BIOL 151 Lecture 6: Bio 151 - Chapter 10

25 views7 pages
9 Feb 2017
School
Department
Course

For unlimited access to Class Notes, a Class+ subscription is required.

BIO 151 - Chapter 10
10. 1 Tissues and Organs
Tissues and organs are communities of cells
o Tissue: a collection of cells that work together to perform a specific function
o Organ: when two or more tissues combine and function together
o Tissues and organs have distinctive shapes that reflect how they work and what
they do
Likewise, the different cell types that make up these organs have
distinctive shapes based on what they do in the organ
In animals, the shape of the cells is determined and maintained by
structural protein networks in the cytoplasm called the
Cytoskeleton
o The shape and structural integrity depends on the ability of
cells to adhere to one another
The adhesion of cells to one another depends on cell
adhesion molecules and other cytosolic proteins that
assemble into structures called Cellular Junction
Another important concept is the ability of cells to adhere to a meshwork
of proteins and polysaccharides outside the cell, known as the
Extracellular Matrix
The structure of skin relates to its function
o There are two main layers
Epidermis: the outer layer; serves as a water-resistant, protective barrier
It’s several cell layers thick
o Cells arranged in one or more layers are called epithelial
cells and all together make up a tissue called the Epithelial
Tissue
The tissue covers the outside of the body and lines
many internal structures, such as the digestive tract
and vertebrate blood vessels
The epidermal layer of skin is primarily composed of epithelial
cells called keratinocytes, and also contains melanocytes that
produce the pigment for the skin color
o Keratinocytes are specialized to protect underlying tissue
and organs, and are able to form this function because of
their system of cytoskeletal filaments
The filaments are often connected to cellular
junctions that hold adjacent keratinocytes together
o The junctions also connect the bottom layer of
keratinocytes to a specialized form of extracellular matrix
called the Basal Lamina (basement membrane)
find more resources at oneclass.com
find more resources at oneclass.com
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 7 pages and 3 million more documents.

Already have an account? Log in
BIO 151 - Chapter 10
Dermis: layer beneath the epidermis; supports the epidermis, both
physically and by supplying it with nutrients; provides a cushion
surrounding the body
Made up of mostly Connective Tissue: characterized by a few
cells and substantial amounts of extracellular matrix
Dermis is strong and flexible because of its composition of tough
protein fibers of the extracellular matrix
Contains many blood vessels and nerve endings
The main type of cell in the dermis is the Fibroblast, which
synthesizes the extracellular matrix and repair wounds
10.2 The Cytoskeleton
All eukaryotic cells have at least two cytoskeletal elements, Microtubules and
Microfilaments, and animal cells contain a third element, Intermediate Filaments
o All three are long chains (polymers), made up of protein subunits
Microtubules are hollow, tubelike polymers of tubulin dimers
o They have the largest diameter of the three elements
o Each protein dimer is made up of two slightly different tubulin proteins, called α
(alpha) and β (beta) tubulin
One α tubulin and one β tubulin combine to make a tubulin dimer
Tubulin dimers are assembled into microtubules
It’s the quaternary structure because there is two
o They have diverse functions
In animal cells, the microtubules radiate outward to the periphery sides of
the cell from the organizing center called the Centromere
This arrangement of the microtubules help cells withstand
compression, which helps maintain their shape
They also provide tracks for the transport of material from one part of the
cell to another
Found specially arranged in cilia and flagella, organelles that
propel the movement of cells or substances surrounding the cell
o They also form the spindle apparatus that separates replicated chromosomes
during eukaryotic cell division
Microfilaments are helical polymers of actin
o They are polymers of actin monomers, arranged to form a helix
o Are the thinnest of the three cytoskeletal fibers, are relatively short, and are
present in the cytoplasm, especially in the cell cortex, which is the area of the
cytoplasm underneath the plasma membrane
Microfilaments at the cortex reinforce the plasma membrane and organize
proteins associated with it
These cortical microfilaments also maintain the shape of a cell
find more resources at oneclass.com
find more resources at oneclass.com
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 7 pages and 3 million more documents.

Already have an account? Log in

Get access

Grade+
$10 USD/m
Billed $120 USD annually
Homework Help
Class Notes
Textbook Notes
40 Verified Answers
Study Guides
1 Booster Class
Class+
$8 USD/m
Billed $96 USD annually
Homework Help
Class Notes
Textbook Notes
30 Verified Answers
Study Guides
1 Booster Class