Quest #3 Study Guide Flashcards

These flashcards cover key terms and concepts from Chapters 7 & 9, focusing on cell interactions, cytoskeletal elements, and muscle contraction.

Glycocalyx

A carbohydrate-rich layer surrounding the cell membrane, involved in cell recognition and protection.

Extracellular Matrix (ECM)

A complex network of proteins and carbohydrates that provide structural and biochemical support to surrounding cells.

Basement Membrane

A thin layer of ECM that anchors epithelial tissues to underlying connective tissues; functions in structural support and filtration.

Collagens

A family of proteins that provide structural support and strength in tissues.

Fibronectins

Glycoproteins that facilitate cell adhesion to the ECM and promote cellular migration.

Proteoglycans

Large proteins bound to glycosaminoglycans; they help to retain water in the ECM and play a role in cell signaling.

Hyaluronic Acid

A non-sulfated glycosaminoglycan involved in tissue hydration, lubrication, and cell migration.

GAGs (Glycosaminoglycans)

Long unbranched carbohydrates that play a critical role in maintaining ECM structure and hydration.

Laminins

Key components of the basal lamina that influence cell differentiation, migration, and adhesion.

Matrix Metalloproteinases (MMPs)

Enzymes that degrade components of the ECM, crucial for tissue remodeling and repair.

Integrins

Transmembrane receptors that mediate cell-ECM adhesion and signal transduction.

Focal Adhesions

Complexes that link the ECM to the cytoskeleton, playing a significant role in cell signaling and migration.

Hemidesmosomes

Structures that anchor epithelial cells to the basement membrane, providing mechanical stability.

Selectins

Cell adhesion molecules that mediate the attachment of leukocytes to the endothelium.

IgSF Proteins (Immunoglobulin Superfamily)

A large group of proteins involved in cell recognition and adhesion.

Cadherins

Calcium-dependent glycoproteins that mediate cell-cell adhesion.

Adherens Junctions

Cell junctions that connect the actin cytoskeleton of one cell to another, involved in maintaining tissue integrity.

Gap Junctions

Channels that allow for direct communication between adjacent cells by permitting the passage of ions and small molecules.

Tight Junctions

Connections that create a seal between epithelial cells, preventing paracellular movement of solutes.

Desmosomes

Strong adhesion complexes that link neighboring cells together, providing mechanical stability.

Blood-Brain Barrier Junctions

Formed primarily by tight junctions that restrict the passage of substances between blood and brain tissue.

Connexins

Proteins that form gap junctions, allowing intercellular communication.

Connexons

Hollow structures formed by six connexin proteins that create channels between cells.

Tunneling Nanotubes

Thin, long cytoplasmic protrusions that facilitate communication and transport between cells.

Plasmodesmata

Channels that traverse the cell walls of plant cells, allowing for transport and communication.

Cytoskeleton

A network of fibers that provide structural support, shape, and movement to cells.

Functions of the Cytoskeleton

Support, shape maintenance, intracellular transport, and cell division.

Eukaryotic Cytoskeletal Elements

Microtubules, microfilaments, and intermediate filaments.

Building Blocks of Microtubules

Tubulin dimers (alpha and beta tubulin).

Microfilaments Building Block

Actin monomers.

Intermediate Filament Building Blocks

Various proteins, including keratins, desmin, and vimentin.

Bacterial Homologues for Microtubules

FtsZ protein.

Bacterial Homologues for Microfilaments

MreB and Mlb protein.

Bacterial Homologues for Intermediate Filaments

Crescentin protein.

Microtubule Ultrastructure

Hollow tubes composed of 13 protofilaments arranged in a cylinder.

Dynamic Instability

The phenomenon where microtubules rapidly grow and shrink, allowing for adaptability.

Treadmilling

A process where the addition of tubulin dimers at the plus end and the loss at the minus end occurs concurrently, maintaining a constant length.

GTP Importance

GTP-bound tubulin promotes microtubule assembly and stability.

Functions of Microtubules

Cell shape maintenance, transport of organelles, and cell division (mitotic spindle formation).

FtsZ Function

A protein that plays a critical role in prokaryotic cell division.

Colchicine Effect on Microtubules

Inhibits microtubule polymerization, preventing mitotic spindle formation.

Taxol Effect on Microtubules

Promotes microtubule stabilization, preventing their depolymerization.

Microfilaments Functions

Involved in muscle contraction, cell shape maintenance, and cell motility.

MreB Function

An actin homolog that helps maintain bacterial cell shape.

Microfilament Assembly

Actin monomers polymerize to form filaments; requires ATP.

Microfilaments Compared to Microtubules

Microfilaments are thinner and made of actin, while microtubules are thicker and made of tubulin.

Actin Branch Formation Requirement

Nucleating proteins such as Arp2/3 complex are needed.

