Ch 13-17

Ch 13-17 - Chapter 13 Meiosis and Sexual Life Cycles...

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Chapter 13 Meiosis and Sexual Life Cycles Heredity: the transmission of traits from one generation to the next. Variation: the concept that is there along with inherited similarity, differences between children and their parents. Genetics: the scientific study of heredity and hereditary variation. 13.1 Offspring acquire genes from parents by inheriting chromosomes. Parents endow their offspring with coded information in the form of units called genes. These genes are the genetic link to our parents and account for the resemblances that we share with our parents. Gametes: reproductive cells which are the vehicles that transmit genes from one generation to the next. Humans have 46 chromosomes. Locus: a genes specific location along the length of a chromosome. Only asexual reproduction produces exact copies of themselves as offspring. In asexual reproduction, a single individual is the sole parent and passes copies of all its genes to its offspring. This offspring is then called a clone, a group of genetically identical individuals. The only changes that may occur in this type of reproduction is changes in the DNA due to mutations. Sexual Reproduction: is the other type of reproduction where 2 parents give rise to a offspring that has a unique combination of genes inherited from the two parents. These are not direct copies of their parents but instead are variations on a common theme. Concept Check 13.1 Traits of parents are transmitted to their offspring through genes . Asexually reproducing organisms produce offspring that are genetically identical to each other and their parents because they do this through mitotic cell division where it results in two identical sister cells. She should clone it because now she wants identical copies of it. Originally she was breeding to find the unique combination of desirable traits and now that she has found it, she just wants to clone it. 13.2 Fertilization and meiosis alternate in sexual life cycles. A life cycle: generation-to-generation sequence of stages in the reproductive history of an organisms, from conception to production of its own offspring. In humans there are 46 chromosomes in the somatic cell, any cell other than those involved in gamete formation. During mitosis, the chromosomes become condensed enough to be visible in a light microscope. There are 2 chromosomes of each 23 types and this becomes clear when they are arranged in pairs in a display called the karyotype. Homologous chromosomes: (homologs) are two chromosomes composing a pair having the same length, centromere position, and staining pattern. Two distinct chromosomes are that females have a XX chromosome in their pair of 23 and the males have a XY. Only small parts of the XY chromosome are homologs. These X Y chromosomes are called the sex chromosomes
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Ch 13-17 - Chapter 13 Meiosis and Sexual Life Cycles...

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