Inherited change
Genetic information is transmitted from generation to generation to maintain the continuity of life. In
sexual reproduction, meiosis introduces genetic variation so that offspring resemble their parents but
are not identical to them. Genetic crosses reveal how some features are inherited. The phenotype
of organisms is determined partly by the genes they have inherited and partly by the effect of the
environment. Genes determine how organisms develop and gene control in bacteria gives us a glimpse of
this process in action.
Passage of information from parent to offspring
Diploid organisms contain pairs of homologous chromosomes. The behaviour of maternal and paternal
chromosomes during meiosis generates much variation amongst individuals of the next generation.
Homologous chromosomes: are a pair of chromosomes in a diploid cell that have the
same structure as each other, with the same genes (but not necessarily he same alleles of
those genes) at the same loci, and that pair together to form a bivalent during the first
division of meiosis.
Diploid (2n): a diploid cell is one that possess 2 complete sets of chromosomes.
Haploid (n): a haploid cell is one that possesses one complete set of chromosomes.
N= the number of chromosomes in one set of chromosomes
In humans normal body cells are diploid, with 46 chromosomes, and gametes are
haploid with 23 chromosomes.
Meiosis is a special type of cell division concerned with producing sex cells (gametes)
fro sexual reproduction.
Fro the life cycle to contain sexual reproduction. Before fertilisation chromosome is
haled results in gametes containing only one set of chromosomes instead of 2.
If not number of chromosomes would double each generation. Meiosis = nuclear
division that halves the chromosomes. ( reduction division)
Genetic information is transmitted from generation to generation to maintain the continuity of life. In
sexual reproduction, meiosis introduces genetic variation so that offspring resemble their parents but
are not identical to them. Genetic crosses reveal how some features are inherited. The phenotype
of organisms is determined partly by the genes they have inherited and partly by the effect of the
environment. Genes determine how organisms develop and gene control in bacteria gives us a glimpse of
this process in action.
Passage of information from parent to offspring
Diploid organisms contain pairs of homologous chromosomes. The behaviour of maternal and paternal
chromosomes during meiosis generates much variation amongst individuals of the next generation.
Homologous chromosomes: are a pair of chromosomes in a diploid cell that have the
same structure as each other, with the same genes (but not necessarily he same alleles of
those genes) at the same loci, and that pair together to form a bivalent during the first
division of meiosis.
Diploid (2n): a diploid cell is one that possess 2 complete sets of chromosomes.
Haploid (n): a haploid cell is one that possesses one complete set of chromosomes.
N= the number of chromosomes in one set of chromosomes
In humans normal body cells are diploid, with 46 chromosomes, and gametes are
haploid with 23 chromosomes.
Meiosis is a special type of cell division concerned with producing sex cells (gametes)
fro sexual reproduction.
Fro the life cycle to contain sexual reproduction. Before fertilisation chromosome is
haled results in gametes containing only one set of chromosomes instead of 2.
If not number of chromosomes would double each generation. Meiosis = nuclear
division that halves the chromosomes. ( reduction division)
