Module 10 Flashcards
Tissue
A collection of cells that work together to perform a specific function.
Cell Junctions
A complex of proteins in the cell membrane where a cell makes contact with another cell or the extracellular matrix (physically connect one cell to the next and anchor cells to the extracellular matrix).
Microfilaments
A double helix of actin monomers. Smallest diameter. Maintain cell shape and used in muscle cell contractions.
Intermediate Filaments
A strong fiber composed of intermediate filament protein subunits. Medium diameter. Provide cells with mechanical strength.
Alpha Tubulin
One half of a tubulin dimer.
Beta Tubulin
One half of a tubulin dimer.
Dynamic Instability
Cycles of polymerization and depolymerization in microtubules.
Motor Proteins
Any of various proteins that are involved in intracellular transport or cause muscle contraction by moving the actin microfilaments inside the muscle cells (small accessory proteins).
Cell Adhesion Molecules
Allow cells to attach to other cells and to the extracellular matrix.
Integrins
Integral transmembrane glycoproteins for cells to attach to ECM. Occurs between the cell and the ECM. Attaches to the cytoskeleton.
Adherens Junction
A beltlike junctional complex composed of cadherins that attaches a band of actin to the cell membrane (goes around the circumference of the cell).
Hemidesmosome
A type of cell junction that anchors cells to the extracellular matrix (like desmosomes but use integrins not cadherins).
Gap Junction
A type of connection between the cell membranes of adjacent animal cells that permits material to pass directly from the cytoplasm of one cell to the cytoplasm of another (cell-to-cell communication).
Extracellular Matrix (ECM)
A meshwork of proteins and polysaccharides outside animal cells. The main constituent of connective tissue. For plants it is the cell wall and for animals it is abundant connective tissue. Influence the shape of the cells and the gene expression of the cells.
Laminin
A fibrous protein present in the basal lamina of the epithelia.
Cytoskeleton
An internal protein scaffold that helps cells to maintain their shape and serves as a network of tracks for the movement of substances within cells.
Microtubules
A hollow tube formed from tubulin dimers (α and β). Largest diameter. Maintain cell shape and make up spindles in cell division.
Actin
A protein that forms microfilaments. It associates with the motor protein myosin in muscles to contract and generate force.
Centrosome
A compact structure that is the microtubule organizing center for animal cells.
Myosin
A motor protein found in cells that carries cargo to the plus ends of microfilaments and is also used by both striated and smooth muscles to contract and generate force.
Kinesin
Moves the cargo towards the microtubule’s plus end.
Dynein
Moves the cargo towards the microtubule’s minus end.
Cadherins
Integral transmembrane glycoproteins for cell-to-cell attachment. Occurs in the extracellular domain. Attaches to the cytoskeleton.
Anchoring Junctions
Connect adjacent cells and are reinforced by the cytoskeleton.
Desmosomes
A buttonlike cell junction that holds the cell membranes of adjacent cells together (specific spots of dense clusters of cadherins).
Tight Junction
Prevent the movement of substances through the space between cells. Able to seal the extracellular space.
Plasmodesmata
Connections between the cell membranes of adjacent plant cells that permit molecules to pass directly from the cytoplasm of one cell to the cytoplasm of another (are continuous). Allow plant cells to transfer RNA molecules and proteins.
Collagen
The most abundant protein in the animal ECM. Composed of intertwined fibers (triple helix) that makes it stronger than if it were a single fiber of the same diameter.
Basal Lamina (Basement Membrane)
A specialized form of extracellular matrix that underlies and supports all epithelial tissues. Acts as a scaffold for other proteins to assemble on.
Organ
Two or more tissues that combine and function together.
4 Types of Tissues in Animals
1) Epithelial
2) Connective
3) Nervous
4) Muscle
Epidermis
The outermost layer of cells in multicellular organisms such as plants and animals that serves as a water-resistant and protective barrier.
Dermis
The layer of skin beneath the epidermis. It supports the epidermis both physically and by supplying it with nutrients and provides a cushion surrounding the body. Contains nerves and blood vessels.
Plus End
The faster-assembling end. Project outwards toward the cell membrane.
Minus End
The slower-assembling end.
Cilia
A hairlike structure that extends from the surface of cells.
Nonmotile Cilia
Non-moving cilia.
Motile Cilia
Moving cilia.
3 Major Types and Functions of Cell Junctions
1) Anchoring (connect cells together).
2) Barrier (prevent substances from going through).
3) Communicating (allow for cell communication).
Epithelial Tissue
Covers the outside of the body and lines many internal structures of the body.
Keratinocytes
Epithelial cells specialized to protect underlying tissues and organs.
Melanocytes
Produce the pigments of skin.
Connective Tissue
Provides structure and support.
Fibroblast
Found in the dermis. Produces the extracellular matrix.
Microfilament Functions
1) Transport of materials inside cells.
2) Shortening of muscle cells during contraction.
3) Separation of daughter cells at the end of animal cell division.
Microtubule Catastrophe
A dramatic shrinkage.
Types of Cell Junctions
1) Adherens Junctions
2) Desmosomes
3) Hemidesmosomes
4) Tight Junctions
5) Gap Junctions
Intracellularly Adherens Junctions
The belt of cadherins attaches to a band of actin microfilaments in the cytoplasm. Near the apical side (facing outside the cell body).
Extracellularly Adherens Junctions
The cadherins in adjacent cells attach to each other.
ECM Functions
1) Act as a supportive and protective material.
2) Allow for expression of different cell functions.
Cell Wall Layers
1) Middle Lamella
2) Primary Cell Wall
3) Secondary Cell Wall
Middle Lamella
Made of carbohydrates. Main mechanism by which plant cells adhere to one another.
Primary Cell Wall
Made of cellulose fibers, pectin, and several other proteins. Thin and flexible.
Secondary Cell Wall
Made of cellulose and lignin. Hardens the cell wall and makes it water resistant. Rigid.
Apical
Facing outside the cell body or lumen.
Basal
Attached to basal lamina.
Type I Collagen
The most abundant type of collagen. Found in the dermis of human skin and provides support.
Fibril
Composed of collagen bundles.
Fibers
Composed of fibrils.
Animal ECM
Composed of large fibrous proteins such as collagen, elastin, and laminin.
Keratins
Intermediate filaments found in epithelial cells.
Vimentins
Intermediate filaments found in fibroblasts.
Neurofilaments
Intermediate filaments found in neurons.
Lamins
Intermediate filaments found in the nucleus.
