Transcript Slide 1
Traits and the Environment Chapter 2 Section 1 What are traits? All the features that an organism inherits The color of your eyes and the shape of your ears are two of your traits. Characteristics of DNA Contains information needed to produce a living organism Exists as chromosomes in cells with a nucleus Has segments of the DNA code on a chromosome called genes What is a gene? Part of the DNA code on a chromosome The genes an organism has (genetic makeup) is called its genotype What is the difference between genotype and phenotype? Genotype is the genetic makeup—the actual genes that a person has Phenotype is what you see—combination of genes and the environmental effect – – – – Blond hair Blue eyes Pink flowers Large leaves What does the environment have to do with genes? Doesn’t have much effect on some phenotypes—like eye color Other phenotypes are mostly due to environment influence – Hydrangea plant – Pink or blue flowers depending on soil conditions Some influences external – Amount of light – Temperature Some influences internal – Brain cells require thyroid hormone for development How is growth effected by the environment? Trees grow differently in a dense forest from the way that they grow when they are alone. Competition for factors such as food, sun, water – Significant effects to tree population How is appearance effected by the environment? The water buttercup has leaves that are shaped differently depending on where the leaves develop. Leaves that grow submerged in water are threadlike and those that grow above the water are broad. Difference—presence of water The color markings on a Siamese cat are another phenotype affected by the environment. Because the gene for colored fur is less active in heat, colored markings develop more quickly on cooler parts of the cat’s body, such as the ears. How is gender effected by the environment? Most living things are born male or female and remain that way for life. However, some species of fish, including many clownfish, parrot fish, wrasses, and sea bass, are born with the ability to change sex. This allows these species to maintain a desired male-tofemale ratio in a group under different conditions. A few fish have the ability to switch back and forth between sexes.