Listeria Monocytogenes Movement Mechanism

Uses the host's actin polymerization machinery to propel itself.

Cytoskeletal Element of ParM Homolog

Microfilaments.

Plasmid Partitioning Mechanism

Mediated by ParM that helps segregate plasmids during cell division.

Properties of Intermediate Filaments

Provide mechanical strength and structural support; are more stable than microfilaments and microtubules.

Intermediate Filament Bacterial Homologue

Bacterial protein called CreS, which influences curvature.

Cytoskeletal Element Properties

Each type has distinct building blocks, nucleotide requirements, diameters, polarities, and functions.

Molecular Motor Protein Energy Sources

Generated by the hydrolysis of ATP.

Categories of Molecular Motors

Myosins, kinesins, and dyneins.

Molecular Motor Cargo Types

Transport organelles, vesicles, and proteins within cells.

Kinesin Structure

Consists of two heavy chains and two light chains with a motor domain.

Kinesin Track Element

Microtubules.

Kinesin Direction of Movement

Moves towards the plus end of microtubules.

Cargo Specificity Mechanism

Achieved through binding to specific adapter proteins.

Highly Processive Definition

Ability to take continuous steps along a filament without detaching.

Dynein Functions

Transporting cellular cargo towards the minus end of microtubules, and in cilia and flagella movement.

Dynein Structure

Large, complex protein with multiple subunits including motor domains.

Dynein Movement Direction

Moves towards the minus end of microtubules.

Dynactin Role with Dynein

Acts as a binding platform for dynein to cargo.

Cilia and Flagella Locomotion Mechanism

Based on the sliding of microtubules powered by dynein activity.

Myosin Definition

A motor protein involved in muscle contraction and cellular movement.

Conventional Myosins

Myosins that interact with actin filaments to generate muscle contractions.

Myosin II Structure

Two heavy chains, two essential light chains, and two regulatory light chains.

Muscle Fiber Definition

A long, cylindrical cell containing multiple myofibrils.

Myofibril Definition

A long, filamentous organelle found in muscle fibers, responsible for contraction.

Sarcomere Definition

The fundamental unit of muscle contraction composed of actin and myosin filaments.

Sliding Filament Model Explanation

Describes muscle contraction through the sliding of actin filaments along myosin filaments.

Tropomyosin Function

Regulates contraction by blocking myosin binding sites on actin.

Troponin Function

Binds calcium ions to regulate tropomyosin and initiate contraction.

Titin Definition

A large protein that acts as a molecular spring, stabilizing the sarcomere structure.

Bacterial Chromosomes

Circular DNA molecules that contain essential genetic information for bacterial function.

How are plasmids partitioned?

Plasmids are partitioned during cell division through specific mechanisms that ensure their equal distribution to daughter cells, often involving partitioning proteins.

What are the properties of intermediate filaments?

Intermediate filaments are strong, flexible protein fibers that provide structural support to cells, maintain cell shape, and anchor organelles.

Bacterial homologue for intermediate filament proteins and its function

is known as "crescentin," which provides structural support to maintain the shape of rod-shaped bacteria.

Two groups of myosin

are classified as "class 1 and class 2 myosins," which differ in structure and function, primarily involved in muscle contraction and intracellular transport.

Microtubules are made up of this monomer

tubulin, which is a protein that polymerizes to form hollow tubes important for cell shape and transport.

A microtubule has the following nucleotide requirements:

GTP

This type of tubulin nucleates microtubule assembly at MTOCs

gamma-tubulin

A microtubule is made up of how many protofilaments?

13

The microtubules of cilia and flagella have what type of arrangement?

9+2 arrangement

Mirofilaments are made of which monomer?

actin

Actin is an?

ATPase that plays a critical role in muscle contraction and cell shape maintenance.

Monomeric actin is called what?

G-actin

Actin branches are nucleated by?

the Arp2/3 complex.

The thin filaments in a sarcomere are made up of which protein?

Actin

What are intermediate filaments made from?

A variety of proteins which can include Lamin, Keratin, and Peripherin.

What nucleotide requirement do intermediate filaments have?

None, they don’t require any.

Do intermediate filaments exhibit polarity?

No, intermediate filaments do not exhibit polarity, as they are non-polar structures that provide structural support and stability in cells.

Diameter of intermediate filaments

10-12 nm

This type of cell-ECM interaction connects intermediate filaments to the cell surroundings

Hemidesmosomes

MreB and Mbl are what type of cytoskeletal homologue in bacteria?

Actin-like proteins

FtsZ requires what nucleotide for polymerization?

GTP

What type of cytoskeletal homologue is crescentin?

intermediate filament

The pathogenic bacterium Listeria monocytogenes hijacks the cell’s what?

Actin