Bios 208 1st Edition Lecture 28Outline of Last Lecture I. The Cell Cycle Control SystemII. The Cell Cycle Clock: Cyclins and Cyclin Dependent KinasesIII. Stop and Go Signs: Internal and External Signals at the CheckpointsIV. Loss of Cell Cycle Controls in Cancer CellsOutline of Current Lecture I. Living OrganismsII. Comparison of Asexual and Sexual ReproductionIII. Fertilization and meiosis alternate in sexual life cyclesIV. Sets of Chromosomes in Human CellsCurrent LectureI. Living OrganismsA. Living organisms are distinguished by their ability to reproduce their own kindB. Genetics is the scientific study of heredity and variationC. Heredity is the transmission of traits from one generation to the nextD. Variation is demonstrated by the differences in appearance that offspring show from parents and siblingsE. Offspring acquire genes from parents by inheriting chromosomesF. In a literal sense, children do not inherit particular physical traits from their parentsG. It is genes that are actually inheritedH. Genes are the units of heredity, and are made up of segments of DNAI. Genes are passed to the next generation via reproductive cells called gametes (sperm and eggs)J. Each gene has a specific location called a locus on a certain chromosomeK. Most DNA is packaged into chromosomesII. Comparison of Asexual and Sexual ReproductionA. In asexual reproduction, a single individual passes genes to its offspring without the fusion of gametesB. A clone is a group of genetically identical individuals from the same parentThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.C. In sexual reproduction, two parents give rise to offspring that have unique combinations of genes inherited from the two parentsD. Mitosis of the zygote (2n; fertilized egg) produces a multicellular organism composed of genetically identical cells. These cells are a clone.E. A group of cells can detach from the parent and become a complete individual. The “bud” is a clone of the parentIII. Fertilization and meiosis alternate in sexual life cyclesA. A life cycle is the generation-to-generation sequence of stages in the reproductive history of an organismB. Sexual life cycles introduce variation to offspring. No offspring produced by sexual reproduction are exactly like a parent.IV. Sets of Chromosomes in Human CellsA. Human somatic cells (any cell other than a gamete) haveB. 23 pairs of chromosomesC. A karyotype is an ordered display of the pairs of chromosomes from a cellD. The two chromosomes in each pair are called homologous chromosomes, or homologsE. Chromosomes in a homologous pair are the same length and shape and carry genes controlling the same inherited charactersF. The sex chromosomes, which determine the sex of the individual, are called X and YG. Human females have a homologous pair of X chromosomes (XX)H. Human males have one X and one Y chromosomeI. The remaining 22 pairs of chromosomes are called autosomesJ. Each pair of homologous chromosomes includes one chromosome from each parentK. The 46 chromosomes in a human somatic cell are two sets of 23: one from the mother and one from the fatherL. A diploid cell (2n) has two sets of chromosomesM. For humans, the diploid number is 46 (2n = 46)N. In a cell in which DNA synthesis has occurred, each chromosome is replicatedO. Each replicated chromosome consists of two identical sister chromatidsP. A gamete (sperm or egg) contains a single set of chromosomes, and is haploid (n)Q. For humans, the haploid number is 23 (n = 23)R. Each set of 23 consists of 22 autosomes and a single sex chromosomeS. In an unfertilized egg (ovum), the sex chromosome is XT. In a sperm cell, the sex chromosome may be either X or
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