Introduction to Molecular Biology, Cell Structure & Organelles

Vocabulary flashcards covering fundamental terms from the lecture on molecular biology and cellular organelles.

Central Dogma

Flow of genetic information: DNA → RNA → Protein.

DNA

Double-helical molecule storing genetic information; composed of A-T and C-G base pairs.

DNA Replication

Process by which DNA makes an identical copy of itself before cell division.

Reverse Transcription

Synthesis of DNA from an RNA template.

Chromatin

DNA-protein complex that packages eukaryotic DNA inside the nucleus.

Chromosome

Condensed form of chromatin visible during cell division.

mRNA

Messenger RNA; carries coding information from DNA to ribosomes.

tRNA

Transfer RNA; adaptor that delivers specific amino acids during translation.

rRNA

Ribosomal RNA; forms the structural and catalytic core of ribosomes.

miRNA

MicroRNA; small non-coding RNA that down-regulates gene expression, often dysregulated in cancer.

siRNA

Small interfering RNA; short double-stranded RNA that silences gene expression.

snRNA

Small nuclear RNA; functions in RNA splicing within the nucleus.

snoRNA

Small nucleolar RNA; guides chemical modifications of other RNAs.

lncRNA

Long non-coding RNA; regulates gene expression at multiple levels.

Transcription

Synthesis of RNA from a DNA template in the nucleus.

Translation

Protein synthesis from an mRNA template on ribosomes.

Ribosome (80S)

Eukaryotic protein factory composed of 60S and 40S subunits.

Ribosome (70S)

Prokaryotic ribosome targeted by many antibiotics.

Nucleus

Double-membrane organelle housing DNA and site of transcription.

Nucleolus

Nuclear substructure that synthesizes rRNA and assembles ribosomal subunits.

Rough Endoplasmic Reticulum

Membrane network with bound ribosomes; site of synthesis/folding of secretory and membrane proteins.

Smooth Endoplasmic Reticulum

Ribosome-free ER; functions in lipid synthesis, detoxification, glycogen metabolism, and Ca²⁺ storage.

Golgi Apparatus

Organelle that modifies, sorts, and packages proteins and lipids; has cis and trans faces.

I-cell Disease

Congenital disorder caused by failure to phosphorylate mannose on lysosomal enzymes.

Mitochondria

ATP-producing organelles with their own maternal DNA; regulate apoptosis and Ca²⁺.

Oxidative Phosphorylation

Mitochondrial process that couples electron transport to ATP synthesis.

Lysosome

Acidic vesicle containing hydrolytic enzymes for degradation and autophagy.

Tay-Sachs Disease

Lysosomal storage disorder due to hexosaminidase A deficiency; presents with cherry-red macula.

Peroxisome

Organelle that performs β-oxidation of very long-chain fatty acids and detoxifies H₂O₂.

Zellweger Syndrome

PEX gene mutation causing absent peroxisomes and accumulation of VLCFAs.

Cytoskeleton

Network of actin filaments, intermediate filaments, and microtubules providing structure and transport.

Microtubule

Tubulin polymer involved in intracellular transport, cilia, flagella, and mitotic spindle.

Centrosome

Microtubule-organizing center containing two orthogonally arranged centrioles.

Kartagener Syndrome

Dynein arm defect leading to immotile cilia, sinusitis, infertility, and dextrocardia.

Plasma Membrane

Phospholipid bilayer with proteins and cholesterol; controls transport and cell signaling.

CFTR

Chloride channel defective in cystic fibrosis; encoded on chromosome 7.

Cystic Fibrosis

Autosomal recessive disease due to CFTR mutations causing thick secretions and salty sweat.

Cytoplasm

Cellular contents outside the nucleus; includes cytosol and organelles.

Cytosol

Aqueous component of cytoplasm; site of glycolysis, protein translation, and fatty-acid synthesis.

Actin (Microfilament)

Thin filament involved in cell movement, cytokinesis, and muscle contraction.

Intermediate Filament

Cytoskeletal fiber providing mechanical strength; examples include keratin and lamins.

Prokaryotic Cell

Unicellular organism lacking a nucleus and membrane-bound organelles; has circular DNA.

Eukaryotic Cell

Cell with membrane-bound organelles and a true nucleus containing linear chromosomes.

Laminopathies

Diseases caused by mutations in nuclear lamina proteins, e.g., Hutchinson-Gilford progeria.

Colchicine

Drug that inhibits microtubule polymerization, disrupting mitosis and neutrophil migration.

Paclitaxel

Chemotherapy agent that stabilizes microtubules, preventing their depolymerization.

Vincristine

Anticancer drug that inhibits microtubule assembly, blocking mitotic spindle formation.

Maternal Inheritance

Transmission pattern of mitochondrial DNA where traits are passed from mother to all offspring.