Cell Biology, Cell Cycle, and Genetics

Comprehensive vocabulary flashcards covering cellular organisation, microscopy, cell organelles, nuclear structure, mitosis, meiosis, and cytogenetics.

Levels of Organisation

The hierarchical degrees of complexity in which matter is structured, where each successive level is composed of elements from the preceding level.

Organic Biomolecules

Chemical substances exclusive to living organisms, consisting of glucids, lipids, proteins, and nucleic acids.

Inorganic Biomolecules

Chemical substances present in both living and non-living matter, specifically water and mineral salts.

Metabolism

The total set of chemical reactions by which living organisms transform nutrients and exchange matter and energy with their environment.

Optical Microscope

The oldest design of microscope that uses visible light and a system of lenses to magnify specimens, historically used when the Cell Theory was established.

Transmission Electron Microscope (TEM)

An electron microscope that transmits beams of electrons through ultra-thin sliced samples to visualize fine internal details of non-living specimens.

Scanning Electron Microscope (SEM)

An electron microscope that scans beams of electrons over the surface of chemically preserved, dehydrated specimens to generate three-dimensional (3D) surface images.

Nucleoid

The region in prokaryotic cells containing free genetic material consisting of two circular, coiled chains of DNA without an enclosing membrane.

Plasmid

A small circular ring of accessory DNA in bacteria that contains specific genetic information independent of the nucleoid.

Cytoskeleton

A network of protein filaments in eukaryotic cells that maintains cell shape, mediates cellular motility, facilitates intracellular organelle transport, and directs cell division.

Rough Endoplasmic Reticulum (RER)

A network of membranous tubules and sacs studded with ribosomes on its outer surface that stores and modifies synthesized proteins before transporting them to the Golgi apparatus.

Smooth Endoplasmic Reticulum (SER)

A ribosome-free membranous network continuous with the rough ER that synthesizes lipids and neutralizes toxic substances.

Golgi Apparatus

An organelle formed by flattened sacs and vesicles that receives substances from the endoplasmic reticulum and packages them into vesicles for secretion.

Lysosomes

Digestive vesicles originating from the Golgi apparatus that contain hydrolytic enzymes to break down complex molecules, recycle old organelles, and digest food particles.

Mitochondrion

A double-membraned organelle containing cristae, its own DNA, and ribosomes, responsible for ATP synthesis via cellular respiration.

Centrioles

Cylindrical structures found exclusively in animal cells that coordinate the movement of cilia and flagella and organize the distribution of chromosomes during division.

Chloroplast

A double-membraned organelle in plants and algae that contains chlorophyll pigments, thylakoids, stroma, and its own DNA, functioning as the site of photosynthesis.

Nuclear Lamina

A network-like protein scaffold lining the inner nuclear membrane that provides structural support and maintains the shape and organization of the nucleus.

Nuclear Pores

Openings in the nuclear envelope that regulate the transport of macromolecules, RNA, and small solutes between the nucleoplasm and cytoplasm.

Nucleolus

A non-membrane-bound dense subnuclear structure responsible for the transcription and assembly of ribosomes.

Histones

Basic proteins around which linear eukaryotic DNA wraps to form nucleosomes, condensing the genetic material by approximately $1{,}000$ times to fit inside the nucleus.

Euchromatin

The lightly stained, less condensed form of nuclear chromatin under electron microscopy that represents transcriptionally active DNA.

Heterochromatin

The darkly stained, highly condensed regions of chromatin typically located adjacent to the nuclear membrane and nucleolus.

Interphase

The preparatory, non-dividing phase of the cell cycle consisting of $G_1$, $S$, and $G_2$ stages, lasting approximately $24\,\text{h}$ in standard dividing cells.

$$G_0\text{ Phase}$$

A permanent or semi-permanent quiescent state entered from $G_1$ by specialized non-dividing cells, such as neurons and cardiac muscle cells.

$$S\text{ Phase}$$

The synthesis period of interphase during which DNA is replicated, histones are synthesized, and centrioles duplicate.

Centromere

The primary constriction of a chromosome where sister chromatids are held together and where kinetochores assemble for spindle fiber attachment.

Telomeres

The specialized terminal ends of chromatids that protect chromosome ends from degradation.

Metacentric Chromosome

A chromosome with its centromere located centrally, giving rise to two arms of equal length.

Submetacentric Chromosome

A chromosome whose centromere is displaced from the center, resulting in one arm being noticeably longer than the other.

Acrocentric Chromosome

A chromosome whose centromere is positioned near one end, producing one very short arm and one long arm.

Telocentric Chromosome

A chromosome whose centromere is located at the very terminus, such that only one arm is visible.

Autosomes

Numbered chromosomes that encode somatic and general organismal characteristics; humans possess $22$ pairs ($44$ autosomes).

Sex Chromosomes

The pair of chromosomes (designated $X$ and $Y$ in mammals) responsible for determining the sex of an organism.

Karyotype

A photographic arrangement of all chromosomes from a single cell, ordered systematically by homologous pairs, size, and centromere location.

Idiogram

A standardized schematic representation illustrating the size, shape, and distinctive banding pattern of an organism's chromosome complement.

Mitotic Spindle

A bipolar structure composed of microtubule protein filaments that organizes, aligns, and segregates chromosomes during nuclear division.

Kinetochore

A protein complex located at the centromere of each chromatid that mediates attachment to the microtubules of the mitotic spindle.

Contractile Ring

A band of microfilaments that constricts the plasma membrane of animal cells to create a cleavage furrow, splitting the cytoplasm during cytokinesis.

Phragmoplast

A provisional plant cell partitioning structure formed by the coalescence of Golgi-derived vesicles along the equatorial plane to build a new cell plate.

Crossover

The reciprocal exchange of genetic segments between non-sister chromatids of paired homologous chromosomes during Prophase I of meiosis.

Spermatogenesis

The male gametogenic pathway in the testes where a diploid primary spermatocyte undergoes meiosis to generate four viable haploid spermatozoa.

Oogenesis

The female gametogenic pathway in the ovaries where a diploid primary oocyte undergoes meiosis to yield one functional haploid ovum and three degenerating polar bodies.