Concept 13.1 Lecture Outline

Parents 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.

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Lesson Summary