Genetics: Chromosomes, Cell Division, and Biotechnology

Vocabulary flashcards covering the principles of genetics, cellular division (mitosis and meiosis), DNA structure and replication, chromosomal inheritance, gametogenesis, prenatal testing, and genetic technologies.

Genetics

The study of heredity and the variation of inherited characteristics.

Cell Theory

A fundamental biological theory stating that: 1. All living things are made of one or more cells; 2. Cells are the smallest units of living organisms; 3. New cells only come from pre-existing cells through cell division.

Somatic Cells

Any plant or animal cell of a living organism, excluding reproductive cells, that goes through a cell cycle lasting $12\text{--}24\,\text{hours}$.

Interphase

The stage of the cell cycle dedicated to cell growth and normal cellular activities, comprising three phases: Growth 1 ($G_1$), Synthesis ($S$), and Growth 2 ($G_2$).

Mitosis

The division of the cell's nucleus and genetic material into two identical sets.

Cytokinesis

The physical division of the cytoplasm and cell body to form distinct daughter cells.

Spindle Fibre

A microtubule structure that facilitates the movement and separation of chromosomes during cell division.

Chromosome

A structured package inside the cell nucleus that contains DNA.

Sister Chromatid

One of two identical copies comprising a replicated chromosome, joined together by a centromere.

Centromere

The specialized region of a chromosome where sister chromatids are held together.

Growth 1 ($G_1$) Phase

The initial growth phase of interphase representing a major period of cellular growth.

Synthesis ($S$) Phase

The phase of interphase during which DNA is replicated.

Growth 2 ($G_2$) Phase

The final sub-phase of interphase involving further growth, molecule synthesis, and preparation for division.

Prophase

The first phase of mitosis where chromatin coils into visible chromosomes, the nuclear membrane begins to dissolve, and spindle fibres form as centrosomes move toward the cell poles.

Metaphase

The phase of mitosis where the nuclear membrane completely dissolves, and spindle fibres attach to centromeres to align chromosomes along the cell equator.

Anaphase

The phase of mitosis in which each centromere splits apart and sister chromatids separate to opposite poles of the cell.

Telophase

The mitotic phase where spindle fibres shorten and break down, chromosomes unwind back into chromatin, and nuclear membranes reform around separated chromosomes.

Cell Plate

A structure that forms during plant cell cytokinesis across which the new cell wall is synthesized to divide the daughter cells.

James Watson and Francis Crick

Scientists who discovered the double helix molecular structure of DNA in 1953 and received the Nobel Prize in 1962.

Deoxyribonucleic Acid (DNA)

A molecule composed of nucleotides (phosphate, pentose sugar, and nitrogenous base) joined to form a sugar-phosphate backbone and two anti-parallel strands in a double helix.

Genome

The complete DNA sequence of an organism.

Semi-Conservative Replication

The mechanism of DNA replication in which the double helix unwinds and each original single strand acts as a template, producing new double helices composed of one original strand and one newly synthesized strand.

Homologous Chromosomes

Pairs of chromosomes that share the same sequence of genes, length, centromere position, and banding pattern, but may carry different alleles.

Sex Chromosomes

The 23rd pair of chromosomes that determine biological sex, designated as XX (identical pair) in females and XY (different pair) in males.

Karyotype

An organized visual profile of a person's complete set of chromosomes, collected and imaged during metaphase.

Gamete

A haploid ($n$) male or female reproductive cell (sperm or egg) that fuses with another during fertilization.

Zygote

The diploid ($2n$) cell produced by the union of two haploid gametes during fertilization.

Haploid

A cell or organism possessing a single set of unpaired chromosomes, represented as $n$.

Diploid

A cell or organism possessing two complete sets of chromosomes, represented as $2n$.

Synapsis

The pairing of homologous chromosomes side by side during prophase I of meiosis.

Crossing Over

The exchange of genetic material between non-sister chromatids of homologous chromosomes during prophase I of meiosis.

Independent Assortment

The random alignment and distribution of maternal and paternal homologous chromosome pairs along the equator during metaphase I of meiosis.

Spermatogenesis

The male gametogenesis process where spermatogonia undergo mitosis followed by meiosis to continuously produce sperm daily.

Oogenesis

The female gametogenesis process where oogonia divide by mitosis before birth and enter meiosis arrested at prophase I, resuming at puberty to produce one mature egg per month through unequal cytoplasmic division.

Fraternal Twins

Offspring that develop simultaneously when more than one mature egg is released and fertilized by different sperm.

Identical Twins

Offspring produced when a single fertilized egg (zygote) divides into two separate embryos within the first few days of development.

Nondisjunction

An error in meiosis where homologous chromosomes or sister chromatids fail to separate properly during anaphase I or anaphase II.

Trisomy

A chromosomal condition characterized by the presence of three copies of a particular chromosome rather than the normal two.

Monosomy

A chromosomal condition characterized by the presence of only a single copy of a chromosome rather than the normal homologous pair.

Amniocentesis

An invasive prenatal genetic test wherein amniotic fluid containing fetal cells is sampled and analyzed for chromosomal abnormalities.

Chorionic Villus Sampling

An invasive prenatal procedure where cells from the placenta are collected and tested for genetic disorders.

Artificial Insemination

An assisted reproductive procedure where collected and concentrated sperm is directly introduced into a woman's reproductive tract.

In Vitro Fertilization (IVF)

An assisted reproductive technology in which immature eggs are retrieved, fertilized with sperm in a laboratory, and the resulting embryos are transferred into the uterus.

Preimplantation Genetic Diagnosis

A diagnostic procedure performed alongside IVF in which a single cell from an embryo is screened for genetic disorders before uterine implantation.

Gene Cloning

The technique of manipulating DNA to produce multiple identical copies of a specific gene or DNA segment inside foreign host cells.

Therapeutic & Reproductive Cloning

A biotechnological method involving the transfer of DNA containing desired genes into a de-nucleated egg cell.

Genetically Modified Organism (GMO)

An organism whose genome has been altered by inserting foreign DNA from another species into its genetic material.