharides
* Composition:
* Large fibrous proteins
(including collagen,
elastin, and laminin)
* Tensile strength
* Gel-like polyshaccharide matrix (negatively charged)
* Protection against compression, physical stress
Collagen
Composition?
The most abundant protein in ECM of animals and the most abundant animal protein on planet
* Ninety percent of collagen = type I collagen:
* dermis of skin
* provides support
Composition:
* intertwined fibers
* polypeptides wound
in a triple helix
* One bundle forms a fibril
* Fibrils assembled into fibers
ECM, Cell Shape and Gene
Expression
Structure of ECM can influence?,ex: fibrolasts
Composition of ECM can influence? ex: neurons
Structure of ECM
can influence cell
shape:
-fibroblasts grown on a two-dimensional matrix attach and become flattened
-fibroblasts grown in a three-dimensional matrix are spindle shaped and look as they do in tissues
Composition of ECM can
influence cell shape:
-Neurons maintained in the absence of Laminin attach to the surface but do not take on the appearance of a nerve cell (-)
-Neurons cultured on a surface coated with laminin develop axon-like extensions of the cell membrane (+)
ECM, Cell Shape and Gene Expression
Structure and composition of ECM can influence
gene expression:
Grow mouse mammary epithelial cells in milk-inducing hormone prolactin–> cells express genes for
milk proteins
* Grow same cells on plain glass coated with collagen–>grow and live but secrete only small amount of milk
protein
* Grow same cells in 3D collagen gel–>synthesize and secrete 10x more milk protein
Adherens Junction
1. Associated adhesion Molecules or composition
2.How do they anchor to other cells
3.How do they anchor to cytoplasm
4.Function
1.Cadherins
2.Streaklike attachments
3.Microfilaments
4.Cell-cell adhesion
Desmosomes
1. Associated adhesion Molecules or composition
2.How do they anchor to other cells
3.How do they anchor to cytoplasm
4.Function
1.Cadherins
2.some proteins extend across the intermembrane filaments whole others anchor to the junction within cell
3.Intermiediate filaments
4.Cell-cell adhesion
Hemidesmosomes
1. Associated adhesion Molecules or composition
2.How do they anchor to other cells
3.How do they anchor to cytoplasm
4.Function
1.integrins
2.stable adhesion of basal epithelial cells to the underlying basement membrane
3.intermediate filaments
4.cell-extra cellular matric adhesion
Tight Junctions
1. Associated adhesion Molecules or composition
2.How do they anchor to other cells
3.How do they anchor to cytoplasm
4.Function
1.Claudins, Occludins
2.held tightly against each other
3.
4.epithelial boundary
Gap Junctions
1. Associated adhesion Molecules or composition
2.How do they anchor to other cells
3.How do they anchor to cytoplasm
4.Function
complex of integral membrane arranged in a ring are called
1. connexions
2.forms a channel allow cytoplasm of adjacent
3.
4.communcaiton between animal cells
Plasmodesmata
1. Associated adhesion Molecules or composition
2.How do they anchor to other cells
3.How do they anchor to cytoplasm
4.Function
permit materials to pass directly from cytoplasm of one cell to cytoplasm of anchor
1.cell membrane
2.plasma membrane
3.
4. communication between plant cells
Cadherins
(calcium-dependent adherence protein)
may only bind to another cadherin or the same type ex-amphibian embryos
are transmembrane proteins
E-cadherins
(epidermal cadherin)
present on surface of embryonic epidermal cells
N-cadherin
(neural cadherin)
present on neuronal cells
Integrins
*cells attach to proteins of the extracellular matrix through cell adhesion molecules called integrins
present on surface of every animal cell, also act as receptors that communicate info about extracellular matrix to interior of the cell
Anchoring Junction
connect adjacent cells and are reinforced by cytoskeleton
cadherins and integrins are organized into which cell junctions?
*cells junctions are complex structure in the cell membrane that allow cells to adhere to one another
2 types of cell junctions
1.adherens junctions
2.desmosomes
- adherens junctions-band of actin attached to the cell membrane by cadherins in a belt like structure (form belt around circumference of cells)
- desmosomes-allow cells to adhere to one another (buttonlike point of adhesion)
Tight junctions prevent?
prevent movement of substances through the space between
