Genetics and Cell Division Vocabulary

Fundamental Concepts in Genetics and DNA Structure

  • Genetics: The scientific study of genes and the mechanisms of inheritance.

  • DNA (Deoxyribonucleic acid): The fundamental molecule that carries the genetic information for all living organisms.

  • Genome: The complete set of all the DNA contained within a single cell of an organism.

  • Nucleotide: The primary building block of DNA. DNA is formed by chains of these units.

  • Gene: A specific, small section of DNA that provides the necessary instructions for a trait or function.

  • Locus: The specific, fixed location or place of a particular gene on a chromosome.

  • Chromatin: DNA in its loose, uncoiled form when it is not tightly packed into structures.

  • Chromosome: A long, organized structure composed of DNA that carries genetic information in the form of genes.

  • Autosome: Any chromosome that is not categorized as a sex chromosome.

  • Sex Chromosomes: The specific chromosomes that determine the biological sex of an individual.

  • Centromere: The middle portion of a chromosome that serves to hold the structure together during various cellular processes.

  • Sister Chromatids: Two identical copies of a single chromosome that are formed during DNA replication.

  • Telomeres: The protective caps or ends found at the extremities of chromosomes.

  • Complementary Base Pairing: The specific matching of DNA bases in pairs, where Adenine (AA) always pairs with Thymine (TT) and Cytosine (CC) always pairs with Guanine (GG).

  • Hydrogen Bonds: The relatively weak chemical bonds that hold the two strands of DNA together through their base pairs.

  • Karyotype: A visual image or picture used to document and examine all the chromosomes within a cell.

  • Somatic Cells: All the cells in the body of an organism, excluding the sex cells (gametes).

Genetic Mutations and Chromosomal Abnormalities

  • Mutation: Any change in the DNA sequence.

  • Gene Mutation: A localized change occurring within a single gene.

  • Chromosome Mutation: A significant change that affects the structure or number of an entire chromosome.

  • Somatic Mutation: A mutation that occurs specifically within body cells rather than reproductive cells.

  • Spontaneous Mutation: A mutation that occurs naturally without any external influence.

  • Trisomy: A chromosomal condition characterized by having one extra chromosome in a set (e.g., three chromosomes instead of the standard pair).

Mitosis and the Cell Cycle

  • Parent Cell: The original cell that initiates the process of cell division.

  • Mitosis Cell Division: The comprehensive process through which a parent cell divides to generate new cells.

  • Mitosis: A specific type of cell division resulting in two daughter cells that are genetically identical to the parent cell. This process is essential for biological growth and tissue repair.

  • Interphase: The preparatory stage occurring before mitosis begins. During this phase, the cell grows, replicates its DNA, and prepares for the upcoming division.

  • DNA Replication: The critical process of copying DNA during Interphase to ensure that each resulting daughter cell receives a complete and identical set of genetic material.

  • Prophase: The initial stage of mitosis characterized by the condensation of chromosomes, the breakdown of the nuclear membrane, and the initiation of spindle fibre formation.

  • Metaphase: The stage of mitosis where chromosomes align themselves along the middle (equator) of the cell.

  • Anaphase: The phase where sister chromatids are physically pulled apart and move toward opposite ends of the cell.

  • Spindle Fibres: Specialized protein structures responsible for pulling chromatids apart during the stages of mitosis.

  • Telophase: The stage where nuclear membranes begin to reform around each of the two sets of chromosomes, and the chromosomes begin to uncoil back into chromatin.

  • Cytokinesis: The final division of the cytoplasm, which completes the cell division process and results in two distinct daughter cells.

  • Daughter Cells: The two new cells produced through mitosis; they contain a genetic profile identical to the parent cell.

  • Apoptosis: A programmed process of cell self-destruction that occurs when a cell is damaged, aged, or is no longer required by the organism.

Meiosis and Sexual Reproduction

  • Sexual Reproduction: The process of producing offspring through the contribution of genetic material from two distinct parents.

  • Meiosis: A specialized form of cell division dedicated to the production of sex cells (gametes).

  • Gametes: The reproductive sex cells, specifically the sperm in males and the egg in females.

  • Haploid (nn): A cell containing only one single set of chromosomes.

  • Diploid (2n2n): A cell containing two complete sets of chromosomes.

  • Fertilisation: The biological event where a sperm cell and an egg cell join together.

  • Embryo: An organism in its very early developmental stage following fertilisation.

  • Homologous Chromosomes: Pairs of chromosomes that carry the same types of genes, with one chromosome inherited from each parent.

  • Recombination: The mixing of genes that occurs during the process of meiosis.

The Stages of Meiosis

  • Prophase I: The stage where chromosomes condense and homologous chromosomes pair up. During this time, the process of "crossing over" occurs.

  • Crossing Over: A vital process where homologous chromosomes exchange segments of DNA, which serves to increase genetic variation in the offspring.

  • Metaphase I: The stage where homologous pairs of chromosomes align in the middle of the cell.

  • Anaphase I: The stage where homologous chromosomes are pulled to opposite ends of the cell, while the sister chromatids remain together.

  • Telophase I: Two separate nuclei form and the cell undergoes its first division, resulting in two haploid cells.

  • Prophase II: Chromosomes condense again within each of the two haploid cells produced in Meiosis I.

  • Metaphase II: Chromosomes align themselves in the centre of each of the two cells.

  • Anaphase II: Sister chromatids are finally pulled apart to opposite sides of the cells.

  • Telophase II: The final stage resulting in the formation of four haploid cells. Each of these four cells is genetically unique.

Principles of Inheritance and Heredity

  • Heredity: The biological process describing how traits are passed from parents to their children.

  • Inheritance: The mechanism by which genetic qualities are transmitted from parent to offspring.

  • Allele: A different version or variant of the same gene.

  • Genotype: The specific set of genes possessed by an organism.

  • Phenotype: The observable physical traits or characteristics of an organism, such as eye colour.

  • Homozygous: A genetic condition where an individual has two identical alleles for a particular gene.

  • Heterozygous: A genetic condition where an individual has two different alleles for a particular gene.

  • Dominant: A gene whose trait is expressed in the phenotype even if only one copy is present.

  • Recessive: A gene whose trait only appears in the phenotype if two copies are present.

  • Codominance: A genetic scenario where both alleles for a gene are expressed simultaneously in the phenotype.

  • Incomplete Dominance: A genetic scenario where a mix or blend of two traits is displayed in the phenotype.

  • Carrier: An individual who possesses a specific gene for a trait but does not outwardly show that trait in their phenotype.

  • Punnett Square: A standardized grid used by geneticists to predict the possible traits of offspring.

  • Monohybrid Cross: A genetic cross performed to study the inheritance of a single trait.

  • Test Cross: A specific genetic cross used to determine the unknown genotype of an individual organism.