Genetics, Cell Division, and Inheritance

Comprehensive vocabulary flashcards covering Mendelian inheritance, DNA structure, mitosis, meiosis, Punnett squares, and pedigree charts.

Monohybrid cross

A genetic cross involving one gene with two alleles.

Dominant allele

An allele that is expressed whenever present (e.g., L for long stem in pea plants).

Recessive allele

An allele that is masked unless homozygous (e.g., l for short stem in pea plants).

Genotype

The genetic makeup of an organism (e.g., LL, Ll, ll).

Phenotype

The observable physical trait of an organism (e.g., long or short stem).

Homozygous dominant

A genotype consisting of two dominant alleles (e.g., LL).

Homozygous recessive

A genotype consisting of two recessive alleles (e.g., ll).

Heterozygous

A genotype carrying a dominant and a recessive allele (e.g., Ll), which exhibits the dominant trait.

Filial generation ($F_1$, $F_2$)

The offspring generations resulting from a parental cross.

Elementen

Gregor Mendel's term for the hereditary units that are now known as genes.

Allele

A specific variant or form of a gene (e.g., long and short alleles for stem height).

DNA (Deoxyribonucleic Acid)

A double helix molecule constructed from bonded atoms that determines the characteristics of most living organisms.

Nucleotide

The fundamental building block of DNA, composed of a deoxyribose sugar, a phosphate group, and a nitrogenous base.

Nitrogenous base

A nitrogen-containing ring molecule found in DNA, comprising adenine (A), thymine (T), guanine (G), or cytosine (C).

Hydrogen bond

A weak attraction that holds complementary nitrogenous base pairs together in the DNA double helix.

Chargaff's Rule

The biological principle stating that DNA possesses equal quantities of adenine and thymine ($A = T$), as well as equal quantities of guanine and cytosine ($G = C$).

Mitosis

Nuclear cell division of somatic cells that produces two genetically identical diploid ($2n$) daughter cells for growth, tissue repair, and cell replacement.

Somatic cells

Non-reproductive body cells.

Interphase

The phase of the cell cycle during which the cell grows, functions normally, and duplicates its DNA prior to division (comprising $G_1$, S, and $G_2$ phases).

Chromatin

Uncoiled, thread-like DNA present in the nucleus during interphase.

Chromosome

Tightly coiled, condensed DNA visible during stages of nuclear division.

Centrioles

Cellular organelles that duplicate and migrate to opposite poles to form spindle fibres during cell division.

Spindle fibres

Protein structures that attach to centromeres to maneuver chromosomes and separate chromatids during cell division.

Centromere

The specialised structural region where sister chromatids are held together and where spindle fibres attach.

Cytokinesis

The physical division of the cytoplasm into separate daughter cells following nuclear division.

Meiosis

Cell division occurring in the gonads (ovaries and testes) that yields four genetically distinct haploid ($n$) gametes from diploid ($2n$) germline cells.

Haploid ($n$)

Describing a cell containing a single set of chromosomes.

Diploid ($2n$)

Describing a cell containing two complete sets of chromosomes.

Gametes

Specialised sex cells (sperm and egg) that carry half the normal number of chromosomes.

Zygote

A diploid ($2n$) cell produced by the union of two gametes during fertilisation.

Germline cells

Diploid cells situated in the gonads that undergo meiosis to form gametes.

Crossing over

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

Chiasma

The anatomical point of contact where crossing over takes place between non-sister chromatids.

Random assortment

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

Punnett square

A grid diagram used to show all possible combinations of genotypes and phenotypes in the offspring of a genetic cross.

Pedigree chart

A diagrammatic chart used to map the transmission of specific traits or genetic disorders across multiple generations of a family.

Mode of inheritance

The characteristic biological pattern by which a genetic trait, gene, or disorder is transmitted from parents to offspring.

Genetic disorder

A disease or condition caused by abnormalities or changes in DNA sequences.

Albinism

An autosomal recessive condition that frequently skips generations and affects males and females in equal frequencies.

Huntington's disease

An autosomal dominant disorder that appears in every generation, requiring affected individuals to have at least one affected parent.