Genetics and Inheritance 7th Grade Science

Think How is it possible for a child to show a recessive trait if both of their parents show a dominant trait?

Genes are carried on chromosomes These chromosomes are given to offspring during sexual reproduction when fertilization (parent cells meet) occurs Half of the genetic material is carried in each cell (gamete) Due to different variation of combinations offspring may show different traits from their parents Think of siblings. They have the same parents and may have some similar traits, but also have some differences. This is because they have a different combination of the genes passed from their parents.

Human Influence on Genetics Selective Breeding Sometimes humans breed certain organisms together in order to get a desired trait or a mixture of two desired traits There are two types of selective breeding: hybridization and Inbreeding. Hybridization: Crossing two different organisms in order to get two different traits hopefully in the same organism Example: Zorse (zebra and horse) originally crossed to develop a transportation animal with resistance to African sleeping sickness Inbreeding: Crossing two similar organisms to get a desirable trait Example: I want a friendly golden retriever so I cross two friendly golden retrievers in order to have a higher probability of getting that characteristic

Example Wheat now days is very different than wheat used to be. This is because wheat has been crossbred in order to get desired characteristics. Modern wheat is shorter in size with different protein structure than it originally was. Scientists speculate (or hypothesize) that this may be part of the reason why there is an increase in gluten sensitivity now

Genetic Engineering This is when scientists manipulate genetic material deliberately (on purpose) This can be by removing parts of DNA, adding parts from another cell, or both This can produce medicines and improve food crops. *When you see non-GMO on a food item, that means that it is not a Genetically Modified Organism

Cloning A clone is an organism that has the same genes as the organism from which it was produced.

Adaptation An adaptation is a characteristic or behavior that helps the organisms to survive when conditions change. Adaptations occur over many generations. Only organisms that have adaptations are likely to survive and reproduce. Therefore, organisms that do not have the favorable characteristics are likely to diminish in population over time and even die out. This concept is called natural selection (organisms that are better suited for survival will survive; aka: survival of the fittest) These are main components of the theory of evolution This also explains why we may find fossils of organisms that no longer are in existence (environmental change)