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Notes Summary for Chapter 10: Meiosis and Sexual Life Cycles
A note on the notes: Hopefully this will be helpful, but keep in mind that taking the time to summarize the notes on your own is in itself a good way to study.
Like begets like. Organisms reproduce and pass on traits (characteristics that can be inherited). Heredity is the passing on of traits. Offspring tend to resemble their parents, but also show variation (they are different from their parents and siblings). Genetics is the study of heredity and variation.
Genes are responsible for heredity; they are segments of DNA on chromosomes which are passed from parents to offspring via gametes (reproductive cells; sperm and eggs).
Chromosome number varies by species. Humans have 46 chromosomes in their somatic (non-sex) cells. A locus is the site of a certain gene on a chromosome.
Reproduction may be asexual or sexual. Asexual reproduction is when a single individual reproduces, making clones (genetically identical offspring). Sexual reproduction involves two parents producing genetically variable offspring.
A karyotype is a composite photograph that shows all the chromosomes of an organism lined up neatly.
Chromosomes in somatic cells are in pairs; humans have 23 pairs (46 total). The members of a pair are homologous chromosomes; they are the same size and have genes controlling the same traits. Each pair consists of one chromosome from the mother and one chromosome from the father. Since somatic cells contain pairs of chromosomes, one from each parent, they are called diploid cells (2n for short). So, the diploid number for us is 46.
In humans, most chromosomes (22 pairs) are autosomes (non-sex chromosomes). The sex chromosomes, X and Y, determine gender. Females have XX (a homologous pair), males have XY.
During the cell cycle, DNA synthesis doubles the number of chromosomes, so each member of a homologous pair has two sister chromatids.
Gametes have half the number of...