Traits and How They Change Traits and the

Traits and How They Change Traits and the Environment

What are traits? ―Observing Traits • Traits are features organisms inherit. • To improve organisms, they were breed using desired observable traits. ―Phenotypes and Genotypes • DNA – coded info of hereditary material in every • • • cell, shaped like twisted ladder Gene – part of DNA code on a chromosome Genotype – genetic makeup Phenotype – observable traits

Effects of the Environment ―Growth • Trees are in competition for environmental factors in a forest • Compete for light, water, soil minerals • Effects tree population ―Appearance • Organism may have same genes, but appearances can be different if not in same environment (water buttercup plant) • Temperatures where an organism lives can change an organisms phenotype (Siamese cat and Arctic Fox)

―Gender • Some species of fish have ability to change genders (clownfish) • Helps maintain desired male-to-female ratio • Switch back and forth depending on number of males and females in population

Questions Write out each question & Answer in Complete Sentences for Full Credit!!! 1. 2. 3. 4. 5. What are traits? How were organisms improved? What is an organism’s genotype? What is a phenotype? Which 3 environmental factors effect the population of trees? 6. How do organisms with the same genes look different? 7. Why are some species of fish able to change back and forth from male to female?

Traits and How They Change Genetics

Science of Genetics ―What is genetics? • Heredity – passing of traits from parents to offspring • The study of heredity is genetics • Genetics and cell processes explain how species change over time

Beginning with Mendel ―Dominant and Recessive Traits • Gregor Mendel first to use numbers describing results of genetic experiments • Conclusion – traits are determined by different factors (factors = genes) • Allele – different forms of a gene • Principle of Dominance – when only one form of a trait is shown when both alleles are present. • Dominant Alleles – show effect on phenotype whenever present in genotype. • Recessive Alleles – show effect on phenotype only when 2 of them are present.

―From Parents to Offspring • Principle of Segregation – each parent passes only one allele for each trait to its offspring. • Explains how offspring can look different from each other • Each sex cell has 3 chromosomes, which can be combined in 8 possible ways • Humans have 46 chromosomes, so 8 million combinations are possible every time sex cells form • Law of Independent Assortment – different traits are inherited with no relation of each other

Predicting Genetic Outcomes ―Punnett Square • Makes genetic predictions by crossing different organisms with known genotypes • Hybrid – organism with 2 different alleles for a trait • Monohybrid Cross – only one trait, make predictions difficult ―Understanding Results • Each result is independent of the ones that came before and after • Probability the prediction is right increases when large numbers are studied

Questions – Write ? ’s out and Answer in Complete Sentences!!! 1. What is genetics? 2. What is the Principle of Dominance? 3. Which type of allele is shown in the phenotype when two are present? 4. How is offspring explained when they do not look the same? 5. How many chromosomes can be found in humans? 6. What is a Punnett Square? 7. How can the predictions made by a Punnett Square become more reliable?

Traits and How They Change Environmental Impact Over Time

Survival and the Environment ―Nonliving Influences • Temperature and rainfall • Pollution affect survival • Factors can change species appearances • Fire, height of mountains, volcanic activity, and flooding can be positive or negative factors ―Interactions with Other Organisms • Predators • Availability of food • Population of species

Species and the Environment ―Natural Selection (Charles Darwin) • Evolution – changes that happen over time due to adaptation to the environment. • Natural Selection – organisms that are better adapted to survive and reproduce at a greater rate than another, produces new species. ―Mutation • Process where DNA changes result new alleles • Some can be advantageous for survival and reproduction and trait is passed on • Some can keep an organism from surviving and reproducing

―Selective Breeding • Humans can select different variations to produce many different breeds • Could happen naturally in an environment ―Direction of Evolution • Natural Selection can lead to 2 or more new species if more than one variation of a trait is favored • Adaptive Radiation – production of several species from one ancestral species

―Extinction of Species • Last individual of species dies • Rate of extinction today is as great or greater than the past • Reasons for extinction: • Destruction of habitat • New species • Human impact • Predators • Overcrowding

Questions 1. What nonliving influences affect the survival of species in an environment? 2. How do other organisms affect the survival of a species? 3. What is natural selection? 4. When is a mutated trait passed on to offspring? 5. What causes the production of several species from one ancestral species? 6. What are the causes of extinction?