This blog post is a part of STEMTalksNC’s ever expanding General Biology Series.
Living Organisms are distinguished by their ability to reproduce their own kind. Heredity is the transmission of traits from one generation to the next. Along with these these inherited traits, there is also variation– the offspring differ somewhat in appearance from parents and siblings. We will first establish that offspring acquire genes from parents by inheriting chromosomes. We will later continue our study of Genetics by examining how chromosomes pass from parents to offspring in sexually reproducing organisms. The processes of meiosis and fertilization maintains genetic variation in a species, which we will examine in the next general biology post.
Offspring acquire genes from parents by inheriting chromosomes
Family friends may tell you have your mother’s hair or you have your father’s chin. However, parents don’t give their children these traits in a literal sense. Parents provide their offspring with coded information in the form of hereditary units called genes. Genes are segments of DNA and inherited information that is passed on in the form of each gene’s sequence of nucleotides. Most genes program cells to synthesize enzymes and other proteins whose cumulative action produces the organisms inherited traits. The genes that we inherit from our parents form our genome. The transmission of hereditary traits is done through DNA replication, which passes genes. The passing of genes happens when male and female gametes (sperm and egg) unite. Gametes are reproductive cells.
The relationship between DNA, Genes, and Chromosomes
The DNA of a Eukaryotic cell is subdivided into chromosomes within the nucleus. Chromosomes consist of a single long DNA molecule elaborately coiled in association with various proteins (which we will discuss later on). Each living species has a specific number of chromosomes. One chromosome includes several hundred to a few thousand genes, each of which is a specific sequence of nucleotides within the DNA molecule. A gene’s specific location along the length of a chromosome is called the gene’s locus.
Comparison of Asexual and Sexual Reproduction
In asexual reproduction, there is one parent that passes copies of all its genes to its offspring. Asexual Reproduction gives rise to a clone, a group of genetically identical individuals. Occasionally, genetic difference will arise in asexual reproduction due to mutations, but generally the offspring are identical to the parent. In sexual reproduction, two parents give rise to offspring that have unique combinations of genes inherited from the two parents. In contrast to a clone, offspring of sexual reproduction vary genetically from their siblings and both parents. Genetic Variation is actually an important consequence of sexual reproduction. In our next post, we will examine the behavior of chromosomes during the sexual life cycle that causes genetic variation in sexual reproduction.
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