Lecture 12-Cell and Tissue form

Question 1

Tissues and Organs
What are tissues?
when it comes to shape cells,tissues and organs have?

Answer 1

– Tissue - a collection of cells that work together to
perform a specific function

Cells, tissues and organs have distinct shapes (form fits
function!)

Question 2

Precap MOTOR PROTEINS
what are the motor proteins for the microtubules?
what are the motor proteins for the microfilaments

Answer 2

microtubules motor proteins are kinesin and dynein
microfilaments motor protein is myosin (actins motor proteins is myosin)

Question 3

Two or more tissues combined and functioning together

Answer 3

organ

Cells, tissues and organs have distinct shapes (form fits
function!)

Question 4

Cytoskeleton (in animals)

Answer 4

cell shape

Question 5

Extracellular matrix (ECM) and cellular junctions
In plants why is ECM important?
what is adherence?

Answer 5

structural integrity of tissues or organs (adherence)
In plants –> ECM important in cellular shape and
adherence

Question 6

Cytoskeleton
The protein fibers of cytoskeleton provide what?

Answer 6

internal support for cells

Question 7

All eukaryotic cells have:
(micro,micro)
Animals cells have what?

Answer 7

Microfilaments and Microtubules
* Animal cells also have intermediate filaments

Question 8

Cytoskeleton: Microtubules
what are microtubules?
what is each dimer composed of?

Answer 8

Microtubules are
polymers of protein
dimers.
* Each dimer is made of
two tubulin proteins:
* α tubulin
* β tubulin

Question 9

Microtubule Examples
In animal cells:
what is centrosome
what does centrosome help maintain? and withstand?

Answer 9

– centrosome (microtubule
organizing center) this helps maintain a cell’s shape and allows it to withstand compression

Question 10

MIcrotubules also provide? found in_________ appartus? and make up?
Examples:

Answer 10

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

Question 11

Cytoskeleton: Microfilaments
Are polymers of?
monomers of?
double helix of?
length?
where?
reinforcement of?
organize?____ membrane

Answer 11

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

Question 12

Microfilament Example:
Epithelial Cells of Small Intestine
where are these microfilament found?
What do these microfilaments also take part in?

Answer 12

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

Question 13

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?

Answer 13

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

Question 14

Dynamic Instability in Microtubules
Depolymerization?
and Polymerization?
Microtubule plus end undergoes?

Answer 14

• Microtubule plus ends also undergo random cycles of rapid
  shrinkage (depolymerization) followed by slower growth
  (polymerization) = dynamic instability

Question 15

What does dynamic instability in Microtubules allow? (Spindle microtubules)
allows spindle microtubules to _____ find and attach to chromosomes during _____ _________
\

Answer 15

Allows spindle microtubules to quickly find and attach to
chromosomes during
cell division

Question 16

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?

Answer 16

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

Question 17

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?

Answer 17

• Kinesin moves the cargo
  towards plus end
• Dynein moves it toward the
  minus end

Motor proteins undergo
conformational changes
* Powered by ATP

Question 18

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?

Answer 18

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

Question 19

What can microfilament act as? move? muscle contraction also uses?
Motor protein= myosin which moves towards what end of microfilaments?

Answer 19

• 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

Question 20

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?

Answer 20

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.

Question 21

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

Answer 21

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

Question 22

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)

Answer 22

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)

Question 23

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?

Answer 23

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

Question 24

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

Answer 24

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

Question 25

Microfilaments
Cytoskeletal Element
Subunits?
Major Functions?
cell ____ and support, ____ movement (by crawling), ____ division(cytokinesis), vesicle transport, muscle ___________.

Answer 25

Cytoskeletal Element: Microfilaments

Subunits: Actin Monomers

Major Functions: Cell shape and support, cell movement (by crawling), cell division (cytokinesis), vesicle transport, muscle contraction

Question 26

Intermediate filaments
Cytoskeletal Element
Subunits
Major Functions

Answer 26

Intermediate Filaments

Subunits: proteinsubunits

Major Functions: Cell shape and support

Question 27

Microtubules
Cytoskeletal element
Subunits
Major Functions
Cell ____ and support, cell ____ (by cilia, flagella), cell division (chromosome segregation), vesicle ____, ______ arrangement

Answer 27

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

Question 28

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).

Answer 28

*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

Question 29

Extracellular Matrix in Plants
What is the ECM in plants? it provides support by forming?
Composition of ECM in plants?

Answer 29

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

Question 30

Where is cellulose part of ECM assembled (plant cells)
how are glucose monomers and enzymes for assembly transported

Answer 30

Cellulose part of ECM assembled outside of plasma membrane
– Glucose monomers and enzymes for assembly are transported outside from inside the cell via microtubules

Question 31

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

Answer 31

1. Middle lamella (outermost):
   - Glue-like complex carbohydrate
   - Allows cells to stick
2. Primary cell wall
   – Thin, flexible
   – Mainly cellulose + other molecules including pectin
3. 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

Question 32

Extracellular Matrix in Animals
Mixture of?
composition?

Answer 32

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

Question 33

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

Answer 33

Composition:
* intertwined fibers
* polypeptides wound
in a triple helix
* One bundle forms a fibril
* Fibrils assembled into fibers

Question 34

ECM, Cell Shape and Gene
Expression
Structure of ECM can influence?,ex: fibrolasts
Composition of ECM can influence? ex: neurons

Answer 34

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 (+)

Question 35

ECM, Cell Shape and Gene Expression
Structure and composition of ECM can influence
gene expression:

Answer 35

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

Question 36

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

Answer 36

1.Cadherins
2.Streaklike attachments
3.Microfilaments
4.Cell-cell adhesion

Question 37

Desmosomes
1. Associated adhesion Molecules or composition
2.How do they anchor to other cells
3.How do they anchor to cytoplasm
4.Function

Answer 37

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

Question 38

Hemidesmosomes
1. Associated adhesion Molecules or composition
2.How do they anchor to other cells
3.How do they anchor to cytoplasm
4.Function

Answer 38

1.integrins
2.stable adhesion of basal epithelial cells to the underlying basement membrane
3.intermediate filaments
4.cell-extra cellular matric adhesion

Question 39

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

Answer 39

1.Claudins, Occludins
2.held tightly against each other
3.
4.epithelial boundary

Question 40

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

Answer 40

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

Question 41

Plasmodesmata
1. Associated adhesion Molecules or composition
2.How do they anchor to other cells
3.How do they anchor to cytoplasm
4.Function

Answer 41

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

Question 42

Cadherins
(calcium-dependent adherence protein)

Answer 42

may only bind to another cadherin or the same type ex-amphibian embryos
are transmembrane proteins

Question 43

E-cadherins
(epidermal cadherin)

Answer 43

present on surface of embryonic epidermal cells

Question 44

N-cadherin
(neural cadherin)

Answer 44

present on neuronal cells

Question 45

Integrins
*cells attach to proteins of the extracellular matrix through cell adhesion molecules called integrins

Answer 45

present on surface of every animal cell, also act as receptors that communicate info about extracellular matrix to interior of the cell

Question 46

Anchoring Junction

Answer 46

connect adjacent cells and are reinforced by cytoskeleton

Question 47

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

Answer 47

1. adherens junctions-band of actin attached to the cell membrane by cadherins in a belt like structure (form belt around circumference of cells)
2. desmosomes-allow cells to adhere to one another (buttonlike point of adhesion)

Question 48

Tight junctions prevent?

Answer 48

prevent movement of substances through the space between