Question | Answer |
Allele | An allele is a variant form of a gene. Some genes have a variety of different forms, which are located at the same position. |
Autosome | An autosome is a chromosome that is not a sex chromosome. |
Dihybrid | Dihybrid cross is a cross between two pure lines (varieties, strains) that differ in two observed traits |
Dominant Allele | The first allele is dominant and the second allele is recessive. For genes on any chromosome other than a sex chromosome, the alleles and their associated traits are autosomal dominant or autosomal recessive. |
Genotype | A genotype is an individual's collection of genes. |
Heterozygous | A diploid organism is heterozygous at a gene locus when its cells contain two different alleles of a gene. The cell or organism is called a heterozygote specifically for the allele |
Homozygous | Homozygous is a genetic condition where an individual inherits the same alleles for a particular gene from both parents. |
Monohybrid | A monohybrid cross is a mating between two individuals with different alleles at one genetic locus of interest |
Multiple allele | Typically, we teach with genes for which only two alleles are known, but many genes have more than two different alleles--thus, "multiple" alleles. |
Phenotype | Phenotype is the composite of an organism's observable characteristics or traits |
Punnett Square | The Punnett square is a diagram that is used to predict an outcome of a particular cross or breeding experiment. |
Recessive allele | allele that produces its characteristic phenotype only when its paired allele is identical |
Sex Chromosome | a chromosome involved with determining the sex of an organism, typically one of two kinds. |
Sex-linked Trait | genes on the sex chromosomes, males have just one copy. The Y chromosome has few genes, but the X chromosome has more than 1,000. |
Test Cross | involves the breeding of a phenotypically dominant individual with a phenotypically recessive individual, in order to determine the zygosity of the former by analyzing proportions of offspring phenotypes |
Apoptosis | Apoptosis is the process of programmed cell death that may occur in multicellular organisms |
Cell Cycle | A cell cycle is a series of events that takes place in a cell as it grows and divides |
Centriole | A centriole is a small set of microtubules arranged in a specific way |
Centromere | The centromere is the part of a chromosome that links sister chromatids. |
Chromatin | Chromatin is a complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells. |
Chromosome | Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of DNA. |
Crossing-over | Chromosomal crossover (or crossing over) is the exchange of genetic material between homologous chromosomes that results in recombinant chromosomes during sexual reproduction. |
Cytokinesis | Cytokinesis is the physical process of cell division, which divides the cytoplasm of a parental cell into two daughter cells. |
Diploid | Diploid is a cell or organism that has paired chromosomes, one from each parent. In humans, cells other than human sex cells, are diploid and have 23 pairs of chromosomes. |
Chromosome Number | Human cells have 23 pairs of chromosomes (22 pairs of autosomes and one pair of sex chromosomes), giving a total of 46 per cell/ |
Homologous Chromosomes | Homologous chromosomes are similar but not identical. Each carries the same genes in the same order, but the alleles for each trait may not be the same. |
Meiosis | A type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores. |
Mitosis | Mitosis is a part of the cell cycle in which chromosomes in a cell nucleus are separated into two identical sets of chromosomes, each in its own nucleus. |
Nondisjunction | Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division. |
somatic cell | A somatic cell is any cell of the body except sperm and egg cells. Somatic cells are diploid, meaning that they contain two sets of chromosomes, one inherited from each parent. |
synapsis | Synapsis is the pairing of two homologous chromosomes that occurs during meiosis. It allows matching-up of homologous pairs prior to their segregation, and possible chromosomal crossover between them |