Concept 13.1 Lecture Outline

Concept 13.1 Lecture OutlineParents endow their offspring with coded information in the form of genes. ○ Your genome is made up of the genes that you inherited from your mother and your father. · Genes program specific traits that emerge as we develop from fertilized eggs into adults. · Genes are segments of DNA. Genetic information is transmitted as specific sequences of the four deoxyribonucleotides in DNA. ○ This process is analogous to the symbolic information of language, in which words and sentences are translated into mental images. ○ Cells translate genetic “sentences” into freckles and other features that have no resemblance to genes. · Most genes program cells to synthesize specific enzymes and other proteins whose cumulative action produces an organism’s inherited traits. · The transmission of hereditary traits has its molecular basis in the precise replication of DNA. ○ The replication of DNA produces copies of genes that can be passed from parents to offspring. · In plants and animals, reproductive cells called gametes transmit genes from one generation to the next. · After fertilization (fusion of a sperm cell and an ovum), genes from both parents are present in the nucleus of the fertilized egg, or zygote. · Almost all the DNA in a eukaryotic cell is subdivided into chromosomes in the nucleus. ○ Tiny amounts of DNA are also found in the mitochondria and chloroplasts. · Every living species has a characteristic number of chromosomes. ○ Humans have 46 chromosomes in their somatic cells – cells other than the gametes and their precursors. · Each chromosome consists of a single DNA molecule associated with various proteins. · Each chromosome has hundreds or thousands of genes, each at a specific location, or locus, along the length of the chromosome.