Cell Division & Molecular Biology Vocabulary

Comprehensive vocabulary flashcards covering cell division, mitosis, meiosis, genetics, DNA structure, protein synthesis, mutations, and biotechnology.

Chromosome

DNA coiled around histone proteins and then condensed into a distinct structure.

Chromatin

An uncoiled strand of DNA found inside the nucleus during interphase and cytokinesis.

Centromere

The structure at the center of a chromosome that joins sister chromatids together and attaches them to the spindle fiber.

Autosomes

Chromosomes numbered $1$ through $22$ in humans that code for somatic (body) cell information.

Sex Chromosomes

The $23\text{rd}$ pair of chromosomes that determine the sex of an organism ($XX$ for females, $XY$ for males).

Homologous Chromosomes

A pair of chromosomes carrying the same genes at the same locus; one is inherited from the mother and one from the father.

Gene

A segment of DNA that codes for a specific trait or protein.

Allele

Different forms or variations of the same gene.

Diploid ($2n$)

Refers to cells that contain two complete sets of chromosomes (copies), such as somatic cells ($46$ chromosomes in humans).

Haploid ($n$)

Refers to cells that contain one set of chromosomes (copy), such as sex cells or gametes ($23$ chromosomes in humans).

Polyploidy

A condition in which an organism has more than two sets of chromosomes, having a multiple of its haploid number other than $2n$ (e.g., $3n$, $4n$, $8n$).

Chromatid

One half of a replicated chromosome.

Replicated Chromosome

A chromosome containing two identical sister chromatids attached at a centromere, formed during the $S$ phase of interphase.

Mitosis

Cell division occurring in body cells for growth, tissue repair, maintenance, or asexual reproduction, producing $2$ genetically identical daughter cells.

Meiosis

Cell division occurring in gonads for sexual reproduction, producing $4$ genetically diverse haploid gametes.

Cell Cycle

The life cycle of a cell consisting of Interphase ($G_1$, $S$, $G_2$), Mitosis (Prophase, Metaphase, Anaphase, Telophase), and Cytokinesis.

Interphase

The longest phase of the cell cycle where DNA is in uncoiled chromatin form; consists of cell growth, protein synthesis ($G_1$ and $G_2$), and DNA replication ($S$ phase).

Prophase

The first phase of mitosis where chromatin condenses into chromosomes, the nuclear envelope breaks down, and spindle fibers begin to form.

Metaphase

The phase of mitosis where replicated chromosomes line up along the metaphase plate in the middle of the cell.

Anaphase

The phase of mitosis where centromeres split and sister chromatids separate, moving toward opposite poles of the cell.

Telophase

The phase of cell division where chromosomes reach the poles, uncoil back into chromatin, nuclear envelopes reform, and a cleavage furrow forms.

Cytokinesis

The division of the parent cell's cytoplasm and organelles into two distinct daughter cells.

Cancer

A disease characterized by the uncontrolled division of abnormal cells in the body.

Tumor

A swelling or abnormal growth of cells in the body without inflammation, which can be benign or malignant.

Malignant Tumor

A tumor composed of cancer cells that has the potential to spread to other locations in the body.

Benign Tumor

An abnormal cell growth or tumor that is not made of cancer cells and does not spread.

Metastasis

The development of secondary malignant growths at a distance from the primary site of cancer.

Mutagen

An agent, such as radiation or chemicals, that causes a genetic mutation.

Carcinogen

A chemical substance or type of mutagen capable of causing cancer.

Oncogene

A gene that, under certain circumstances, can transform a cell into a tumor cell.

Tumor Suppressor Gene

An antioncogene that protects a cell from becoming cancerous by slowing cell division and signaling potential cancer cells to undergo apoptosis.

Tetrad

A pair of homologous chromosomes consisting of four sister chromatids that pair up during Prophase I of meiosis.

Crossing Over

The process during Prophase I of meiosis where homologous chromosomes swap segments of genetic material, creating new combinations of alleles.

