Chapter 3: Cell Structure and Function - Sections 3.3 & 3.4 Vocabulary

Vocabulary practice flashcards covering Section 3.3 (The Cytoskeleton) and Section 3.4 (Plasma Membrane Structure and Function) from Chapter 3 of BC Biology 12.

Cytoskeleton

A network of interconnected protein filaments extending from the nucleus to the plasma membrane that allows eukaryotic cells to maintain their shape and organelles to move.

Actin Filaments

Long, extremely thin ($\sim 7\,\text{nm}$ in diameter), flexible fibres composed of two chains of globular actin monomers twisted in a helix that form dense structural webs and participate in cell movement.

Myosin

A motor molecule in muscle cells whose head interacts with ATP and actin and whose tail interacts with the membrane, pulling actin filaments along using ATP for energy.

Intermediate Filaments

Rope-like assemblies of fibrous polypeptides ($8\text{ to }10\,\text{nm}$ in diameter) intermediate in size between actin filaments and microtubules that provide structural support, such as strengthening hair.

Microtubules

Small, hollow cylinders ($\sim 25\,\text{nm}$ in diameter and $0.2\text{ to }25\,\mu\text{m}$ in length) composed of $13$ rows of alpha and beta tubulin dimers surrounding an empty core.

Centrosome

The main microtubule organizing centre in most eukaryotic cells that regulates microtubule assembly and contains a pair of centrioles in animal cells.

Centrioles

Short cylinders in animal cells located in the centrosome, composed of microtubules in a $9 + 0$ pattern of triplets (a ring of nine sets of microtubule triplets) lying at right angles to each other.

Cilia and Flagella

Hair-like extensions that provide cell movement, consisting of membrane-bound cylinders composed of a $9 + 2$ pattern of microtubules (nine microtubule doublets in a circle around two central microtubules).

Dynein

A motor molecule protein forming side arms on microtubule doublets in cilia and flagella that uses ATP to reach out to neighboring doublets and cause bending movement.

Fluid-Mosaic Model

A model describing the plasma membrane structure where a lipid bilayer has the fluid consistency of light oil (hydrophilic heads facing outwards/inwards and hydrophobic tails in the interior) embedded with laterally moving proteins.

Peripheral Proteins

Proteins partially embedded on one side of the plasma membrane that play structural roles in stabilizing and shaping the membrane or function in signalling pathways.

Integral Proteins

Proteins that span the entire plasma membrane and move laterally, determining specific membrane functions including transport, cell recognition, reception, and catalysis.

Channel Proteins

Integral membrane proteins that allow a particular molecule or ion to cross the plasma membrane freely by forming an open passage.

Carrier Proteins

Integral membrane proteins that selectively interact with a specific molecule or ion (such as GLUT carriers transferring glucose) to facilitate its movement across the plasma membrane.

Cell Recognition Proteins

Glycoproteins in the plasma membrane involved in cell identification and recognizing pathogens or foreign tissues.

MHC Glycoproteins

Major histocompatibility complex glycoproteins unique to each person that enable white blood cells to distinguish self from non-self, making organ transplants difficult to achieve.

Receptor Proteins

Plasma membrane proteins shaped in such a way that a specific molecule (such as growth hormone) can bind to them, causing a cellular response.

Enzymatic Proteins

Plasma membrane proteins that directly catalyze specific metabolic reactions (such as adenylate cyclase, which is involved in ATP metabolism).

Glycolipids

Membrane lipids that have attached carbohydrate chains protruding into the extracellular environment.

Glycoproteins

Membrane proteins that have attached carbohydrate chains protruding into the extracellular environment.

Homeostasis

The internal stability and maintenance of constant conditions within a cell, regulated by the plasma membrane controlling the entrance and exit of substances.