Lesson 1.3: Cell Modifications

Vocabulary practice cards covering apical, basal, and lateral epithelial modifications, as well as specialized modifications in plant and animal cells.

Cell Modification

Also known as cell differentiation or specialization, it is a process after cell division to produce newly formed cells that are structurally modified to perform functions effectively and efficiently.

Epithelial tissue

One of the main types of tissues in the human body that covers or lines every surface and acts as a selective permeable barrier.

Apical Modifications

Modifications found on the apical surface of epithelial cells responsible for functions such as secretion, absorption, and movement.

Cilia

Hair-like, membrane-bound structures covering the apical surface that have a beating motion like waves; usually used for locomotion in microscopic organisms.

Flagella

Hair-like structures mainly used for the locomotion of cells; cells possessing these are referred to as flagellates.

Microvilli

Also known as brush or striated border, these are small, finger-like projections that increase surface area for absorption and secretion.

Basal Modifications

Cell modifications found specifically on the basal surface of epithelial cells.

Basal Lamina

A structure that provides support to the overlying epithelium, limits contact between epithelial cells and other tissue types, and helps cells anchor to underlying connective tissue.

Hemidesmosomes

Protein filaments that provide a strong connection between the epithelial cell, its basement lamina, and the underlying connective tissue.

Lateral Modifications

Modifications of cells found on the lateral surface or sides of epithelial cells.

Tight junctions

Also known as zonula occludens, these zipperlike fastenings between adjacent cells are responsible for blocking the flow of fluids between epithelia.

Adherens junctions

Also known as zonula adherens, these provide a strong bond between the sides of adjacent epithelial cell membranes.

Desmosomes

Also known as macula adherens, these form a link between cells and are most common in skin cells; they are found beneath adherens junctions.

Gap junctions

Connections formed by joining two identical plasma membrane channels that allow direct passage of molecules and communication between two different cells.

Root hairs

Projections from root-hair cells in plants responsible for water and mineral absorption; they contain many mitochondria for active transport energy requirements.

Xylem Vessels

Long tubes made of individual cells joined end to end with cell walls made of lignin; they transport water and minerals and provide structural support to the plant.

Guard cells

Cells in the plant epidermis that surround the stomata; they open the stomata when turgid (bending outward) and close them when flaccid (bending inward).

Trichomes

Hair-like or gland-like outgrowths from the plant epidermal cell-layer that reduce water loss, reflect intense light, and secrete defense chemicals.

Erythrocytes

Also known as red blood cells, these are specialized cells that do not contain a nucleus and use iron-containing hemoglobin to combine with oxygen.

Neurons

Also known as nerve cells, they contain dendrites to receive electrical signals and axons to transmit signals to other neurons.

Muscle cells

Cells composed of special proteins called actin and myosin, which allow the muscles to contract.

Sperm cells

Specialized cells necessary for human reproduction consisting of a head (containing the nucleus and acrosome), neck, middle piece (containing spiral-shaped mitochondria), and a tail.