Questions and Answers
Which macromolecules form the extracellular matrix (ECM) components mentioned?
Cadherins are responsible for forming hemidesmosomes.
False
What proteins form hexameric complexes in gap junctions?
Connexins
The adhesive glycoprotein mentioned that holds laminin and type IV collagen networks together is called ________.
Signup and view all the answers
Match the following structures with their functions or characteristics:
Signup and view all the answers
What is the primary role of cadherins in epithelial cells?
Signup and view all the answers
The central hydrophilic pore of connexons is 1.5 nm in diameter.
Signup and view all the answers
The process by which integrins bind extracellular macromolecules is facilitated by the presence of ________.
Signup and view all the answers
What is the primary function of glycolipids in the cell membrane?
Signup and view all the answers
The glycoproteins in the glyocalyx do not assist in cell recognition.
Signup and view all the answers
What enables cells to adhere to one another and provides protection against extracellular fluid?
Signup and view all the answers
In the mitochondrial matrix, there exists a double-stranded circular _____ that is self-replicating.
Signup and view all the answers
Which of the following incorrectly describes the properties of the phospholipid bilayer?
Signup and view all the answers
Match the following cellular components with their roles:
Signup and view all the answers
Steroid rings in the membrane primarily function as enzymes.
Signup and view all the answers
What is the name of the space between the outer and inner membranes of mitochondria?
Signup and view all the answers
What shape of cells typically has elongated nuclei?
Signup and view all the answers
Cuboidal or pyramidal cells have flattened nuclei.
Signup and view all the answers
What is the connective tissue that underlies the epithelial lining in organs?
Signup and view all the answers
The area of contact between the epithelium and connective tissue may be increased by small evaginations called __________.
Signup and view all the answers
Which type of junction is the most apical and frequently found in epithelial tissues?
Signup and view all the answers
Match the following types of cells with their corresponding nucleus shape:
Signup and view all the answers
Epithelial cells generally show a lack of polarity.
Signup and view all the answers
What are the contact points between plasma membranes of tissue cells called?
Signup and view all the answers
Study Notes
Extracellular Matrix (ECM) Components
- ECM consists of laminin and type IV collagen, forming 3-dimensional arrays.
- Laminin and type IV collagen networks are interconnected by the adhesive glycoprotein entactin/nidogen and the proteoglycan perlecan.
Adherens Junctions (Zonula Adherens)
- Form a continuous band beneath tight junctions, located at the luminal end of lateral membranes.
- Cell adhesion is mediated by cadherins—transmembrane glycoproteins that link to catenins and actin filaments.
- Function:
- Links cytoskeletons of adjacent cells, contributing to a cohesive epithelial layer.
- Part of the terminal web, involved in cytoplasmic motility.
Hemidesmosomes
- Modified desmosomes located at the basal surface of columnar epithelium.
- Transmembrane proteins known as integrins bind laminin and collagen type IV, functioning in the presence of calcium ions (Ca2+).
- Function:
- Anchors the cytoskeleton to the basal lamina.
Gap Junctions (Nexus)
- Facilitate intercellular communication via connexins that form hexameric complexes (connexons) with a central 1.5 nm pore.
- Nuclear shapes vary according to cell morphology: elongated nuclei in tall cells, flattened in squamous cells, spherical in cuboidal/pyramidal cells.
Cell Junctions
- Contact points between plasma membranes of tissue cells, crucial for adhesion and communication.
- Found in the lamina propria, connective tissue supporting various epithelial linings including digestive, respiratory, and urinary systems.
- Junctions are typically organized at the apical end of epithelial cells, with irregularities (papillae) enhancing contact area with connective tissue.
Tight Junctions (Zonula Occludens)
- Located at the most apical end of epithelial cells, forming bands encircling each cell.
- Common in epithelial tissues, especially those subject to friction, such as skin or tongue.
- Structure: Comprises web-like strands of transmembrane proteins, restricting passage between cells.
Membrane Structure and Function
- Epithelial cells exhibit polarity with differing characteristics on each side of their membranes.
- Glycolipids (5% of membrane composition) have attached carbohydrate groups, contributing to asymmetry.
- Glycocalyx is a sugary coating from glycolipids and glycoproteins, enabling cell recognition and adhesion.
Mitochondrial Structure
- Intermembranous space exists between the outer and inner mitochondrial membranes.
- Mitochondrial matrix contains double-stranded circular DNA, ribosomes, and dense matrix granules, contributing to self-replication and enzyme functionality.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz covers the structures and functions of macromolecules secreted by epithelial cells, particularly focusing on the extracellular matrix (ECM) components such as laminin and type IV collagen. Additionally, it explores the role of adherent junctions and hemidesmosomes in cellular organization.
