Genetics Definitions

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Definitions:

Centromere - The structure that holds chromatids together

Chromatid - One of the two chromosome strands resulting from the duplication of a chromosome. The pair are called sister chromatids and they remain attached at their centromere until separated during mitosis.

Chromosomes - Long threads of genetic material found in the nucleus of cells.

Centrioles - Small protein bodies that are found in the cytoplasm of animal cells.

Spindle fibres - Protein structures that guide chromosomes during cell division.

Interphase - the time interval between nuclear divisions. during this phase, a cell increases in mass , roughly doubles in the cytoplasmic components, and duplicates its chromosomes.

Prophase - Cell biology the first stage of mitosis or meiosis in eukaryotic cell division, during which the nuclear envelope breaks down and strands of chromatin for into chromosomes.

Metaphase - The stage in mitosis or meiosis in which the duplicated chromosomes line up along the equatorial plate of the spindle.

Anaphase - The stage in mitosis or meiosis in which the daughter chromosomes move away from teach other to opposite ends of the cell.

Telophase - The final stage of mitosis or meiosis in which the separated chromosomes reach the opposite poles of the dividing cell and the nuclei of the daughter cells from around the two sets of chromosomes.

Meiosis - Two stage cell devision in which eh chromosome number of the parental cell is reduced by half. Meiosis is the process in which the gametes are formed.

Gametes - Sex cells that have haploid chromosome number.

Haploid - Refers to the number of chromosomes in a gamete.

Diploid - Refers to twice the number of chromosomes in a gamete. Every cell of the body, with exception sex cells, contains a diploid chromosome number.

Tetrad - A pair of homologous chromosomes, each with two chromatids

Homologous chromosomes - Paired chromosomes similar in shape, size, gene arrangement, and then information.

Zygote - A cell resulting from the union of a male and female sex cell, until it divides and then there is an embryo.

Synapsis - The pairing of homologous chromosomes.

Crossing over - The exchange of genetic material between two homologous chromosomes.

Autosomes - The chromosomes not involved in sex determination.

Trisomy - The condition where there are three homologous chromosomes in place of a homologous pair.

Monosomy - The condition where there is a single chromosome in place of a homologous pair.

Down syndrome - A triatomic disorder in which a zygote receives three chromosomes for chromosome pair 21.

Karyotype chart - A picture of chromosomes arranged in homologous pairs.

Turner syndrome - A monosomic disorder in which the female has a single X chromosome.

Klinefelter syndrome - A triatomic disorder in which the male caries an XXY condition.

Heredity - The passing of traits from parents to offspring.

Hybrids - Offspring that differ from their parents in one or more traits. Interspecifically hybrids result from the fusion/union of two different species.

Alleles - Two or more alternate forms of a gene. The alleles are located at the same position on one of the pairs of homologous chromosomes.

Dominant - Alleles of this type determine the expression of the genetic trait in offspring.

Recessive - Alleles of this type are over ruled by dominant alleles, which t=determine the genetic trait.

Genotype - The alleles an organism contains.

Phenotype - The obsvalbe traits of an organism that arise because of the interaction between genes and the environment.

Homozygous - A genotype in which both alleles of a pair are the same.

Heterozygous - A genotype in which the alleles of a pair are different.

Monohybrid cross - A cross that involves one allele pair of contrasting traits.

Punnet square - A chart used by geneticists to show the possible combination of alleles in offspring.

Monohybrid cross - Learn about he basic principles that govern Mendelian inheritance in plants and animals

Dihybrid cross - Investigate the principles; that govern inheritance of different traits in dihybrid cross

Sex linked inheritance 1 - Understand the principles that govern inheritance of genes on sex chromosomes.

Sex linked inheritance 2 - Explore sex linked inheritance with a special twist crossing over between two traits.

Somatic cells - All the cells of an organism other than the sex cells.

Mutation - A heritable change in the molecular structure of DNA. Many mutations change the appearance of the organism.

Sex linked traits - Traits that are controlled by genes located on the sex chromosomes.

Recessive lethal - A trait that, when both recessive alleles are present, results in death or severe malformation.

The process of sperm production.

Oogenesis - The process of egg production.