生物专业英语期末打印版.doc

Homozygous（纯合的）：A diploid organism that has two identical alleles for particular characteristic. Heterozygous (杂合的):A diploid organism that has two different alletic forms of a particular gene. Phenotype（表型）：The physical, chemical, and psychological expression of genes possessed by an organism. Genotype（基因型）：The catalog of genes of an organism, whether or not these genes are expressed. Allele（等位基因）：Alternative forms of a gene for a particular characteristic (e.g., attached earlobe genes and free earlobe genes are alternative alleles for ear shape). Monohybrid Crosses(单因子杂种)：a hybrid produced by crossing parents that are homozygous except for a single gene locus that has two alleles. Dihybrid crosses(双因子杂种，双因子杂合子):A cross between individuals that differ with respect to two specified gene pairs. Law of independent assortment(独立分配定律，自由组合定律)::Members of one gene pair will separate from each other independently of the members of other gene pairs. Semiconservative replication(半保留复制):The method of replication of DNA in which the molecule divides longitudinally, each half being conserved and acting as a template for the formation of a new strand. Lagging strand(后随链): is synthesized in short stretches known as Okazaki fragments. DNA polymerase( DNA 聚合酶):An enzyme that brings new DNA triphosphate nucleotides into position for bonding on another DNA molecule. Age structure(年龄结构):Of a population, the number of individuals in each of several or many age categories. Density-dependent factors(密度依赖因子，密度制约因子):population-limiting factors that become more effective as the size of the population increases. 1.As mitosis proceeds, the spindle microtubules play a crucial role in ensuring that both paired and separated chromatids move in the right directions at the proper times.??Each half of the spindle forms as microtubules extend from each pole of a dividing cell to the region of the metaphase plate.??During prophase, other microtubules, the centromeric fibers, extend o