The Genetic Control Center and Cell Dynamics

A set of vocabulary flashcards covering cell organelles, structures, and transport mechanisms based on the lecture notes.

Nucleus

A double-membrane envelope punctured by nuclear pores that stores the cell's genetic blueprint ($DNA$/chromatin) and coordinates cell division and protein synthesis.

Nucleolus

A dense, spherical structure located entirely inside the nucleus that produces and assembles ribosomes.

Ribosomes

Tiny, non-membranous complexes made of $RNA$ and proteins that serve as the sites of protein synthesis.

Rough Endoplasmic Reticulum (Rough ER)

A network of interconnected, flattened membrane sacs studded with ribosomes that synthesizes, folds, and modifies proteins for export or the cell membrane.

Smooth Endoplasmic Reticulum (Smooth ER)

A network of tube-like membrane structures that lack ribosomes; it synthesizes lipids and steroid hormones while detoxifying harmful chemicals.

Golgi Apparatus

A stack of flat, membrane-enclosed sacs called cisternae that modifies, sorts, and packages proteins and lipids into vesicles.

Mitochondria

The powerhouse of the cell featuring inner membrane folds called cristae, where nutrients are converted into $ATP$ (cellular energy) via cellular respiration.

Chloroplasts

Organelles found in plant cells containing thylakoids (grana) and stroma that convert sunlight, water, and $CO_2$ into glucose via photosynthesis.

Vacuoles

Sac-like membrane vesicles that store water, salts, pigments, and waste; in plants, a large central version helps maintain turgor pressure.

Lysosomes

Small, spherical, membrane-bound sacs filled with hydrolytic enzymes that break down worn-out cell parts, debris, and foreign invaders.

Peroxisomes

Small, single-membrane vesicles that break down fatty acids and detoxify hydrogen peroxide ($H_2O_2$) into water and oxygen.

Cytoskeleton

A network of protein filaments (microtubules, microfilaments, and intermediate filaments) that maintains cell shape and provides tracks for organelle movement.

Centrioles & Centrosome

Paired, barrel-shaped organelles composed of microtubules that organize microtubule assembly and help pull chromosomes apart during cell division.

Cilia and Flagella

Hair-like (cilia) or whip-like (flagella) projections made of microtubules that aid in cell movement or moving fluids across the cell surface.

Cell Membrane (Plasma Membrane)

A selectively permeable phospholipid bilayer containing proteins and cholesterol that controls the movement of substances in and out of the cell.

Cell Wall

A rigid outer layer composed of cellulose (in plants) or chitin (in fungi) that provides structural support and protection.

Eukaryotic Cells

Cells that contain membrane-bound organelles to compartmentalize functions.

Prokaryotic Cells

Cells that completely lack membrane-bound organelles.

Osmosis

The movement of water across a selectively permeable membrane from an area of high water concentration to an area of low water concentration.

Facilitated Diffusion

The movement of substances down their concentration gradient (high to low) through transport proteins without requiring $ATP$.

Active Transport

The movement of substances across a membrane against their concentration gradient (low to high) using energy in the form of $ATP$.

Concentration Gradient

The difference in the concentration of a substance between two areas.

Isotonic Solution

A solution where the concentration of solute is the same inside and outside the cell, resulting in no net movement of water.

Hypotonic Solution

A solution with a lower solute concentration outside the cell, causing water to move into the cell, making it swell.

Hypertonic Solution

A solution with a higher solute concentration outside the cell, causing water to move out of the cell, making it shrink.

Fluid Mosaic Model

A model describing the cell membrane as a flexible phospholipid bilayer with various proteins, cholesterol, and carbohydrates scattered throughout it.