Cell Biology and Molecular Genetics

Comprehensive vocabulary flashcards covering cell division, the cell cycle, mitosis, meiosis, chromosome morphology, DNA structure, and RNA-mediated protein synthesis based on the Cell Biology and Molecular Genetics lecture.

Cell Division

The biological process by which a cell distributes its genetic material and cytoplasm, giving rise to new daughter cells for growth, gamete production, or prokaryotic reproduction.

Binary Fission

A form of asexual reproduction and cell division in prokaryotes where the circular DNA is replicated, uncoiled, and separated to produce an exact copy or clone of the parent cell.

Mitosis

Vegetative eukaryotic cell division in which one parent cell divides to produce two genetically identical daughter cells, serving functions in growth, development, and tissue repair.

Meiosis

A specialized eukaryotic cell division where a diploid parent cell divides twice to yield four haploid daughter cells, each containing half the chromosome complement of somatic cells.

$G_0$ Phase (Gap 0)

A resting state of the cell cycle where the cell has exited the active cycle and stopped dividing.

$G_1$ Phase (Gap 1)

The interphase period of active cell growth regulated by the $G_1$ checkpoint to verify that all conditions are ready for DNA synthesis.

$S$ Phase (Synthesis)

The stage of the eukaryotic cell cycle dedicated to the complete replication of nuclear DNA.

$G_2$ Phase (Gap 2)

The phase of growth and final preparation for mitosis, monitored by the $G_2$ checkpoint to confirm the cell is ready to enter the $M$ phase.

$M$ Phase (Mitosis)

The cell division stage of the cell cycle where nuclear division occurs, regulated by the Metaphase Checkpoint before completing division.

Cell Cycle

The ordered sequence of events consisting of interphase ($G_1$, $S$, and $G_2$), mitotic division ($M$), and an alternate resting state ($G_0$).

Mitotic Spindle

A cellular apparatus composed of microtubules that originates between centrosomes at opposite poles to organize and separate chromosomes during mitosis.

Prometaphase (Late Prophase)

The stage of mitosis where the nuclear envelope fully breaks down and spindle microtubules begin capturing and organizing condensed chromosomes.

Replicated Metaphase Chromosome

A condensed eukaryotic chromosome structure measuring $0.2\text{--}20\,\mu\text{m}$ consisting of sister chromatids (1), a central centromere (2), a short arm (3), and a long arm (4).

Metaphase Plate

The central equatorial plane of the cell along which chromosomes align during metaphase.

Spindle Checkpoint

A regulatory control mechanism during metaphase that ensures all kinetochores are properly attached to spindle microtubules before anaphase begins.

Anaphase

The mitotic stage in which the protein glue holding sister chromatids breaks, allowing motor proteins and spindle fibers to pull individual chromosomes to opposite poles.

Cleavage Furrow

The contractile pinch crease formed by a band of actin protein filaments that splits an animal cell into two daughter cells during cytokinesis.

Cell Plate

The structure that forms down the middle of a dividing plant cell during cytokinesis to separate the daughter cells within rigid cell walls.

Crossing Over (Recombination)

The process during Prophase I of meiosis in which homologous chromosome pairs exchange corresponding segments of DNA.

Gametogenesis

The meiotic process of producing haploid sex cells, generating four functional sperm cells in males and a single egg cell with three polar bodies in females.

Polar Bodies

Small haploid cellular byproducts formed during female oogenesis that do not develop into functional egg cells.

Genetics

The scientific study of genes and heredity, examining how traits are transmitted from parents to offspring via variations in DNA sequence.

Gene

A distinct segment of DNA that contains specific biochemical instructions for building one or more functional molecules in the body.

Chromosomes

Thread-like nuclear structures in eukaryotic cells composed of DNA molecules tightly coiled around histone proteins.

Nucleotide

The fundamental monomer of nucleic acids, consisting of a nitrogenous base, a five-carbon pentose sugar, and one or more phosphate groups.

Pentose Sugar Carbon Numbering

The system of numbering carbons $1'$ through $5'$ in a nucleotide sugar, where the nitrogenous base attaches to the $1'$ carbon and the phosphate group attaches to the $5'$ carbon.

Purines

A class of nitrogenous bases characterized by a double-ring structure, which includes Adenine ($A$) and Guanine ($G$).

Pyrimidines

A class of nitrogenous bases characterized by a single-ring structure, which includes Cytosine ($C$), Thymine ($T$), and Uracil ($U$).

Deoxyribose

The five-carbon pentose sugar found in DNA that contains a hydrogen atom ($-H$) instead of a hydroxyl group ($-OH$) at the $2'$ carbon position.

Ribose

The five-carbon pentose sugar found in RNA that contains a hydroxyl group ($-OH$) attached to the $2'$ carbon position.

Phosphodiester Linkage

The covalent bond that links the $5'$ phosphate group of an incoming nucleotide to the $3'$ hydroxyl group of the existing polynucleotide chain.

DNA Double Helix

The molecular structure of DNA formed by two spiraling sugar-phosphate backbones on the outside and complementary, hydrogen-bonded base pairs stacked inside at intervals of $0.34\,\text{nm}$.

Antiparallel Strands

The relative orientation in double-stranded DNA where the $5'$ carbon end of one strand faces and aligns opposite the $3'$ carbon end of the complementary strand.

Base Complementary Rule

The pairing rule in nucleic acids dictating that a specific purine only bonds with a specific pyrimidine, specifically Adenine with Thymine ($A\text{--}T$) and Guanine with Cytosine ($G\text{--}C$) in DNA.

Messenger RNA (mRNA)

A single-stranded RNA molecule transcribed from DNA that travels from the nucleus to the cytoplasm to specify the amino acid sequence of proteins.

Transfer RNA (tRNA)

A small adaptor RNA molecule ($70\text{--}90$ nucleotides long) that recognizes mRNA codons via complementary base pairing and delivers the corresponding amino acids to the growing polypeptide chain.

Codon

A discrete set of three consecutive nucleotide bases on an mRNA molecule that codes for a single specific amino acid.

Ribosomal RNA (rRNA)

A primary component of ribosomes that aligns mRNA within the ribosomal subunits and catalyzes peptide bond formation.

Peptidyl Transferase

The enzymatic activity carried out by rRNA within the ribosome that catalyzes the formation of peptide bonds between adjacent amino acids.

Translation Complex

The macromolecular assembly consisting of the large and small ribosomal subunits, an mRNA transcript running $5'$ to $3'$, and bound tRNAs synthesizing a growing peptide chain.