| Term | Definition |
|---|---|
| cell plate | The structure that forms during cytokinesis in plant cells to divide the cytoplasm and create a new cell wall. |
| centromere | The region of a chromosome where sister chromatids are joined and where kinetochores attach. |
| centrosomes | Cellular structures that serve as the main microtubule-organizing centers and move to opposite poles of the cell during mitosis. |
| chiasmata | Points where homologous chromosomes physically connect and exchange genetic material during meiosis. |
| chromosomes | Structures in eukaryotic cells composed of DNA and proteins that carry genetic information and are transmitted to daughter cells during mitosis. |
| cleavage furrow | The indentation that forms during cytokinesis in animal cells to divide the cytoplasm. |
| cytokinesis | The division of the cytoplasm that occurs after mitosis, resulting in the physical separation of a parent cell into two daughter cells. |
| daughter cells | The two genetically identical cells produced as a result of mitosis. |
| diploid | A cell or organism containing two complete sets of chromosomes, typically represented as 2n. |
| gamete | A haploid reproductive cell (sperm or egg) produced by meiosis that fuses with another gamete during fertilization. |
| genetic content | The total amount and composition of DNA and genes present in a cell. |
| haploid | A cell or organism containing a single set of chromosomes, typically represented as n. |
| homologous chromosomes | Pairs of chromosomes, one inherited from each parent, that have the same genes at corresponding locations. |
| kinetochore | A protein structure at the centromere where microtubules of the meiotic spindle attach to pull chromatids apart. |
| meiosis | A process of cell division in diploid organisms that produces haploid gamete cells, reducing chromosome number by half for sexual reproduction. |
| meiotic spindle | The structure of microtubules that forms during meiosis to separate chromosomes toward opposite poles of the cell. |
| metaphase plate | The equatorial region of the cell where chromosomes align during metaphase of meiosis. |
| microtubule | Protein filaments that make up the meiotic spindle and pull chromosomes toward opposite poles of the cell. |
| mitosis | A process of cell division in eukaryotes that produces two genetically identical daughter cells, each with a complete copy of the parent cell's genome. |
| nuclear envelope | A membrane-bound component of the endomembrane system that surrounds the nucleus. |
| sister chromatids | Two identical copies of a chromosome joined at the centromere, formed after DNA replication. |
| spindle apparatus | A structure composed of microtubules that forms during cell division and is responsible for moving and separating chromosomes. |
| synapsis | The pairing and alignment of homologous chromosomes during Prophase I of meiosis. |
| Term | Definition |
|---|---|
| crossing over | The exchange of genetic material between non-sister chromatids of homologous chromosomes during prophase I of meiosis. |
| fertilization | The fusion of two gametes to form a diploid zygote, combining genetic material from both parents. |
| gamete | A haploid reproductive cell (sperm or egg) produced by meiosis that fuses with another gamete during fertilization. |
| genetic diversity | The variety of different alleles and genes present within a population or species. |
| haploid | A cell or organism containing a single set of chromosomes, typically represented as n. |
| homologous chromosomes | Pairs of chromosomes, one inherited from each parent, that have the same genes at corresponding locations. |
| maternal chromosomes | Chromosomes inherited from the mother. |
| meiosis | A process of cell division in diploid organisms that produces haploid gamete cells, reducing chromosome number by half for sexual reproduction. |
| meiosis I | The first division of meiosis in which homologous chromosomes separate, reducing the chromosome number from diploid to haploid. |
| meiosis II | The second division of meiosis in which sister chromatids separate, similar to mitosis. |
| non-sister chromatids | Chromatids from different homologous chromosomes that can exchange genetic material during crossing over. |
| nondisjunction | The failure of chromosomes to separate properly during mitosis or meiosis, resulting in changes in chromosome number. |
| paternal chromosomes | Chromosomes inherited from the father. |
| prophase I | The first stage of meiosis I in which homologous chromosomes pair up and crossing over occurs. |
| random assortment | The random distribution of homologous chromosome pairs to daughter cells during meiosis I, contributing to genetic variation. |
| recombination | The process by which genetic material is exchanged between homologous chromosomes, creating new combinations of alleles. |
| sexual reproduction | Reproduction involving the fusion of gametes from two parents, producing genetically diverse offspring. |
| sister chromatids | Two identical copies of a chromosome joined at the centromere, formed after DNA replication. |
| Term | Definition |
|---|---|
