sex factor

F plas·mid

the prototype conjugative plasmid associated with conjugation in the K-12 strain of Escherichia coli. Synonym(s): fertility factor, sex factor

sex factor

n. A bacterial plasmid that enables one bacterium to donate its genetic material to another bacterium by conjugation, resulting in genetic recombination. Also called fertility factor, f factor.

sex factor

HOMOGAMETIC SEX. In humans the male is heterogametic, sex being determined by the presence of a Y-chromosome rather than the presence of two X-chromosomes (see KLINEFELTERS'S SYNDROME and TURNER'S SYNDROME). In birds, reptiles, some amphibia and lepidopterans, the situation is reversed, with females being the heterogametic sex. In fruit flies, sex is determined by the ratio of the number of X-chromosomes to the number of sets of autosomes (A). When the ratio of X/A = 1.0 the individual is female, when X/A = 0.5 a male results. In other DIPTERANS such as the yellow-fever mosquito, sex is determined by a single locus with two alleles, the heterozygote being the male (M/m) and a homozygote the female (mm). Plants too can have XX, XY sex determination where they are DIOECIOUS, but various other mechanisms also can occur. For example, sex in asparagus is controlled by a single pair of alleles, with maleness dominant.

sex factor

see F FACTOR.

单词	sex factor
释义	sex factor sex factor n. A bacterial plasmid that enables one bacterium to donate its genetic material to another bacterium by conjugation, resulting in genetic recombination. Also called fertility factor, f factor. sex factor sex factor [′seks ‚fak·tər] (genetics) fertility factor sex factor F plas·mid the prototype conjugative plasmid associated with conjugation in the K-12 strain of Escherichia coli. Synonym(s): fertility factor, sex factor sex factor n. A bacterial plasmid that enables one bacterium to donate its genetic material to another bacterium by conjugation, resulting in genetic recombination. Also called fertility factor, f factor. sex factor HOMOGAMETIC SEX. In humans the male is heterogametic, sex being determined by the presence of a Y-chromosome rather than the presence of two X-chromosomes (see KLINEFELTERS'S SYNDROME and TURNER'S SYNDROME). In birds, reptiles, some amphibia and lepidopterans, the situation is reversed, with females being the heterogametic sex. In fruit flies, sex is determined by the ratio of the number of X-chromosomes to the number of sets of autosomes (A). When the ratio of X/A = 1.0 the individual is female, when X/A = 0.5 a male results. In other DIPTERANS such as the yellow-fever mosquito, sex is determined by a single locus with two alleles, the heterozygote being the male (M/m) and a homozygote the female (mm). Plants too can have XX, XY sex determination where they are DIOECIOUS, but various other mechanisms also can occur. For example, sex in asparagus is controlled by a single pair of alleles, with maleness dominant. sex factor see F FACTOR.
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