3b - Genes and Inheritance

Allele

等位基因 (děngwèi jīyīn) Different forms or versions of the same gene, found at the same locus (position) on homologous chromosomes, coding for different variations of a trait.

Codominant

共显性（等位基因）(gòngxiǎnxìng (děngwèi jīyīn)) A situation where two different alleles for a gene are both fully expressed in the phenotype of a heterozygous individual (e.g., AB blood type).

Dominant

显性（等位基因）(xiǎnxìng (děngwèi jīyīn)) An allele that is always expressed in the phenotype when present, masking the effect of a recessive allele in a heterozygous individual.

F1 generation (First Filial Generation)

子一代 (zǐyīdài) The first generation of offspring resulting from a genetic cross between two parent organisms (P generation).

F2 generation (Second Filial Generation)

子二代 (zǐ'èrdài) The generation of offspring produced by interbreeding individuals from the F1 generation.

Gene

基因 (jīyīn) A segment of DNA on a chromosome that codes for a specific protein or functional RNA, thereby controlling a particular characteristic or trait. The basic unit of heredity.

Genetic Diagram

遗传图解 (yíchuán tújiě) / 遗传杂交 (yíchuán zájiāo) A diagram used to predict the genotypes and phenotypes of offspring from a specific cross, often involving a Punnett square.

Genotype

基因型 (jīyīnxíng) The specific combination of alleles an organism possesses for a particular gene or set of genes (e.g., AA, Aa, aa).

Heterozygous

杂合的 (záhéde) / 杂合子 (záhézǐ) Having two different alleles for a particular gene (e.g., Aa).

Homozygous

纯合的 (chúnhéde) / 纯合子 (chúnhézǐ) Having two identical alleles for a particular gene (e.g., AA or aa).

Locus (plural: Loci)

基因座 (jīyīnzuò) The specific physical location of a gene on a chromosome.

Monohybrid

单基因杂交 (dānjīyīn zájiāo) / 单基因遗传 (dānjīyīn yíchuán) A genetic cross or pattern of inheritance involving a single gene (one pair of contrasting traits).

Pedigree

系谱图 (xìpǔtú) A diagram or chart that shows the inheritance of a specific genetic trait or disorder through several generations of a family.

Phenotype

表现型 (biǎoxiànxíng) The observable physical, biochemical, or behavioral characteristics of an organism, resulting from the interaction of its genotype and the environment.

Polygenes

多基因 (duōjīyīn) A group of multiple genes that collectively influence a single quantitative (continuous) trait, with each gene having a small additive effect.

Polygenic inheritance

多基因遗传 (duōjīyīn yíchuán) A pattern of inheritance where a single characteristic (e.g., height, skin color) is controlled by the cumulative effects of two or more genes (polygenes). Leads to continuous variation.

Punnett square

旁氏表 (Pángshì biǎo) / 棋盘格 (qípángé) A grid-like diagram used to predict all possible genotypes and phenotypes of offspring from a genetic cross by showing how alleles from parents can combine.

Recessive

隐性（等位基因）(yǐnxìng (děngwèi jīyīn)) An allele whose phenotypic effect is only expressed when two copies are present (i.e., in a homozygous recessive individual); its effect is masked by a dominant allele in a heterozygote.

Sex chromosomes

性染色体 (xìng rǎnsètǐ) Chromosomes that determine the sex of an individual (e.g., X and Y chromosomes in humans). They also carry genes for other traits (sex-linked traits).

Sex-linked characteristic/trait

伴性遗传特征 (bànxìng yíchuán tèzhēng) A characteristic or trait determined by a gene located on one of the sex chromosomes (usually the X chromosome in humans), leading to different patterns of inheritance in males and females.

Test cross

测交 (cèjiāo) A genetic cross between an individual with a dominant phenotype (but unknown genotype) and a homozygous recessive individual. Used to determine if the dominant individual is homozygous or heterozygous.