| allele | Different versions of a gene that can exist at the same location on a chromosome. |
| autosomal inheritance | Inheritance of traits controlled by genes located on autosomes (non-sex chromosomes). |
| dihybrid cross | A cross between two organisms that differ in two traits controlled by two different genes. |
| diploid | A cell or organism containing two complete sets of chromosomes, typically represented as 2n. |
| dominant allele | An allele that is expressed in the phenotype when present in either homozygous or heterozygous condition. |
| genetic variation | Differences in DNA sequences and alleles that exist within a population. |
| genetically linked | Genes located close together on the same chromosome that tend to be inherited together. |
| genotype | The genetic makeup of an organism; the specific alleles present for each gene. |
| haploid gametes | Sex cells (sperm or egg) that contain half the chromosome number of the parent organism. |
| heterozygous | Having two different alleles for a particular gene. |
| homozygous | Having two identical alleles for a particular gene. |
| Mendel's law of independent assortment | The principle that alleles of different genes assort independently during gamete formation when genes are on different chromosomes. |
| Mendel's laws of segregation | The principle that allele pairs separate during gamete formation, with each gamete receiving one allele for each gene. |
| monohybrid cross | A cross between two organisms that differ in a single trait controlled by one gene. |
| pedigree | A diagram showing the inheritance of a trait through multiple generations of a family. |
| phenotype | The observable physical and biochemical characteristics of an organism, determined by both genetic and environmental factors. |
| Punnett square | A diagram used to predict the genotypes and phenotypes of offspring from a cross between two parents. |
| recessive allele | An allele that is expressed in the phenotype only when present in homozygous condition. |
| sex-linked inheritance | Inheritance of traits controlled by genes located on sex chromosomes. |
| test cross | A cross between an organism expressing a dominant phenotype and a homozygous recessive organism to determine the genotype. |
| zygote | A fertilized egg cell formed from the fusion of two gametes. |
| Term | Definition |
|---|---|
| chloroplast DNA | Genetic material located in chloroplasts that can be inherited independently of nuclear DNA, typically through the maternal lineage in plants. |
| codominance | A pattern of inheritance in which both alleles are fully expressed in the heterozygote, resulting in a phenotype different from either homozygote. |
| deviations from Mendel's model | Patterns of inheritance that do not follow the predicted ratios and rules established by Mendel's laws of inheritance. |
| genetic mapping | The process of determining the relative positions and distances of genes on a chromosome based on recombination frequencies. |
| genetically linked | Genes located close together on the same chromosome that tend to be inherited together. |
| incomplete dominance | A pattern of inheritance in which neither allele is completely dominant, resulting in a blended phenotype in the heterozygote that is intermediate between the two homozygous phenotypes. |
| map distance | The relative distance between two genes on a chromosome, measured in map units and calculated based on the frequency of recombination between them. |
| maternal inheritance | A pattern of inheritance in which traits are transmitted only or primarily through the female parent, typically due to organellar DNA in the egg or ovule. |
| mitochondrial DNA | Genetic material located in mitochondria that can be inherited independently of nuclear DNA, typically through the maternal lineage. |
| non-nuclear inheritance | Inheritance of traits determined by genes located in organelles such as mitochondria and chloroplasts rather than in the nucleus. |
| phenotypic ratios | The proportions of different observable traits in offspring, compared to predicted ratios based on genetic crosses. |
| pleiotropy | A phenomenon in which a single gene influences the expression of multiple, seemingly unrelated traits. |
| sex-linked traits | Traits determined by genes located on sex chromosomes (X or Y), which show inheritance patterns different from autosomal traits. |
| Term | Definition |
|---|---|
| environmental conditions | External factors such as temperature, light, pH, and other physical or chemical factors that influence gene expression and phenotype development. |
| gene expression | The process by which information from a gene is used to synthesize functional gene products, typically proteins, which can be influenced by environmental conditions. |
| genotype | The genetic makeup of an organism; the specific alleles present for each gene. |
| phenotype | The observable physical and biochemical characteristics of an organism, determined by both genetic and environmental factors. |
| phenotypic plasticity | The ability of a single genotype to produce different phenotypes in response to different environmental conditions. |