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Biology CH. 6
Meiosis and Mendel
Term | Definition |
---|---|
Somatic Cell | Cell that makes up all of the body tissues and organs, except gametes. |
Gamete | Sex cell; an egg or a sperm cell. |
Homologous Chromosomes | Chromosomes that have the same length, appearance, and copies of genes, although the alleles may differ. |
Diploid | Cell that has two copies of each chromosome, one from an egg and one from a sperm. |
Haploid | Cell that has only one copy of each chromosome. |
Meiosis | Form of nuclear division that divides a diploid cell into haploid cells; important in forming gametes for sexual reproduction. |
Cross | Mating of two organisms. |
Law of Segregation | Mendel's first law, stating that (1) organisms inherit two copies of genes, one from each parent, and (2) organisms donate only one copy of each gene in their gametes because the genes separate during gamete formation. |
Gene | Specific region of DNA that codes for a particular protein. |
Allele | Any of the alternative forms of a gene that occurs at a specific place on a chromosome. |
Homozygous | Characteristic of having two of the same alleles at the same locus of sister chromatids. |
Heterozygous | Characteristic of having two different alleles that appear at the same locus of sister chromatids. |
Genotype | Collection of all of an organism's genetic information that codes for traits. |
Phenotype | Collection of all of an organism's physical characteristics. |
Dominant | Allele that is expressed when two different alleles are present in an organism's genotype. |
Recessive | Allele that is not expressed unless two copies are present in an organism's genotype. |
Test Cross | Cross between an organism with an unknown genotype and an organism with a recessive phenotype. |
Law of Independent Assortment | Mendel's second law, stating that allele pairs separate from one another during gamete formation. |