Dental and Biomedical Sciences 1 - Cell Biology Part A

Vocabulary practice flashcards covering cell structure, membrane biochemistry, lipid classes, membrane proteins, the nucleus, nuclear pore complexes, and post-transcriptional RNA processing from Cell Biology Part A.

Cell

The basic organisational unit used by all living organisms, consisting of a membrane-enclosed compartment with a high concentration of biomolecules and the capacity to replicate itself.

The Central Dogma

The principle describing the directional flow of genetic information in cells via the transcription of DNA instructions into RNA, followed by translation into protein.

Cytoskeleton

A network of three types of fine protein filaments criss-crossing the cytosol that provides structural support, facilitates cell movement, transports internal cargo, and segregates chromosomes and organelles during mitosis.

Cytosol

The intracellular fluid environment of the cell that is physically segregated from internal organelle contents by intracellular membranes.

Nuclear Envelope

A double-layered membrane envelope that encloses the nucleus, compartmentalizing genomic DNA and remaining continuous with the endoplasmic reticulum.

Phospholipid Bilayer

A self-assembling membrane barrier measuring approximately $5\,\text{nm}$ in thickness, formed by two parallel rows of amphipathic phospholipids with hydrophilic heads facing outwards and hydrophobic fatty acid tails facing inwards.

Amphipathic

A chemical property describing molecules that possess both hydrophilic (water-soluble) and hydrophobic (water-insoluble) regions, such as phospholipids, sterols, and glycolipids.

Saturated Fatty Acid

A fatty acid hydrocarbon tail characterized by the complete absence of carbon-carbon double bonds, yielding a straight conformation.

Unsaturated Fatty Acid

A fatty acid hydrocarbon tail containing one or more carbon-carbon double bonds, which introduces kinks into the hydrocarbon chain.

Phosphatidylcholine

A major cell membrane phospholipid composed of two hydrophobic fatty acid tails linked to a glycerol backbone, which is joined to a hydrophilic phosphate group bonded to choline.

Liposome

A closed spherical vesicle formed spontaneously by amphipathic phospholipids in an aqueous medium to prevent the exposure of hydrophobic tails to water.

Transporter Proteins

Membrane proteins that selectively mediate solute movement across biological membranes by actively pumping or channeling ions and molecules.

Anchor Proteins

Membrane proteins that tether intracellular structures and organelles to the cytoskeleton and participate in cellular migration.

Receptor Proteins

Membrane proteins that detect and bind specific extracellular signaling molecules, such as growth factors or pathogen components, to initiate intracellular responses.

Nuclear Lamina

A supportive protein meshwork lining the inner nuclear membrane that provides mechanical structural integrity to the nuclear envelope.

Perinuclear Space

The lumen situated between the inner and outer nuclear membranes of the nuclear envelope, continuous with the lumen of the endoplasmic reticulum.

Nuclear Pore Complex

A large multi-protein gate embedded across the nuclear envelope composed of cytosolic fibrils, pore complex proteins, and a nuclear basket that regulates selective macromolecular transport between the nucleus and cytosol.

$5^\prime$ Capping

An eukaryotic RNA processing modification involving the covalent attachment of a methylated guanine nucleotide to the $5^\prime$ end of a nascent transcript to enhance stability and facilitate nuclear export.

Polyadenylation

The post-transcriptional addition of a tail composed of a few hundred adenine nucleotides to the $3^\prime$ end of an mRNA transcript to improve stability and facilitate nuclear export for cytosolic translation.

RNA Splicing

The eukaryotic post-transcriptional process that selectively excises non-coding intervening sequences (introns) from primary transcripts prior to cytoplasmic export.