Traits and How They Change

Traits and the EnvironmentTraits and the Environment

What are traits?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 EnvironmentEffects of the Environment―GrowthGrowth

• Trees are in competition for environmental factors in a forest

• Compete for light, water, soil minerals• Effects tree population

―AppearanceAppearance• 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

QuestionsQuestionsWrite out each question & Answer in Complete

Sentences for Full Credit!!!1. What are traits?2. How were organisms improved?3. What is an organism’s genotype?4. What is a phenotype?5. 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 ChangeGeneticsGenetics

Science of GeneticsScience 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 MendelBeginning 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 OutcomesPredicting 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 Questions – Write ?’s out and Answer in Complete Sentences!!!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 ChangeEnvironmental Impact Over Time

Survival and the EnvironmentSurvival and the Environment―Nonliving InfluencesNonliving 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 OrganismsInteractions with Other Organisms

• Predators• Availability of food• Population of species

Species and the EnvironmentSpecies and the Environment―Natural Selection (Charles Darwin)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.

―MutationMutation• 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 BreedingSelective Breeding• Humans can select different variations to produce

many different breeds• Could happen naturally in an environment

―Direction of EvolutionDirection 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 SpeciesExtinction 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

QuestionsQuestions1. 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?