Cytoplasm, Cellular Organelles, and Gene Expression

Vocabulary practice flashcards generated from lecture notes on membrane transport, cell organelles, structural features, and protein synthesis.

Secondary Active Transport

A cellular transport process moving molecules across a membrane against their concentration gradient using energy stored in an ion gradient created by primary active transport rather than directly using ATP.

Phagocytosis

A type of endocytosis commonly called 'cell eating' where a cell engulfs large particles or invading pathogens.

Pinocytosis

A nonspecific form of endocytosis commonly referred to as 'cell drinking' in which cell membrane infolding brings fluid containing dissolved substances into the cell.

Lysosomes

Enzyme-filled cellular compartments that digest and break down unneeded cellular components or foreign materials ingested by white blood cells.

Macrophage

A cell that utilizes internal lysosomes filled with enzymes to digest foreign materials and cellular debris.

Exocytosis

An active transport process in which intracellular vesicles fuse with the plasma membrane to release molecules and waste out of the cell.

Cytosol

The jelly-like fluid within the cell that serves as the medium for biochemical reactions.

Cytoplasm

The structural material composed of cytosol and cellular organelles taken together.

Endoplasmic Reticulum (ER)

A continuous system of lipid bilayer channels connected to the nuclear membrane that transports, synthesizes, and stores materials in the cell.

Rough Endoplasmic Reticulum (RER)

A region of the ER covered with ribosomes that synthesizes proteins destined for cell membrane insertion or export from the cell.

Smooth Endoplasmic Reticulum

An ER structure that synthesizes phospholipids and steroid hormones, regulates cellular $Ca^{++}$ concentration, and breaks down toxins.

Ribosome

An organelle composed of rRNA and protein organized into small and large subunits that acts as the site of protein synthesis.

Nucleolus

A non-membrane-bound nuclear region responsible for ribosome synthesis through rRNA transcription and assembly with proteins.

Golgi Apparatus

An organelle resembling stacked flattened discs that receives transport vesicles, modifies their contents, and releases them inside secretory vesicles.

Mitochondria

Membranous, bean-shaped organelles with folded inner membranes (cristae) that perform cellular respiration to generate usable cellular energy in the form of ATP.

Adenosine Triphosphate (ATP)

The primary energy currency molecule of the cell that releases energy upon hydrolysis into adenosine diphosphate (ADP) and a phosphate ion.

Cytoskeleton

A network of fibrous proteins—composed of microtubules, microfilaments, and intermediate filaments—that provides structural support, motility, and internal transport.

Microtubules

Cytoskeletal elements that position organelles, assist in cell division, and form the core structure of cilia.

Microfilaments

Thin actin filaments that work alongside myosin to produce muscle contraction.

Intermediate Filaments

Cytoskeletal structures intermediate in thickness that help maintain cell shape and resist mechanical tension.

Cilia

Short, hair-like motile surface structures constructed from a ring of nine outer microtubule doublets surrounding two central singlet microtubules.

Nucleus

The largest cellular organelle acting as the control center by storing all genetic instructions for protein production.

Nuclear Envelope

A double-layer lipid bilayer membrane surrounding the nucleus containing tiny passageways called nuclear pores.

Nuclear Pore

A tiny passageway spanning the nuclear envelope that regulates passage of materials into and out of the nucleus.

Genome

An organism's complete set of DNA.

Gene

A specific segment of DNA that contains the genetic code for producing a particular protein.

Nucleotide

The structural monomer unit of nucleic acids, consisting of a nitrogenous base, a pentose sugar, and a phosphate group.

Ribose

The pentose sugar found in RNA that possesses an extra oxygen atom compared to 2-deoxyribose.

Transcription

The first phase of protein synthesis where genetic information from a DNA template strand is rewritten into a complementary mRNA transcript.

Codon

A sequence of three adjacent nucleotide bases on mRNA that specifies a particular amino acid.

RNA Polymerase

The main enzyme involved in transcription that unwinds DNA, reads the template strand, and connects RNA nucleotides into an mRNA strand.

Translation

The cellular process occurring at ribosomes where mRNA codons are decoded into a chain of amino acids called a polypeptide.

Transfer RNA (tRNA)

An RNA molecule with a specific amino acid binding site at one end and an anticodon sequence at the other that matches complementary mRNA codons.