Chapter 3 - Part I: Cell Biology and Structures

Vocabulary practice flashcards generated from Chapter 3 - Part I lecture transcript on cell structures, membrane dynamics, organelles, and nuclear components.

Human Body Cell Count

Multi-cellular human bodies are made up of approximately $75\text{ trillion}$ cells, along with their products and fluids.

Genome

The complete set of genes in an organism; nearly all cell types in a multi-cellular organism share the same genome but access different parts of it.

Organelles

Specialized structures within a cell that perform specific biological functions.

Cell Membrane

The outermost, selectively permeable component of a cell (also called plasma membrane) that encloses cytoplasm, allows signal transduction, and enables attachment to form tissues.

Fluid Mosaic Model

A structural description of the cell membrane where proteins and cholesterol float and move within a dynamic bilayer matrix of phospholipids.

Phospholipid Bilayer

A double layer of lipid molecules forming the cell membrane, consisting of polar hydrophilic phosphate heads and nonpolar hydrophobic fatty acid tails.

Channels

Membrane transport proteins functioning as open or gated pores that allow water, small water-soluble molecules, or specific ions to enter or leave the cell.

Carriers

Membrane transport proteins that bind specific substances and move them across the plasma membrane.

Glycoproteins

Molecules composed of proteins with branching carbohydrate groups attached that determine blood types, serve as pathogen receptors, and facilitate cell-to-cell recognition.

Cytoplasm

The gel-like material filling most of the cell's volume, consisting of cytosol and cytoskeleton, which holds organelles in place and acts as the site for most cellular activities.

Cytosol

The liquid portion of the cytoplasm in which cellular components and organelles are suspended.

Cytoskeleton

A cell framework composed of protein rods and tubules (microfilaments and microtubules) that provides structural support, anchors organelles, and enables cell shape changes.

Endoplasmic Reticulum (ER)

A tubular network of membrane-bound flattened sacs, canals, and vesicles extending from the nucleus to the cell membrane that transports materials and produces proteins and lipids.

Rough ER

A region of the endoplasmic reticulum studded with ribosomes, located near the nucleus, that functions as the primary site of protein synthesis.

Ribosomes

Structures located on the rough ER or floating freely in cytoplasm that assemble amino acids into proteins.

Polysomes

Clusters of free-floating ribosomes in the cytoplasm that enable rapid synthesis of proteins needed in large quantities.

Smooth ER

A region of the endoplasmic reticulum lacking ribosomes, located near the cell membrane, containing enzymes for lipid production, fat absorption, and drug metabolism.

Golgi Apparatus

Stacks of membrane-bound sacs that collect, refine, sort, package, and distribute proteins produced in the cell.

Mitochondria

Mobile, elongate organelles that reproduce by division, feature inner membrane folds called cristae, and produce ATP energy for the cell.

Cristae

Folds within the inner membrane of mitochondria lined with enzymes that regulate cellular respiration.

Lysosomes

Acidic membrane sacs budding from the Golgi apparatus containing enzymes that digest foreign substances, nutrient molecules, and worn-out cell structures.

Peroxisomes

Enzyme-containing organelles abundant in liver and kidney cells that catalyze fatty acid breakdown, hydrogen peroxide destruction, and alcohol detoxification.

Cilia

Multiple hair-like membrane projections arranged in precise patterns that beat in successive waves to move materials across the cell surface.

Flagellum

A single tail-like cell projection (such as in sperm) that moves in an undulating wave motion to propel the entire cell.

Nucleus

A rounded organelle housing the cell's DNA that acts as the central control center for cellular activity.

Nuclear Envelope

A double-layered membrane boundary consisting of inner and outer lipid bilayers that encloses the nucleus.

Nuclear Pores

Protein-lined openings in the nuclear envelope that regulate the passage of substances into and out of the nucleus.

Chromosome

A tightly coiled nuclear structure composed of DNA and proteins that carries genetic information.

Chromatin

Uncoiled, relaxed chromosomes inside the nucleus resembling a loose bundle of string.

Nucleolus

A dense structure located within the nucleus responsible for producing ribosomes.