Independent Assortment

The random alignment of homologous chromosome pairs along the metaphase plate during Metaphase I, generating unique genetic combinations.

Spermatogenesis

The process of male gametogenesis occurring in the testicles to produce four functional haploid sperm cells.

Oogenesis

The process of female gametogenesis occurring in the ovaries to produce one functional egg cell and three polar bodies.

Fertilization

The union of a haploid sperm cell ($n$) and a haploid egg cell ($n$) to form a diploid zygote ($2n$).

Zygote

The single diploid cell resulting from the fertilization of an egg by a sperm.

Nondisjunction

The failure of homologous chromosomes to separate during Anaphase I or sister chromatids to separate during Anaphase II, leading to abnormal chromosome numbers in gametes.

Trisomy

A chromosomal abnormality where a cell contains three copies of a specific chromosome instead of the normal pair ($2n + 1$).

Monosomy

A chromosomal abnormality where a cell contains only a single copy of a chromosome instead of a pair ($2n - 1$).

Chargaff's Rule

The principle stating that in a DNA molecule, the percentage of adenine equals thymine ($A = T$) and the percentage of guanine equals cytosine ($G = C$).

Nucleotide

The monomer and functional unit of nucleic acids, composed of a deoxyribose sugar, a phosphate group, and a nitrogenous base ($A$, $T$, $C$, or $G$).

Semiconservative Replication

The method of DNA replication in which each newly formed double helix consists of one original parental strand and one newly synthesized strand.

Helicase

An enzyme that unwinds and unzips the DNA double helix by breaking hydrogen bonds prior to replication.

DNA Polymerase

An enzyme that base-pairs free nucleotides to the original template strand and joins the sugar-phosphate backbone during DNA replication.

Transcription

The process occurring in the nucleus where mRNA copies genetic instructions from a non-coding DNA template strand.

Translation

The process occurring in the cytoplasm at a ribosome where tRNA molecules decode mRNA codons into a sequence of amino acids.

Codon

A triplet sequence of three nitrogenous bases on an mRNA molecule that codes for a specific amino acid.

Anticodon

A triplet sequence of three nitrogenous bases on a tRNA molecule that is complementary to a specific mRNA codon.

Peptide Bond

The chemical bond formed between adjacent amino acids to build a polypeptide chain during translation.

Genetic Engineering

The manipulation of an organism's DNA by adding, removing, or modifying genes, also known as recombinant DNA technology.

Recombinant DNA

DNA produced by combining genetic material from two or more different organisms.

Restriction Enzyme

An enzyme used in genetic engineering to cut DNA at specific nucleotide sequences, creating sticky ends.

DNA Ligase

An enzyme used to join or splice foreign DNA fragments into a plasmid or vector backbone.

Plasmid

A small circular ring of DNA found in bacteria (such as E. coli) that replicates independently and is used as a vector in cloning.

Gel Electrophoresis

A technique that uses an electric current applied to a gel to separate DNA fragments based on size, with shorter fragments migrating further toward the positive pole.

Polymerase Chain Reaction (PCR)

An automated laboratory process used to produce millions of identical copies of a specific DNA segment from a small sample.

Point Mutation

A gene mutation arising from errors in replication where a single base pair in DNA is altered, substituted, added, or deleted.

Frameshift Mutation

A point mutation caused by the addition or deletion of a nucleotide base, shifting the reading frame of all subsequent codons.

Karyotyping

A diagnostic procedure where metaphase chromosomes are stained, photographed, and arranged into pairs by length, centromere location, and banding pattern to identify genetic disorders.

Amniocentesis

A prenatal procedure in which a needle is used to withdraw amniotic fluid containing fetal cells to construct a karyotype.

Chorionic Villus Sampling (CVS)

A prenatal procedure that extracts cells from the outer membrane (chorion) surrounding the embryo to prepare a karyotype.