Bio 250: Advanced Cell and Molecular Biology - Introduction to the Cell Unit 1 Handouts Part A

Comprehensive vocabulary flashcards covering cell structure, organelles, membranes, the cell cycle, mitosis, apoptosis, and stem cells from Bio 250: Advanced Cell and Molecular Biology.

Approximate number of cells in the human body

About $37$ trillion cells, with all cells containing the entire genome except red blood cells (RBCs).

Somatic cells

Body cells containing two complete copies of the genome, rendering them diploid.

Diploid

Describing a cell that contains two complete sets or copies of the genome, typical of human somatic cells.

Haploid

Describing a cell that contains only one copy of the genome, such as human sperm and egg cells.

Stem cells

Relatively unspecialized cells that provide a reserve supply of cells by replicating themselves through self-renewal and dividing to produce differentiated cells.

Connective tissues

A variety of cell types and surrounding materials that protect, support, bind to cells, and fill spaces throughout the body, including cartilage, bone, blood, and fat.

Epithelium

Tight cell layers forming protective linings that function in protection, secretion, absorption, and excretion.

Muscle tissue

Tissue composed of specialized cells that contract to provide bodily movement.

Nervous tissue

Tissue composed of neurons that transmit information via electrochemical impulses to coordinate movement and respond to environmental stimuli, along with supportive neuroglia.

Prokaryotes (Archaea and Bacteria)

Unicellular organisms belonging to the domains Archaea and Bacteria that lack a membrane-bound nucleus and complex internal organelles.

Eukarya

The biological domain comprising unicellular and multicellular organisms whose cells contain membrane-bounded organelles and a defined nucleus.

Ribosomes

Globular assemblies of RNA and protein found across all biological domains that act as scaffolds and catalysts essential for protein synthesis.

Organelles

Membrane-bound internal compartments that divide cellular labor by partitioning specific functions and keeping related biochemicals close together to interact efficiently.

Nuclear envelope

The membranous boundary surrounding the nucleus that separates genetic material from the cytoplasm.

Nuclear pores

Protein complexes puncturing the nuclear envelope that allow the regulated movement of biochemicals between the nucleus and the cytoplasm.

Nuclear lamina

A fibrous structural network within the nucleus that provides mechanical support and holds nuclear pores in place.

Nucleolus

A dense structure inside the nucleus where ribosomes are produced.

Endoplasmic Reticulum (ER)

A network of interconnected membranous tubules and sacs extending from the nuclear envelope toward the plasma membrane, functioning in protein and lipid synthesis.

Rough ER

The portion of the endoplasmic reticulum studded with ribosomes, directly involved in protein synthesis and folding.

Smooth ER

The portion of the endoplasmic reticulum that lacks ribosomes and is responsible for lipid synthesis.

Vesicles

Membrane-bounded, saclike organelles that temporarily store or transport cellular products throughout or out of the cell.

Golgi Apparatus

Stacks of interconnected, flat, membrane-enclosed sacs where sugars are synthesized, linked to proteins and lipids (forming glycoproteins and glycolipids), and secretions are packaged into budding vesicles.

Lysosomes

Membrane-bound sacs containing approximately $43$ types of digestive enzymes that dismantle bacterial remnants, worn-out organelles, and excess cholesterol.

Autophagy

The cellular self-cleaning process ("self-eating") wherein lysosomes degrade damaged or worn-out internal components and minor debris to preserve cell health.

Tay-Sachs disease

A fatal, inherited neurodegenerative lysosomal storage disorder caused by a deficiency in the enzyme hexosaminidase-A, resulting in progressive neuronal damage.

Peroxisomes

Enzyme-studded sacs with outer membranes that break down lipids and rare biochemicals, synthesize bile acids, and detoxify oxygen free radicals; abundant in liver and kidney cells.

Mitochondria

Double-membraned organelles with enzyme-studded inner cristae that liberate energy by breaking chemical bonds in nutrient molecules and storing it as adenosine triphosphate ($\text{ATP}$).

