Protein Synthesis and Cell Transport

Vocabulary flashcards covering cellular organelles, protein synthesis (transcription and translation), DNA replication, and cell membrane transport mechanisms.

Nucleus

A double-membrane enclosed organelle that communicates through nuclear pores and houses DNA, serving as the site for DNA synthesis and transcription.

Rough Endoplasmic Reticulum

A ribosome-encrusted organelle responsible for protein synthesis.

Ribosome

An RNA-based structure consisting of large and small subunits that serves as the site of protein assembly.

Golgi Apparatus

An organelle consisting of cisternae with cis and trans faces that modifies proteins from the rough ER and packages them into transport vesicles.

DNA

A double-stranded nucleic acid that carries the genetic information necessary to synthesize cellular proteins.

mRNA

A short, single-stranded nucleic acid derived from a parent DNA strand that carries the instructions needed to synthesize a specific protein.

rRNA

A structural and functional type of nucleic acid that forms the composition of ribosomes.

tRNA

A nucleic acid molecule containing an anticodon and an amino acid-accepting end, responsible for reading mRNA codons and bringing amino acids in sequence.

Transcription

The enzymatic process in which an RNA molecule is synthesized from a specific DNA segment.

RNA Polymerase

An enzyme that unwinds DNA, stabilizes single strands, and catalyzes RNA-DNA base pairing ($U-A$ and $C-G$).

Transcription Factors

A family of regulatory molecules that promote or inhibit the transcription of genes.

Translation

The process by which a polypeptide chain is assembled on a ribosome following the mRNA nucleotide sequence.

DNA Replication

The process through which a new, identical molecule of double-stranded DNA is synthesized.

DNA Polymerase

An enzyme responsible for unwinding DNA, stabilizing unwound strands, and promoting DNA nucleotide base pairing ($T-A$ and $C-G$).

Plasma Membrane

A selectively permeable phospholipid bilayer that separates internal and external cellular environments and regulates transport.

Concentration Gradient

The difference in the concentration of a chemical substance across a membrane, driving the movement of molecules.

Passive Transport

The movement of molecules down their concentration gradient (from high to low concentration) without requiring cellular energy.

Simple Diffusion

Non-carrier mediated passive movement of nonpolar or hydrophobic molecules directly through the phospholipid membrane.

Facilitated Diffusion

Passive transport of inorganic ions or polar molecules down their concentration gradient aided by channel or carrier proteins.

Active Transport

The movement of molecules against their concentration gradient requiring cellular energy in the form of $ATP$.

Primary Active Transport

Active transport in which a membrane protein channel directly hydrolyzes $ATP$ to move molecules across the membrane.

Secondary Active Transport

Active transport powered indirectly by a concentration gradient established by the primary transport of a different ion, such as $Na^+$.

Carrier-Mediated Transport

Transmembrane passage requiring a substrate-specific protein that undergoes a conformational change to move molecules across.

Conformational Change

A temporary shift in a protein's tertiary structure that allows bound substrate molecules to cross a membrane.

Bulk Transport

The active transportation of large amounts of substances or particles across the cell membrane utilizing vesicles.

Phagocytosis

A form of endocytosis where cytoplasmic extensions called pseudopods engulf large particles and encapsulate them inside a vacuole.

Pinocytosis

A type of endocytosis known as 'cell drinking', where the plasma membrane invaginates to ingest droplets of extracellular fluid within tiny vesicles.

Receptor-Mediated Endocytosis

A selective endocytic process where specific target extracellular molecules bind to receptor proteins, forming clathrin-coated vesicles.

Exocytosis

The process by which cellular materials packaged in secretory vesicles are released outside the cell through vesicle fusion with the plasma membrane.

Isotonic Solution

A solution in which the surrounding interstitial fluid has the same solute concentration as cytosol, resulting in no net water movement across the membrane.

Hypotonic Solution

A solution with a lower solute concentration than the cytosol, causing water to diffuse into erythrocytes and leading toward hemolysis.

Hypertonic Solution

A solution with a higher solute concentration than the cytosol, causing water to diffuse out of erythrocytes and leading to cell crenation.

Resting Membrane Potential

The electric potential across a resting neuronal membrane maintained by active transport of $Na^+$ out and $K^+$ in via the $Na^+/K^+$ transporter pump.