Cell Division and Protein Synthesis

Comprehensive vocabulary flashcards covering the cell cycle, DNA replication, mitosis, protein synthesis (transcription and translation), cellular lifecycle controls, and clinical conditions based on the lecture material.

Cell Cycle Diagram

A schematic representation of the phases a cell undergoes from formation to reproduction, showing Interphase ($G_1$, $S$, $G_2$), Mitotic phase ($M$), and the non-dividing state ($G_0$).

Cell Cycle

A series of changes a cell undergoes from the time it is formed until it reproduces, divided into Interphase and the Mitotic ($M$) phase.

Interphase Micrograph

A histological view showing a cell in interphase with nuclear material maintained in an uncondensed chromatin state.

Interphase

The period from cell formation to cell division, during which the cell grows, performs routine activities, and replicates its DNA while chromatin remains uncondensed.

$G_1$ Phase

The gap 1 subphase of interphase characterized by vigorous cell growth and active metabolism.

$G_0$ Phase

The state occupied by cells that permanently cease dividing or temporarily exit the active cell cycle.

$S$ Phase

The synthetic subphase of interphase during which total DNA replication takes place.

$G_2$ Phase

The gap 2 subphase of interphase where final preparations and protein synthesis for cell division occur.

DNA Replication Fork Diagram

An illustration showing helicase unwinding template DNA at the replication fork, while DNA polymerase synthesizes leading and lagging strands.

Replication Fork

The Y-shaped point where double-stranded DNA unwinds and separates into two single template strands during replication.

DNA Polymerase

The primary enzyme that attaches to an RNA primer and adds complementary nucleotides to build new DNA strands in a single direction.

DNA Ligase

The enzyme responsible for splicing together discontinuous segments (Okazaki fragments) on the lagging strand during DNA replication.

Semiconservative Replication

The mechanism of DNA replication wherein each newly synthesized double helix consists of one original parent strand and one new daughter strand.

Mitosis

The division of the cell nucleus, consisting of four sequential phases: prophase, metaphase, anaphase, and telophase.

Prophase Micrograph

A microscopic view of a cell in prophase displaying condensed chromosomes and nuclear envelope breakdown.

Early Prophase

Subphase of mitosis where chromatin condenses into visible chromosomes (sister chromatids attached at centromeres) and centrosomes construct the mitotic spindle.

Late Prophase

Subphase of mitosis where the nuclear envelope disintegrates and kinetochore microfilaments connect to centromeres to propel chromosomes toward the equator.

Metaphase Micrograph

A microscopic image showing chromosomes lined up along the central equatorial plane of the cell.

Metaphase

The mitotic phase where centromeres of sister chromatids align precisely along the metaphase plate at the cell equator.

Anaphase Micrograph

A microscopic view illustrating separated sister chromatids being pulled apart toward opposite cell poles.

Anaphase

The shortest mitotic stage, where centromeres split and identical sister chromatids are pulled to opposite poles by kinetochore motor proteins.

Telophase Micrograph

A microscopic view of telophase showing two reforming nuclei containing uncoiling chromatin at opposite ends of the cell.

Telophase

The final mitotic phase where chromosome movement ceases, nuclear membranes rebuild around uncoiling chromatin, and nucleoli reappear.

Cytokinesis

The division of the cytoplasm, starting in late anaphase, driven by an actin microfilament ring forming a cleavage furrow that pinches the cell into two.

Contact Inhibition

A regulatory stop signal where normal cells stop dividing once they physically touch neighboring cells.

Cyclins

Regulatory proteins that accumulate during interphase and bind with specific kinases to control cell cycle progression.

Cyclin-Dependent Kinases (CDKs)

Enzymes that become activated when bound to cyclins, initiating enzymatic pathways that drive a cell into division phases.

Cell Cycle Checkpoints Diagram

A circular regulatory diagram detailing the $G_1$, $G_2$, and $M$ checkpoints along with corresponding Cyclin-CDK complexes.

$G_1$ Checkpoint

The primary restriction point in the cell cycle; if passed, the cell completes division, but if denied, it exits into $G_0$.

Gene

A distinct segment of DNA containing a sequence of base triplets that codes for a specific polypeptide chain.

Exons

The expressed regions of a gene that encode the final amino acid sequence of a polypeptide.

Introns

Noncoding DNA segments interspersed between exons that are spliced out prior to mRNA translation.

Transcription Diagram

A diagram illustrating RNA polymerase binding to DNA to synthesize an RNA transcript.

Transcription

The step of protein synthesis in which genetic instructions on a DNA template strand are copied into a complementary mRNA strand.

Translation

The cellular process of reading mRNA nucleotide codons at a ribosome to assemble corresponding amino acids into a polypeptide.

Messenger RNA (mRNA)

A single-stranded RNA carrier that transcribes code from the DNA template strand in the nucleus and delivers it to ribosomes.

Ribosomal RNA (rRNA)

The structural RNA component of ribosomes that facilitates translation along with transfer RNA.

Transfer RNA Structure Diagram

An illustration of a tRNA molecule carrying a specific amino acid (Met) at its stem and possessing a complementary anticodon (UAC) at its base.

Transfer RNA (tRNA)

A clover-shaped RNA carrier that delivers specific amino acids to ribosomes by pairing its anticodon with an mRNA codon.

Promoter

A specific nucleotide sequence on the DNA template strand that marks the starting point for transcription factor and RNA polymerase binding.

RNA Polymerase

The enzyme that opens DNA helices and aligns complementary RNA nucleotides to synthesize an mRNA strand during transcription.

Spliceosomes

Enzymatic protein complexes that edit pre-mRNA by removing noncoding introns and rejoining coding exons.

Codon

A three-base sequence on mRNA that specifies a particular amino acid or a termination signal.

Anticodon

A specific three-base triplet on tRNA that binds to its complementary codon on an mRNA molecule.

Polyribosome Diagram

A diagram illustrating multiple ribosomes reading a single strand of mRNA simultaneously to construct multiple protein copies.

Polyribosome

A functional complex of multiple ribosomes translating a single mRNA strand at the same time to produce proteins rapidly.

Translation Termination Diagram

A diagram showing a release factor binding to a stop codon at the A site, ending elongation and detaching the completed polypeptide.

Autophagy

The process of cellular self-digestion where obsolete organelles and cytoplasmic components are swept into autophagosomes for degradation by lysosomes.

Ubiquitin

A small regulatory protein attached to unneeded, misfolded, or damaged proteins to target them for destruction.

Proteasomes

Barrel-shaped protein complexes that dismantle ubiquitin-tagged proteins and recycle their amino acids.

Apoptosis

Programmed cell death triggered by mitochondrial leakage, leading caspase activation to systematically break down cellular components.

Cell Differentiation

The developmental process by which unspecialized cells acquire specific structural and functional characteristics through selective gene activation.

Hyperplasia

Accelerated cell multiplication leading to an increase in total cell numbers within a tissue.

Atrophy

A decrease in the size of an organ or tissue resulting from cell shrinkage or loss of stimulation and use.

Telomeres

Protective nucleotide caps located at chromosome tips that shorten with every round of cell division.

Telomerase

An enzyme that lengthens chromosome telomeres, providing cellular immortality; active in embryonic germ cells and cancer cells.

Progeria

A rare genetic disorder caused by defective progerin protein, resulting in nuclear membrane instability and accelerated premature aging.