Phospholipid bilayer

The structural backbone of biological membranes, consisting of hydrophilic phosphate heads oriented outwards and hydrophobic fatty acid chains facing inwards.

Signal transduction

A communication pathway formed by membrane-associated molecules that detects external chemical cues and transmits the signals into the cell interior.

Cellular adhesion

The plasma-membrane-mediated process that enables cells to physically attach to specific other cells.

Cytoskeleton

A meshwork of protein rods and tubules that maintains cellular shape, links adjacent cells, and serves as tracks to transport organelles and cellular cargo.

Microtubules

Hollow cytoskeletal cylinders measuring approximately $23\text{ nm}$ in diameter, assembled from tubulin dimers, that compose cilia and the mitotic spindle.

Intermediate filaments

Cytoskeletal elements measuring approximately $10\text{ nm}$ in diameter composed of coiled protein dimers that reinforce structural integrity.

Microfilaments

Solid cytoskeletal fibers measuring approximately $7\text{ nm}$ in diameter, built of actin molecules, that provide contractile force and mediate cytokinesis.

Cilia

Motile hairlike cellular extensions built from microtubules that coordinate wave-like movements to transport substances, such as mucus, along epithelial cell surfaces.

Apoptosis

A precise, genetically programmed sequence of events leading to coordinated cell death.

Cell cycle

The orderly sequence of events associated with cell division, encompassing interphase, mitosis, and cytokinesis.

Interphase

The preparation phase of the cell cycle comprising $G_1$, $S$, and $G_2$ phases, during which cellular components, organelles, and DNA are replicated.

$$G_0\text{ phase}$$

A quiescent 'quit' phase entered from $G_1$ where cells exit the active cell cycle to remain specialized without dividing.

Centromere

The constricted chromosomal region that physically joins two identical sister chromatid copies formed during the $S$ phase.

Mitosis

The nuclear division phase of the cell cycle wherein duplicated DNA is precisely divided into two identical nuclei.

Prophase

The initial phase of mitosis in which DNA condenses into tight coils, microtubules organize into the spindle, the nuclear envelope degrades, and the nucleolus vanishes.

Metaphase

The mitotic phase during which chromosomes attach to the mitotic spindle via their centromeres and align along the equatorial plane under equal opposing forces.

Anaphase

The stage of mitosis where centromeres split and sister chromatids separate into distinct chromosomes, migrating to opposite cellular poles.

Telophase

The final stage of mitosis wherein the mitotic spindle disassembles and nuclear envelopes and nucleoli re-form around the separated chromosomal clusters.

Cytokinesis

The division of the cytoplasm following mitosis, driven by the contraction of a microfilament ring that pinches the cell into two distinct daughter cells.

Telomeres

Repetitive 6-base DNA sequences located at chromosome ends that lose $50\text{--}200$ bases per cell division, acting as a cellular clock that halts division after approximately $50$ cycles.

Telomerase

An enzyme produced in sperm, egg, bone marrow, and cancer cells that synthesizes telomeric repeats to counteract telomere shortening and sustain proliferation.

Caspases

Killer proteolytic enzymes activated during apoptosis that systematically dismantle cellular proteins and internal structures.

Blebs

Irregular bulbous bulges protruding from the surface of a dying cell during apoptosis prior to fragmentation and engulfment by phagocytes.

Progenitor cells

Partially differentiated stem cell descendants that can divide to give rise to specialized cells but lack the capability of self-renewal.

Totipotent

The developmental capacity of a stem cell to give rise to every conceivable cell type in an organism.

Pluripotent

Stem cells possessing developmental potential to differentiate into many cell types, though having fewer possible developmental fates than totipotent cells.

Multipotent

Stem or progenitor cells whose developmental options are restricted to only a few related specialized cell types.

Induced pluripotent stem (iPS) cells

Somatic body cells that have been experimentally reprogrammed back into a less-differentiated, pluripotent state capable of yielding multiple specialized lineages.

Human microbiome

The complex community of microorganisms living in and on the human body, accounting for approximately $90\%$ of all cells in a human body.